Electronic Servicin R a a HOWARD W

March, 1976 Li 75 cents

Electronic Servicin R a A HOWARD W. SAMS PUBLICATION

COLOR CASEBOOK Audio Quiz

www.americanradiohistory.com You've Got IJs Where You Want LTS

CANADA

Ouz ?'Jecueat SEATTLE .docatio«re - j. !`.r, PORTLAND MONTREAL

MINNEAPOLIS NGFIELOr BUFFALO MILWAUKEE' PATERSON CLEVE INDIANA S F`Yf ILADELPHIA BLOOMINGTON "'ITTSBURG}Ir P ER SPRING 4 1,j'2COLUMBUS S SACRAMENTO ARVADA CINCINNATI

KANSAS CITY ST. LOUIS NOR OLK LOS A$ l°ES, r ä1N DIEGO CHARLOTTE

MEMPHIS 40` OKLAHOMA CITY PHOENIX ti f BIRMINGHAM ay LONGVIEW JACKSONVILLE METAIRIE r a fi (f Yr.

HOUSTON '2-

Even though we're the world's largest service. Bring us a tuner ... any tuner... tuner repair service, recommended by at 8 a.m. and it's repaired and tested by more TV manufacturers than any other 4 p.m. Then there's quality . . . original company, we think small. Really! We parts, and once repaired, it's good as could put the whole thing under one new. Oh sure, being the world's largest roof. Instead, we have 35 small service is something we're proud of. But we also centers across the country, staffed by like the fact that with 35 service more than 200 professional technicians. locations, we can be small enough to Why? Service for one thing ... same -day give every tuner repair job a personal as well as a professional touch.

.... NICS, INC. 11....u.... 5 ..11..11.....1111....11 PECISIO TJ\ER SPVICE

Consult the white pages of your telephone directory for the address and telephone number of the PTS center nearest you.

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www.americanradiohistory.com IN/OUT OF CIRCtJï TEST

NOW WITH HI/LO DRIVE

ACCURATE TESTING IN OR OUT OF CIRCUIT All bipolar transistors, including hard -to -check Darlingtons. B&K-PRECISION Model 520B Transistor Tester FET's, SCR's, Diodes $160.00 In -circuit semiconductor testing and lead identification -automatically

New,The HI/LO power drive circuitry of which each probe is connected. Two LED's auto- the B&K-PRECISION Model 520B matically telli you whether the device is PNP provides two important benefits. or NPN. You now can test accurately even more transistors Out -of -circuit tests are equally easy and fast with and semiconductors in-circuit-and with shunt the convenerrt mini -lock probes or the plug-in test resistances as low as 10 ohms and shunt capaci- socket. Leakage tests can be made without refer- tances up to 15 µF. You won't waste time resolder- ring to charts. The meter panel is marked for both ing leads because of faulty in -circuit testing. germanium and silicon devices, which are auto- Second, in LO drive you get positive, automatic matically identified by LED indicator lamps. identification of all three transistor leads. Ask for a demonstration of the 520B at your local The new Model 520B transistor tester is fast. too. A distributor. Or write for our full color brochure complete test can take less than nine seconds! explaining how the B&K-PRECISION Model 520B With the tester in LO drive, just connect any test Transistor Tester will end time -wasting diagnostic clip to any lead of the device to be tested. Move errors and speed your solid state testing and the test switch through its six positions until you service. hear a pulsating audio tone, which indicates a good semiconductor, plus lead identification. If you don't get a tone, switch to HI drive and operate the switch again. Now a tone indicates a good «PRECISION semiconductor and identifies the base. PRODUCTS OF DYNASCAN With the Dynapeak"M transistor testing method, 1801 West Belle Plaine Avenue you can be confident of a valid in -circuit - and out Chicago, Illinois 60613 312/525-3990 of -circuit test. A window indicates the leads to In Canada: Atlas Electronics, Toronto

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March, 1976 1

www.americanradiohistory.com March, 1976 Volume 26, No. 3 EDITORIAL RONALD N. MERRELL, Director CARL H. BABCOKE Managing Editor SHARON ELWOOD. Editorial Assistant DUDLEY ROSE, Graphic Designer

ELECTRONIC SERVICING 1014 Wyandotte Street Electr'onìc Seriicino Kansas City, Missouri 64105

TECHNICAL CONSULTANT JOE A. GROVES

EDITORIAL ADVISORY BOARD LES NELSON, Chairman Howard W. Sams & Co., Indianapolis 15 Man's Best Friend...His TV!-A new shop owner discovers the CIRCULATION fanatical devotion of a viewer for his TV receiver-Terry L. EVELYN ROGERS, Manager Turner. ADVERTISING SALES Kansas City, Missouri 64105 18 Color Casebook-Pages from an expert's record of the best Tele: 9131888.4664 methods used to repair various defects-Robert L. Goodman, MIKE KREITER, Director JOHN COX CET. GLORIA PARMENTER, Production

23 Servicing Stereo Audio Systems, Part 7-Take this review quiz covering the first six parts of the basic audio series-Carl REGIONAL ADVERTISING SALES OFFICES Indianapolis, Indiana 46280 Babcoke. CET. ROY HENRY 2469 E. 98th St. Tele: 317/846-7026 25 Medical Electronics Notebook, Part 3-Here is another helpful listing of medical -electronic equipment, how to pronounce the Greenlawn, New York 11740 names, and what each device does Ed Bukstein. CHARLES C. HORNER P.O. Box 175 Tele: (516) 757-8868 28 Reports From The Test Lab-Features and performance of the Hewlett-Packard Model 3476A digital multimeter; the first Mountain View, California 94043 autoranging, autopolarity meter we have examined-Carl DENINIS TRIOLA 2680 Bayshore Frontage Road, Room 102 Babcoke. Tele: 415/961-0378

32 Servicing RCA XL -100, Part 5-HV-regulation and pincushion London W. C. 2, England JOHN ASHCRAFT & CO. circuits are analyzed and distinctive waveforms caused by 12 Bear Street defects are shown-Gill Grieshaber, CET. Leicester Square parts Tele: 930-0525 41 Ohmward Bound!-Relax while you work this pinwheel puzzle A. Braun. Badhoevedorp, Holland that's based on electronics Edmund John Ashcraft & Co., John J. Lucassen, Mgr. Sloterweg 303 ABOUT THE COVER Marvin Jungemeyer of Bob Hipps TV in Loveland, Colorado is Tokyo Japan INTERNATIONAL MEDIA shown using a Hewlett-Packard Model 3476A digital multimeter REPRESENTATIVES LTD. a color TV. Photo courtesy of Hewlett-Packard. 1, Shiba-Kotohiracho, Minatoku to test Tele: 502-0656 DEPARTMENTS Electronic Scanner 4 s Symcure 8 ABP I>o Troubleshooting Tips 10 feu i 0 Reader's Exchange 11 ELECTRONIC SERVICING (with which is combined PF Reporter) is published Product Report 45 monthly by Intertec Publishing Corp., 42 1014 Wyandotte Street, Kansas City, Test Equipment Missouri 64105. Book Review 49 Subscription Prices: 1 year - $6.00, 2 Photofact 49 years - $10.00, 3 years - $13.00, in the its Catalogs and Literature 52 U.S.A. and possessions. Advertiser's Index S4 All other foreign countries: 1 year - $7.00, 2 years - $12.00, 3 years - $16.00. Single copy 75c; back copies $1. Adjustment necessitated by subscritpion termination to single copy rate. Second class postage paid at Shawnee Mission, Kansas and additional mailing offices. Published monthly at 9221 Ouivira Road, Shawnee Mission, Kansas 66215 by Intertec Form 3579 to 9221 Publishing Corp , 1014 Wyandotte St., Kansas City, Mo. 64105. Send Robert E. Hertel, Publisher Ouivira Road. Shawnee Mission, Ks. 66215. INTERTEC PUBLISHING CORP. © Copyright, 1976, Howard W. Sams & Co., Inc. All rights reserved. Material may not be Subsid ary of HOWARD W. SAMS& CO., INC. reproduced or photocopied in any form without written permission of publisher.

www.americanradiohistory.com I . IL Buss® Fuss Specialize

Now . . . four new BUSS fuse assortments exclusively designed with replacement fuses to service most Citizen Band Radios - offering a whole new area of opportunities for increased profits. Two assortments contain 48 - 5 in metal boxes (240 fuses). BUSS No. 240CB-3 fuse assortment comes in a handy metal display stand. BUSS No. 240CB-4 fuse assortment is packed in a compact plastic display box. In addition, there are two fuse assortments containing 16 - 5 in metal boxes (80 fuses). BUSS No. 80CB-1 fuse assortment packed in a metal No. 240CB-3 No. 80CB-1 display stand and BUSS No. 80CB-2 fuse assort- Metal Display Stand Metal Display Stand ment in a plastic display box. Both BUSS fuse assortments contain a careful selection of the most popular fuses used in CB radios. CB dealers can now have the fuses they need in a neat complete package to service all their customers fuse needs. For full fuse assortment details, write for BUSS Bulletin CBA. No. 240CB-4 No. 80CB-2 Plastic Display Box Plastic Display Box

BUSSMANN MANUFACTURING a McGraw -Edison Company Division St. Louis, Missouri 63107 [e] THE QUALITY UNE S

March, 1976 3

www.americanradiohistory.com ifliscannor news of the ndustry

Newest idea of auto electronics is the combination of CB and FM -stereo functions in one radio. Panasonic Auto Products now offers an in -dash radio having AM/FM-stereo with pushbuttons, and 23 -channel CB. In addition to the usual CB features of metered power and sensitivity, variable squelch control, and Delta tuning, there is a standby monitor that permits the reception of CB calls while the radio is tuned to AM or FM broadcasts. Four-way adjustable control shafts are said to allow installation in the dash of most cars. The first company to market a stereo/CB combination was J.I.L. Corporation, which last summer introduced a CB/AM/FM/8-track stereo unit. Other manufacturers appear to be waiting for public acceptance before marketing similar combinations.

Retail sales authorities predict sales increases during 1976 for projection TV, home -security systems, telephone -answering devices, CB equipment, scanner radios, and microwave ovens.

B&K Dynascan reports a 32% increase of test equipment sales, and a 400% sales increase of CB radio equipment for 1975 compared to 1974.

Litton has expanded the warranty on its microwave ovens and reduced the price of the magnetron tube. The 600 -watt magnetron tubes (produced in Japan) formerly listed at $129, and now are offered for $78 retail. Both parts and labor are covered for one year, and the magnetron is warranted for 4 additional years without labor. Total industry sales of microwave ovens are expected to exceed 3 million units by 1980.

RCA Corporation has announced the closing of its receiving -tube plant in Harrison, New Jersey by July 30th of this year. Approximately 1,100 employees will be affected by the closing, and RCA will help them relocate. Peak production was 87 million tubes a year, but since 1966 industry sales of receiving tubes have declined by almost 80%, with most of the present production going into older equipment, according to RCA. However, RCA intends to continue selling receiving tubes.

Toshiba is the sixth Japanese company to sign a licensing agreement to acquire RCA technology on the video -disc player. According to Home Furnishings Daily, the other companies that have received the RCA license are Sharp, Pioneer Electronic, General, New Nippon Electric, and Clarion. RCA said it will be ready to produce video -disc players by the end of this year.

A 47% increase of first-quarter sales of test instruments over the same quarter of last year was reported by Sencore, Inc., according to Radio & Television Weekly.

New figures submitted to the National Electronic Service Dealers Association (NESDA) by ten major state or city licensing boards around the country show a 6.5% increase in the number of electronic technicians, or an additional 12,781 workers of the 196,347 total. Contrasting that figure is the total of service businesses which declined by 6,165. Dick Glass, Executive Vice President of NESDA. attributes the 6.5% increase in technicians nationwide to the recession.

(Continued on page 6)

4 ELECTRONIC SERVICING

www.americanradiohistory.com R SERVI RATIO ONE YEAR LL ONLY SIIßSiIuIfß JUST GUARANTEE $i95 .A NLY t ONLY WITH CABLES MAJOR PARTS ;...,,, AND SHIPPING CHARGED AT COST

PROVIDES YOU WITH A COMPLETE SERVICE C FEATURES FOR ALL YOUR TELEVISION TUNER REQUIREMENTS. A UHF Tuner with 70 channels which are detented and indicated just like VHF channels. A VHF Hi Gain Solid State Tuner. VHF OR UHF ANY TYPE (U.S.A. ONLY) $ 9.95 UHF/VHF COMBINATION (U S.A. ONLY) $15.00 AC Powered 90 Day Warranty MAJOR PARTS AND SHIPPING CHARGED AT COST Demonstrate the to Fast, efficient service at our conveniently located your customers and show improved Service Centers. All tuners are ultrasonically cleaned, repaired, reception with their TV sets. realigned, and air tested. You may place your order through any of the Centers listed below. UNIVERSAL REPLACEMENT TUNER $12.95 (U.S.A. only) This price buys you a complete new tuner built spe- NEWS FLASH! cifically by Sarkes Tarzian Inc. for this purpose. All shafts have a maximum length of 101/2" which NOW AVAILABLE-TUNER SERVICE can be cut to 11/2". PARTS CATALOG OF ALL SARKES Specify heater type parallel and series 450 mA. or 600 mA. TARZIAN VHF AND UHF TUNERS, IN- CLUDING EXPLODED VIEW DRAWINGS.

OVER 200 PAGES. ORDER YOUR COPY Customized tuners are available at a cost of only $15.95. With trade-in $13.95. TODAY. SEND $2.50 WITH ORDER TO (U.S.A. only) Send in your original tuner for comparison purposes BLOOMINGTON HEAD OFFICE. to any of the Centers listed below.

HEADQUARTERS BLOOMINGTON, INDIANA 47401 537 South Walnut Street Tel. 812-334-0411 ARIZONA ...TUCSON, ARIZONA 857130 1528 S. 6th Ave. Tel. 602- 243 CALIFORNIA . , . ... \ RTH HOLLYWOQ CALIF. 91601 10654 Magnolia Boulevard Tel. 213-7y20 TRLINGRME, CALIF .1324 st=n Ro. .. , Tel. 15- MODESTO, CALIF. 0 'P51 u= Tel. r 1 FLORIDA TSC i TAMPA, FLORIDA 43606 1505 ypress - .y' ...... Te r- 324 FT. LAUDERDAL-E.,-,FL -IDA 33315 .... 30 'r 14 GEORGIA` ATLANTA, GA. 30810 ...... na st S.W.. I. 404+ 2 ILLINOIS CHAMPAIGN, ILLINOIS : r 405 Ea t Unl slty .T: 17- DOLTON, 9 1507 r St.. .. el. 3 r. -4444 SKOKIE, ILIA t Brow ..Tel. 3 75-0230 INDI INDIANAPOLIS, INDI A 204 112 W. t St. Cla . ,,. 2-3493 IOWA DES MOINES, IOWA ''319 5005 r 1 :. 7 278-4217 KENTUCKY LOUISVILLE., KENTUCKY 4020 rsvlll. ' 52-1191 LOUISIANA SHREVEPORT LOUISIANA 71 04 3025 Hlghl nd Av 221-3027 MARYLAND BALTIMORE, MARYLAND 212 5 5505 Relat. stown 58-1186 MASSACHUSETTS SPRINGFIELD, MASS. 0 . , +'-788-8 MISSOURI ST. LOUIS MISSOURI 63132 .11530 Page venue 4-429-0633 NEVADA LAS VEGAS, NEVADA 89102 .. .1 12 West: Aven `702-384-4235 NEW JERSEY TRENTON, NEW JERSEY 086 : ,1 r : Ivanla 609-393-0999 JERSEY CITY, NEW JERSEY '7307 547-49 Tonn el. 201-792-3730 N. CAROLINA GREENSBORO, N.C. 27405...... 2914 EgMar el. 919-273-6276 OHIO CINCINNATI, OHIO 4521 .. 7450 Vine Str I,I. 513-821.5080 CLEVELAND, OHIO 44109 4525 Pearl Ro ` 216-741-2314 OREGON PORTLAND, OREGON 97210 1732 N.W. ver Box 10141 r3-222-9059 PENNSYLVANIA PITTSBURGH, PA. 15209 r 31 `Avenue 12-821-4004 TENNESSEE MEMPHIS, TENNESSEE 38111 3 : Baron Avenue ' r1-458-2355 TEXAS r DALLAS, TEXAS 75218 11 ' arland Road T - . 14-327-8413 VIRGINIA NORFOLK. VIRGINIA 23513 3295 a tos Street Tel. 804-855-2518 CANADA ST. LAURENT, QUEBEC H4N-2L7 305 Decarle Boulevard Tel. 514-748-8803 WATCH US CALGARY, ALBERTA T2H-OL1 448 42nd Avenue S.E Tel. 403-243-0971 GROW P.O. Box 5823, Stn. "A" IF YOU WANT TO BRANCH OUT INTO THE TV TUNER REPAIR BUSINESS, WRITE TO THE BLOOMINGTON HEADQUARTERS ABOUT A FRANCHISE. For More Details Circle (5) on Reply Card www.americanradiohistory.com g_I;canner- o news of th,, ndus ry

(Continued from page 4)

A technical seminar for 61 installers and users of the Blonder-Tongue line of MATV and CATV equipment was conducted recently in Atlanta, Georgia by Dwight Staehler and Marc Winchester. The two -full -day seminar covered equipment selection, system design, and maintenance and troubleshooting. A practical hands-on workshop also was included.

RCA plans to sell its electronic -instrument business to Viz Manufacturing Company of Philadelphia. The contract is subject to approval by the boards of both companies. RCA Distributor and Special Products Division decided to restructure its operations to emphasize other product lines. Viz plans to take over distribution of the present inventory of RCA instruments and to continue manufacture of these type instruments, augmented by an expanded line of high - quality instruments under its own trade name. Viz has been a supplier to RCA of electronic instruments since 1958, and has produced many of the well-known RCA volt-ohm-milliammeters, oscilloscopes, signal generators, and a variety of probe assemblies and battery testers.

Zenith Radio Corporation was advised by the Bureau of Radiological Health (BRH) that Zenith color television receivers using the 22-7233 capacitor do not "create a significant risk of injury, including genetic injury to any person". The Bureau, therefore, granted Zenith an exemption from the requirements of notification and repair of these receivers. The 22-7233 capacitor was not used in Zenith dolor TV receivers sold before January 1, 1974; and it is not used in Zenith current -model color television receivers. Zenith is continuing to honor claims for replacing this capacitor.

The Veteran Wireless Operators Association (VWOA) celebrated the fiftieth year of its founding by presenting President Gerald Ford with a telegraph sounder. J. R. Poppele made the award to the chief executive. VWOA has over 360 current and former wireless operators in its membership. Guglielmo Marconi, Lee DeForest, and David Sarnoff were members.

6 ELECTRONIC SERVICING

www.americanradiohistory.com I 1 ü Just off the press from Sams. The latest guides, manuals, and licensing handbooks all designed to save type-lectronics technician time and money!

