Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. FEBRUARY 1960 VOL. 2 NO. 2 SPECIAL COMPONENTS IN TELEVISION RECEIVERS An examination of the so-called "special" capacitors listed in television service manuals today is apt to prove very confusing to the average serviceman. This is understandable, unless he has taken the trouble to investigate the significance of the various designations which are used. The natural outcome of this condition results in the use of some capacitor close to the specified value, which happens to be handy and is assumed to be "just as good". This practice frequently leads to the addition of a new fault in the receiver although it may have corrected the original problem. When a manufacturer specifies a particular type or characteristic for a capacitor, he has excellent reasons for doing so. As a ser- viceman, if you replace one of these components with an improper unit, you are in some manner degrading the performance capabiliuies of the receiver and, at the same time, you are not doing the proper job for your customer. A few of the problems which may be intro- duced by this practice are: 1. Regeneration or oscillation in I-F or R-F circuits. 2. Loss of sensitivity at certain frequencies. 3. Frequency drift in critical circuits. 4. Changes in some performance factors with changes in operating temperatures. There are several designations which may be applied to "special" capacitors, and which may require some clarification. The most commonly used designations and their meanings are listed below. Designation Type Capacity change with increased temp. HiK Tubular Up to 50% change Disc Feed Thru Semi-HiK Tubular Up to 35% change Disc Semi-Stab. HiK Tubular Up to 15% change Disc Stab. HiK Tubular Up_ to 7 1/2% change NPO Zero change N750 Negative temperature co-efficient of 750 parts per million, per degree increase P100 Positive temperature co-efficient of 100 parts per million, per degree increase P100-N750 Range from positive 100 to negative 750 parts per million, per degree increase Tv SERVICE MANUALS FOR 1960 1 AMUST FOR EVERY G-E TV DEALER AND ALL SERVICEMEN... EACH SERVICE MANUAL CONTAINS: • . SCHEMATIC DIAGRAMS Complete with waveforms and voltages .. • . COMPONENT LOCATION DIAGRAMS it PHOTOS— clearly locates every component .. ACCURATE ALIGNMENT DATA— Test equipment connec- tions, alignment charts, suggested methods .. COMPLETE REPLACEMENT PARTS LISTS All com4 ponents catalogued and listed for easy reference .. IN ADDITION YOU WILL RECEIVE .. • • Periodic mailings of preliminary and advanced service information presenting current tube and circuit releases • Up-to-date parts price listings •New chapters of "Television Servicing Techniques" • Monthly feature articles in "Service Talk" •Bimonthly copies of "Techni- talk" Subscriptions cover period from yanuary I, 1960 to December 31, 1960. A WEALTH OF MATERIAL FOR ONLY $5.00 AVAILABLE NOW AT GENERAL ELECTRIC TUBE AND TV RECEIVER DISTRIBUTORS4 ORDER YOUR "PLAN D" SUBSCRIPTION" EARLY. Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. MARCH 1960 VOL.2 NO.3 AUDIO BUZZ IN 17 INCH M5 CHASSIS TELEVISION MODELS Residual audio buzz in the 17 inch M5 chassis models may be caused by the leads from the vertical hold control run- ning too close to the volume control terminals. This verti- cal pick-up on the volume control terminals appears as a buzz in the speaker which may be changed in pitch by the vertical hold control. The simple cure is to dress the gray and yellow vertical hold control leads away from the volume control terminals e to eliminate the buzz condition. USE OF 6GH8 TUBE TO REPLACE 6EA8 TUBE IN 4-CHANNEL WIRELESS REMOTE RECEIVERS (M5 AND U4 CHASSIS MODELS) When it becomes necessary to replace the 6EA8 tube in wireless remote receivers for any reason, it is recommended that a 6GH8 tube be used as a direct replacement. The 6GH8 is an improved tube developed to replace the 6EA8 where gain is a factor, This recommendation, as a direct replacement, is only for this one application and not for replacement as a chassis tuner tube. INSTALLING KNOB COMPRESSION RINGS An easy way to place the knob compression ring on a TV knob shank is to use an installation tool available from Snap-On Tools Corporation. This pair of pliers is used to • expand the ring for quick insertion on the knob and bears the Snap-On catalog number 70A. • Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. APRIL 1960 VOL. 2 NO. 4 "U4" Chassis Sync Instability Certain instances of poor horizontal sync stability and a soft vertical hold condition may be traced to the AGC fil- ter capacitor C252. This condition results from the capaci- tor