February, 1979 Electronic servicing - RADIO and ......Radio Supply Co., Inc. (316) 267-5216 MARYLAND...

February, 1979 $2.25

Electronic servicing

L'''5 TM 4AJ' JfliIv76 xr9qtl-zi 74r7 r -7W9

7 T V-199(17/L6TT.9

The last timeyou saw a reallyiewbench/portable DMM was 1972.

That's the year our 8000A wasintroduced. Its custom LSI and solidowner benefits quickly establishedit as the world's leading DMM.

Now, look at the new 8010Aand 8012A: single -chip CMOS de-signs for problem -solving in theeighties!

RAZOR- SHARP LCD for large,no -strain answers at first glance-in any light.

TOUCH AND HOLD probeoption, so you can thread your waythrough a component jungle andcapture the reading you need.

FUNCTION POWER: 22 rangesof AC and DC volts and current,six ranges of resistance, and threeranges of conductance - the mis-sing function on other bench multi -

meters.CONDUCTANCE RANGES

for noise -free leakage measurementsto 10,000 M(1. A valuable functionfor bench -testing boards and com-ponents, conductance also meas-ures transistor beta (using a biasresistor) and light intensity (by usinga photocell).

OVERLOAD -PROTECTED-like no other DMM, including re-jection of 6000V transients and upto 600V applied to the current ter-minals.

HONEST AC ANSWERS de-rived from a Fluke hybrid true rmsconverter. You'll even see the dif-ference on your AC line betweenthe correct value and what youraverage -responding meter reads.And 50 kHz bandwidth won't letany significant distortion productsgo unmeasured. Plus, 10 times thebasic response you may be limitedto now!

SPECS YOU EXPECT fromFluke - like ±0.1% on DC for oneyear. Both models available withrechargeable batteries, and backedby the same solid warranty andworldwide service that helped makethe 8000A the industry standard.

LEADERSHIP HAS TO BEEARNED. And we're committedto keeping the price of your confi-dence as realistic as possible. Like$239 for the 8010A with a l0A cur-rent range, and $299 for the 8012Awith two extra -low ohms rangesthat allow measurements from0.0010 to 10,000 MSZ - makingit the widest range ohmmeter avail-able!

Contact one of the more than 100 Flukeoffices and representatives, worldwide, orCALL (800) 426-0361' TOLL FREE. In theU.S., and all countries outside Europe, write:John Fluke Mfg. Co., Inc., P.O. Box 43210,Mountlake Terrace, WA 98043, U.S.A.

In Europe, contact Fluke (Nederland)B.V., P.O. Box 5053, Tilburg, The Nether-lands. Telephone: (013) 673973. Telex:52237.

Prices U.S. only.'.Alaska, Hawaii, Washington residents - please call (206)

FLUKE

For Demonstration Only Circle (1) on Reply CardFor Literature Only Circle (2) on Reply Card

2502-8010

AUTHORIZED FLUKE DISTRIBUTORSFor immediate stock availability of these and other precision Fluke instruments and acces-sories, please contact the Fluke distributor in the following cities. For the location of Flukeoffices and representatives in other areas, please CALL (800) 426-0361 TOLL FREE (Alaska,Hawaii, Washington residents - call (206) 774-2481).

ARIZONAPhoenixLiberty Electronics(602) 249-2232Metermaster(602) 243-4111ScottsdaleBarnhill Assoc., Inc.(602) 947-7841

CALIFORNIAEl SegundoLiberty Electronics(213) 322-8100Los AngelesMetermaster(213) 685-4340Mt. ViewElmar Electronics(415) 961-3611NapaAvionics Assoc., Inc.(707) 252-2121Palo AltoMetermaster(415) 968-0313San DiegoLiberty Electronics(714) 565-9171Metermaster(714) 560-4841Sun ValleyLeasametric(213) 768-4200

COLORADOCommerce CityElmar Electronics(303) 287-9611DenverBarnhill Assoc., Inc.(303) 750-1222

CONNECTICUTMiddletonThe Mancib Company(203) 346-6646FLORIDAOrlandoBrownell Electro, Inc.(305) 843-6770GEORGIAAtlantaBrownell Electro, Inc.(404) 762-5181

HAWAIIHonoluluEMC Corporation(808) 847-1138

ILLINOISChicagoJoseph Electronics(312) 297-4200Elk Grove VillageMetermaster(312) 593-8650JolietAvionics Assoc., Inc.(815) 729-0820

INDIANAIndianapolisP.A.D.I.(317) 849-3682

KANSASWichitaRadio Supply Co., Inc.(316) 267-5216

MARYLANDGaithersburgPioneer/Instrumentation(301) 424-3300

MASSACHUSETTSBillericaMetermaster(617) 667-8346BurlingtonThe Mancib Company(617) 272-9450FraminghamCalcotron(617) 879-7650

MISSOURISt. LouisOlive Electronics(314) 426-4500

NEBRASKALincolnScott Electronic Supply Co.(402) 466-8221OmahaScott Electronic Supply Co.(402) 734-6750