Servicing Electrocardiographs Electronic Organs (Volume 3) Troubleshooting with the by Elliott S. Kanter by Norman H. Crowhurst Oscilloscope (3rd Edition) Discusses many models of ECG's, includ- Complete circuit discussions of organs by Robert G. Middleton ing the new portables. Filled with instruc- produced by ten well-known manufactur- All about troubleshooting, signal -tracing, tions for troubleshooting, repair, and ers. Block diagrams and schematics of and testing TV, radio, and audio equipment. assembly. 224 pages. NO. 21210-$12.95 various models that include new IC and LSI New material on dual -trace, triggered - circuitry. 144 pages. NO. 21176-$7.95 Scanner sweep, and triggered time -base scopes. -Monitor Servicing Guide 192 pages. NO. 21103-$5.50 by Robert G. Middleton Semiconductor Replacement A brand-new guide to scanner -monitor Guide Mobile Radio Servicing Made Easy receivers and their unique circuitry. All the by Howard W. Sams Engineering Staff by Leo G. Sands data you need to take advantage of servic- "Quick -find" manual for looking up replace- Features the latest troubleshooting, repair, ing opportunities in this booming field. ment parts. Lists bi -polar and field-effect and even business techniques-all training - 96 pages. NO. 21306-$4.95 transistors, diodes, rectifiers, or integrated school perfected. Covers 2 -way radio circuits from seven manufacturers. Digital Equipment meters, analyzers, counters, and genera- Servicing Guide 256 pages. NO. 21092-$3.95 tors. 144 pages. NO. 21178-$4.95 by Robert G. Middleton Helps technicians expand beyond radio Transistor Specifications Manual Frequency and its Measurement and TV "linear" circuitry. \ n -illustrated, (7th Edition) by Rufus P. Turner step-by-step guidance all on kinds of digital by Howard W. Sams Engineering Staff Far more facts on measuring frequency equipment. 104 pages. NO. 21200-$5.95 Why search hard for electrical and physical than found in most textbooks. Helps you data on a specific transistor type? Here are find the right measurement methods-fast. specs on nearly every bipolar transistor. 96 pages. NO. 21179-$3.95 224 pages. NO. 21208-$5.95 r______Clip Out -Mail Today! 161

Send books checked at right. $ enclosed* I understand

that, if not completely satisfied, I may return my order within 10 LI 21210 Marine Radiotelegraph Operator days for full refund. License Handbook 21306 By Edward M. Noll 21200 Name (please print) New guide for passing radiotelegraph 21176 license exams. Covers rules and regula- n tions. Hundreds of answers on amplifiers, Address 21092 transmitters, antennas, and more. Also includes radar endorsement to FCC license. 21208 320 pages. NO. 21109-$9.95 City 21103 Study Guide for Associate CET 21178 Examinations State Zip *Include sales tax where applicable. Canadian prices slightly higher. 21179 by J. A. Wilson, R. Glass & R. Crow TC 15 A thorough review of knowledge needed to -I 21109 ' be a Certified Electronic Technician, asso- Howard W. Sams & Co., Inc. 20972 Each is I ciate level. section of the exam 4300 West 62nd Street/Indianapolis, Indiana 46206 covered by a single, easy-to -read chapter. 320 pages. NO. 20972-$ 7.95 11: MI MIMI NMI

March, 1976 7

..1 www.americanradiohistory.com t IAI Symptoms and cures compiled from field reports 1117 cure of recurring troubles ------11 r CTC58 I s RCA CTC58 Chassis-RCA PHOTO FACT -1 428-2 PHOTOFACT-1428-2

CC406) I R341 PULSES TO PIN SOF I HORIZ YOKE F--- ALL MAD001 PULSES TRIPS I MODULES .22 (CR10). CR40) I

100 KS2 CR307) \NOISE C I

1 +245 V

Symptom-Noise streaks in the video Symptom-Circuit breaker trips from increased Cure-As a test, replace CR307 brightness I I Cure-As a test, replace SCR102 4-- CTC68 I Chassis-RCA CTC58 Chassis-RCA I I PHOTOFACT-1428-2 PHOTOFACT-1378-2

I HOLD- ( DOWN TO HORIZ TO YOKE HOLD C406 R405 AND I FLYBACK

I .075 4.7Q VERTICAL LINES TRIPS A I 3300 Q @CR10) C BREAKER I GE . CRD FROM FLYBACK I I I breaker trips, when channels are I Symptom-Vertical lines in picture, and bending at Symptom-Circuit high brightness. changed I Cure-Replace CR408 Cure-Replace------SCR101 Chassis-RCA CTC72 Chassis-RCA CTC72 I PHOTOFACT-1439-2 PHOTOFACT-1439-2 I

+V I

I TO HOLD rr l I 33 S2 1i Iji III I I I TEST ,TEST 1.5µF Jr MAG004A'L TO HEIGHT 3 , 1> 2.2 MQ `JJ19 /47iI LEAKY 1

TO HEIGHT 2 27 V 3952 2200 Q REPLACE I

I Symptom-No vertical sweep Symptom-Foldover at bottom, stretching at top I Cure-Check or replace CR405, R424, and R422 Cure-Test or replace C418 I I L_------J 8 ELECTRONIC SERVICING

www.americanradiohistory.com Until now,the 1 toughest part of CB servicing was getting the part. Sylvania's ECG'" semiconductor replacement line has 138 devices for the transistors, diodes, rectifiers, integrated circuits and modules you need for Citizen's Band repairs. And they're all at your Sylvania Distributor. That means you can spend your time in the s instead of in search of the right parts house. It can also make the difference between turning away a potential customer, and turning out a profitable repair job. The latest ECG Semiconductor Replacement Guide and Supplement cross-references (CB devices by original manufacturer's part numbers. In practically all cases, you'll find a direct replacement, not a part that's "something like" the original. So don't waste valuable time hunting for parts wh you can have ECG's electronics supermarket right in your own shop.

We're helping you make it. ® SYLVANIA www.americanradiohistory.com While analyzing the DC voltages in the regulator circuit, I found troubleshooting that the DC voltage at the base of Send e your helpful rips-we pay' Q404 (error amplifier) was not TV dead from double troubles changing enough when the HV - Panasonic Model TR -425 adjust control was varied. I dis- (Photofact 1235-1) connected a few resistors to obtain COMPLETE SERVICE ON When this "pop-up" type b -w accurate resistance readings, and Panasonic TV carne in, it was found that R404 was slightly above ALL MAKES OF TV TUNERS completely dead. Not even the CRT tolerance (2% rating). filament seemed to be lit. The power supply was working, al- Maximum Time In Shop 24 Hrs. CD eERROR was 10% AMP CD though the voltage about 288 100KO 00 pf 102.0v low. 18K0 (WE SHIP C.O.D.) zs 6.07 V Scope checks proved there was YOU PAY SHIPPING # HIGH Cri) )3 KO (Warranty: One Full Year) VOLTAGE no drive to the base of the E 5. 55 Iw 750 () 5f $9.95 horizontal -output transistor. A new 289 R VOLT 291 L403 driver transformer eliminated 2300 O Black & CD 2s ()REG 27KO White that problem. 1w 5s or Color 290 22KO rA ECG 11.4 2.1 BIAS VHF or 230 V i_ UHF

UV Combo's $16.50 Replacement of the resistor, and Price includes all labor and parts ex- proper adjustment of the high cept Tubes, Diodes & Transistors. If voltage, cured the problem. combo tuner needs only one unit repaired, disassemble and ship only Walter B. Porzucek defective unit. Otherwise there will Endicott, New York be a charge for a combo tuner. When sending tuners for repair, re- Now the raster was present, but move mounting brackets, knobs, indi- with serious "christmas -treeing". Electrical interference cator dials, remote fine tuning ar- waveforms showed the fre- RCA CTC36XH rangements and remote control drive Scope units. quency was too high. I checked the (Photofact 1362-2) TR41 oscillator transistor in -circuit, This repair job, brought to me by WE UNCONDITIONALLY and it seemed okay. All other a local dealer, should be an easy frequency -determining components one, I thought. Video, sound, and GUARANTEE All Tuners were tested so far as possible, but color were perfect, but what ap- without success. peared to be electrical interference FOR ONE FULL YEAR Finally, I replaced the oscillator was severe, especially on weaker transistor, and obtained normal stations. operation. The defective transistor All ground connections to the checked "good" on a reliable picture tube were good, and no arc transistor tester. Questions: what of any kind could be seen or heard defect caused the transistor to around the high -voltage section. My oscillate at a wrong frequency? And first suspect was the HV tripler. Af- why didn't the transistor tester spot ter that idea proved wrong, I pulled it? the chassis and connected it to a Jordan Bier, CET test jig, to check the picture tube Plantation, Florida and yoke. The problem remained. All tuners are serviced by EXPERTLY At I found inter- TRAINED TECHNICIANS with years this point, the of experience in this specialized ference could be fine-tuned in or field. All tuners are ALIGNED TO out, similar to color. Then I de- MANUFACTURER'S SPECIFICA- Erratic hold-down operation cided the problem might originate TION on crystal controlled equip- RCA CTC71 (Photofact 1380-2) in the tuner. Before replacing the ment and air checked on monitor I he symptoms included an inter- I thought I'd try a new before shipping to assure that tuner tuner, is operating properly. mittent activation of the hold-down 3HQ5 RF tube (the only plug-in circuit (out of horizontal lock), and component on that tuner). high voltage above 31 KV, but Sure enough, when the tube GEM CITY adjustable. The HV -adjust control warmed up, clearing the snow, required setting to the end giving there was no trace of "electrical TUNER SERVICE minimum high voltage. Any other interference". Can you explain what Box 6G Dabel Station setting activated the hold-down caused it? 1621 Mardon Drive circuit, throwing the horizontal out Larry Huckeba Dayton, Ohio 45420 of lock. Newnan, Georgia

10 ELECTRONIC SERVICING

www.americanradiohistory.com 1 1 ., I L III

Needed: Operating manual, probe and schematic for Century VTVM, Model VT -10. ó Eddie Jackson ii'ixcbanue 3025 E. 111th St. Cleveland, Ohio 44104

Wanted: Vibrator for a 1939 Buick Sonomatic auto For Sale: Kay 154C sweep generator, 50KHz to 110 radio Model 1308221. MHz. Make offer; will consider dual -trace, triggered Earl G. Brown oscilloscope in trade. 2 Beadart Place James C. Amer Hyde Park, New York 12538 6214 Pinelock Drive Jacksonville, Florida 32211 Needed: Schematic and service data for a Reader's Digest digital clock radio, Model TDC-300R-D. Will Needed: Schematic of Marlin Model MPX2000; will buy, or copy and return. copy and return. Also, schematic of Monarch Model Gerald L. Faurote SAT 260X; need power transformer; will copy and 2621 Elmwood Ave. return. Lafayette, Indiana 47904 Dean's Repair Service 201 N. Union Needed: Schematic for a "My Secretary" answering Coffeyville, Kansas 67337 service, made by Bel -Air, Model MS -1. Will pay $5.00; $10.00 if service manual included. For Sale: A set of Riders Manuals (including Granville Electronics Service abridged 1-5), numbers 6 through 15. Also, other old North Lane 2 auto radio and radio -phonograph manuals, an old W. Granville, Massachusetts 01034 pre-war ACDC Detrola AM radio in wood case, a Philco pre-war chassis and speaker (working), and a Needed: Schematic for a Calrad multimeter, Model large table -model wood -cabinet tube type radio 65-273. (complete, but not working). Will consider all offers. Dawson L. Huff, Jr. Paul Segars NAESU USMCAS, Box 233 2008 4th Street North FPO Seattle, Washington 98764 St. Petersburg, Florida 33704

(Continued on page 12)

How to stock 300 instead of 112,000. All it takes is RCA's "Top of the Line" SK Series 1976 Replacement Guide. Our most comprehensive list to date of transistors, rectifiers, thyristors and integrated circuits - 300 RCA types to replace 112,000 in entertainment or industrial equipment. Excellent Product. Excellent Catalog. As a product, RCA SK replacement semiconductors measure up to strict AQL stand- ards. As a catalog, our 1976 Replacement Guide is a thorough, accurate informa- tional source, representing thousands of engineering man-hours. Get the "top of the line" now. With RCA's SK Series and RCA's SK Replacement Guide. Contact your RCA Distributor. Or send $1.00 (check or money order) to RCA Distributor and Special Products Division, P.O. Box 85, Runnemede, N.J. 08078.

SK Replacement Rea Semiconductors

March, 1976 11

www.americanradiohistory.com (Continued from page 11)

Needed: Kit or factory -wired RCA VoltOmyst If you WV -77E. Clifford J. Wright 10205 Miller Rd. repair foreign Daisy. Tennessee 37319 For Sale: Many older -type radio and TV tubes. Send for list. electronics... Stewarts Radio & TV 400 Sycamore Street Shenandoah. Iowa 51601

Needed: Schematic and service information for Accurate Instrument Genometer, Model 156. Will buy, or copy and return. Caswell Davis, Jr. 601 Delmar, Apt. 2 San Antonio, Texas 78210

Needed: Schematic and service information for a Stewart -Warner Model R -1815-A 3 -band radio. Will buy, or copy and return. Steve A. Fahnestock, U.S.N 525 Franklin Road Lexington Park, Maryland 20653

Needed: Schematic and manual for a Sensitive ...the GE Foreign Research Model THACH, volt-amp-milliammeter, "Poly -Ranger" dynamometer AC/DC instrument. Will buy, or copy and return. Exchange Kit Richard B. Ely 32-354 Camilla Circle is basic. Thousand Palms, California 92276 For Sale: Nine -month -old B&K Model 290 electronic 24 types crossover 15,000 JEDEC multimeter, complete. Best reasonable offer. numbers. David A. Day P.O. Box 476 75% of Japanese Covers about Apalachicola, Florida 32320 JEDEC list for audio, TV, and CB equipment popular in the U.S. Needed: Schematic for Emerson -Rittenhouse inter- Lets you handle foreign units easily, com Model RM -2 all transistor radio (Probably built quickly, and profitably. in early 1960's). Can copy schematic and return. Brad Phillips Handy drawer storage. 1716 Windsor Drive Includes cross-reference list. Bloomington, Indiana 47401 See your authorized GE distributor Needed: Power transformer for a Heathkit Model for kits, individual replacements, 0-10 scope, either new or used. and full details. S. C. Austin 2845 Monogram Long Beach, California 90815

Needed: A 15 -watt 50,000 -ohm power rheostat for an old Sprague Model TO -3 Tel-Ohmike. Also, a meter (Model 522-46K, chrome, flush, square, 0-500 micro - amps) for a Model 209A Hickok VTVM. Ray Parsons, Jr. TUBE PRODUCTS DEPARTMENT Ave. GENERAL ELECTRIC COMPANY RFD Portsmouth OWENSBORO, KENTUCKY 42301 Stratham, New Hampshire 03885 GENERAL ELECTRIC

12 ELECTRONIC SERVICING

www.americanradiohistory.com The

For Sale: B&K Model 415 sweep and market 5 SECOND generator, like new, complete with all cables. Lewis Radio and TV CLEANS! Route 1 Central City, Nebraska 68826 LUBRICATES! RESTORER POLISHES! Needed: Schematic and service manual for Precision Apparatus signal generator Type E200 or E200C. J. J. Bobrow 827 -12th Street Santa Monica, California 90403 Spray TUN -0 -POWER on tuner contacts, rotate the tuner and within 5 seconds you get beautiful color pictures on Needed: Schematic and service manual for Vernon all channels. It's a minor miracle! Model 47/26 tape recorder, manufactured by OKI TUN -Q -POWER is the most powerful Electric Industry. polisher and lubricant ever developed. It works so well, you use a lot less. You can David E. Spickard Company spray twice as many tuners with TUN - 3060 Portsmouth Avenue 0 -POWER as you can with an ordinary cleaner/lubricant. Cincinnati, Ohio 45208 What's more. TUN -O -POWER lubricant lasts for months longer than ordinary sprays. Detent action stays smooth as Needed: Service manual a silk so you never have to worry about for Precision Apparatus callbacks. Model E -200-C RF signal generator. Franklin Hawkes U.S. Route 302, ÇCHMTRONICS Highland Lake Corner ncevINCORPORATED 000nrcn 45 Westbrook, Maine 04092 HOFFMAN AVE.. HAUPPAUGE. N Y 11787 (516) 582 3322 Our business is improving yours!

For Sale: BSK Model 1246 Digital-IC color genera - tor, excellent condition, one-year old. Best offer. John Fitzpatrick 138 Westfield Rd. Holyoke, Maine 01040 WE'RE ON TRIAL But, you're the judge. To introduce you to Dana's quality tested Danameter 2000A For Sale: Eico Model 369 TV/FM sweep generator we're offering you a thirty day free trial period to use and post -injection marker, like -new. $125, or highest our DVM and judge its new reliable features. If it bidder. doesn't fit your needs, return it...that's right, Walter A. Wilson return it. Why make such a fantastic 527 Amethyst St. offer? Just look at what the Cape Girardeau, Missouri 63701 Danameter 2000A offers!

Needed: Schematics or service manuals for a Sears Silvertone b -w chassis 528.712214, and an AM/FM receiver Sears Silvertone chassis 528.54730. Will buy, or copy and return. George Paulik Skyway Electronics Unequalled P.O. Box 66 accuracy New Manistee, Michigan 49660 brighter, faster "Super" LCD Needed: Company address, or suitable part number (reads even in sunlight) E Direct substitute for Symphonette power transformer PTH- answers, no time-consuming calculating 57003U. Also, need schematic for Lexington stereo 1 full year battery life E LSI-CMOS circuitry music system Model LE -3 manufactured in Japan. And best of all...it costs only $199.50! Any information will be appreciated. Send for more details now...put us on trial. The new Edgar R. France Danameter 2000A will come out ahead. For Lot #13 VHFS immediate action, call Cliff Warrenton, Virginia 22186 Hamilton at 714/833-1234. D A n A (Continued on page 14) Others measure by us For More Details Circle (8) on Reply Card

March, 1976 13

www.americanradiohistory.com (Continued from page 13)

the britffit one For Sale: Many hard -to -find radio tubes, parts, and books. Write for list. new photphor pi ture _L be T. Wojciechowski wrth tw ce _he k rightness 101-45 94th Street Ozone Park, New York 11416

Needed: Erase head for Heathkit tape recorder, Model TR -1E. Robert Verreault 436 Place -Marchand Matane P. Quebec Canada G4W 2J8 Needed: Power transformer, part number 80B-61-1 for Admiral combination hi-fi amplifier, Chassis 6D3. Elmer L. Mosley 1609 Pine Street Kenova, West Virginia 25530

Needed: Power transformer, part number 14-62 for Jackson TV, Model G-2. Albert Hopkins Route 1, Box 231-A Diamond, Missouri 64840 Needed: Schematic, manual or any information about a Sun Mark black -and -white portable transistor TV, Model SM-12TV. Danny Klecka 3379 Marbury Drive St. Louis, Missouri 63129 Needed: Someone to record two spools of recording 10-60 automatic dual -trace wire to cassette. Spool measures 2-3/4 inches outside triggered -sweep oscilloscope with 1-5/8 inch hole. Will cover all shipping and expenses. has double the brightness for bright P-31 prosphor CRT Joe Omen in high speed dual -trace modes. Band- displays even 400 North Fourth Avenue width: DC to 15 mhz. Unique features for the industry's 85705 greatest value are: Automatic Triggering Automatic Tucson, Arizona Astigmation Automatic Horizontal Sweep Automatic Horiz/Vert. TV Triggering (provides positive display on Needed: The following plug-in coil assemblies for composite video signals. Vertical sensitivity: .01 National Communications receiver, Model HRO-50R: volts/cm to 20 volts/cm in 1-2-5 step sequence. AA 27-30 MHz, AB 25-35 MHz, AC 21-21.5 MHz, E Horizontal Sweep Speeds: .2 sec/cm to .5,14 sec/cm in 900-2000 KHz, F 500-900 KHz. 1-2-5 step sequence. Has 5X magnifier at all sweep Byron E. Sauve speeds. External Horiz. Amp. Benchnridth: DC to .5 mhz; 16270 West 13th Avenue 1 volt Sensitivity: .5 volts/cm. Calibrated Test Signal: Golden, Colorado 80401 P -P square wave. Power: 105 125 volts, 60 cycles, 65 watts For Sale: One B&K sweep -and -marker generator, Model TO -60 Less Probes. Net $489.50 Model 415. Will sell for $359.00 or best offer. Also have a Knight oscilloscope and RF generator for sale. TO -55 automatic singile-trace triggered sweep oscillo- Pedro J. Taboada scope. Features same as TO -60 except Vert. Bandwidth is DC to 10 mhz. Box 1034 Model TO -55 Less Probes. Net $379,50 El Paso, Texas 79946

For the "bright one," see your distributor, or write: Needed: Operating manual for Heathkit TV alignment generator, Model TS -4A. Will buy, or pay for copy. nic. Gabe's TV eLECTRCTECH, 12230 Klingerman Street 5810 N Western Avenue, Chicago, Illinois 60659 El Monte, California 91732 L Area (3121 769-6262

For More Details Cl role (11) on Reply Card ELECTRONIC SERVICING 14

www.americanradiohistory.com W

I I -Ie .

