Instruction Manual 1720/1721 Vectorscope (S/N B060000 & Above) 070-5846-07 Warning The servicing instructions are for use by qualified personnel only. To avoid personal injury, do not perform any servicing unless you are qualified to do so. Refer to all safety summaries prior to performing service. www.tektronix.com Copyright E Tektronix, Inc., 1986, 1990, 1993, 1995. All rights reserved. Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published ma- terial. Specifications and price change privileges reserved. The following are registered trademarks: TEKTRONIX and TEK. For product related information, phone: 800-TEKWIDE (800-835-9433), ext. TV. For further information, contact: Tektronix, Inc., Corporate Offices, P.O. Box 1000, Wilsonville, OR 97070--1000, U.S.A. Phone: (503) 627--7111; TLX: 192825; TWX: (910) 467--8708; Cable: TEKWSGT. WARRANTY Tektronix warrants that this product, that it manufactures and sells, will be free from defects in materials and workmanship for a period of three (3) years from the date of shipment. If any such product proves defec- tive during this warranty period, Tektronix, at its option, either will repair the defective product without charge for parts and labor, or will provide a replacement in exchange for the defective product. In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expi- ration of the warranty period and make suitable arrangements for the performance of service. Customer shall be responsible for packaging and shipping the defective product to the service center designated by Tektronix, with shipping charges prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the Tektronix service center is located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any other charges for products re- turned to any other locations. This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inade- quate maintenance and care. Tektronix shall not be obligated to furnish service under this warranty a) to repair damage resulting from attempts by personnel other than Tektronix representatives to install, repair or service the product; b) to repair damage resulting from improper use or connection to incompatible equipment; c) to repair any damage or malfunction caused by the use of non-Tektronix supplies; or d) to service a product that has been modified or integrated with other products when the effect of such modifica- tion or integration increases the time or difficulty of servicing the product. THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR IMPLIED. TEKTRONIX AND ITS VEN- DORS DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE DE- FECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUS- TOMER FOR BREACH OF THIS WARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAM- AGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NO- TICE OF THE POSSIBILITY OF SUCH DAMAGES. Table of Contents Table of Contents....................................................... i General Safety Summary................................................ viii Preface ............................................................... x Section 1 Introduction and Specification .................................... 1--1 Accessories ............................................................ 1--2 Standard Accessories................................................. 1--2 Optional Accessories................................................. 1--2 Options ............................................................... 1--2 CRT Options........................................................ 1--2 Power Cord Options.................................................. 1--2 Safety Information...................................................... 1--3 Specifications .......................................................... 1--3 Section 2 Operating Instructions ........................................... 2--1 Front-Panel Controls and Indicators......................................... 2--1 INPUT ............................................................ 2--2 GAIN ............................................................. 2--2 PHASE ............................................................ 2--3 DISPLAY.......................................................... 2--3 MISCELLANEOUS.................................................. 2--3 Rear-Panel Connectors................................................... 2--4 BNC Connectors.................................................... 2--4 Subminiature D-Type Connectors....................................... 2--5 Power Input........................................................ 2--6 Miscellaneous....................................................... 2--6 Using the 1720/1721 in Auxiliary Mode..................................... 2--6 INPUT Switching.................................................... 2--7 REF Switching...................................................... 2--7 LINE SELECT...................................................... 2--7 STORE ............................................................ 2--7 RECALL .......................................................... 2--7 Measurement Applications................................................ 2--14 Color Measurements................................................. 2--14 Functional Use of the Vector Graticule...................................... 2--18 Measurement of Color Bars............................................ 2--18 Differential Gain and Phase Measurements............................... 2--20 X Y Measurements...................................................... 2--22 Making Stereo Audio Phase Measurements............................... 2--22 Looking at Incidental Carrier Phase Modulation........................... 2--23 Service Safety Summary................................................. s--1 Section 3 Installation ..................................................... 3--1 Packaging.......................................................... 3--1 Electrical Installation.................................................... 3--1 1720/1721 i Table of Contents Power Source....................................................... 3--1 Mains Frequency and Voltage Ranges.................................... 3--1 Operating Options................................................... 3--1 X Y INPUT Connector............................................... 3--1 Auxiliary Connector.................................................. 3--3 Mechanical Installation................................................... 3--4 Cabinetizing........................................................ 3--4 Securing the Instrument in its Cabinet................................... 3--6 Rack Mounting...................................................... 3--7 Custom Installation.................................................. 3--9 Section 4 Theory of Operation ............................................. 4--1 Overview .............................................................. 4--1 Block Diagram......................................................... 4--2 Video Input......................................................... 4--2 Luminance Processing................................................ 4--2 Microprocessor...................................................... 4--2 Gain Cell .......................................................... 4--3 Chrominance Processing.............................................. 4--3 Demodulators....................................................... 4--4 Output Amplifiers................................................... 4--4 CRT Blanking...................................................... 4--4 Circuit Descriptions..................................................... 4--5 DIAGRAM 1 INPUT AND DEFLECTION AMPLIFIERS....................... 4--5 Video Input Amplifiers............................................... 4--5 Gain Cell .......................................................... 4--6 DIAGRAM 2 SUBCARRIER REGENERATOR............................... 4--6 Reference Switch.................................................... 4--7 Luminance and Chrominance Amplifiers................................. 4--8 Sync Separator...................................................... 4--8 Bowes Oscillator.................................................... 4--8 Back Porch Sample.................................................. 4--8 Loop Phase Detector and Amplifier..................................... 4--8 Quadrature Phase Detector and Amplifier................................. 4--9 Burst Clamp........................................................ 4--9 Lock Detector and Bandwidth Switch.................................... 4--9 Error Amplifier..................................................... 4--9 PAL Phasing........................................................ 4--10 VCXO ............................................................. 4--10 DIAGRAM 3 DEMODULATOR........................................... 4--11 V-Axis Switcher..................................................... 4--11 Chrominance