NEW JERSEYMidland ParkLeasametrics(201) 444-0662TotowaAmpower(201) 790-6750

NEW MEXICOAlbuquerqueBarnhill Assoc., Inc.(505) 299-7658NEW YORKCorningCorning Electronics(607) 962-0555FarmingdaleAmpower(516) 752-1078Long IslandHarvey Electronics(516) 921-8700New York CityAdvance Electronics(212) 687-2224ThornwoodElectronic Tool Company(914) 769-8070VestalHarvey Electronics(607) 748-8211

NORTH CAROLINACharlotteBrownell Electro, Inc.(704) 394-4341Dixie Electronics(704) 377-5413

OHIOClevelandPioneer/Instrumentation(216) 587-3600DaytonN.I.D.I.(513) 434-7500

OREGONEugeneUnited Radio & Supply, Inc.(503) 342-3381MedfordUnited Radio & Supply, Inc.(503) 779-7933PortlandLiberty Electronics(503) 292-9234United Radio & Supply, Inc.(503) 233-5341

PENNSYLVANIAPhiladelphiaSunshine Scientific(215) 673-5600PittsburghPioneer/Instrumentation(412) 782-2300Plymouth MeetingTechni-Tool(215) 825-4990Spring HouseAvionics Assoc., Inc.(215) 643-6555SOUTH CAROLINAColumbiaDixie Electronics(803) 779-5332GreenvilleDixie Electronics(803) 229-4554TEXASAustinBarnhill III(512) 451-0217REDCO(214) 653-1041DallasBarnhill Ill(214) 231-9012HoustonBarnhill Ill(713) 688-9971

UTAHSalt Lake CityBarnhill Assoc., Inc.(801) 484-4496VIRGINIAChesapeakeI.T.R.(804) 424-5121RichmondI.T.R.(804) 275-1431

WASHINGTONBellevueApplied Engineering(206) 455-4922Liberty Electronics(206) 453-8300SeattleWestern Electronics(206) 284-0200

WISCONSINGreen BayNorthern Radio & TV Corp.(414) 435-8331

CANADAALBERTACalgaryACA Electronics CentreAllan Crawford Assoc., Ltd.(403) 276-9658EdmontonCardinal IndustrialElectronics, Ltd.(403) 455-4122

BRITISH COLUMBIAVancouverACA Electronics CentreAllan Crawford Assoc., Ltd.(604) 294-1326VernonInterior Electronics, Ltd.(604) 545-2394MANITOBAWinnipegW.E.S. Ltd.(204) 632-1260

NOVA SCOTIADartmouthAllan Crawford Assoc., Ltd.(902) 469-7865

ONTARIOTorontoACA Electronics CentreAllan Crawford Assoc., Ltd.(416) 678-1500OttawaAllan Crawford Assoc., Ltd.(416) 678-1500OttawaAllan Crawford Assoc., Ltd.(613) 829-9651

QUEBECMontrealACA Electronics CentreAllan Crawford Assoc., Ltd.(514) 670-1212

February 1979 Electronic Servicing 1

February, 1979

Volume 29, No. 2 Electronic Servicing.

20 Servicing GE 13" color TV, part 6Gill Grieshaber

Defects in modern solid-state video circuits usuallyaffect brightness more than contrast.

31 Quick TV tipsWayne Lemons

In this case history, two good technicians were baffledfor a time. Can you solve the mystery?

32 Typical radio repairsHomer L. Davidson

These case histories show the non -spectacular natureof most radio repairs while they also give you ideas forefficient tests.

38 Sam Wilson's technical notebookJ. A. "Sam" Wilson

A solution for glitches, some corrected schematics andmore capacitor facts are the subjects this month.

42 Difficult analysis of a narrow pictureFrank Wolff

By a combination of logical servicing techniques andsome helpful tips from past Electronic Servicingarticles, the unusual problem was solved.

46 MAW gain versus noiseJames E. Kluge

Most MATV designs are based on signal levels, but firstpriority should be given to signal-to-noise ratio.

Departments 6 Electronic scanner8 Symcure

11 Readers' exchange16 Troubleshooting tips

50 Test equipment52 The marketplace52.::' dvertisers' index

About the cover John D. Liljestrand Jr. is using modern test equipmentto troubleshoot an older color TV receiver.

Application to Mail at Controlled Circulation Postage is pending at Shawnee Mission, KS, andat additional offices. Published monthly at 9221 Quivira Road, Overland Park, Kansas 66212 byIntertec Publishing Corp., 9221 Quivira Road, Overland Park, Kansas 66212. Send Form 3579 to9221 Quivira Road, P.O. Box 12901, Overland Park, Kansas 66212.

©Copyright, 1979, by Intertec Publishing Corporation. All rights reserved. Material maynot be reproduced or photocopied In any form without written permission of publisher.

2 Electronic Servicing February 1979

PIÉCE DERESISTAN

Sylvania, of course. And there are 59Lmore just as good. It's the most completeline of flameproof resistors in the industry.