"This must be the place." "Please stop shouting 'Money is no object'-

I'll fix it as fast as I can!"

Man's Best Friend... His TV' By Terry L Turner

Recently, I moved from the rat ly, he allowed me to take his will it be ready?" he asked with his race of Los Angeles to the quiet of receiver away. huge face almost touching mine. a small midwestern town, where I The next day, Mr. Brown came "Uh...very soon. I'm right on top opened a TV repair shop. In to the shop wanting to know how of the problem. It's just a matter of California, I worked in the engi- the repairs were going. "Well, I time. Oh, by the way, I hear you neering department of a large elec- really haven't had a chance to used to play football for State U." tronic manufacturing company, and check it yet", I explained. I thought "Yeah, that's right. I was the best also helped part-time as a bench I was being very polite, because I tackle they ever had," he said, man for several TV shops. None of had picked up the set about 5:30 straightening up and throwing back these activities required me to deal PM, and now it was only 8:05 AM his shoulders. "Someone started to directly with the public; but now, in the following morning. tell me about that big game you my own shop, I have daily contact Then the telephone rang. "Ex- were in, but I didn't get to hear the with those strange creatures com- cuse me, Mr. Brown," I said as I finish." "Must have been in '49 monly known as "customers". went to the phone. When I hung against Fairbury Tech." "Yes, that Through these daily contacts, I up, I looked around and thought he was it," I lied. have learned that Man and TV are had gone. But then I saw him, Actually, I hadn't heard anything one entity. Any attempt to separate sitting by the front window, with about the game, but figured every them, even temporarily, can result the most forlorn and sad look I football player must have had at in anguish for the set owner, and have ever seen on a human being. least one big game. Mr. Smith much ill will for you, the villain. "Uh...Mr. Brown?" He looked up. proceeded to describe every play; "Yes?" "I just received a new and by the end of the story, he had No Loaner portable TV this morning. Would calmed down. Fortunately, I was For example, consider the case of you like to take it home with you able to return his TV soon after- a man who was one of my first until I finish yours?" His eyes wards. customers. At that time, I hadn't brightened and learned his face glowed, as about the special bond he took the portable and rushed While He Watches between Man and TV, so I bluntly through the door. A few days later, Another type of customer is the told him that I couldn't repair his I was able to reunite him with his one who refuses to be separated set there, but would have to take it beloved TV, and all was back to from his TV, no matter what. to the shop. normal. "You busy?" I looked up from "Take it to the shop?" he the ancient b -w console I was repeated, as though having diffi- The Big Game working on, past the sea of sets culty in understanding the words. Sometimes the separation of Man waiting to be repaired, and on to "Yes sir, I'm afraid so." He looked and "boob tube" can result in near the doorway. This elderly man was down at the ailing set and asked in violence. Not long ago, the front carrying a 12" GE portable that a quiet voice, as though he didn't shop door opened and 6' 4", was missing the channel -selector want it to hear, "Do you have a TV 300 -pound Mr. Smith walked in. "I knob and the tip of the built-in I could use while mine is being want my TV," he said, pounding antenna. fixed?" "No, Mr. Brown, I'm sorry. his ham -like fist on the counter. "Well, yes, I am," I replied. I'm just getting started and haven't "I...uh..." I stammered as I looked "But what can I do for you?" "Oh, gotten any loaners yet." Reluctant- up at the menacing figure. "When me and the missus were watching

March, 1976 15

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For More Details Circle (12) on Reply Card March, 1976 17

www.americanradiohistory.com COLOR CASEBOOK

Here are more case histories and suggested techniques to help you repair color -TV receivers.

By Robert L. Goodman, CET

a few minutes, the sc een Case #1 : Fading Video ated for showed only a blank, bright r ter Symptoms with retrace lines (Figure 1). The video slowly faded and the brightness increased. After the Preliminary analysis General Electric with the 16QA Sound and color changed ery chassis (Photofact 1405-1) had oper- little during the fading contrast so it seemed certain the defect wa in one of the video stages. Six video stages are used in his model, if you count the color i ut - puts where the three color sig als and the video are matrixed. wo stages can be eliminated f om suspicion, because they handle .oth color and video, and only the vi s eo fades. Video and chroma tr vel together to the collector of Q 04, the first video transistor, where the chroma is picked off; and the c for output transistors handle both c for and video. Any of the remai ing four stages can cause simultaneus changes of contrast and bright ess without affecting the color . nd sound. All of the video stages are di ect coupled, except for one coupl ng capacitor between Q1O6, the sec nd Fig. 1 The main visual symptom was a bright raster without video amplifier, and the third vi i eo any picture. Other video troubles can black out the screen. However, the ef- Whatever the brightness condition, it can provide valuable transistor, Q108. clues about where to look. fects of direct coupling are obtai ed

POSITIVE- GO ING

VIDEO POS ITIVE-GOING VIDEO TO BASE OFQ107 +DC FROM BR IGHTNESS CONTROL

in a Fig. 2 Reduction of signal and DC voltages at the delay line helped pinpoint the defect 16QA General Electric.

18 ELECTRONIC SERVICI G

www.americanradiohistory.com by diode Y1O6 which acts as a DC The first drifting reading hap- and the positive DC at the base of restorer to make the base of QI08 pened at the third video amplifier, Q107. more positive when the video level 0108. Base voltage was stable, but Only one polarity -inverting stage increases (Figure 2). the emitter voltage went down is located between the delay line slightly. The change of emitter and the grids of the picture tube. Testing techniques voltage was so small, I decided to Therefore, a decreased positive volt- When all the video stages are AC test one more stage. Both the DC age at the delay line caused the coupled, a fast and accurate techni- and AC video voltages at the base picture -tube grids to become more que is to analyze the DC voltages of of Q1O7 decreased more than the positive, giving a brighter raster. each tube or transistor. But with emitter of Q108 had. DC coupling between stages, us- Evidently the defect was between Case #2: Tripping Breaker ually all DC voltages following the the emitter of Q108 and the base of Symptoms defect are wrong. Therefore, DC Q107, and only five components The circuit breaker of a Cl - analysis is not the best method were there. chassis General Electric color TV here. (Photofact 1100-2) had tripped, As next choice, I prefer to use Defective component eliminating both raster and sound. my dual -trace scope, with DC After much heat testing, moving When the breaker was reset, it coupling and the probes connected the components, and unsoldering would trip again after about five to input and output of each stage them for ohmmeter tests, I dis- seconds. in turn. This tests both the DC and covered leakage in L117 delay line. AC voltages in each measurement, Most delay -line defects are opens, Preliminary analysis and the dual -trace monitors the but this line developed leakage An overload of this magnitude is signals at two points, thus saving from coil to the ground foil, and likely to originate only in the B+ time. the leakage reduced both the video power supply, or in the horizontal -

Fig. 3 When they are overloaded sufficiently, car- bon -composition resistors can become near-shorts. Usually they will appear discolored VIDEO from the ex- OUTPUT RED 8.A cessive temperature, as L9 CATHODE these were in the General BLUE Electric Cl. NEGATIVE - CATHODE GOING VIDEO GREEN CATHODE

- BURNED 2 0 27K

Fig. 4 Operation of the new GE ACAC circuit is described in the text. The DC voltage at pin #3 of '22v IC210 determines the color TO saturation. An open R236 51K0 IC210 made it impossible to turn #3 down the color.

22K0 CHROMA -0---1 FROM COLOR .O1 2200 2.2µF 1lF 82000 CONTROL ,G-8-3)§1000 OPEN +10 100 10K0

March, 1976 19

www.americanradiohistory.com Fig. 5 A defective video stage was indicated by a low - contrast picture, with good sound, color, and sweep locking.

output stage. According to the sche- the heat. That applied more B+ to special type of automatic color level matic, tubes are used for nearly all the other resistor, which in turn control, called Automatic -Chroma - functions, with transistors operating heated excessively and lost resis- Averaging -Circuit or ACAC, also in the sync and AGC stages. tance. And so the sequence con- affects the DC voltage from the None of the tubes could have tinued, with each decrease of resis- color control. warmed sufficiently in five seconds tance overloading the other com- Figure 4 gives the circuit of the to draw such an excessive current, ponent even more, until finally both ACAC (sometimes nicknamed ack- and it seemed unlikely that a low- resistors were burned to near ack) stage. Q280 is biased just at level transistor could draw so much shorts. cut-off by the voltage dividers at current at any time. Incidentally, if R191 and R189 base and emitter. In addition, the Of these suspects, only the B+ increase in resistance, or open, the supply marked +12 volts is part of remained in question. picture will seem to be normal. the picture -control circuit, which When checking for shorts across However, the drive controls will can change the exact cut-off point. a power supply that feeds transis- have no significant effect, and the Chroma coming in through C284 tors, you should be sure the polarity gray -scale tracking probably will be acts as bias. The positive peaks of ohmmeter voltage reverse biases poor. If L166 should open for any produce collector current, and the the base/collector junction of all reason, the cathodes of the picture negative peaks are ignored because transistors. In this case, the positive tube would have zero voltage, and the transistor already is cut-off. ohmmeter lead should go to B+ the grids remain positive. The Therefore, stronger color causes a and the negative to ground (of picture tube current would become correspondingly increased collector course, that's also the correct several times normal, and kill the current. C280 and C218 bypass any polarity for the filter capacitors). high voltage. Usually the raster dis- ripple of chroma that is produced appears so fast that you can't see it by this class -B amplitude detection. Defective components leave, if the coil is intermittently Increased collector current of The main +270 -volt supply mea- open. Q280 (because of stronger chroma sured less than 1000 ohms, proving IF signal) decreases the positive DC that excessive leakage there was Case #3: Excessive Color voltage (coming from R372 and causing the overload. Symptoms R236) at pin number 3 of IC210, After opening several branches of The General Electric 17YA chas- and this reduces the chroma gain the B+ supply, I pinpointed the sis (Photofact 1495-1) had excessive inside IC210. Of course, a weaker short in the area around the plate color. In fact, the chroma seemed chroma IF signal has the opposite of the video amplifier. Now that my to be at maximum gain, and the effect, allowing pin 3 DC voltage to attention was focussed there, I color control had no effect. rise and produce more chroma could see both R191 and R189 were gain. burned (Figure 3). Circuit analysis Another use for C280 and C218 is I replaced the two defective resis- Many all -solid-state color re- to slow down the voltage change so tors and resoldered the B+ leads ceivers have IC's in the chroma rapid, normal variations of chroma that had been opened during the channel, and the color control signal do not change the chroma IF search, then the receiver came to changes a DC voltage that's applied gain. Instead, only longer -term life. to one pin of the IC. In other average chroma signal level changes words, the color control has no AC control the ACAC action. Comments chroma signal, but it adjusts a DC Most other ACC circuits control Resistors don't often burn unless voltage of the IC, and the IC the gain of the chroma IF stages another component has overloaded internally adjusts the gain. So it is according to the amplitude of the them. But in this case, either R191 in the GE YA chassis. burst, which is supposed to be the or R189 lost resistance because of But there's one difference. A same at all times. However, the

20 ELECTRONIC SERVICING

www.americanradiohistory.com burst amplitude is not always the control to reduce the color satura- Circuit analysis same as it is broadcast by some TV tion. Figure 6 gives a schematic of the stations. It's possible, therefore, for Case #4: Weak Contrast first and second video stages, plus wrong burst amplitude to produce Symptoms the delay line and blanker. Nega- excessive or insufficient color at Strong color, normal sound, and tive -going video is developed at the Evidently, times. the ACAC circuit a bright raster with very little con- emitter of Q301, the first video was designed to minimize such trast were the symptoms of the amplifier; from there the chroma problems. General Electric Cl chassis (Photo - signal is coupled through C501 to fact 1231-2), as shown in Figure 5. the chroma take-off coil. Troubleshooting Positive -going video comes from DC voltage at pin #3 of IC210 Preliminary analysis the collector of Q301, and it is fed was slightly high, and it did not When tuned to a blank channel, to the base of the sync amplifier change as the color control was the receiver showed weak snow, just and the base of Q304, the second rotated. At the color control, the as it had showed lbw contrast with video amplifier. This transistor DC reading changed normally. This a station. On channel, the vertical gives very little gain, because the was proof that the defect was be- and horizontal locked as they emitter resistor is not bypassed, and tween those two points, and the should.' All of these symptoms a small -value resistor is used at the only component between them was pointed towards a weak video - collector. R236. After R236 was removed amplifier stage following Q301, Q304 has a gain of about 1, be- from the circuit, it measured open, where the sync and chroma signals cause of the unbypassed emitter re- and a new one enabled the color were obtained. sistor and the small -value collector

+22 V

1ST VIDEO AMP TO SYNC SEP DELAY LINE

2ND 820Q V IDEO AMP 6.5 VDC NEGATIVE -GO ING 150 K VIDEO TO GRID OF C NEGATIVE -GOING 68 pF VIDEO OUTPUT (R 18) 10000 VIDEO FROM DETECTOR 10000

TO CHROMA 560 pF 470 pF BLANKING 3900 / 4700

/330Q VERT AND . HORIZ PULSES DEFECTIVE +22 V

Fig. 6 DC coupling of all video stages is employed in the C2/L1 General Electric. Many video defects change the brightness level, and so the amount of brightness can be a valuable symptom.

Fig. 7 An excellent way to find a loss of color is to use a scope to trace the progress of the pulses of a color -bar pattern. In the Zenith 15Y6C15, the color OPEN signal was normal at the color 2ND CHROMA control, but was missing at the 1200Q base of Q6 because C137 was L `rte 220 pF COLOR open. 47 pF

1ST CHROMA HUE

25000 6KT8 R167 220Q ww 100 pF

+25 V

March, 1976 21

www.americanradiohistory.com 1 11 Fig. 8 The top scope trace shows no signal at the base of 06, while the trace at the bottom shows a normal "comb" pattern at the plate of the first-bandpass tube. Color was lost between those two points.

resistors. R181 and R183 each have made, plus other defects and symp- ment (even then, the b -w picture a value of 1000 ohms to prevent toms: indicates something is wrong). standing waves (a type of ghosts) in If a raster can be seen, adjusting the delay line. the brightness control should vary Troubleshooting The blanking transistor (Q305) the brightness, otherwise there's a My favorite method with com- appears to be an amplifier of defect in the video -output tube or plaints of loss of color is to tune in vertical and horizontal pulses that circuit; a color bar pattern, defeat the color after amplification are used to Shorting the delay line to ground killer, and use my dual -trace scope supplement the blanking pulses should decrease the brightness, if to locate where the color "comb" from the TV station. However, the the circuit is okay from there to the pattern stops. Then I check the DC transistor has no bias except the picture tube; voltages and resistances in the stage incoming large -amplitude pulses. A C/E short in Q304 gives exces- where the color disappeared. Therefore, it functions not as a sive brightness without any video; The part of the bandpass circuit linear amplifier, but as an on -off and where the trouble was located is switch. If Q305 blanker is open, the pic- shown in Figure 7. I was lucky this A positive -going vertical or hori- ture will not be affected, but time, and came close to the trouble zontal pulse reaching the base retrace lines appear when the on the first try. saturates the transistor, causing the vertical is rolling. A normal set of color-bar pulses collector/emitter path to ground all In this case, scope waveforms were found at the plate of V1B signal and DC voltages at the showed strong blanking pulses at (lower trace in Figure 8), but no output of the delay line. After the delay line, but very little video. signal at the base of Q6, the inversion by the video -output tube, When Q304 transistor was replaced, second -chroma amplifier (top trace each temporary "ground" becomes the performance became normal. of Figure 8). That proved the loss a positive -going pulse at the cath- of color was somewhere between odes of the picture tube, thus Case #5: No Color those two points. Color pulses were eliminating all brightness for the Symptoms found at the top and center lugs of duration of the pulse. The Zenith 15Y6C15 (Photofact the color control. Between the color 983-2) produced a good b -w picture. control and the base of Q6 was Troubleshooting Unfortunately, it was a color re- C137 and the connecting wires. In this chassis, all three video ceiver that wouldn't show color. Yes, C137 was open. Replacement stages are direct coupled, so one of the capacitor and a touchup of method of troubleshooting is based Preliminary analysis the adjustments finished a job that on whether the raster brightness is Far too often, we technicians had seemed difficult before it was excessive or too dark. look for a loss of color in the started. For example, a black raster can chroma bandpass amplifiers, for- Comments be caused by: getting that the 3.58 -MHz carrier is No one troubleshooting technique a B/E or E/C short in Q301; equally important. Therefore, any can be fastest and most accurate an open in Q304 from collector - complete analysis should include for all defects in all models. But, to -emitter or from base -to -emitter; the burst amplifier, color killer, the ones most often used with a C/E short in Q305 blanker 3.58 -MHz oscillator, color demodu- success are DC voltage analysis and transistor; and lators, and bandpass amplifiers. A the operation of a good scope to an open delay line or L162. complete loss of color seldom is show the actual waveforms and Here are other tests that can be caused by poor picture -IF align- serve as a signal -tracer.

22 ELECTRONIC SERVICING

www.americanradiohistory.com Servicing Stereo Audio Systems

Part 7/By Carl H. Babcoke, CET

Basic audio theory and other Audio Review Test 8. In Figure 2, a likely cause of a facts about stereo audio sys- 1. What is the major difference thickening of the peaks of the sine tems have been included in the between a volume control and a wave is: preceding six articles of this loudness control?: (A) flicker noise. series. About 20 percent of the (A) A loudness control is used in (B) parasitic oscillation. questions in the journeyman low-priced equipment (such as a audio CET test involve funda- child's record player), but a volume mentals similar to these. In control is used exclusively in high- this article, we are presenting a est -priced equipment. multiple-choice review test. (B) Loudness controls change both After you have taken the test, loudness and frequency response, grade yourself by the answers while volume controls change only given on another page. the loudness.

Taking The Test 2. Thermal -agitation noise is These are not "trick" questions, caused by current flowing through such as ones with two right answers a semiconductor material. It also is or no right answers. Ignore non- called: typical or special cases; instead (A) partition noise. answer according to what is true in (B) Johnson noise. general. Figure 2 Circle the (A) or (B) that's before 3. Three types of four -channel the answer you choose. The page stereo systems are matrix, imita- 9. Which of these types has the number for the answers is listed at tion, and: higher amplitude of output signal the end of the test. (A) capacitive discharge. when playing the same phonograph (B) discrete. record?: (A) a ceramic cartridge. (B) a magnetic 4. Which of the circuits in Figure 1 cartridge. is a low-pass filter?: 10. HIGH AND (A) the circuit of Figure 1A. In order to record good high - LOW 0. HIGH frequency response, the gap of a FREQUENCIES FREQUENCY (B) the circuit of Figure 1B. recording head should be: 5. Which is more desirable in a (A) wide. (B) narrow. A phonograph cartridge?: (A) high compliance. (B) low compliance.

HIGH AND 6. LOW LOW Transient distortion is most FREQUENCIES FREQUENCY likely to occur in: (A) a preamplifier. (B) a speaker.

B 7. A de -emphasis circuit is used in: (A) an FM receiver. Figure 1 (B) an FM transmitter. Figure 3

March, 1976 23

www.americanradiohistory.com 11. Degaussing is: HEAD GAP (A) demagnetizing the tape -player

head. RECORDED TRACK (B) reduction of azimuth distortion.