becoming open. When measured with a VTVM, the average AGC voltage may be normal but examining the waveform at Test Point VII (AGC line) shows the presence of the Keyer pulse. The scope should be set to give two waveforms of 60 cycle sync. Fur- ther checking of Test Point IV at the video detector shows an excessively peaked and narrowed sync pulse as shown below. This waveform results from the cancelling of AGC at pulse e time by the keying pulse and therefore produces greatly exaggerated sync spikes which cause the sync instability. The cure for this condition is to replace the capacitor, G-E catalog number WT25X23. The red durez dipped type capa- citor should be used as a replacement rather than those with a black molded case. TV Service Guides New editions of Volume 1 and Volume 2 Service Guides are now being made available. These Guides have been well accept- ed as a reference for service schematics and parts information. • Both volumes have been completely revised and corrected and have a parts cross reference section to convert old catalog numbers to the new "WT" system. Each guide carries a price cf $2.50. Combined, they cover years 1947 thru 1955. • Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. MAY 1960 VOL. 2 NO. 5 M6 Chassis Stepping Relay Service The remote control system, being introduced to the field presently, employs a stepping type relay for volume level sel- ection. It has been noted on some early shipments that the flexible actuating arm of this relay may become stuck during shipping or when the receiver is subjected to a sudden jar. If this condition occurs, it is necessa ry to open the remote re- ceiver chassis and move the flexible arm away from the ratchet wheel to its natural position. This will clear the condition as long as the receiver is not transported. However, to per- manently remove the possibility of a sticking relay, a detector mounting clip (dT3X48) may be installed and soldered to the actuator arm as shown below. It is not necessary to remove the ay from the unit to make this modification. tr Relays now supplied have been modified to prevent future complaint. FLEXIBLE ACTUATOR ARM RATCHET WHEEL The Danger of Anode Grounding Every General Electric receiver carries a label warning persons not to discharge the anode to earth ground. Always discharge the anode lead to the main chassis to prevent shock hazard. Should a bench ground or water pipe be used for grounding, there is a possibility of breaking down the insulation between the primary and secondary of the power transformer. While the defect may not be noticeable in the iperation of the receiver, Whis does remove the secondary iaolaLion and places the chassis at line potential thus creating the ;hock aaz‘ad. Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. JUNE 1960 VOL. 2 NO. 6 Identifying Dual Diodes N The new line of General Electric television receivers employs three dual diode combinations. One is employed as the horizontal phase detector (WT16X7). Two are used in the Sonic Remote Receiver Circuitry, the first as a Signal Detec- tor (WT16X8) and the other as a Bias Rectifier (WT16X9). Phys- ically these diodes appear to be much the same but electrically they differ greatly. The Phase Detector has common anodes, and the Bias Rectifier is series connected. While each diode is plainly marked, a simple ohmmeter check can eliminate any con- fusion with these components. The diagram below shows the measurements taken with a Aempson 260 meter. A VTVM may be used and the polarities of D Illtnduction shown will remain the same; however, the values may differ with meters as is the case of using other VOM types. TOP VIEWS WT 16> 7 WII6X13 wT16X9 E SONIC F.- ASE DETECTOR SIGNAL DETECTOR BIAS RECTIFIER r-fl-f-}<1 fl<rr''h r°F-f-f>E1 COM CON CON 12 K 12 INF I2 —+-- INK NF INK 250e — + COM COM COm SIMPSON 260 METER SET FOR HIGH OHMS (R XI0,000) Tube Saver A note of caution for those not already informed about breakage of new 6CD6 horizontal output tubes on "EE" chassis television receivers. The new design of the glass on the 6CD6GA tube interferes with the tube retainer causing glass breakage. 0 The tube retainer is primarily a shipping security device; tnerefore, it is of little consequence to remove the retainer. Bending the retainer back and forth to break it off is all that is necessary and the new tube will not be subject to damage. Service Talk FROM TELEVISION RECEIVER PRODUCT SERVICE ELECTRONICS PARK SYRACUSE, N. Y. JULY 1960 VOL. 2 NO, 7 SONIC REMOTE CONTROL These corrections and additions to the sonic remote control system alignment, covered in the M6 preliminary 32-2000-60 should be noted.