Our flameproof resistors come in '/o, /2, 1and 2 -Watt sizes for use in home entertain-ment, communications, industrial equip-ment or any job requiring a fuse resistor.They can replace carbon composition, car-bon film, metal film, wirewound and fuseresistors with tolerances of 2, 5, 10 or 2)percent. And noncombustible ceramic con-struction provides stable resistance plusindefinite shelf life.

All Sylvania flameproof resistors comein color -coded blister packs for easy iden-tification. For a good look see your nearestdistributor. You can find his location by con-tacting GTE Sylvania, Distributor and Spe-cial Markets Div., 1025 Westminster Dr ve,Williamsport, Pa. 17701.

Syli/lIN IFR175

2% toi ey750 ohms 2r.

ECGC WONEI\!TS

ME1NR;SIS1+

OF

SYLVANIACircle (3) on Reply Card

ElectronicComponents CID

Here's how tobecome as gooda businessman asyou are a servicetechnician..

u+

o

SIGHT ANO SOUND BUSINESS MANAGEMENT I

Intr,r,l,1 I Selo, I,. ,'I L.".rn , Il1.2 Insurenc,

PSSE.[ZE ZRPNNG, .. N....»

PoGRPM

Tape 1

Side 1

Business management course for service technicians-proved in classroomuse for over 3 years-now available on audio cassettes with 48 -page workbook!

Whether you work for yourself ornot, it's important for you to know thedollars -and -cents side of the electronicsbusiness.

How and why rates are set andrevised periodically, for example. How toorganize and maintain customers' records.Different techniques, too, for speedingup collections.

These are just some of the businessmanagement subjects-originally testedand proved in actual classroom use byZenith-now available to you on audiocassettes with a 48 -page workbook.

There's simply no easier, faster,more convenient way for you to becomeas good a businessman as you are aservice technician)

You listen and learn at your ownpace...at your own convenience. Andthen you review and refresh yourself onany one or all of the subjects wheneveryou choose.

You'll learn about inventory controlof parts, about budgets, about how toprepare a balance sheet, a profit andloss statement.

Such subjects as site selection arecovered, too. Accounts receivable andpayable. Insurance. Purchasing. Taxes.Telephone usage. Analyzing incomeand expenses. Equipment depreciation.

All in all, the 19 essentials ofmanagement-as they apply in today'sinflationary economy-are discussedthoroughly and clearly as they relatedirectly to your profitable performanceas a service technician.

'There's even a "case study"-patterned after the teaching method ofthe graduate schools of business manage-ment-to prove dramatically how muchyou've learned so easily, so quickly,so well.

Order your Business Management 1self -training program now by completingand mailing the coupon below)

Your livelihood may depend on it.

EMThe quality goes in before the name goes ong

Please send one set of four audio cassettes and the 48 -page workbook of the ServiceTechnicians' Business Management I self -training program. Enclosed is a check for$39.95 to cover the cost of the complete program plus shipping and handling expenses.

Name

Company Name

Address

City State Zip

Please complete and mail this coupon with a check or money order to: Zenith Radio Corporation,Business Management Services, Dept. 10, 11000 Seymour Avenue, Franklin Park, Illinois 60131.

Electronic ServicingEditorial, advertising and circulation corre-spondence should be addressed to: 9221Quivira Road, P.O. Box 12901, Overland Park,KS 66212 (a suburb of Kansas City, MO)-(913) 888-4664.

EDITORIAL

Bill Rhodes, Editorial DirectorCarl Babcoke, Editor

Cindy Nelson, Managing EditorBeth Brugman, Editorial Assistant

JoAnn Vella, Editorial AssistantDudley Rose, Art Director

Linda Franzblau, Graphic Designer

EDITORIAL ADVISORY BOARD

Les Nelson, Chairman

Howard W. Sams & Co., IndianapolisJoe A. Groves, Technical ConsultantHoward W. Sams & Co., Indianapolis

CIRCULATION

John C. Arnst, DirectorEvelyn Rogers, Manager

ADMINISTRATION

George H. Seferovich, President

George Laughead, Publisher

ADVERTISING SALES

Marilyn Carroll, ProductionRegional and Advertising Sales Offices

near Advertising Index

ELECTRONIC SERVICING (ISSN 0013-497X)(with which is combined PF Reporter) is pub-lished monthly by Intertec Publishing Corp.,9221 Quivira Road, Overland Park, KS 66212.

ELECTRONIC SERVICING is edited for tech-nicians who repair home -entertainment elec-tronic equipment (such as TV, radio, tape,stereo and record players) and for industrialtechnicians who repair defective production -line merchandise, test equipment, or indus-trial controls in factories.

Subscription prices to qualified subscribers:1 year-$10, 2 years-$16, 3 years-$20, inthe USA and its possessions. All otherforeign countries: 1 year-$13, 2 years-$22.Subscription prices to all others: 1 year-$25, 2 years-$50, in the USA and itspossessions. All other foreign countries:1 year-$34, 2 years-$68. Single copy price$2.25; back copies $3.00. Adjustment neces-sitated by subscription termination to singlecopy rate. Allow 6 to 8 weeks delivery forchange of address. Allow 6 to 8 weeks fornew subscriptions.