12. During a square -wave test of an audio amplifier, the scope wave- Figure 5 form of Figure 3 indicates: (A) poor low -frequency response. Figure 8 (B) poor high -frequency response. used to process the output signal of: (A) a ceramic phono cartridge. (B) a magnetic phono cartridge. 24. The type of clipping distortion shown in Figure 7 is likely to be 20. Figure 6 illustrates: caused by: (A) Doppler distortion. (A) incorrect bias. (B) crossover distortion. (B) a non-linear transfer curve.

21. Equalization is used in audio 25. If a shielded cable is run systems to: between two chassis, lower noise (A) restore the frequency response, and hum usually is produced when: compensating for any undesired (A) the shield is grounded only to changes caused by the transmission one chassis. or recording of sound. (B) the shield is grounded to both (B) maintain a constant output chassis. voltage, so the output power is 26. Almost everything that's done Figure 4 independent of the amplifier gain. to increase the gain of an amplifier 22. Which characteristic is more also: 13. The bend of a record player desirable?: (A) increases its noise. tone arm is designed to:' (A) a low damping factor. (B) decreases its noise. (A) reduce vertical tracking force. (B) a high damping factor. (B) reduce horizontal tracking 27. The second harmonic of a 1000 error. 23. Which of these statements is Hz pure sinewave: correct?: (A) does not exist. 14. Ringing on the top and bottom (A) Ceramic cartridges have a (B) has a frequency of 2000 Hz. of a square wave indicates: "constant -amplitude" frequency re- (A) phase -shift distortion. sponse, and magnetic cartridges 28. In a tape playback system, (B) a peak in the high -frequency have a "constant -velocity" response. equalization normally is accom- response. (B) Ceramic cartridges have a plished: "constant -velocity" frequency re- (A) in the power amplifier. 15. Crystal cartridges in modern sponse, and magnetic cartridges (B) in the pre -amplifier. disc record players use: have a "constant -amplitude" re- (A) Rochelle salt crystals. sponse. 29. The lissajous pattern of Figure (B) ceramic crystals. 8 indicates: (A) clipping. 16. In Figure 4, selecting a large (B) rolloff. value of emitter capacitor (C3) will: (A) increase the gain of the stage. 30. An example of low -frequency (B) decrease the gain of the stage. noise is: (A) white noise. 17. Most circuits and parts values (B) pink noise. that increase the gain of an amplifier also: Answers are ,found on page 53. (A) increase (widen) the bandwidth. Figure 6 (B) decrease (narrow) the band- Comments width. This is the last installment of the series about the basics of audio and 18. In Figure 5, the tape -head gap stereo systems. We plan another is not properly aligned with the series which will cover more ad- track. The type of adjustment vanced audio principles, including needed is: servicing procedures. (A) azimuth. In the meantime, we invite your (B) height. comments about the preceding material, and your Suggestions of 19. A pre -amp and equalizer are Figure 7 areas to be studied next. O

24 ELECTRONIC SERVICING

www.americanradiohistory.com A technician working with any item of medical -electronic equipment should know the correct name, how to pronounce it, and what the instrument is used for. These explanations complete the list which was started several months ago.

Suppose a doctor called you to often allowing the heart to regain Electroencephalograph (ee-LEK-tro- his office to repair the electro- the normal rhythm. Operation of a en-SEF-ah-lo-graph): is an instru- cardiograph. You certainly can't defibrillator is a favorite activity of ment which records the electrical afford the embarrassment of ask- the make-believe doctors on TV activity of the brain. Metal elec- ing, "What's an electrocardio- shows, because it is a true life - -and trodes, placed on the surface of the graph?" death matter made dramatic by Medical science is notorious for convulsions of the patient following scalp, pick up the voltage generated the overabundant use of prefixes, the shock. by the brain. Some practitioners suffixes, and compound words prefer to use needle electrodes that produce such tongue -twisters Echocardiograph (ECHO -CAR -dee - rather than surface electrodes. as "electroencephalograph" and oh -graph): applies ultrasonic vibra- The brain waveform is roughly "phonocardiography". Any techni- tions to the chest and detects the sinusoidal, varying in both fre- cian working with medical -elec- echos returning from the heart. The quency and amplitide. Typically, tronic equipment must know what echos, displayed on a cathode ray the peak -to -peak voltage is approximately 50 microvolts, each instrument does and the tube in radar -like fashion, indicate and the domi- the position and motion of the nant rhythm-the so-called alpha correct name for it. rhythm-has a frequency range of After you finally get heart borders and valves. inside the approximately 8 to 12 Hertz. instruments, you'll feel on familiar After amplification in a low - ground. A diode is a diode whether Electrocardiograph (ee-LEK-tro- noise, low it's -frequency, high -gain in an audio amplifier or a CAR-dee-oh-graph): records the amplifier, the signal drives a re- "defibrillator". And repairing a electrical activity of the heart, using cording pen which writes on a medical oscilloscope is no more dif- a long strip of graph paper. The moving strip of paper. The record- ficult than working on a TV voltage generated by the beating ing is known as an electroence- receiver. heart is picked up by small, metal phalogram, abbreviated EEG. Typi- The following list describes many electrodes strapped to the arms, cal instruments have 8 or 16 of the basic medical -electronic in- legs and chest of the patient. channels (8 or 16 amplifiers and a struments, and gives the pronuncia- Typically, the peak -to -peak value of like number of recording pens) so tion when needed. the voltage picked up by the elec- that waveforms from various areas trodes is one millivolt; therefore, of the brain can be recorded simul- Defibrillator (de -FIB -rill -ay -tor): an the amplifier must discriminate taneously. instrument which applies an electric against common -mode hum and shock to the heart through two noise, while giving high amplifica- metal electrodes placed on the sur- tion. Because the heartbeat repeti- Electromyograph (ee-LEK-tro-MY- face of the chest. This instrument is tion rate is only slightly faster than oh-graph): records the electrical employed when the heart is in a one per second, the bandwidth re- activity of muscles. By means of dangerous condition known as ven- quired extends from DC to a few - surface electrodes or needles, volt- tricular fibrillation. The muscle hundred Hertz. One advantage of age is picked up from the muscle to fibers of the heart "quiver" rather the restricted bandwidth is that the be studied. The voltage then is than contract forcefully. As a re- waveform can be recorded by a pen amplified and displayed on a sult, the heart no longer pumps which writes on a moving strip of cathode ray tube. blood through the body, a condition paper (see writer). The recorded Muscle signals can range in fre- that is fatal to the patient unless waveform is known as an electro- quency up to several kiloHertz. corrected within a few minutes. The cardiogram, abbreviated either Therefore, they can't be recorded electric shock stops the quivering, ECG or EKG. properly by writers of the pen -and -

March, 1976 25

www.americanradiohistory.com This is the Burdick Model EK-5A Electrocardiograph, which uses the hot -stylus technique to provide a permanent heartbeat waveform on the tape.

paper types. Of course, a hardcopy with a long -persistence phosphor. (catheter) is threaded through an of the waveform can be obtained by However, because of the slow arm vein into the heart. The pace- photographing the screen of the sweep-approximately 1 to 10 maker is connected to the external scope. Also, the signal can be re- seconds per sweep-the left side of end of the wire, feeding pulses corded on magnetic tape for play- the trace has already faded by the through the wire into the heart. back and study at a later date. time the sweep has reached the If long-term pacing is required, a right side of the screen. As a result, tiny pacemaker is implanted surgic- the display on the screen appears as ally under the skin, and is con- Fetal monitor (FEE -tal monitor): an a slowly -moving spot of light rather nected through thin wires to the instrument for monitoring the heart than a continuous trace. This is heart wall. Battery discharge limits rate of an unborn baby during often referred to as a "bouncing the life of the pacemaker to labor and. delivery. As the mother's ball" display. approximately 24 to 30 months. uterus periodically contracts to The non -fade oscilloscope, also Then, the pacemaker must be expel the fetus (unborn baby), the known as a refreshed-display oscil- replaced surgically with a new unit. increased pressure on the fetus may loscope, employs either a loop of affect its heart rate. This must be magnetic tape or a digital memory monitored closely so that emergency to store the ECG waveform. With Patient monitoring system: a system measures can be taken if the fetus the waveform available in memory, of instruments for "electronically is "in trouble." a faster sweep can be used, and the watching" the patient, and sound- The fetal monitor records two waveform is displayed as a con- ing an alarm when an emergency waveforms on a long strip of chart tinuous line rather than a moving condition arises. paper. One waveform represents the spot. Each patient is connected to bed- fetal heart rate (FHR) and the other side instruments such as heart -rate shows the uterine contractions (UC). meter, blood -pressure monitor and The time relationship between these Pacemaker: a pulse generator used oscilloscope. The bedside instru- two waveforms is diagnostically im- to stimulate the heart, and thus ments of each patient are connected portant, and determines whether control the number of beats per by cable to the nurses station. Here, the process is proceeding normally minute. Normally, the heartbeat the cables are connected to oscillo- or whether medical intervention is rate is initiated by electrical im- scopes, automatic alarms, and a required. pulses generated within the heart strip -chart recorder. The oscillo- The fetal heart rate is "sensed" itself. These impulses travel through scopes display the electrocardio- either by surface electrodes or an conductive pathways within the grams of the patients, permitting ultrasonic transducer placed on heart, causing contraction of the the nurses to watch all patients for the mother's abdomen. Pressure in- heart walls. It is these contractions signs of heart irregularities. side the uterus is measured by a that pump the blood out of the The heart -rate instruments can strain gauge connected to a liquid - heart and through the body. be preset for upper and lower filled tube (catheter) inserted into In certain types of heart diseases, limits. If a patient's heart rate the uterus. the conducting pathways are im- should rise above or fall below paired and the heart is not properly these limits, an alarm will sound at stimulated. In these cases, an artifi- the nurses station, a numeral will Non -fade scope: a medical oscillo- cial pacemaker is used to trigger light up to show which patient is in scope for displaying the patient's contractions of the heart. distress, and that patient's electro- ECG (heart waveform). The conven- Under emergency conditions, an cardiogram will be recorded auto- tional oscilloscope used for this external pacemaker is employed. A matically on the strip -chart instru- purpose uses a cathode ray tube thin wire inside a flexible tube ment.

ELECTRONIC SERVICING 26

www.americanradiohistory.com An IVAC electronic thermometer measures a patient's temperature in about 15 seconds, with the exact temperature shown by a digital readout. The probe covers are made of plastic, and a new one is used for each patient. (Courtesy of GTE -Sylvania, Inc.)

Phonocardiograph: an instrument Pressure monitor: continuously Writer: an instrument which traces for recording the sounds of a monitors blood pressure. The in- waveforms on a strip of chart beating heart. The sounds are strument is interfaced with the paper. In older instruments, the picked up by a special microphone patient through a liquid -filled, flex- pen or stylus was a hollow, pointed that's strapped to the patient's ible tube, which is inserted into tube connected to an ink supply. chest. Displacement transducers either an artery or a vein. Pressure Most modern instruments employ also might be used to pick up the of the blood stream is transmitted the thermographie or "heat writing" low frequency vibrations of the through the saline solution inside technique. In these, a heated stylus chest walls. The signal is amplified the catheter to a strain gauge at the writes on plastic -coated paper which and either displayed on an oscillo- other end. Resistance of a strain turns dark where it is contacted by scope, or recorded on magnetic gauge changes in step with pressure the hot stylus. tape, or both. variations, and the circuit translates The strip of paper is pulled from The stethoscope-the hollow -tube resistance changes into voltage a supply roll by a motor -and -gears device with which doctors have tra- changes. This voltage signal is drive mechanism. As the paper is ditionally listened to the heart amplified and displayed on a meter, pulled past the hot stylus, making a sounds-is a purely -acoustic device which is calibrated in millimeters of dark trace on the paper, the stylus of poor sensitivity and sharply - mercury, or mm Hg. That's because is deflected back and forth across limited frequency response. By con- mechanical instruments indicate the width of the paper by a gal- trast, the phonocardiograph detects pressure by the height of a column vanometer -type driving mechanism. diagnostically -significant sounds of mercury (chemical symbol Hg) in The writer, also known as a strip that are either too low in amplitude a glass tube. chart recorder, can be a separate or too high in frequency to be Pressure monitors for arterial instrument or it might be a built- detected through a stethoscope. pressure typically are calibrated up in part of a more elaborate instru- to 300 mm Hg, while venous ment such as the electrocardio- monitors read up to 30 mm Hg. graph.

March, 1976 P7

www.americanradiohistory.com I II for current. With the test leads /Th removed, the panel (with the mark- ings) can be slid to the right, so the 0 two fuses can be popped out, when required for test or replacement. A heavy-duty 3 -wire power cable plugs into the left side, and a wire bail underneath can be adjusted to Miesilab By Carl Babcoke any of three positions to raise the front of the meter as desired. Six pushbuttons, located to the Each report about an item of electronic test equipment is based on right of the readout, select all in the ELECTRONIC examination and operation of the device functions, as explained in Figure 3. SERVICING laboratory. Personal observations about the performance, and details of new and useful features are spotlighted, along with tips Autoranging DC Volts about using the equipment for best results. The autoranging operates at all times to select either a higher or lower range as needed. Shift up and Autoranging Digital Multimeter five dashes across the readout; and shift down does not occur at A brief listing of features and voltage readings are in volts, precisely the same voltage because specs for the Model 3476A Hewlett- current readings are in amperes, a small overlap is necessary to Packard digital multimeter include: and resistance readings are in prevent "dead" spots. Therefore, no automatic selection of all ranges kilohms (thousands of ohms). voltage within the range of the (autoranging), with a "hold" button instrument can cause a missing, to lock the range when needed; Outside Features false, or misleading reading. automatic polarity indication; Digital multimeters often are Overrange (excessive reading) of automatic zero circuit (no adjust- small in size and light of weight, any range or function is indicated ment required); which can cause minor irritations if by five non -flashing dashes (Figure high -accuracy readings of five you try to change ranges or scales 4), so it cannot be confused with automatic ranges for ohms and and find the instrument sliding any reading. AC/DC volts, and two automatic around on the bench. With the Autopolarity also helps avoid ranges for AC/DC current; Model 3476A, the problem is solved errors of interpretation. Positive input resistance is 10 megohms (even though pushbuttons are used) numbers have no prefix, but nega- (paralleled by 30 picofarads) for all by a sloping rim above the buttons. tive readings have a minus sign voltage ranges; Just grasp the rim with a couple of before the numbers (Figure 5). resistance and current functions fingers and punch the required It's fascinating to apply a vari- are protected by fuses; button with a thumb (as shown in able DC voltage and watch the 3-1/2 digit red LED readout with Figure 1). display change polarity, decimal continuous lines and automatic On the right side are three points, and number of digits. decimal point; banana jacks (Figure 2) for the test Although the specs call this a 3-1/2 over -ranging condition shown by leads. The third jack is used only digit action, there are certain voltages that cause the readout to have four digits. Most digital meters of this rating have three digits that can assume any number from 1 through 9, plus a digit at the left that doesn't light, or it indicates a 1. The Model 3476A has four full digits, plus the extra 1, which counts as a half, although most actual readings show only three digits. Note the progression of readings in Figure 6. Maximum reading of the most -sensitive range is .11 volts. Above that point the meter switches itself to the 1.1 -volt range, followed by the 11 -volt, 110 -volt, and 1100 - volt ranges, if the input voltage rises enough. Maximum recom- Appearance of the Hewlett-Packard Model 3476A digital multimeter. mended voltage is 1000 volts DC,

28 ELECTRONIC SERVICING

www.americanradiohistory.com Fig. 1 Depressing and the input resistance is 10 the pushbuttons megohms. without moving the unit is easy by The sampling rate is about three times per second; grasping the however, the curved rim at the display is steady without flashing or top. blinking, unless the input voltage changes. When four numbers were displayed, Fig. 2 Only current the digit at the right readings require sometimes had "bobble", which is moving the "hot" a change from one number to test lead. Reversal another (for example, a reading of of the test leads 10.22 might change occasionally to f Am for DC readings is 10.23). But when three numbers not necessary, were displayed, I did not notice because of bobble at any time. (Of course, autopolarity. bobble is natural with digital meters because a count might begin or end in the center of a pulse.) This represents good performance. Fig. 3 Button at Accuracy of DC -voltage measure- the left turns ments typically is .5% or better. power on or off; There is a slight change of accuracy the second button between ranges. A readout of .0001 has a curved line is 100 microvolts or .1 millivolts, which points to the and is the smallest voltage that can DC symbol when be measured. out, and the sine wave symbol for Autoranging AC Volts E7ER AC when latched in; pressing AC -voltage RRJ any of operation was very the next three similar to that of DC, including the buttons releases same ranges. There is no polarity - the other, for indication, of course, and the AC selecting voltage, converter is average -responding and current, or calibrated in RMS. In other words, resistance the readings are accurate only for measurements; sine waves. and the last button Frequency response checked good also has a curved over the audio band. The response line showing that out gives "auto" was -1 dB at about 45 KHz and -6 operation, and in dB at 60 KHz, which was much is to lock or "hold" better than the factory specs. Basic t7tr:TAl P/tutI the range that is in accuracy at low frequencies is said r r . c> A use. to be 2%, or better. Factory specs call for AC readings down to 300 microvolts (.0003), while this sample had a minimum Fig. 4 A series of reading of .0004 with the test leads non -flashing dashes indicates shorted together. Input resistance is overload or 10 megohms, so this small amount overrange. of hum and noise is satisfactory. Input voltage should not exceed 700 -volts RMS or 1100 -volts peak, 34 7.6A EAGITAI... Rillt_T - to prevent damage to the meter. NE'N,E T " PACK ! Fig. 5 Negative Autoranging Current Readings voltages produce a Two current ranges are provided minus sign before to give 1% accuracy of DC current the readout; no indication is used from 1 milliampere to 1.1 amperes, and for positive approximately 3% accuracy for voltages or AC currents from 3 milliamperes to currents.

March, 1976 29 www.americanradiohistory.com 7f;A DFGITAL. NçIILTM1 Eh/7'W34 K /.t 'IF t - Ut- A : AR0

Fig. 6 This 1.1 amperes. The readout is in sequence shows amperes. how the Input resistance is 1.5 ohms for autoranging all measurements of both AC and changes the DC currents, and the frequency readouts. (A) The for AC current is the same zero -to -.11 -volt response for AC voltage. range gives a full as that given four -digit reading; (B) Less than one Autoranging Resistance volt on the 1.1 range provides Readings three digits, which All resistance readings are in changes to four thousands of ohms. A readout of (C) between digits .001 is 1 ohm, 10.4 is 10.4K ohms, 1.000 and 1.1 and the top readout of 11000 is Above volts; (D) 11000K (or 11M) ohms. change to the Voltage across the test leads with 1.1 -to -11 volts, the reading has three no load was about 3 volts, with the digits to 9.99, then "hot" wire positive and the com- four (E) above mon wire negative. However, the 10.00. (F) Above highest resistance not causing over - 11 volts, the meter ranging produced a voltage between gives three digits 1 volt and .1 volt, depending on the until the change at range. 110 volts; then (G) In fact, for a time I thought this digits to 999 three low ohmmeter voltage would pre- volts, and four vent forward conduction tests of digits above. silicon diodes and transistor junctions. Ohmmeter voltages are very important for testing circuits containing semiconductors, as well as checking out -of-circuit diode junctions, so I always measure the voltages of all ranges. A chart was made up of the DC voltages across the test prods when measuring various resistances within each ohmmeter range (with the range on hold). Open circuit voltages were about 2.95 volts, but some readings brought the voltage down as low as .002 volts. E The Hewlett-Packard manual deals with the problem of testing diode junction resistance, but the first time through, I read it too fast and missed a point. So, I developed my own method of testing, and was chagrined to find the extra trouble was unnecessary. Anyway, the manual partially F said "the 3476A must be down - ranged to the lowest ohms range in order to measure semiconductor resistance". Downranging to the lowest resistance range can be done either by shorting together the test leads and pushing the "Hold" button, or switching to current function and then to hold. Un - G fortunately, I could not read silicon

ELECTRONIC SERVICING 30

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www.americanradiohistory.com an open R405 or a short across it seems to make little difference in the performance.

Theory of regulation Last month's explanation of the horizontal sweep included only the yoke current that determines width. The large pulses on the trace side were necessary for ringing, but they served no other useful purpose. In the complete machine, the pulses waveform at the collector furnish power to the flyback trans- Fig. 10 Top trace of the left picture shows the normal regulator transistor. SCR101 pulses are included (bottom) for a (T403 in Figure 9). In turn, of 0401, the HV former CR404 is open, the waveform changes to the top trace various pulses phase comparison. When the flyback supplies right picture; regulation is lost, causing excessive HV; and the protec- plus of the for AGC and other functions, tion circuit forces the horizontal out of lock. pulses used for B -boost, focus, and HV DC voltages. C410 acts as an AC ground for the primary of the flyback. Because the yoke and the flyback the circuit breaker trips immedi- waveform when CR404 is open. The are essentially in parallel, regu- ately. reason for including CR404 is a lating the amplitude of flyback Base/emitter rectification of the little obscure. Probably it's there to which pulses also regulates the width. positive -going pulses at the base of clip the retrace waveform The HV ADJUST control (R412) Q401 produces a negative DC otherwise would be induced from if sets the amplitude of the flyback voltage there, and the pulses (acting the other winding. At any rate, pulses before they reach the zener as forward bias) cause strong CR404 is either open or shorted, This diode, CR405, which eliminates a collector current through T402, the the regulation is eliminated. constant portion of the pulses that regulator transformer. causes about 29KV of high voltage, are applied to the base of Q401. An Diode CR404 is paralleled across then the overvoltage protection hori- open CR405 kills the regulation, the collector winding of T402. circuit operates to throw the of lock. causing excessive HV and out -of- Figure 10 shows the normal collec- zontal out of lock horizontal. If CR405 is shorted, tor waveform and the abnormal While we're on the subject

HORIZ TO #3 ,FROM OF MAG001 FLYBACK #1 VERTICAL SWEEP FROM #7 OF CONVERGE 1200 PLUG

2 r VERT YOKE PIN PHASE ,0001 COIL r 8 ) w 820 4

6800 S2 2700 PINCUSHION PIN AMP ÓÖ` . 082 10 KS? < I .27 (Goo),

7 VERT 000} YOKE COIL

GROUND FOR CR406 1 FLYBACK VERTICAL YOKE x7 pl 1.5µF FROM #6 OF CONVERGE 2. 2 Si PLUG IN hiAG001 1200

one circuit. Tilt and amplitude are adjustable for Fig. 11 Both top/bottom and side pincushioning are corrected by this current. R417 and R418 are top/bottom, but side correction is not variable. Arrows show the path of the vertical yoke anti -ring resistors.

ELECTRONIC SERVICING 36

www.americanradiohistory.com 1 I.

forward resistances on the lowest range although germaniums would provide a reading. Again, I examined the charts showing voltage versus range, and noticed that the range above the lowest (1.1K to 11K) had higher voltages than the ones above and below it. After some experimentation, I connected a 5.6K resistor to the test leads, letting the meter autorange, and pushed in the "Hold" Fig. 7 Some of button, locking it to the the screw -in tips 1.1K to 11K range. The readings of for the test prods silicon power supply diodes and are shown here. transistor B/E and B/C junctions then were about the same as when measured on the X1K range of a VTVM that has a 1.5 -volt ohmmeter battery (about 5K typically). Options meters of the operator being unsure A second reading of the manual Several accessories are available which range is in use.) disclosed this method: for the H -P 3476A digital meter. But there is another point. A Connect the diode (or transistor The test -lead kit has a red and a digital meter locked to the 1000 - junction) to the test leads, with the black lead and four different pairs volt DC range, theoretically can anode (P material) to the hot lead, of tips that can be screwed into the measure down to 1 volt, but the and the cathode (N material) to the handles (see Figure 7). These in- readings become very inaccurate common lead; clude alligator, phone tips, banana, near the bottom of the range. No Depress the "A" button (for and needle point types. reading is possible between 1 volt current), causing the meter to An RF probe extends the AC and 2 volts, for example, downrange which to the lowest range; frequency range to 700 MHz, and a could mean an error of nearly Push the "Hold" button to lock soft carrying case has a shoulder 100%. That's why the full tolerance that range; strap, which allows the instrument specification of the 3476A reads, for Depress the K -ohms button (a to be operated while it is being the 1.1 volt and 11 -volt ranges: plus shorted junction will read a low carried. or minus (.3% of reading resistance); added to Model 3476A is AC operated .1% of the range). In the 1 -volt Release the "Hold" button, allow- only, and sells for $225. Hewlett- example, .3% of 1 volt is .003 ing volts autoranging to the next range; Packard explains their development (which is very good), but .1% and of the of "fine -line, tantalum -nitride" re- 1000 -volt range is 1 volt, making Take the reading. (Overrange or a sistors as one reason for the the total tolerance + 1.003 volts. high reading indicates the junction moderate price of an autoranging This could mean that a 1 -volt is open.) Silicons should be around instrument. These resistors are reading might be less than zero, 5K or and germaniums about 800 trimmed by laser to .02% tolerance, it might be 2.003 volts! ohms. Push in the "Hold" button, and exhibit good temperature This is a strong reason to use the in preparation for the following stability because they all are part of lowest voltage scale possible without leakage test. one assembly. overranging. (In fairness, the toler- To measure the junction leakage, Model 3476B is similar but also ance of a 900 -volt reading calcu- reverse the test leads at the diode operates on nickel -cadmium re- lates to be ±3.7 volts, which is or transistor, and release the chargeable batteries ($275). excellent.) Autoranging auto- "Hold" button, allowing the in- Dimensions are 2.3" high, 6.6" matically selects a range giving high strument to autorange up to a wide, and 8.1" deep, with a weight accuracy. reading. of 1-9/16 pounds. Temperature stability appeared I would suggest the meter be to be very good. A "D" cell used on autoranging for resistance Comments produced a reading of 1.56 volts, tests in circuits containing semi- Operating the Hewlett-Packard which did not vary or flicker for the conductors, to minimize the possi- Model 3476A digital multimeter test time of about six hours. At the bility of diode -type conduction giv- was a pleasure. The autoranging end, the case was barely warmer ing false resistance readings. Then feature extends the traditional digi- than room temperature. when you want to check diode tal advantages of accuracy and The Hewlett-Packard 3476A digi- junctions, follow the preceding readability. (Most digital meters tal multimeter proved to be very method of measuring with the next - position the decimal point to pre- satisfactory during tests as well as to -lowest range. vent errors common with analog actual servicing operations.

March, 1976 31

www.americanradiohistory.com SERVICING RCA NL-100

Part 5/By Gill Grieshaber, CET The first discussions explain how some waveforms were made and the significance of other waveforms and voltages; they are followed by information about high -voltage regulation and pincushion -elimination circuits, and finally the waveform analysis of many sweep component failures.

Stretching Scope Waveforms First, I tried to use excessive little except the baseline (Figure 1). The voltages at the output of scope gain, driving the top of the Even then the waveform was to C4O6 caused by trace currents HV pulses off screen. This almost somewhat different according flowing through CR4O1 and worked, because it showed the base where the leads were attached drops across the SCR1O1 ordinarily are not seen on line had a waveform, but making (because of voltage wires). This a scope. During trace time, one or the signal large enough to photo- chassis and common the other of these devices is graph properly overloaded the accounts for the small differences conducting, thus making the vol- scope amplifiers, causing distortion compared to the same waveform in tage drop nearly zero (less than a of the waveform. Step 5. sine waves appear volt across each). During retrace, After some experimentation, I The small that waveforms are nearly 400 -volts PP of HV pulses wired a 1OK resistor and a damper on some of the scope They show only are there. Problem: how do you diode as a shunt clipper that a minor mystery. or voltage view just 2 volts out of 400? removed the positive pulses, leaving on current waveforms, waveforms made small by clipping. Their amplitude and position change according to the brightness of the picture, so it seems definite CONVERGE that they come from the receiver. The same kind of sine waves appear also when the current of a horizontal -output tube is being viewed.

More Explanations Some condensation was necessary to prevent confusion. Now we'll try to clarify a few points.

SCR102 gate drive Precise turn -on time is required by the gate of SCR1O2 (by contrast, the turn-off time of SCRIO1 is critical). Also, there can be no false C406 pulses or double triggering; they would upset the timing of the various steps. P W 400 Figure 2 gives the SCR1O2 gate BOARD waveform with the zero -voltage line added by DC scope action. Notice Q401 REG that the positive -going portion (the only part affecting the SCR) is narrow and clean. The gate has CR401 little typical diode effect; therefore, there's only a small negative voltage, and the zero line is not far from where it would be without the SCR gate. R412 HV Peculiar anode voltages remeem The waveform at the anode of is there only about two- of the horizontal -sweep and regulator components of the SCR1O2 Arrows point to some the time. Yet when it's RCA CTC58 chassis. thirds of

ELECTRONIC SERVICING 32

www.americanradiohistory.com tested by a DC voltmeter, the SCR101 measures about + 50 volts, sured on a scope or a DC meter; reading is almost identical with the yet there is no DC path into the both agree). supply voltage. Have you ever trace section. What is the source of By the way, those HV pulses are wondered how this could be? Other this voltage? not the true waveform across C406, signals that are missing part of the If the pulses of Figure 6 were but just from one end to ground. time have a reduced reading. The supplied through a capacitor, the The top waveform of Figure 7 is the answer is in the waveform of Figure average line across near the base waveshape from the L108 end to 3. B+ supply voltage of this line would represent zero voltage, ground, the center one is the particular set was +151 volts DC, and the effect of the positive wave- SCR101 end of C406, and the trace which appeared at the anode of form above the line would equal the at bottom is the waveform across SCR102 when CR402 stopped con- part below the line. Therefore, the C406. This last waveform was ducting. But the voltage did not DC voltage would be zero. That's obtained by adding the traces maintain the same level, because not the case here. inside the scope, but a single -trace ringing of the regulator circuit The pulses are formed by C406 pattern with the scope connected swung it up and then down in a in reference to ground. In other across C406 (floating) verified its portion of a half-cycle of sine wave. words, the base line is at zero volts, accuracy. (Floating a scope that far Just before conduction of SCR102 and the average line is about +48 above ground is not recommended reduced the voltage nearly to zero, volts from zero (this can be mea - because of the shock hazard.) the instantaneous voltage was about +200 volts (this voltage changes to

fulfill the regulator requirements). Fig. 1 The cathode of CR401 must be Ringing has acted as a DC trans- SCR102 about -1 volt for it to conduct from former! Anyway, the curving top ANODE time TO to T2, and the anode of part of the waveform for a longer SCR101 must be about +1 so it can time equals the bottom part that's conduct from T2 to T3. Therefore, the there for a shorter time. By chance baseline between huge pulses at the the average DC voltage equals the anode of SCR101 cannot be zero. A clipper circuit inserted between anode input supply voltage. SCR101 ZERO ANODE of SCR101 and the scope removed most of the pulse amplitude (center SCR101 gate drive waveform), revealing the small DC Gate signal for SCR101 trace voltages that trigger on and off the SCR comes initially from an extra SCR and trace diode. At T3, the nega- SCR101 tive -going signal through C406 begins winding of the transformer that CURRENT to pinch off the anode current of replenishes the power to the re- ) SCR101. When this current stops (be- trace section. However, the signal CR401 tween T3 and T4) the voltage over- must be shaped by a two -stage CURRENT shoots to become negative, triggering filter, as shown by Figure 4. In a small current through CR401. At TO, I operation, the gate has a positive T3 T4 TO the negative pulse that starts conduc- signal for most of the trace time, tion of CR401 is visible. but the anode doesn't go positive until the middle of the trace. Both gate and anode remain positive (and the SCR conducting) until time T3, when both go negative, Fig. 2 Adding the zero -voltage line to forcing a sudden cessation of the gate -drive waveform of SCR102 shows that the only positive parts of current. ZERO The the waveform are the narrow pulses zero line added to the which give precise triggering. The line waveform of Figure 5 explains why also shows why the negative DC the gate shuts off so suddenly. voltage at the gate is so small. The zero voltage is very near the top of the waveform, so only a SCR102 GATE small amplitude decrease moves the gate down into the zero -voltage area. Then SCR101 stops conduc- Fig. 3 The average voltage at the SCR102 is identical tion as soon as the anode reaches anode of almost to the input B+ supply voltage, at zero, also. normal brightness. Regulation is ac- RING B complished by varying the resonant DC without DC input frequency of the regulator compo- One of the quickie tests of the nents. A higher frequency swings the ringing voltage up to its maximum sweep system is measure to the DC more quickly, thus allowing it to drop voltages at the anodes of SCR102 to a lower voltage (which reduces HV and SCR101. Both are accessible, SCR102 ANODE ZERO and width) before SCR102 conducts. and the cases connect to the The arrow at RING B+ indicates the anodes. SCR102 has supply voltage, DC voltage at the anode of SCR102 as explained before. Surprisingly, when it fires.

March, 1976 33

www.americanradiohistory.com High -Voltage Regulation It seems appropriate for a hori- Fig. 4 These waveforms show the steps of filtering the gate signal of zontal -sweep circuit that operates SCR101. Top trace is the waveshape by controlled ringing to have high - from T401 to the input of C404; the voltage regulation by ringing, also. center waveshape is found at the junc- And this one does. Any increase of tion of C404, R403, and L401: and the picture -tube current must cause a bottom trace shows the gate signal at like increase of power to the sweep the output of L401 and R404. C404 circuit, else the high voltage will and R403 form a high-pass filter, decrease. In addition, any minor while L401 and R404 comprise a low change of line voltage should be pass filter. offset by a change of DC voltage to the SCRs. Ringing first increases the B+ voltage at the anode of SCR102, and then decreases it in the shape Fig. 5 The DC -coupled dual -trace of half a sine wave. When SCR102 scope adds a zero -voltage line to the starts to conduct, the voltage from SCR101 gate signal, showing how ringing (stored in C406 and C407) little the waveform must go down to should be exactly the amount make the gate negative. When both needed for proper sweep and high the anode and gate of SCR101 are voltage. zero volts, conduction is zero. Specifically, regulation is ac- complished by varying the frequency of ringing in the replenishing part of the circuit. A higher frequency of ringing allows the sine wave to reach the positive peak Fig. 6 This waveform explains how a more rapidly; and then to decrease DC meter can read +48 to +50 volts to a lower voltage before SCR102 DC at the anode of SCR101, and yet fires. At the other extreme, a lower there is no path for DC to reach the ringing frequency does not permit the baseline is anode. That's because the voltage to fall so far before it's zero volts; therefore, the average used by SCR. Therefore, a high voltage of the pulses is positive. the ringing frequency reduces the high voltage, while a low ringing frequency increases the high voltage (Figure 8). Measurements with a triggered scope gave a frequency of 9300 Hz, when the screen was Fig. 7 It's difficult to show the wave- black, and about 8000 Hz with a form across C406. One way is to dis- bright raster. play the input waveform (top trace) Figure 9 shows the complete and add it inside the scope to the horizontal -sweep circuit, less only output waveform (center trace) to pro- the pincushion components and waveform (trace at the duce the total some HV and flyback wiring. bottom). Two minor features need men- tioning. The C120 mentioned before is not 3 microfarad as stated, but actually there are two 1.5 micro - farad capacitors in parallel (C120 and C121) to serve as ringing Fig. 8 Normal extremes of the regula- capacitor during the trace time. If tor ringing are shown by this double one of the two opens, the picture exposure. At the top, low line voltage fir becomes wider, but with com- and a dark raster cause the regulator pression of linearity at the right to reduce the ringing voltage that's edge. present when SCR102 fires. The The anode of SCR101 and the bottom trace shows the ringing from cathode of CR401 are not con- high line voltage and a bright raster. nected together directly, but to each More sweep power is needed, so the end of a 1 -turn winding of the fly- voltage is higher at the time SCR102 r conducts. Frequency of the ringing at back, with a damping resistor top is about 9300 Hz, and at bottom it (R405) in parallel. Probably this is about 8000 Hz. provides better linearity; however

34 ELECTRONIC SERVICING

www.americanradiohistory.com diodes, an open or shorted CR403 If L403 is incorrectly adjusted, current through T405 changes the increases the width about a quarter the right side of the raster will be inductance of T405 to cause a inch on the right and raises the HV taller than the left side, or vice variable load on the flyback. about 500 volts. None of the major versa. An open in L403 or T405 can waveforms seem to be affected. Side correction of pincushion dis- cause a trapezoidal raster, similar However, it's likely that a perma- tortion also is provided, but without to that obtained when one vertical nent short would cause T402 to any adjustments. The vertical yoke yoke coil is open. overheat, and an open might overload R125 so it would fail eventu- ally. B+ to replenish the power used by the sweep circuit reaches the retrace section through a winding of T401, which is paralleled by a winding of T402, the saturable - reactor regulator transformer. Saturable -reactor transformers are Fig. 12 An open C122 or R126 specially wound and balanced so produces a high -frequency damped very little AC from one winding is wave train at the anode of SCR102 induced in the other; however, the (top waveform). A different kind of saturation of one winding changes ringing occurs when R126 is shorted, the inductance of the other. In or has a low -resistance value. other words, direct current from 0401 through the "primary" of T402 changes the inductance of the "secondary" winding that helps supply B+ to the retrace stage. During conduction time either SCR101 or CR401 grounds C406, so the resonant circuit for regulator ringing consists of: the inductance ri of T402 and T401 in parallel; L108 (has little effect now); and the parallel capacitance of C406 and C407. Only T402 has a variable value. Fig. 13 Distinctive symptoms and waveforms result from an open C407. HV When excessive amplitude of regulation is poor, and the pulse waveforms at SCR101 anode have wrinkles flyback pulses causes Q401 to draw (lower trace of the picture at left). Also, the negative peak of the signal at the more collector current, the in- input of C406 is distorted (lower trace of the right picture). ductance of the regulator tuned circuit (T401 and T402 in parallel) is decreased. This raises the ringing Fig. 14 A loss of signal on the trace frequency so the voltage at the side of the circuit can be determined by the waveform at anode of SCR102 decreases to a the anode of retrace SCR102. The waveform lower value before SCR102 con- top is normal, while a shorted SCR101 or ducts. The lower "input" voltage CR401 produces the bottom waveform. reduces the width, the high voltage, ro An open C406 causes nearly the same and the pulses at Q401. .r waveshape. Notice the increase of trace time, the shortened retrace base Pincushion Correction line, and the lower oscillator fre- Both horizontal and vertical pin- quency. cushion distortions are corrected by the circuit of Figure 11. Arrows mark the path of the vertical sweep signal from the convergence plug to Fig. 15 If there are no AC waveforms ground. Horizontal pulses from the at the anodes of either SCR102 or pincushion transformer (T405) are SCR101 and the lower waveform is at tuned by L403 and C414, and the gate of SCR102, it's a cinch the adjusted in amplitude by R417. gate/cathode junction of SCR102 is While viewing a crosshatch pattern, open. Gate current in normal opera- turn R417 fully clockwise, adjust tion changes the pulses, as shown by L403 for an upward bulge of the the trace at top. top horizontal line near the center of the raster, then reduce the setting of R417 to make this line straight.