,rto .

51,ABP

INTERTEC PUBLISHING CORP.Subsidiary of HOWARD W. SAMS & CO.,. INC.


The LoneAutoran

If you're looking for a tough little True RMSDMM with 41/2 -digit resolution for bench or field,consider the 8040A.

Built to the same exacting standards of ourlarger DMMs, the 8040A packs the accuracy andconvenience you've come to expect from Fluke.And, since autoranging is so important, then wethink you'll find it stands alone in its class.

Return with us now to yesteryear...When value meant you got something extra

for your (silver) dollar. Compare any other TrueRMS DMM with the Fluke 8040A and discoverhow traditional value keeps Fluke the DMM leadertoday.

The TheCompe- Fluketition 8040An Autoranging plus manual range

selection. Use autoranging for hands-off measurement convenience or lockthe 8040A in a single range for repet-itive measurements.

True RMS. The only way to eliminateerrors from distorted, non -symmetri-cal or other nonsinusoidal waveforms.

41/2 -digit resolution on all five func-tions for a full 19,999 counts, and 10microvolt, 10 nanoamp and 10 milli -ohm sensitivity!

Efl

ori $425*

Versatile power choices. The 8040Acan be powered by disposable or re-chargeable batteries, or an AC adap-tor-your option.

Dependability. The 8040A uses LSItechnology identical to our big DMMs.Backed by worldwide service and ap-plications help. And more.

Price: The bottom line. If the DMMyou're looking at meets all of theabove at this price, it must be an8040A!

Accuracwithresoluy andtion stability-tolike±0.05%

ongo along

, ,

CALL (800) 426-0361, TOLL FREE. We'll sendyou the unmasked truth about True RMS DMM val-ue. John Fluke Mfg. Co., Inc., P.O. Box 43210,

nr_,10(for six months.

Mountlake Terrace, WA 98043. IN EUROPE: FlukeThree-way protection against over - (Nederland) B.V., P.O. Box 5053, Tilburg, Thewrivoltage, overcurrent and transients Netherlands. Tel.: (013) 673973. Telex: 52237.

`U.S. price with disposable batteries.to 6000V.

Command Performance: Demand Fluke DMMs.FLUKE

2501-8040

For Demonstration Only Circle (5) on Reply CardFor Literature Only Circle (6) on Reply Card February 1979 Electronic Servicing 5

if

11:Seannernews of the ndus ry

All locally available Magnavox "Magnavision" videodisc players were sold within ahalf hour after they first were introduced last December 15th in Atlanta, GA. Thethroe dealers had a total of only 5.7 machines for sale, while the demand wasestimated at 2,ZO0. Some customers camped near the stores to be first in line atopening time, and inquiries cams from Paris, New York and Acapulco. One storewas said to have sold more than 1DO anits, most to be delivered during January andFetruart!. About 1000 videodiscs also were sold. Magnavox has selected theSeattle -Tacoma area a:3 the next test market. The videodiscs resemble conventionalphcnograph re,xrds, tut without the grooves. A laser beam in the player reflectslight from the spiral tracks that are made up of many microscopic pits orindentations. Te reflected laser Light is received by a photo cell, and from it comesthe three FM carriers :hat are processed and demodulated to produce onecomposite video signal and two separate sound signals. The beam is kept centeredon :he correct 'groove" by a cor1plex servo mechanism that moves the automatictracking mirror. Retail price of the Magnavision player $695, and the DiscoVisiondiscs are priced between $5.95 and 115.95 according to the playing time.

Quasar Electrcnics has been divided into two separate companies. MatsushitaIndnst,ial Company will perform the engineering and manufacturing of Quasar TVsand other products. At a ater date, 't is expected to begin building Panasonic TVsalso. Quasar Company is to sell and service Quasar products through the presentsystem of distrlutors and dealers

About 447 CB transmitters and Lunar amplifiers were seized by the FCC in aDecember raid at the Brewer Labs of Porter, OK. The seizure is said to be part ofthe FCC's continuing effort to eliminate illegal CB linear amplifiers that cause manykinds of interference.

Sylvania has added five TVs, two stereos and a color video recorder with optionalcolor camera to the 1379 line. The three consoles feature Automatic SharpnessConaro. (_CSC) circuitry. An electronic digital clock and timer in the 4 -hour videoreccrder can he set in advance to record TV programs. The recorder lists for$1075, and $849.95 is the suggested price of the color video camera with built-inmicrophone.

In January, Quasar announced a portable videocassette recorder weighing less than20 pounds and operating from an internal sealer rechargeable battery. AnotherVCR (model VI -11.00) is said to be the first with a remote control channel -changefeature. Quasar also demonstrated a film -to -tape conversion system for transferringmovie film or coror slides to videotape. Top of the 4 -model line of microwave ovensis the Quasar model with Insta-Metic Cooking (model MQ6600).