March, 1976 39

www.americanradiohistory.com A B C or the drive to Fig. 16 A narrow, unstable raster with wide foldover near the center is typical of opens in CR401, SCR101, anode of SCR101. (A) This dim raster was produced by an open CR401. (B) An open CR401 gave these waveforms: focus SCR102 (top); and (bottom) the anode of SCR101. (C) A flashing, too -bright raster, and occasional arcs from HV or resulted from an open SCR101. When L401 was open, the symptoms were similar, but the foldover moved less.

Waveforms And Parts Defects Figure 12) is produced by an open even when the trace section has no Several components that appear C122 or R126. A shorted R126 signal. The retrace circuit merely in Figure 9 were not explained causes a ringing of longer duration, idles, without harm. The waveforms before. For example, C403 and as shown by the bottom trace of of Figure 14 give two examples. An C123 each parallel an SCR to Figure 12. open C406 coupling capacitor or a minimize radiation of switching short on the trace side (for instance, transients which might appear as Poor regulation from the anode of SCR101 to vertical lines in the picture when Symptoms of poor regulation ground, or if CR401 shorts) pro- the signal from the station was (excessive HV with a dim picture duce similar waveforms. weak. The ferrite beads give the and slightly -low HV with normal SCR102 effect of an inductance (RF coil), brightness) might be caused by an Open but do not have the drawback of open C407. Check the waveforms at An SCR102 with an open gate/ self -resonance. C404 and R403 form C407 and the anode of SCR101 for cathode junction is easy to identify a high-pass filter; and L401 and clues (Figure 13). I know of no by the changed gate waveform R404 form a low-pass filter. To- other defect producing that kind of (Figure 15). gether these filters shape the de- a jagged waveform. and whistling sired signal to drive SCR101, as Foldover shown in Figure 4. Dead trace section A narrow raster with bright, wide R126 and C122 damp out one One unique feature of the SCR - foldover in the center, along with kind of unwanted ringing from the sweep circuit is that the retrace an audio tone from the sweep retrace circuit. Short -duration high - circuit will have a nearly -normal circuit, are the general symptoms of frequency ringing (top trace of waveform at the anode of SCR102 an open SCR101, or an open CR401 (Figure 16). A defective component in the gate filter for SCR101 also will cause the same symptoms.

Foldover at left Figure 17 shows the trace and retrace waveforms and the screen when a CR402 retrace diode was open. Operation for a short time without CR402 didn't seem to overload anything, but after three or four minutes R126 started to smoke. The amplitude on the retrace side was more than 1000 B A volts PP! Fig. 17 When CR402 (retrace diode) was open, both the picture and raster were almost normal, except for the white foldover about 4" from the left edge. Next Month 1000 volts PP, and R126 However, the signal at the anode of SCR102 was about Detailed troubleshooting methods a few minutes. (A) Waveform at the anode of SCR102 is started to smoke after and other tips covering the hori- the bottom trace shows the waveform at the anode of SCR101. at the top, and zontal and HV sections of the RCA Notice the extra bump on the baseline. (B) With a blank raster, the foldover will be the subject next appeared as a white vertical line. (The dark lower half of the raster was caused CTC58 by the camera shutter.) month.

40 ELECTRONIC SERVICING

www.americanradiohistory.com OHMWARD BOUND! by Edmund A. Braun

Start going around with this Pinwheel Puzzle and have fun! It's based on 8 Recessed portion of a device into Electronics. The last letter of each word is the first letter of the next word. Each which another part fits. correct answer is worth 4 points; a perfect score is 132. It should be easy to 9 Draw out; make empty of gas or get a high rating, except perhaps for someone who thinks "dipole" is a resident air. of Warsaw who passed away, or that "odograph" refers to the signature of a 10 Cause to rotate or turn. movie star! So take a deep breath and GO! 11 Condition of strain which tends to stretch. 12 In mksa system, unit of force that

will impart an acceleration of 1

mps to a mass of 1 km. 13 Balanced condition which results in zero output from a device or system. 14 The intensity of sound. 15 Thin metal vane which has been perforated with an appropriate wave pattern. 16 Light-sensitive surface of an iconoscope or other TV camera tube. 17 Antenna having radiating elements shaped like a good luck symbol. 18 Heavy wire conductor supplying electricity to other wire conductors. 19 A four sided plane figure with four right angles. 20 Excursion above or below the average peak amplitude. 21 A sturdy resin -type adhesive. 22 Type of directional antenna. 23 A common metallic element; symbol Fe. 24 Neither positive nor negative. 25 Diagram indicating the positions of parts on a chassis or panel. 26 Thread of contrasting color woven into insulation to identify a wire. 27 Radio or TV program originating outside the studio. 28 An electric analog of a permanent magnet. 29 Straight line which touches the circumference of a circle at one point. 30 A ring or ring -like. 31 Unit of optical measurement which 1 A bluish -white crystaline metallic 4 The mean or average; a customary expresses refractive power of a element. condition or degree. lens or prism. 2 Any substance used for making 5 Decimal system of weights and 32 One type of insulation for wire. bodies adhere to each other. measures. 33 A placement in a certain rank or 3 A positive or negative ion which 6 The tiny piece when a hole is class. has been emitted from a heated punched in a card or paper tape. body. 7 Unit of elastance; equals the Now let your fingers do the reciprocal of capacitance. walking to the solution on Page 53.

March, 1976 41

www.americanradiohistory.com 3-1 /2 -Digit Multimeter These are the three voltmeters: Model LMV-89 measures AC voltages test equìpmeot Systron-Donner has introduced a from 100 microvolts to 300 volts in new 3 -1/2 -digit multimeter. Model two channels; a similar range is 7003 has 5 complete functions, 26 covered by Model LMV-87A, with mmel ranges, 2000 count capacity, large higher input impedance of the single These eatures supplied by the 0.4 -inch 7 -segment LED display, and channel, and stabilized power supply; manufacturers are listed at no -charge features a circuit -breaker current and Model LEM -75, a battery -AC to them as a service to our readers. for DC and If you want factory bulletins, circle the overload protection circuit. It is said FET multimeter testing corresponding number on the Reply to be the first such instrument to AC volts and current, plus ohms. This Card and mail it to us. have true RMS AC -measurement meter has an optional probe for capability. An adjustable stand en- measuring ambient temperature. ables the unit to be tilted up or down The LFM-36A solid-state Wow -And - for convenient bench use. Flutter meter also simultaneously measures drift of tape recorder mechanisms. For More Details Circle (27) on Reply Card

Transistor Tester VOM Series The improved Model 520B semicon- The new Weston 660 series of ductor tester from the B&K-Precision VOM's feature "drop -proofed" pro- division of Dynascan features a choice .....o»teeD o..... tection. They are warranted in writ- of Hi -drive or Lo -drive for better ,..d,Muea ing to work even after accidentally accuracy of readings. being dropped five feet. The smallest Model 7003 sells for $295. It is not necessary to connect the precision multimeter on the market, transistor to any specific test leads; For More Details Circle (26) on Reply Card the 660 series incorporates such rotation of the "TEST" switch supplies all six possible connections. LED's marked "PNP" and "NPN" show the polarity, and that the Audio Test Center transistor is good, when they light. An internal speaker sounds an audible Leader Instruments has introduced tone, also, when the transistor is non - 12 test instruments that are suitable defective. If a polarity LED lights on for an "Audio Test Center." There is two positions of the "TEST" switch, a choice of two recurrent -sweep the Lo -drive should be selected. scopes: Model LBO -310A for general- Neither LED lights when the transis- purpose use; and Model LBO -552, tor is defective. which provides two traces (with one The "IDENTIFY -LEAKAGE" large difference from most scopes- switch has a spring to return it to the the traces are side -by -side). center position. It should be rotated The Model LAV-190 is a 3 -in -1 to the "IDENTIFY" position to de- audio analyzer, functioning as an termine whether the transistor is audio generator, attenuator, and AC silicon or germanium. The color of millivoltmeter. A companion instru- LED which lights shows the color of ment is the LDM-170 distortion meter scale to be used for the leakage meter, which also measures signal test. levels and signal-to-noise ratio. Leader also offers 4 generators: Model LSG -231 multiplex or FM - stereo generator with pilot signal; features as: diode -protected meter low -distortion audio generator Model movement; special calibrated scales LAG -125 which also has square waves for dB measurement; pluggable cir- and audio -burst signals; the LAG -120 cuit -board assemblies; and external which sine and square waves SOW 131,00, has fuse replacement. 10 1 Model -....,.... from Hz to MHz; and For More Details Circle (28) on Reply Card LAG -26 for testing transient response and distortion. High -Accuracy Digital Multimeter

Hi -power drive makes in -circuit DC voltage readings with an accu- tests possible when the shunt re- racy of .01% ±1 digit, and a readout sistance is as low as 10 ohms, and the with 4-1/2 digits are two specifica- shunt capacitance is as high as 15 tions of the Model 4600 digital microfarads. multimeter manufactured by Dana Model 520B semiconductor tester is Laboratories. All ranges can be se- AC powered, and has a list price of lected by an "up" or a "down" button, $160. or the instrument can select the best For More Details Circle (25) on Reply Card range by full autoranging, and auto -

42 ELECTRONIC SERVICING

www.americanradiohistory.com polarity. The yellow LED digits are Pocket -Sized Digital There is only .43" high. Multimeter one Ranges of AC and DC volts are Sencore offers Model DVM-35, a from 10 microvolts to 1000 volts, portable battery -operated digital ohms readings are from 10 milliohms multimeter. Some of the features 2- WAY to 20 megohms, and AC/DC current include: 3 -digit readout, with 1% ranges are from 10 nanoamperes to 2 accuracy of DC voltages; four AC and RADIO amperes. Input resistance on the two DC voltage ranges covering 1 volt to lowest voltages is 10,000 megohms. 1000 volts full scale; four AC and DC HOME Dana's combination of a filter and an current ranges from 1 milliampere to integrator is said to give 80 dB 1 ampere full scale; three "low" STUDY rejection of normal -mode noise. power ohms and three "high" power COURSE ohms ranges, together covering from 100 ohms to 10 megohms full scale; and an input resistance of 15 exclusively devoted megohms for all voltage ranges. to professional FM radio equipment A "times two" button on the probe doubles all voltage readings, thus changing the input resistance to 30 megohms and the maximum voltage reading to 2000 volts. Also, on the probe is the "touch on" button, which eliminates all battery drain between measurements. We don't know how many TV repairman or other people there are in electronics who would like to move up to professional FM two-way radio. Nor do we know how many Model 4600 sells for $549. Option 82 servicemen and installers is a HV probe allowing voltage there are measurements up to 5 KV ($40); already in the field Option 83 is a 50 KV probe for $45; who want to expand and Option 84 is a $60 RF probe for and upgrade their knowledge. measurements up to 200 MHz. For More Details Circle (29) on Reply Card But we do know how many home study schools cater exclusively J to both these groups. Portable power is obtained from Test Clip AA -size batteries, or AC operation is possible by use of a Model PA202 ONE! The "Dip Clip", Pomona Electronics' adapter/charger. Probe HP200 allows Model 3916 for attachment of test high voltage measurements up to 50 probes to 15 or 16 lead DIPS, has kilovolts. Model DVM-35 is said to be been revised. The latest version is "drop -proof' and "burn -out -proof', Please send me more information. wider and longer its predecessor and sells for $124. than Name and uses polycarbonate thermoplastic For More Details Circle (31) on Reply Card for insulation. Spring -loaded wiping Address Code

I am a former MTI student.

E I am presently in the military.

E I am a veteran.

8 MT/ Formerly helps. MOTOROLA action of contact pins gives good The Ame TRAINING INSTITUTE electrical connection; a special contact Red Crossri.can design gives positive positioning, pre- The Good Summerdale, PA 17093 venting accidental shorting of ad- 4, Neighbor. (717) 732.3636 jacent leads. For More Details Circle (30) on Reply Card

For More Details Circle (13) on Reply Card March, 1976 43

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Modern Communications Switching Sys. 276 p., 171 il. $17.95 o Understanding & Using the VOM & EVM. 192 p.,187 $4.95 For More Details Circle (34) on Reply Card Electrical Wiring/Lighting For Home/Office. 204 p., 155 il. $4.95 Understanding & Using the Oscilloscope. 272 p., 170 il. $4.95 FM Stereo/Ouad Receiver Svcing Manual. 192 p., 130 il. $4.95 MAN Systems Handbook. 176 p., 91 il. $4.95 T' shooting Solid -State Wave Generating/Shaping Circ. $4.95 2nd Class FCC Encyclopedia. 602 p., 445 il. $7.95 One+ One Intercom Pictorial Guide to Color TV Cir. Troubles. 256 p., ,262 il. $4.95 Marine Electronics Handbook. 192 p., 106 il. $4.95 The One + One Ektacom intercom Installing TV & FM Antennas. 168 p 158 il. $3.95 by Fisher Berkeley Corpora- Simplified TV Trouble Diagnosis. 320 p., 292 il. $5.95 offered p Pictorial Guide to Tape Recorder Repairs. 256 p., 320 il. $4.95 tion has a master unit with one slave Introduction to Medical Electronics. 272 p., 126 il. $6.95 o Troubleshooting Solid-State Amplifiers. 256 p 95 if $4.95 station. The remote station can call How to Solve Solid -State Circuit Troubles. 304 p., 161 il. $5.95 the master, but does not require o T'shooting Solid -State Elec. Power Supplies. 192 p. $4.95 How to Interpret TV Waveforms. 256 p., 250 il. $4.95 switching at that end after the Kwik-Fix TV Service Manual. 384 p. $5.95 How to Repair Musical Instrument AmpIs. 288 p., 250 il. $5.95 conversation begins. The amplifier is Solid -State Circuit T'shooting Guide -2224 p., 15011. $4.95 Installing/Serv. Elec. Protective Systems. 252 p., 160 il. $4.95 Using Elec. Testers for Auto Tune -Up. 252 p., 226 il. $4.95 Model 1235 FilmosonicTM o All -in -One TV Alignment Handbook. 304 p., 145 il. $6.95 XL Super 199 Color TV Troubles & Solutions. 224 p., over 180 il. $4.95 8 magnetic -sound camera is compact 199 Electronic Test & Alignment Tech. 224 p., 13011. $4.95 Digital Electronics: Principles & Practice. 28&p., 191 II. $5.95 and lightweight. The unit retails for Industrial Electrs.: Principles & Practice. 416 p., 380 il. $8.95 $389.95, and also features an ear- o Commercial FCC License Handbook. 444 p., 150 il. $5.95 O Citizens Band Radio Service Manual. 192 p., 36 il. $5.95 phone sound monitor and full-time o Modern Radio Repair Techniques. 260 p., 36 il. $4.95 How to Use Color TV Test Instruments. 256 p., 230 il. $4.95 pushbutton power zoom. Modern Radar-Theory, Operation, & Maint. 480 p. $7.95 For More Details Circle (32) on Reply Card Popular Tube -Transistor Substitution Guide. 256 p. $3.95 199 TV Tough -Dog Problems Solved. 252 p., 199 il. $5.95 o Major Appliance Repair Guide. 288 p., illustrated. $5.95 Computer Technician's Handbook. 480 p., over 40011 $8.95 Vectorscopes-Oscilloscopes/Sweep-Marker Gen. 256 p. $4.95 Electronic Crossover Servicing Modern Hi-Fi Stereo Systems. 248 p., 24 il. $4.95 Designed for use with 2- or 3 -way Pulse 8 Switching Circuits. 256 p., 184 il. $5.95 How to Repair Home/Auto Air Conditioners. 206 p. $4.95 speaker systems, the Shure SR106 solid-state equipped, and does not Home -Call TV Repair Guide. 144 p. $1.95 electronic crossover is a rack -mount- Small Appliance Repair Guide-Vol. 1. 224 p., 100 il. $4.95 require a location near an AC outlet Installing/Serv. Home Audio Systems. 256 p.. 150 il. í5.95 able, unity -gain, line -level, balanced because a separate UL -listed power input NO RISK COUPON -MAIL ENTIRE AD and output selectable -frequency supply is used. A model with heavy- dividing network. duty switches is available. TAB BOOKS, P.O. Box 40 Blue Ridge Summit, Pa. 17214 The device separates the output of For More Details (35) on Reply Card Please send me the books checked above. an audio console or mixer -preamplifier Circle

I enclose $ send postpaid. into two frequency bands for distribution o Please invoice on 10-day FREE trial. Send C.O.D. to separate power amplifiers and low- and high -frequency speaker sys- Tape -Head Demagnetizer Name Phone tems. An economy -model magnetic tape - The SR106 unit provides switch - head demagnetizer has been intro- Company selected crossover frequencies of 500 duced by Robins Industries. Address Hz, 800 Hz, and 2,600 Hz. Net price of The unit should be used about

City State Zip the device is $93.00. every 20 hours to demagnetize the ES Foreign add 10%. Pa. add 6% sales tax . -36 For More Details Circle (33) on Reply Card (Continued on page 48)

For More Details Circle (14) on Reply Card 44 ELECTRONIC SERVICING

www.americanradiohistory.com CB channels; a desk microphone with DIGITAL press -to -talk switch; modulation and uroductJaxull on -the -air lights, a digital clock that These features supp red by the rings an alarm or turns on the CB at manufacturers are listed at no -charge a selected time; automatic noise PERFORMANCE to them as a service to our readers. limiter, and RF noise with If you want factory bulletins, circle the blanker corresponding number on the Reply manual override; jacks for phones, Card and mail it to us. external speaker, or public address; 11011 CAN and mike -gain and tone controls. For More Details Circle (37) on Reply Card RELY ON.

FM Weather Band Converter Aluminum Solder A tiny new FM weather -band Alu -Sol 45D soft solder from Multi - converter for autos, boats, trucks, and core solves problems of soldering campers has been introduced by many aluminum alloys that previously Audiovox Corp. Model WB -70 con- were hard to wet. It has silver, tin, verts any FM radio to receive official and lead, with a special flux in four U.S. weather bureau 24 -hour weather cores near the surface. Alu -Sol 45D is forecasts. The FM radio should be compatible with standard tin -lead tuned to 90 MHz. The converter also solders, and is said to give excellent amplifies weak FM radio signals. results with tin plate, copper, brass, nickel, and nickel -silver materials. Also, good results are claimed with steel, stainless -steel, and zinc alloys. A soldering temperature of 660° F. is recommended. The Hickok Model 334 DMM is For More Details (38) on Reply Card Circle a rugged, non -temperamental, hardworking tool that's easy to use and easy on your eyes. Cable -Installation Tools Hickok has established a unique D'versiBit tool system reduces the reputation in digital electronics time required for in -wall cable instal- during the past 10 years. The lations. The tools can be used for in- Model 334 is another example stallation of coaxial cable and electri- of our engineering expertise - cal cable within all types of building an economical lab quality walls. A standard quarter -inch drill is instrument with exceptional used to drive the tools. durability and accuracy. Easy reading, green 171ee fluorescent display Quickly installed, it mounts anywhere under the dash of a vehicle. 31/2 digit - auto polarity Instructions are included for single -'tobeee1' 26 ranges including 200 mV and dual mounting. AC & DC ranges Suggested list price is $24.95. zzuzzze7 Fast response - For More Details Circle (36) on Reply Card 2.5 readings/sec

Basic Accuracies (% of reading) DC Volts; ±0.2% (±0.5% on 200V, 1200V ranges) Base/Mobile CB Transceiver AC Volts; ±0.5% (±2.0% on 200 mV, 2V ranges) Designed for either mobile or base - OHMS; ±0.5% station operation, the Pearce -Simpson DC Current; ±1.5% AC Current; ±2.0% Bearcat 23-C has: dual power supply, one meter to read receiving signal Ask to see the Model 334 at your strength or relative transmitted Hickok distributor. It's a no power, and another for modulation or compromise DMM at a price VSWR measurements; crystals for 23 The various items that make up the you can afford. system include: a half -inch auger bit with a 54 -inch flexible shaft for easy starting of a clean entrance hole; a x22900 half -inch carbide -tipped masonry bit with a 54 -inch flexible shaft for drilling cement blocks and plaster; HICKOK and a half -inch combination bit with a 54 -inch flexible shaft for greater dura- the value innovator bility and general-purpose use. Also INSTRUMENTATION & CONTROLS DIVISION THE HICKOK ELECTRICAL INSTRUMENT CO. 10514 Dupont Avenue Cleveland. Ohio 44108 (Continued on page 46) (216) 541-8060 TWX: 810-421-8286

For More Details Circle (15) on Reply Card March, 1976 45

www.americanradiohistory.com available is a special alignment tool to Wire Stripper are direct replacements for most guide and hold steady the D'versiBit selenium focus rectifiers in color TV flexible shafts; a line -recovery pulling - A tool with plastic blades to strip receivers. Silicon types change less grip attachment for drawing RG -59 the insulation from wires? Yes, if the from heat and age than seleniums do. and RG -6 coax cable through the plastic is Stilan, which was developed Electronic Devices also has many drilled holes; and a 54 -inch extension originally for the aerospace program. kinds of "Solid Tube" solid-state attachment. The Alpha "Plastic -Blade Stripper" replacements for vacuum tubes. The D'versiBit tool system is mar- has cutting edges that are harder For More Details Circle (43) on Reply Card keted by Blonder -Tongue Labora- than insulation, and softer than cop- tories. per. As you squeeze the handles, the For More Details Circle (39) on Reply Card broad Stilan blades close on the in- Noise Cancelling Microphone sulation; next, the holding blocks grasp the wire. Further movement Astatic's "Trucker II" noise -cancel- Projects Handbook causes the blades and the blocks to ling microphone eliminates most cab Nine state-of-the-art projects are move apart, with the blades cutting noises. In one test, the truck's air included in the Semiconductor Pro- through the insulation, deforming or horns were blown while the cab jects Handbook published by GC Elec- bending around the copper wire, and windows were rolled down, and no tronics, Calectro Division. removing the insulation from the additional noise came over through The Handbook features an assort- wire. Releasing the handles allows the "Trucker II." ment of general -interest projects wire to be removed. It has a transistor amplifier and an varying from a simple decade counter adjustable output level over a range to a complex waveform generator, of approximately 40dB. Compatible including a crystal timebase, SCA de- coder, dual power supply, C-MOS digital thermometer, and others. Each project describes the theory of operation, as well as providing printed circuit board layouts, detailed drawings for suggested enclosures and intended applications. The price is $1.00. For More Details Circle (40) on Reply Card

No adjustment is necessary (or FM Signal Booster possible) for different sizes of wire "Stereo One" is an automobile FM from AWG -12 to AWG -28. Several signal booster designed to minimize wires can be stripped at the same signal fade and flutter associated with time, and the wire can be placed weak -signal FM reception. It can be anywhere along the blades. used with any auto AM/FM radio The manufacturer estimates up to without any adverse effect to normal 50,000 strips with simple hook-up AM/FM reception. The circuit more wire; less with harder insulation (it's than triples the received signal in the not recommended for Teflon and "on" position to clarify FM reception Kynar). However, new blades can be in fringe areas. pushed in place, without tools, in a method similar to that used with injector razor blades. with virtually any outfit, "Trucker II" The Alpha Plastic -Blade Stripper converts easily from "electronic" to lists at $39.95, with three sets of "relay" operation. i blades. For More Details Circle (44) on Reply Card For More Details Circle (42) on Reply Card

Solid -State Guide STEREO ONE Silicon Focus Rectifiers u Auto FM Signa! Booster The 1976 edition of the RCA Solid Silicon rectifiers rated at 8000 peak State Replacement Guide now is rte.,'N N,o .a SMN K reverse voltage and 5 milliamperes available. The book-SPG-202S-cross- references more than 112,000 domestic and foreign solid-state devices which can be replaced with RCA SK - Series types. "Stereo One" is a two-piece unit An additional feature of the Guide of an amplifier section that is an index of RCA SK -Series semi- consisting AEmrtÉI P h 93AS7 P,ab,tlNenP N72t1-0 Nr,E3q6 P N 66%03S I PNikeP N36X0537 P N 2141 mounts close to the auto radio, and an Cuts Manes RCA P 11 1440S7 2 1 S 5113192 conductors and accessories. Also in- tasnonP N817123 San 58nrbn, P N 86663 an 58 P:N 812211781 SybamaPM 13161061 cluded are significant characteristic on-off control switch with LED Myirma P 5380%7 Mods elm? N 0030032 Ywh.TIW PN138%00 2enrM P 112114, 21: N. indicator light that self -mounts on the peek P N NP32IO1N and application information, line dash. drawings of dimensional outlines and All necessary mounting hardware terminal arrangements, and a listing and instructions are supplied with the of mounting hardware. "Stereo One," which is manufactured The 160 -page Guide has a suggested by the Finney Company. price of $1.00. For More Details Circle (41) on Reply Card For More Details Circle (45) on Reply Card

46 ELECTRONIC SERVICING

www.americanradiohistory.com Auto -Noise Filters CB Transceiver F A self-service merchandiser from The E. F. Johnson Company has Some stores Sprague Electric has Q -Line filters announced a new low-cost CB trans- packaged with installation instruc- ceiver, the Messenger 121A. It has sell test tions. Four of the filters are feed - many of the features found in John- through types for mobile applications son's other CB radio models; included equipment and are rated at 20, 40, 60, and 100 are built-in automatic speech com- amperes for minimizing noise from pression on transmit, and automatic at discount noise limiting on receive. The radio also features maximum prices. FCC-permitted power and pushbutton selection of up to five CB channels (crystals for the five chan- At Fordham nels desired are selected and pur- chased separately by the user). It is we discount supplied complete with microphone, mounting bracket, DC power cord and their discount prices.

B&K, EICO, RCA, SENCORE FLUKE, HICKOK, LEADER and SIMPSON Complete line of tubes, tools and electronic supplies FREE CATALOG alternators, generators, ignition coils, FORDHAM RADIO SUPPLY CO., INC. voltage regulators, and other auto built-in loudspeaker. An accessory Morris Ave., Bronx, N.Y. devices. A DC electrolytic battery - is power supply available to convert Tel: (2121 585-0330 power filter is for AM/FM radios and the radio to 110 -volt AC base station tape decks, and the sixth unit is an operation. For More Details Circle (16) on Reply Card AC power -line filter for fixed base - The Messenger 121A is covered by station applications. Johnson's one-year parts and labor For More Details Circle (46) on Reply Card warranty. Suggested retail price is $99.95. For More Details Circle on Reply Card need (48) berts? Video Modulator

Video signals from a TV camera are .0(:)04-e applied to a VCM-4924 modulator (manufactured by Blonder-Tongue), and the modulated -carrier output RF connected to a MATV system in home or apartment. The camera picture can The Good be tuned -in by TV receivers connected to the system, by the usual way. Neighbor 0 is you Standard and special belts and tires ready for immediate ship- ment - fit over 3,000 new and obsolete makes of tape recorders, projectors, dictating machines, video recorders, and turntables. Simplified cross ref- Red1111111 Cross erence system makes ordering The modulator has a vestigial- easy with one day service on sideband filter, has good response wheels, suitable for either monochrome or most items. Drive tires, color, and can be used on any Belong. phono idlers also listed. Call or standard VHF channel. Price is $99 write for free catalog. without crystal control, or $136 with DEALER INQUIRIES INVITED. crystal control. PROJECTOR -RECORDER For More Details Circle (47) on Reply Card BELT CORP. 319Whitewater St., Whitewater, March, 1976 WI 53190 - (414) 473-2151 For More Details Circle (17) on Reply Card www.americanradiohistory.com (Continued from page 44) hundreds of Tetrad type needles, thus Car Stereo reducing stock requirements. It's Model JS -8120 is an AM/FM/MPX tape heads in reel-to-teel, cassette, or available with either diamond or 8 -track in -dash car stereo by Jet cartridge tape recorders and players. sapphire tips. Sounds. Magnetized heads cause noise, hiss, For More Details Circle (51) on Reply Card high -frequency loss, and harmonic distortion. The demagnetizer consists of a line -operated coil with a metal core Deck Tester that extends out of the plastic Aspen has introduced a "Deck housing to form a tip. This tip is Tester", a simplified way of evalu- plastic -covered so it will not damage ating all 8 -track cartridge players. tape heads. The plastic case is Recorded test and voice instruc- flame -retarding and impact -resistant. tions are simple and clear. A tape speed test can be timed over a six -minute period, or the correct It features a 4-3/4" short chassis, a speed can be determined immediately slide bar for easy AM -to -FM switching, local -distance switch, -in- by comparing Middle A of a musical and dial door. The control 160 instrument with the test tone. Also shafts adjust to mm for full-size domestic cars. With included is a right and left speaker side test, and a speaker -rattle test. The the extension, the unit will fit into virtually all domestic im- speakers are electrically thrown in and and out of phase so the listener can ported cars. easily hear the difference. Additional features on the JS -8120 Wow and flutter, head alignment, include an on/off switch, balance, worn head and cross -talk problems volume, tone, and manual -tuning con- Model R25013 lists $8.50, Model at can be detected. trols as well as stereo indicator light R25015 at $11. and illuminated indicators. The Deck Tester lists for $6.98. track For More Details Circle (49) on Reply Card Suggested retail price of the Model For More Details Circle (52) on Reply Card JS -8120 is $89.95. For More Details Circle (54) on Reply Card Trumpet Driver Atlas Sound has a third high -power, Speaker System mid -range compression driver in its Radio Shack has available a 4000 Custom Sound series. moderately -priced theatre -type speak- Automatic Pager Model 4030 driver produces 122 dB er system, the "Realistic Mach One". An electronic instrument that auto- of sound at 30 watts RMS, within a matically links telephones through frequency range of 500 Hz to 7000 Hz. paging computers to personal pagers The 4030 is suitable for use with has been introduced by Gimix. any 1-3/8"-18 female -thread sectoral, The Gimix "Auto Page" fits under reflex or multi -cellular horn having a an office telephone and works with 500 Hz cut-off, or as a component of any answering machine or answering full -range speaker systems. service and paging system. It can be pre-set to page on every message, or only on messages of certain lengths- emergencies, for example, in which callers are instructed to keep talking for at least 20 seconds to activate the

The speaker features a 15 -inch acoustic -suspension woofer with brass voice coil, 4 -cell midrange horn, and a The driver incorporates a self - high -compliance horn tweeter. Re- aligning, field -replaceable, 2 -3/4" - sponse is given as 20-25,000 Hz, and diameter diaphragm/voice-coil with a the Mach One is said to be able to nominal impedance of 16 ohms. Coded handle 100 -watt musical peaks. screw -terminals facilitate proper Midrange and tweeter level con- phasing of amplifier -wiring and multi - trols can be adjusted to suit the speakers. acoustics of any room, and there is a For More Details Circle (50) on Reply Card special L -C crossover network. A removable grille allows custom installation. pager system. If the paging service Phonograph Needle The "Realistic Mach One" is priced lines are busy, the "Auto Page" will The new UNATET N1776 phono- at $199.50. graph needle from Astatic replaces For More Details Circle (53) on Reply Card (Continued on page 50)

48 ELECTRONIC SERVICING

www.americanradiohistory.com uflototict m

BROADMOOR bookuii 2412 B W 1549-1 GENERAL ELECTRIC Chassis 12XB, 15XB 1561-1

Fundamentals of Electronic Devices HITACHI 1-48 Author: David A. Bell 1-28, 1557-1 Publisher: Reston Publishing Company, Inc.. J C PENNEY P.O. Box 547, Reston, Virginia 22090 4901 UA, 4902UA, 4906UA, Size: 467 pages 4914UA, 4915UA, 4916UA 1548-1 Price: $15.95 hardbound Bell's book covers many important electronic MGA devices in general use today, and gives the reader CS -130C 1551-2 an understanding of the characteristics, parameters, circuit applications, and limitations of PANASONIC each device. The author shows how to design a Chassis ETA -10A 1561-2 circuit, estimate circuit gains and impedance, and SANYO analyze practical transistor circuits by h -para- Chassis SF -74000, SF -76000 1563-1 meters. A logical division of chapters covers vacuum tubes, the pentagrid converter, the SEARS modern CRT, zener diodes, UST's, SCR's, and 562.50172500, 562.50730500 1563-2 IC's, as well as tunnel diodes, thermistors, and liquid -crystal cells. Many examples are included SONY to introduce the reader to applications of the KV -1520R (Ch. SCC-25C-B) 1557-2 device under study. A glossary of important terms and a set of review questions are provided at the end of each chapter. The Closed -Circuit Television Handbook, Third Money Generator Edition Author: Leon A. Wortman Publisher: Howard W. Sams & Co., Inc., 4300 West 62nd Street, Indianapolis, Indiana 46268 Size: 288 pages, book number 20197 Price: $7.95 paperback Guiding the technician through the basic concepts of closed-circuit television (CCTV) to the GENERATES equipment requirements for an expanding system, this updated edition covers video-tape MONEY FOR YOU! cassette and cartridge recorders, plus hard -to -find It's a DOG FIGHTER, TOO! The Model ATC-10 is much more than a color bar pattern generator. It information on lighting and optics. Cameras, should be called a portable multipurpoee TV diagnostic and servicing aid, monitors, lenses, wiring, microwave relays, servic- but that's too much of a mouthful. We would have nicknamed it the Dog Fighter (instead of the Money Generator), but that might be misinterpreted ing, accessories, and CCTV applications are to mean that it's only useful in the shop. The versatile ATC-10, a portable, moderately -priced instrument, combines the most essential features of a explained in the text with the use of photographs, color bar pattern generator, a TV "analyzer," and a substitute tuner plus schematics, tables, and drawings. several brand new "dog fighting" and timesaving innovations. With all this extra versatility, however, the ATC-10 is human engineered with only four simple -to-master controls. Contents: What Is Closed -Circuit TV?; Cameras; Two illustrated brochures describe the ATC-l0. The first brochure describes Monitors; Expanding the many unique and unusual features which make the ATC-10 a "dog the System; Video Record- fighter" and a time-saver. The second brochure compares the money -making ing Techniques; Closed -Circuit TV in Education; potential of the ATC-10 with 18 competitive models. It includes a comprehensive chart which compares the features of 19 makes and models, lists Closed -Circuit TV in Commerce and Industry; the estimated timesaving potential of these 33 respective performance features, and then calculates the money making potential of the various Closed -Circuit TV in Research, Medicine, and models. We think you are in for some surprises, such as the potential of Military and Public Service; Lenses, Lighting, the ATC-10 for returning its $299.95 purchase price in as little as three or four months. and Wiring; Microwave Relays; Circuits and These brochures are yours for the asking - write direct for immediate reply. Service. American Technology Corporation 225 Main, Dept. 3A, Canon City, CO 81212

For More Details Circle (18) on Reply Card March, 1976 49

www.americanradiohistory.com (Continued from page 48) All models feature heat -proofed voice coils, compliant foam edge rolls continue re -dialing until the radio and heat -set epoxy bonds between the atea systelis signal is sent. Human handling of voice coil form and the cone. One telephone calls for paging is not °3róß necessary because the "Auto Page" These features supplied by the can link the answering machine di- manufacturers are listed at no -charge computers. to them as a service to our readers. rectly to paging If you want factory bulletins, circle the For More Details Circle (55) on Reply Card corresponding number on the Reply Card and mail it to us. Outdoor Speaker The Kriket KC -45 outdoor speaker is the newest voice communications product available from Acoustic Fiber TV Signal Indicator Sound Systems. "Levelite", developed by Jerrold It features the patented Working model has a 3" co -axially -mounted Electronics, quickly indicates whether Wall enclosure, a patented, cross - tweeter. The entire series consists of the total TV signal level from a laminated, tubular fiberboard con- 4 speakers and 6 kits. MATV system or home antenna is struction. Sound is controlled and For More Details Circle (58) on Reply Card sufficient for good reception or not. distortion is reduced. This small, hand-held test unit has Telephone Recorder two Light -Emitting -Diode (LED) indicators. One LED lights in red to show "Multi -Tele Recorder" is a fully self-contained recorder adequate power from the 9 -volt automatic, battery. Brightness of the red LED is available from Goodrich Products. It determined by the amount of signal, connects easily to any telephone, and and the setting of the "DISTANT - LOCAL" sensitivity switch. In the distant position, the green LED barely glows at -6 dBmV, and shines with full brightness with -2 dBmV of signal. Local sensitivity is + 6 dBmV when the LED is dim, and + 10 dBmV when it's bright. Thus, the Levelite gives an approximate reading of total signal level. Bandwidth has been restricted to Channels 7 through 13 to prevent false readings Built for mounting on external from strong FM signals. boats, sports vehicles, or tractors, only starts when your phone is used. five Input signals are amplified and the KC -45 is said to be the first It will record up to lines as to provide a DC voltage, acoustically -designed weatherproof selected, and does not interfere with detected telephone operation. which drives the green LED. Adapt- It is crafted with an impact - speaker. ers are included for connecting "F", resistant, Duralex cover. Suggested retail price of the Multi - Tele Recorder is $99.95. "G", autoplug, and 300 -ohm fittings at For More Details Circle (56) on Reply Card For More Details Circle (59) on Reply Card any point of an antenna system. The Levelite L-200 tester comes in a padded carrying case that has a belt Stereo Headphones Phone -Answering System clip, and sells to dealers for $47.50, Three new stereo headphones are Ford Industries announces its less battery.

offered by the Calectro Division of GC "Code -A -Phone" Model 222, an auto- For More Details Circle (61) on Reply Card Electronics. matic answering-and -recording system They connect to amplifier outputs designed for home and office use. of 4 to 16 ohms, and feature ad- The Model 222's 20 -minute in- Auto FM Booster justable headbands, removable foam - coming -message tape is voice con- "Stereo One" by the Finney cushion earpieces and a 10 -foot coiled trolled, and shuts off automatically at Company amplifies the FM signal cord with stereo plug. without affecting AM performance, to For More Details Circle (57) on Reply Card minimize flutter and signal fading during FM -stereo reception in autos. The on/off control unit mounts on Powerful Auto Speakers the dash; the amplifier section is A new auto speaker series, the connected in series with the original "Pyle Drivers", has been announced antenna cable, and it mounts near the by Pyle Industries. auto radio. The most powerful model of the FM signal strength is tripled, series is a 6" x 9" with a 61/2 -pound the end of the caller's message. It's according to the manufacturer, and magnet structure and 1'/z" voice coil. designed for announcements up to 28 "Stereo One" should not overload Pyle claims this to be the heaviest seconds in length. even with strong local signals. In- magnet structure and the largest The new unit is small and compact stallation is said to take only a few voice coil ever offered to the auto- and has a built-in speaker and minutes, with instructions and mount- motive speaker market. It will handle microphone. ing hardware furnished. 100 watts of peak power. For More Details Circle (60) on Reply Card For More Details Circle (62) on Reply Card

50 ELECTRONIC SERVICING

www.americanradiohistory.com 4 -Way Amplifier/Splitter Long -Range mizing the effects of terrain problems. Ava Electronics offers Model A515- CB Antenna "Overlord" antenna by Pearce -Simp- 4UV, which is a VHF/FM/UHF son is constructed of white fiberglass amplifier with a built-in 4 -way splitter. A mobile CB antenna 102" high is for strength and visibility, and ma- Bandwidth is said to be between 50 said to increase the range by giving a chined -brass fittings. MHz and 900 MHz, with 75 -ohms better signal-to-noise ratio, and mini- For More Details Circle (66) on Reply Card input impedance and 75 -ohms to each of the splitter outputs. Powered from TV Bandpass Filter

Model BPF-A single -channel band- tude of trapped carriers is -60 dB. pass filters provide a high rejection of Impedance is 75 -ohms input and signals outside the channel. They are output, and the cable connectors are 120 volts AC through an isolation available from Blonder -Tongue for all "F" type. transformer, Model A515-4UV can be low -band, mid -band, and high -band These bandpass filters are intended used with as many as 16 TV receivers VHF TV channels,. The number for MATV and CATV systems to in a MATV system. following BPF-A indicates the correct minimize interference from adjacent The amplifier lists for $49.95. channel. channels, and should be added before For More Details Circle (63) on Reply Card Bandpass is 5.3 MHz ±.3/4 dB for single -channel amplifiers. channels 2 through 6, and the ampli- For More Details Circle (67) on Reply Card All -Weather Couplers A new line of passive all-weather Base -Station CB Antenna TV/FM signal -reception and distribution devices is offered by Jerrold A quarter -wave vertical radiating The assembly includes built-in Electronics. element and three quarter -wave lightning protection, 50 -ohms im- Model 3001 is a transformer -type radials to produce an elevated ground pedance with a SO -239 connector, 2 -set coupler; Model 3007 separates plane (artificial ground) are features high -impact molded base, shunt - FM and TV signals; Model 3008 of the Model 11-101 omni-directional loaded beta -match element, and combines the outputs of yagi and permanent, 27 -MHz antenna offered mounting hardware. broad -band antennas to a single down- by Breaker. For More Details Circle (68) on Reply Card lead; Model 3014 divides VHF and UHF signals at 300 -ohms; Model 3014-75 is the same as Model 3014, except for 75 -ohm operation; Model

3016 combines the signals from hi - band VHF and low -band VHF antennas to a single downlead; and Models 300TT20-2 through 300TT20- 13 are traps giving 20 -dB attenuation of a single VHF channel while passing the others.