RCA is said to be rushing the :nit -eduction of its SelectaVision VideoDisc. Theproject had been side:ined in 1977, but now is expected to have a marketingschedule later t is year. The RCA videodisc has a groove to guide the pickup head,which operates by capacitance changes. Retail price of the disc players is expectedto be around $400.

A single -electron -gun color picture -aim should be introduced by Panasonic nextfall. The first model will have a 4 -1/2 -inch screen, but larger sizes up to 10 inchesare expected scon. Another new product is a line of batteries only /300th -inchthick which are designed to be used in calculators, watches and cameras. Retailprice of each battery is expected to be about $1. For industrial uses, Matsushitahas ;,ntroduced 3 color TV transmitting and receiving system using 1,125 scanninglines.

Industry predictions for 1979 include both good and bad news. Sales of color TVsare expected to ecrease, but increased volume of video products, microwave ovensand home computers should more than compensate..

Major winner of the Sylvania "Tab Terrific" sweepstakes is James Kessler, a TVservice dealer of Mt. Vernon, OH. He received a first prize of 5000 program tabs.


Versatility:Heres why

B&K-PRECISION'snew DMMsoffer more

Selecting a DMM isn t simply a matter oflooking for the highest accuracy. It's a

more complex process of deciding whatfeatures and performance characteristicsyou need, to do as many different jobs asyou're likelyto encounter. In short, versatil-ity is just as important as accuracy!

The new 2830 digital multimeter fromB&K-PRECISION has all the popular fea-tures you'd expect to find on a 31/2 digit labDMM, but it also offers some very uncom-mon features. Because a DMM may beused under poor lighting conditions or ina very bright environment, the 2830 usesbright, high -efficiency 0.43" high LEDdigits. The readability of this premium dis-play is unmatched by other readoutdevices.

The 2830 is also one of the very few DMMsavailable with a 10 ohms range, capable of.01 ohm resolution. This range offers theuser accurate resistance measurement ofswitch and point contacts, or motor or coilcondition. AC and DC current measure-ment capability extends from 100 nA to 20amps without the need for external plug-inshunts. For voltage measurement, the 2830can resolve as little as 100 V. Formaximum versatility in resistance mea-surement, selectable high -/low -powerohms permits resistance measurementwith or without forward biasing semicon-ductor junctions.

The unit is housed in an attractive ruggedcabinet which features a combination tiltstand/handle. Options include a battery

:«PRECIS/ON DYNASCANCORPORATION

6460 W. Cortland Street Chicago, IL 60635.312, 889-9087

Model 2810$130

pack for field use and a carrying case.

B&K-PRECISION's 2810 DMM offers manyof the features of the 2830 but in a mor?compact package and at a substantiallylower price. Features include 100 µV, .01ohm resolution; high -/low -power ohms;autozeroing; high immunity to RF interfer-ence and complete portability.

Free DMM Selection GuideA new B&K-PRECISION DMM selectionguide is now available. This full -colorbrochure details features, applicationsand specifications. It also includes detailsof a new probe that turns any DMM into adigital thermometer. Send for your freecopy today!

In Canada Atlas Electronics Otand International Sales Empire Exporters. Inc 270 Newtown Road. Plainview. L I N Y 11803

Circle (7) on Reply Card February 1979 ,Ellectronic Serviing 7

VY1FCUtOiSymptoms and curescompiled from field reportsof recurring troubles

Chassis-Sylvania E03/E04/E05PHOTOFACT-1414-3, 1425-3, 1420-2

R334

R336

2200

VERT FROM

COUNTDOWN

IC300 PIN 7

R332

62K

+ 120V

INCREASED

R340 1.3M

HEIGHT 1M

+120V

Symptom-Insufficient vertical heightCure-Check R332, and replace it if increased

Chassis-Sylvania E02PHOTOFACT-1324-3

HORIZ

PINCUSHION

T302

TO VERT

22YOKE

Symptom-Vertical linearity stretched at the centerCure-Check R377, and replace it if open

Chassis-Sylvania E03/E04/E05PHOTOFACT-1414-3, 1425-3, 1420-2

VERT OUTPUT

Q310 /

TO VERTC326 C3r36

LIN.22 10µF

R352 220 R368 0.82

-_ -INCREASED

Symptom-Slightly insufficient heightCure-Check resistor R352, and replace it if in-creased.

N


DELAY LINEDL920

SC926

OPENL926 /

1800

VERT BLANKING

Q904

VIDEO DRIVER

R928 1800

+24V

Symptom-Low contrastCure-Check coil L926, and replace it if open

ti


VIDEO AMP BRIGHT RANGEQ902 R921

SC924

C924 150 p

R924 39LEAKING

+24V

HORIZ

BLANKING

Symptom-Horizontal tearing which is changed bybrightnessCure-Check diode SC924, and replace it if leakingor erratic

Chassis-Sylvania D16PHOTOFACT-1178-3

C414

OPEN R416

-1 6800C420

100 p F

R414

AFCDC

R420 8200

TO OSC

COIL01

HORIZ HOLD

R418 R424

120 1000

Symptom-Horizontal hold can't change horiz fre-quencyCure-Check R416, and replace it if open


iIioxcbanooThere is no charge for a listing in Reader's Exchange, butwe reserve the right to edit all copy. If you can help with

a request, write directly to the reader, not to ElectronicServicing.