For More Details Circle (64) on Reply Card

High -Pass Filter/Transformer Functions of a high-pass filter and a 75-to -300 -ohm matching transformer are combined by RMS Electronics in the Model 2600F. The filter action minimizes interference from CB or amateur -radio transmissions, as well as other carriers and noises. This transformer, which has an "F" connector at the 75 -ohm input and twin -lead with lugs at the 300 -ohm output, replaces a conventional balun transformer. Attenuation between 5 MHz and 35 MHz is said to be 28 dB. A wide variety of output connectors are available for use in MATV systems.

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March, 1976 51

www.americanradiohistory.com recorder -care products. Also in- mounting hardware, tools, hook-up flJllfl cluded is a bibliography of helpful wire, intercoms, audio connectors, cataloos rm books for those who wish to learn and decorator telephones. Circle appropriate number on more about tape recording. Reader Service Card. 110. Mountain West Alarm Supply 105. Tektronix-the 48 -page cata- -has a free 96 -page A-76 "Alarm log number A-3183 contains up-to- Equipment Catalog", which de- date data on new TM500 products, scribes more than 500 intrusion and 100. Jensen Tools and Alloys-of- such as the SC502 dual -channel fire -alarm products, many UL fers a free 112 -page tool catalog de- oscilloscope and TM515 Traveler listed. An informative alarm equip- scribing over 2,500 individual items. Mainframe. It also contains full ment application guide (which in- Sections include hand tools, power specifications on the more than 30 cludes general alarm -system dis- tools, metalworking tools, soldering TM500 plug-in modular instru- cussion, basic installation pro- equipment, optical equipment, test ments, and features thirteen articles cedures, and connection diagrams) equipment, and electronic chemi- discussing instrumentation tech- is a featured section. This selection cals. Also featured is a solder nology. of alarm equipment is complete section. from simple kits to the latest ultra- 106. Hickok-has a free 16 -page sonic, radar, and infrared detectors. 101. Channel Master-has available catalog describing its full line of El a UHF antenna catalog. Nine UHF portable and bench test instru- antenna types designed for color ments. Products covered include TV are described and illustrated. single- and dual -trace oscilloscopes, ONE' SE VENTH Sixteen models are shown, plus a digital multimeter, a function various special designs and combi- generator, a curve tracer, FET OF YOUR nations. The brochure covers an- multimeters, semiconductor testers, tennas for every type of reception color -bar generators, tube testers, a area, in all price ranges, and in- CRT tester/rejuvenator, and a EMPLOYEES cludes performance data. sweep -and -marker alignment generator. Features, operating data, and MAY BE DYING. 102. Hewlett-Packard-a 32 -page complete specifications are given brochure-the "Pocket Calculator for each unit. Buyer's Guide"-describes and HELP SAVE gives specifications for the compa- 107. Cleveland Institute of Elec- ny's full line of preprogrammed tronics-offers a 40 -page, four-color THEIR LIVES. and programmable pocket calcula- catalog covering independent home - High Blood Pressure is the tors. The free brochure, #5952- study courses, and containing a 24 - country's leading contributor to 6062D, also includes a complete page section which details each of heart disease and kidney listing of HP pocket -calculator ac- CIE's 13 electronics -training pro- stroke, cessories, support literature and grams. Each course is outlined with failure. Any of which can kill. prerecorded programs. course objective and listing of sub- And, one out of every seven jects covered. Other departments of your workers has it. Half have around 103. Audiovox-offers a free speak- include: information about career no idea they're walking with this time bomb inside them. er application chart. The three - opportunities in electronics; facts color specially -coded chart unfolds on CIE's background and school/ But you can help. By giving a chance to into a 17" X 21" poster for easy student relationship; and an outline your employees interpretation. The chart is de- of the school's employment as- check their blood pressure. Your signed to show the recommended sistance program. own medical or nursing per- speakers and available locations for sonnel can do the job, simply. import and domestic cars back to 108. Shure Brothers-expanded and To help you implement this 1970. It lists the speaker type, updated catalog of Shure pro- life-saving program, we have a dimensions, kit number and mag- fessional products for broadcasting, special kit, "Guidelines for High net weight of the mini, in -door, recording, and motion pictures lists Blood Pressure Control Programs Industry." in -deck, surface, convertible and Shure microphones, audio compo- in Business and coaxial speaker models. nents and accessories, and high- Write to: National High Blood fidelity phonograph cartridges. In- Pressure Education Program, 104. Nortronics Company-has cluded in the free catalog are speci- 120/80, National Institutes of available the 7th edition of its fications and individual per- Health, Room 1012-Landow Bldg., "Nortronics Recorder Care Manu- formance profiles, as well as data Bethesda, Md. 20014. al." It shows step-by-step, illus- about installation. trated methods for maintenance of recording machines and the proper 109. Saxton Products-the 52 -page method for splicing tape. A new catalog features coaxial and twin - HIGH BLOOD PRESSURE. feature of the current edition is a lead cables for CB, amateur radio, Treat it...and live. revised catalog section of consumer and television use, plus antenna -

52 ELECTRONIC SERVICING

www.americanradiohistory.com a 11

Solution to: OHMWARD BOUND!

1 ZinC 18 FeedeR 2 CemenT 19 RectangulaR 3 ThermioN 20 RipplE 4 NorM 21 EpoxY 5 MetriC 22 Yagl 6 ChaD 23 IroN 7 DaraF 24 NeutraL 8 FemalE 25 LayouT 9 ExhausT 26 TraceR 10 TwisT 27 RemotE 11 TensioN 28 ElectreT 12 NewtoN 29 TangenT 13 NulL 30 ToroiD 14 LoudnesS 31 DiopteR 15 SeptuM 32 RubbeR 16 MosaiC 33 Rating 17 CloverleaF "Why not be a good sport and let him fix Start with 132 points and deduct what he thinks is wrong with it?" 4 points for any part you may not have answered correctly.

Your rating: 68 - 80 Well -I -I -I -I. 84 - 96 Pretty good. 100 - 112 Very good. 116 - 128 Excellent. 132 PERFECT! Stop in and we may let you treat us to coffee and...

Audio Test Answers (Continued from page 24)

1. (B) 11. (A) 21. (A) 2. (B) 12. (A) 22. (B) 3. (B) 13. (B) 23. (A) 4. (B) 14. (B) 24. (A) 5. (A) 15. (B) 25. (A) 6. (B) 16. (A) 26. (A) "...And it will allow your wife to ruin a roast 7. (A) 17. (B) 27. (A) in one-fourth the time it used to take her." 8. (B) 18. (A) 28. (B) 9. (A) 19. (B) 29. (A) 10. (B) 20. (B) 30. (B)

FREE ALARM CATALOG Huge selection of burglar & fire sys- , -ÿ terns, supplies. Motion detectors, infrared beams; controls, door switches, bells, sirens. 500 items, 99 pp. packed with technical details, notes. (Outside U.S., send $1.00.) mountain west alarm 4215 n. 16th st., phoenix, az. 85016 For More Details Circle (20) on Reply Card ANTENNAS FIELD -ENGINEERED and TESTED APPLIANCE REPAIR BOOKS in your area Written in easy -to -understand language by experts with ,.ius - t rations 6 diagrams Acclaimed by Instructors & profession- als. How to diagnose 8 repair air conditioners refrigerators. FOR vacuum cleaners, ranges. washers. dryers. steam Irons. port- YOUR AREA able kitchen appliances. wafer heaters; plus how to set up a shop. using test instruments and more Only $2.65 to 64.90 each! CALL or WRITE: SEND FOR FREE DESCRIPTIVE PRICE LIST ACA, P. 0. Box 865, Burlington, IA 52601 Phone: 319/753-1625 C & N, DEPT. ES, 5841 MONTROSE, CHICAGO 60634

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www.americanradiohistory.com It The MARKETPLACE FOR SALE (CONT.) º:,. STOP...don't junk that television set. ASE manu- advertisers' U facturers the world's most complete line of television picture tubes. No other company offers: section is available to This classified Over 1700 types of television picture tubes. Most American Technology electronic technicians and owners or types immediate delivery. Transportation in the Corporation 49 Midwest 1/2 transportation paid in other managers of service shops who have for -paid, states. Tubes for Old or New Models. Complete Antenna Corporation sale surplus supplies and equipment or line of both black & white and color. Full 2 year anywhere. Finest 53 who are seeking employment or recruiting factory warranty. Lowest prices of America today for more information. Allied quality. Write B & K Div., Dynascan employees. Sales & Engineering, Inc., Dept. 27, Pimento, Ind. 47866, Telephone - 812-495-6555. 2-76-2t Advertising rates in the Classi- Corporation 1 fied Section are 35 cents per FOR SALE: Philco Model 89, code 121 radio, one Bussmann Mfg. Div., must tube missing. R. Auman, Box 3, Millheim, Penn. word, each insertion, and Trans- McGraw -Edison 3 cash to 16854. Free for Parts: One "Corsair 11 be accompanied by mitter/rec." Pay Shipping Costs. Hudson Ameri- Castle Electronics, Inc. Cover 4 insure publication. can Corp., New York. 3-76-1t Charous & Niebergall 53 SAMS -1176 through 1479 plus over 50 others, Each initial or abbreviation $695. B&K 415 Sweep marker generator, $295. Chemtronics Incorporated 13 counts a full word. B&K 1460 triggered oscilloscope with new Inc. 13 CRT -needs repair, $175. Entire package, $1100. Dana Laboratories, Jim Anderson, RR2, Box 93E, Beckley, W. Va. Fordham Radio 47 Minimum classified charge $3.00. 25801. 255-1501. 3-76-1t Gem City Tuner 10 For ads on which replies are TELEPHONE MONITOR: Record business, conversations automatically. Limit un- General Electric Company 12 sent to us for forwarding (blind personal authorized calls! Also, PORCELAINS! TOYS! Heath Company 16 ads), there is an additional GIFTS! JEWELRY! 30% OFF, postpaid! 171 -page charge of $3.00 per insertion to catalog, $2. ES3, Box 192, Griffith, In 46319. Hickok Electrical 2-76-2t cover department number, pro- Instrument Co. 45 of replies, and mailing cessing 14 costs. Lectrotech, Inc EDUCATION -INSTRUCTION Mallory Distributor Products 17 Classified columns are not open REPAIR TV TUNERS -High Earnings; Complete Motorola Training Institute 43 to advertising of any products Course Details, 12 Repair Tricks, Many Plans, by manufac- Two Lessons, all for $2. Refundable. Frank Mountain West Alarm regularly produced Redding, Calif. no Bocek, Box 3236 Enterprise, turers unless used and 96001. 10-75-61 Supply Co. 53 longer owned by the manufac- with a copy Precision Tuner turer or a distributor. TV PROBLEMS??? Send symptoms of schematic and self-addressed stamped en- Service Cover 2 velope and $2.00, to Troubleshooter, Box 4553, Downey. Ca. 90241. Results Guaranteed. 9-75-tf Projector -Recorder Belt Co. .47 RCA Distributor and Special 11 FOR SALE BUSINESS OPPORTUNITY Products W. Sams & Add color tele- Howard ADVERTISING PACKAGE FOR TV service shops. DEALER INQUIRIES invited. sales. Send for 7 Inexpensive eye catching ads contain personal phones and accessories to your Company, Inc. business letterhead. message from you -build customer confidence. additional information on Richmond, VA. Sperry Tech, Inc 16 your name before the public weekly. Telectra Sales, Box 9218 -ES, Keeps 2-76-3! PROVEN RESULTS. Thirty ads with instructions 23227. GTE Sylvania - $19.95. Sample $1.00 refundable. TV TIPS, 430 repair and update master South Jefferson, Lebanon, Mo. 65536. 11-75-81 TV SHOPS -Needed to Consumer renewal 9 antenna systems with new patented method. I You will be one of 44 NEW Canadian Magazine "Electronics Work- will train you. No competition. Tab Books technical shop". $5.00 yearly. Sample $1.00. Ethko, Box a select number directly under my Send resume and Tuner Service Corporation ....5 741, Montreal "A" Canada. 10-75-12t assistance by WATS telephone. credit references: Melvin Cohen, Television Winegard Company ....Cover 3 CONVERT any transistorized T.V. tuner to a tuner Broadcast Engineer, May Company Building, substituter. Plans $2.00. New accelerated Radio 3651 Prospect Avenue, Riviera Beach, Fla. 33404. & T.V. course. RADIO TELEVISION TRAINING, Enclose 13 cents addressed envelope. Be patient Box 279, ES -36, Syracuse, N.Y. 13206. 8-75-tf for my reply. 11-75-6t

TEKTRONIX SCOPES -Hewlett-Packard genera- INCREASE SERVICE PROFITS -Avoid consumer tors, other test and electronic equipment parts, problems. Business Manual tells how. Contract tubes, "ham" supplies, surplus, and older parts. Manual shows how to get paid before you service ELECTRONIC SPECIALTIES, 1659 W. Wetmore, and hold customers. Either book $15.00, both Tucson, Az. 85705. (602) 887-9729. 1-76-12t $25.00. NATESA, 5908 S. Troy, Chicago 60629. 2-76-3t TELLPHUNL MONITOR! ficuord business, personal conversations automatically. Limit un- TV SHOPS: Qualify for my telephone assistance authorized calls! Also, PORCELAINS! TOYS! to solve your "Tough Dog" TV repairs that waste GIFTS! JEWELRY 30% OFF, postpaid! 171 -page bench space. Send resume and credit references: catalog, $2. ES2, Box 192, Griffith, IN 46319. Melvin Cohen, Television Broadcast Engineer, 2-76-2t May Company Building, 3651 Prospect Avenue, Riviera Beach, Fla. 33404. Enclose 13 cent REJUVENATE TV Picture l ubes without expen- addressed envelope. Be patient for my reply. sive equipment. Use clip leads in power from set 3-76-21 1 and tube manual. Plans $5.00; W. R. Collins Jr.; 4 TC BDE PPO APO, NY, NY 09451. 2-76-2t CALIFORNIA BOUND? Take over established TV/HiFi shop on easy terms. Nets $20,000+. COLOR TELEPHONES -New American made Box 157, Palo Alto, 94301. (415) 327-5320. 3-76-3t with one year warranty. Free information or send $1. for color digest and prices. Telectra Sales, s. Box 9218 -ES, Richmond, VA. 23227. 2-76-3t WANTED The American OLDER & OBSOLETE Radio and TV tubes all new part Red Cmross. and boxed. We have several thousand. Send for NEEDED: Flyback for R.C.A. Chassis CTC9, The Good L. Cantrell, 205 N. Donley St., Tulia, list & prices. Garrett, P.O. Box 2055, San Diego, #106359. R. Neighbor. California 92112. 2-76-2t Texas. 79088. 3 -76 -lt Rep. of Ohio. FOR SALE: B&K Alignment generator. Model WANTED: Factory Sales for state 415, perfect -$300.00. Telesonic TV, 173 Lexing- Rebuilt TV picture tubes and special purpose ton Ave., Mt. Kisco, N.Y. 10549. (914) 666-3902. C.R.T. Contact Newlon Electronics, Inc., 401 Ash 3 -76 -lt St., Willard, Ohio. (419) 935-5175. 3-76-1t

ELECTRONIC SERVICING 54

www.americanradiohistory.com 1 II

elJohn Buckner, independent installer says: Winegard Chromstar has proved it does a beautiful job:'

WINEGApD ' @orciu Enetpail

These statements are from John A. Buckner, "... quality of Winegard products, President of Buckner Co., Lyndon, Kentucky, who ... far surpasses other brands ..." adds in his letter,* "We have a unique situation in the Louisville area, with all television signals "We depend on the Winegard Chromstar coming from a ridge west of town, and their power Antenna for quality color reception." output varying greatly. We have two VHF stations -Ch. 3 and 11- and four UHF stations- Ch. 15, "... tremendously pleased with the 32, 41, and 68. We must cover a broad range of signals, and an even wider variation of power out- reception the Winegard Chromstar put levels from these stations. The Winegard antenna gets in our area." Chromstar antenna has proved to us and our customers that it does a beautiful job." Get all the facts from your Winegard Distributor. you on request. Free Spec Charts on all models. *A copy of Mr. Buckner's letter will be sent to LOOK TO CHROMSTAR FOR QUALITY AND PERFORMANCE

CH -7080 CH -9085 VHF -UHF -FM UHF only r1 1111.11..7 WINEGARD®COMPANY 3000 Kirkwood Burlington, Iowa 52601 TV ANTENNAS MORE PEOPLE LOOK UP TO. For More Details Circle (2) on Reply Card

www.americanradiohistory.com The Timer People

... offer something New

Custom Service ... for the Professional

Yes! Castle, the pioneer of TV Tuner overhauling, gives you 25 years of expertise and professional experience behind every tuner processed under our new Custom Service.

Each order is handled on an individual basis with documentation of performance and service recorded for each tuner. This Custom Service guarantees you expert analysis of the tuner; precise, skilled alignment ... and no harmful, unusual cleaning processes. Your need to return for further service in warranty is reduced to an absolute minimum ... when you receive the tuner under Castle's Custom Service you know that it is right!

What does this Custom Service cost? Castle Custom Overhaul Service. Individual overhauling of any TV Tuner, tubes and transistors extra. $12.95 Send defective tuner only to Castle, remove ALL accessories.

Castle Custom Stock Replacement Tuners. Engineered by Castle to provide exact replacement ... giving original, or improved performance. Purchase outright - no exchange required - send for list of tuners available. $17.95 Castle Custom Exchange Replacement Service and Custom Rebuilding. This is a custom service offered when the original tuner is unfit for overhaul and a Castle Custom Stock Replacement is not available. Each tuner is exchanged for an exact replacement tailored to custom order; or the original tuner is professionally rebuilt to perform to original specifications. All inclusive price. VHF $21.95 UHF $17.95 REMEMBER ... Castle Custom Service is as near as your Post Office. All prices are f.o.b. our plant. We will ship C.O.D. CASTLE TV TUNER SERVICE

5701 N. Western Ave., Chicago, III. 60645 Ph. (312) 728-1800

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