Needed: TV field strength meter. Prefer Sencore orJerrold. L.C. McCall, P.O. Box 158, Hiawassee, GA30546.

Needed: Used test equipment for TV and audioequipment. Also, will sell early Photofacts and oldradio tubes. Vision Electronics, 7226 Taft, Hollywood,FL 33024.

Needed: A copy of Repairing Home Audio System byE. Ecklund. Bob Kramer, 539 South Stat, Aurora, IL60505.

Needed: Technicians interested in not -for -pay partici-pation for the design of a super -small personal walkie-talkie for repeater operation. Send self-addressedenvelope to: Smith, 8636 Grand, River Grove, IL60171.

For Sale: Rider's manual abridged I -V, VI throughXIX, no indexes; PA manual number 1; RCA Victorservice books: Volume 1 (1923-1937), Volume 2(1938-1942); Stromberg Carson service notes circa1950. All in mint condition, prices negotiable. You payfreight. Walter J. Blair, 35 Arroyo Way, SanFrancisco, CA 94127.

Needed: Owner's manual with schematic for SupremeElectronics set tester, model 504-B. Also, owner'smanual and schematic for EMC (Electronic Measure-ment Corp.) RF/AF crystal-marker/TV-bar generator,model 700. Will buy, or copy and return. JohnBrovzakis, RD2 Box 602B, Charleroi, PA 15022.

For Sale or Trade: Tubes: old, antique, oddball,hard -to -find types. Troch's, 290 Main Street, Spots-wood, NJ 08884.

Needed: Deflection Yoke part 361285-1 (T -D74 -U) forMagnavox TV chassis T922 -01 -AA. Harry K. Murphy,1230 St. Antoine, Florissant, MO 63031.

For Sale or Trade: Tennelec Memoryscan model MS -1,$125; EICO 380 color generator, $45; Paco Z-80 signaltracer, $25; Precision 10-54 tube and set tester, $15.Norman Round, 29 Elmwood Road, Methuen, MA01844.

For Sale: Color or monochrome picture tube rebuilder,never used, complete with supplies and duds, cost$5500. Will sell for $1500 or best offer. Eugene Faber,1112 W. 31st South, Wichita, KS 67217.

For Sale: Sweep tubes at 25 cents each; small tubes at10 cents each. New tubes in cartons. You pay freight.W.E. Papy, 913 E. 22 Street, Hialeah, FL 33013.

Needed: Help from someone who specializes in repairof photoflash units. I have a Singer Graflex 500

Strobematic but don't have much test equipment.Elmer L. Mosley, 720 Poplar Street, Keneva, WV25530.

For Sale: RCA WO -33B 3 -inch scope with manual andprobes, excellent condition, $125; Sencore CG -22color/bar generator, as is, $10. Also, about 200Clarostat controls with switches and shafts; bestoffer. Mark Hughes, Route 2, Box 271, KingsMountain, NC 28086.

Needed: Convergence -yoke assembly part 94D303 -5Sfor Admiral color TV chassis 4H10. Leslie Welch, 616Valencia Drive, Belleville, IL 62223.

For Trade: Good used color picture tubes. I need16VACP22 and 400BNB22. I have 155P22, 16CYP22,19GYP22, 19HCP22, and 19HYP22. Send for list ofB&W CRTs I have and need. Gordon Handy, Jr., 300Vienna Drive #214, Palm Springs, FL 33460.

Needed: Antique Marconi -Deforest wireless gear andliterature for my collection. Also, Atwater Kent,breadboard parts, crystal sets, catalogs and literaturefor them. Will pay best prices. A&M In -The -Home TVCare, 84 West Muriel, Orlando, FL 32806.

For Sale or Trade: Sylvania model 500 sweepgenerator, new in carton, $65; Philco VTVM with9 -inch meter for panel mounting, with instructionmanual, $35; Rider's TV manuals volumes 1 through26, with index, $135; Black & Decker 1/2 -inch electricdrill, $20; and a 7 -inch Ram 88 circular saw, $25. M.Seligsohn, 1455 -55th Street, Brooklyn, NY 11219.

Needed: Schematic of AM/FM-stereo with 8 -tracktape chassis number 0640 made by Mayfair SoundProducts. Or address of Mayfair. Terry Stremcha,Dakota, MN 55925.

For Sale: B&K-Precision model 1077B televisionAnalyst, like new, $295; and the following Heathkitinstruments: model IT -5230 CRT tester/rejuvenator,$100; model IM -17 VOM, $10; model IT -18 transistortester, $10, model 4110 frequency counter, $180, andmodel 5218 VTVM, $25. Eugene Maples, P.O. Box 503,Flippen, GA 30215.

For Sale: Heath IG-18 sine -square audio generator,$85; Heath IG-37 stereo generator, $70; Heath IM -48audio analyzer, $35; Heath IM -58 distortion meter,$35; Heath IB-1100 frequency counter, $100; IB-102frequency scaler for above, $90; Continental res/capbridge, DM -3, $75; Continental Design -Mate circuitdesigner with 5 V supply, $70; EICO model 369 RFsweep generator w/probes, $35; EICO model 680transistor tester, $45; EICO model 214 VTVM,collectors item, works good, $60; B&K model 801capacitor Analyst, $90; B&K model 260 3 -digit VOM,


Reader's exchange

~gh VoltageMultipliers

I fin me

'Erns.0~

Thodarson Meissner wrote the book on highvoltage transformers. And now we offer youTech-MateTM high voltage multipliers. At lastyou can select exact replacement high voltagemultipliers from the most complete line in theindustry. Items that previously were difficult orimpossible for you to obtain.

Quality built, exact replacement Tech-MateTMhigh voltage multipliers are here. YourThordarson distributor has them. Make yourjob easier and be assured of reliable per-formance. Start using them today.

THORDARSONMEISSNER, INC.

Electronic Center/Mt. Carmel, Illinois 62863

Circle Reply Card

$55; Leader LSG-14 signal generator, $50; MilitaryAN/USM-34 multimeter with RF probe, $30; Ballantinemodel 301A ac VTVM, $50; and TS-4977URR signalgenerator, 10-400 MHz, $125. Will ship prepaid uponreceipt of certified check. Electronic Service Com-pany, 1412 Mayfield Ave., Morgantown, WV 26505.

For Sale: Precision E200C signal -marking generator;EICO 368 sweep/marker generator; EICO 460 scope;Heath IO-57A post/marker sweep generator, almostnew; Heath I0-101 vectorscope, new, factory cali-brated; Heath IG-18 sine/square generator, factorycalibrated, almost new. All equipment with manualsand leads. Robert J. Sheehan, 89 Strattford Ave.,Pittsfield, MA 01201.

Needed: Schematic and parts list for a Fada radio,model 260. Will buy, or copy and return. RaymondFriend, 236 W. Pearl Street, Butler, PA 16001.

For Sale: Obsolete tubes. Send your list of needs.Also, home built transistor tester by Zenering, $15.Elmwood TV, 13G Market Square, Newington, CT06111.

Needed: Power transformer Sylvania part 55-23915-1.A.R. Pumphrey, 15109 Copter Lane, Lockport, IL60441.

Needed: Volume control with on/off switch (4 megtapped at 2 meg) part RRC226 for GE radio/phono

NEW -TONE ELECTRONICS INTERNATIONALOriginal Japanese Replacement Parts for TV, Stereo and CB

25 -UP 110-20 45 25-UP i 10-24 I 1-9 LSTUr 10.19 11-5 25 -UP 10-24 1 9 25-0Pj

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AN115 2.00 2.15 2.25 rA7061P .85 1.05 1.15 UP0857C 7.90 8.30 9.40 6C458 ,C1096 .40 .50 .55 2562029 1.45 1.75 1.95AN2140 1.45 1.65 1.86 1070620 1.05 1.20 1.35 UP0858C 5.90 6.20 6.90 60 ".C1114 3.30 3.50 3.70 25C2072 3.50 3.70 3.90AN234 5.04 5.51 6.00 07063P .55 .65 .75 UP 618616 7.80 820 9.30 .481 .90 1-10 125 .611160 3.30 3.45 3.80 2502076 .40 .55 .60AN239 4.10 4.30 4.80 070747 2.40 2.60 2.80 25A102 .20 .25 .30 6482 .80 .95 1.30 .C1124 .75 .85 .95 2502091 .80 1.00 1.10AN247P 2.40 2.60 2.90 rA7089P 1.80 2.10 2.30 25A473 .45 .55 .60 :a85 .95 1.15 1.30 .'5C1127 .75 .85 .95 2502092 1.70 1.90 2.10AN274 1.40 1.65 1.85 TA7092P 9.50 10.00 10.50 25A484 120 1.40 1.60 : a95 .30 .40 50 2561162 .60 .70 .80 2502098 2.90 3.10 3.35AN313 2.90 3.10 3.30 TA7120P .85 .95 1.05 25A495 .25 .30 35 :509 .25 .30 .35 2561166 .20 .25 .30 25072 .45 .60 .65AN315 1.75 1.95 2.20 TA7139P 1.55 1.75 1.95 25A509 .30 .35 40 .51] 1.80 2.00 2.40 25611728 3.00 3.50 3.85 ?5091 125 1.40 1.55BA511A 1.60 1.80 2.05 1A7152P 5.70 5.90 6.10 2SA562 .25 .30 +35 .25 .30 .35 2561173 .45 .50 .55 25092 125 1.35 1.4513A521 1.80 2.00 2.30 TA7203P 2.40 2.60 2.80 25A564 25 .30 620 .25 .35 .40 2501177 10.80 12.30 13.70 256178 .85 .90 1.05HA1151 1.45 1.70 1.85 TA7204P 1.90 2.10 2.40 25A634 .35 .40 632A .30 .35 .40 2561209 .25 .30 .35 250187 .30 .40 A5HA1156w 1.55 1.75 1.95 TA7205P 1.50 1.70 1.90 25A636 75 .95 1 .1 5 ,t:634A .30 .35 .40 2561222 .20 .25 .30 250218 2.40 2.60 2.90HA1306W 1.90 2.10 2.40 TA7214P 4.10 4.30 4.50 25A643 30 .35 .40 0697A 2.65 2.95 3.20 25C1226A .50 .55 250234 .55 .65 .75HA1322 2.10 2.50 2.80 TA7310P 1.25 1.40 1.55 25A673 .30 .35 .40 C 710 .18 .25 .27 2561237 1.60 1.80 2.05 250235 .55 .65 .75HA1339A 2.40 2.60 2.90 TA7607P 5.80 6.00 6.20 25.8678 .30 .35 .40 tSC711 .18 .25 .27 2501239 2.00 2.55 2.75 250261 .30 .05 .40HA1342 2.50 2.70 3.00 TA7609P 4.00 4.32 4.80 25A683 .30 .35 .40 256712 .18 25 2561306 1.30 1.45 1.60 250287 2.45 2.65 2.85LA1222 1.50 1.55 1.60 TBA8105 2.75 2.97 3.30 25A684 35 .40 .45 256717 .30 .35 AO 2561307 1.85 2.05 2.35 250291 2.05 2.45 2.75LA3101 3.45 3.60 3.75 TC5081P 2.90 3.10 3.30 259695 .35 .40 .55 256730 2.80 3.00 3.20 25[1318 .30 .35 .40 250313 .55 .65 .70LA4031P 1.75 1.95 2.20 TC5082P 3.30 3.45 3.80 25A699A .40 .50 .60 25C732 .20 .25 .30 2561364 .25 .35 .40 250315 .55 .65 .70LA4032P 1.75 1.95 2.20 TC9100P 7.54 8.02 8.50 2577206 .80 .95 1.05 25C733 .20 .25 25[1383 .25 .30 .35 250325 .55 .65 .70LA4220 2.25 2.40 2.55 UHIC001 4.10 4.30 4.80 25A720 .25 .30 .35 25C734 .20 .25 .30 2561384 .25 .30 .35 250330 .55 .55 .70LA4400 1.85 2.05 2.35 UHIC002 4.10 4.30 4.80. 2SA7458 3.60 3.80 420 256735 .20 .25 .30 25C1424 2.60 2.70 2.80 250356 .65 .75 .85L03191 1.70 1.80 1.90 UHIC003 4.10 4.30 4.80 25822 .25 .30 .35 256756A 1.30 1.60 1.80 2561448A .60 .70 .80 250358 .65 .7,5 .85M5115P 7.90 8.05 8.25 11H1C004 4.10 4.30 4.80 25854 .20 .27 .30 2SC761 .30 .32 .35 2561475 .60 .70 .80 250359 .75 .85 .95M51513L 2.00 2.20 2.50 UHIC005 4.10 4.30 4.80 25877 30 .40 .45 25C778 2.70 3.00 3.20 2561509 .40 .45 .50 250427 1.75 1.95 220MN 3001 13.75 14.85 16.50 UHIC006 4.10 4.30 4.80 258175 20 .27 .30 256781 1.85 2.05 2.35 2561567 .50 .60 .70 250525 .70 1.00 1.10MN3002 9.62 10.40 11.55 UPC20C 2.00 2.40 2.50 258186 .20 .27 .30 256784 .25 .30 .35 2501675 20 .25 .30 250526 .55 .8s .75

MN3003 5.87 6.34 7.04 UPC1,41C 2.14 2.32 2.50 258187 .20 .27 .30 25C789 .75 .85 .95 2561678 1.00 1.15 1.30 25019 .45 90 .55PLL01A 3.00 4.20 4.60 UPC157A 3.25 3.45 3.65 258324 .25 .30 .35 256793 1.90 2.10 2.40 2501687 .35 .40 .46 251423A .65 .75 .85PLLO2A 5.00 520 5.90 UPC554C 1.25 1.40 1.55 258367 85 .95 1.10 256799 1.95 2.15 2.45 2561727 1.55 1.65 1.75 25K30A .40 .5 .50PLLO3A 7.60 8.00 8.80 UPC555H 125 140 1.55 250405 .25 .30 .35 25C828 .20 .25 .30 2501728 .60 .70 .80 25K33 .55 .65 .75

50264A 624 7.02 7.80 UPC572C 3.45 3.55 3.65 258407 .65 .80 .90 256829 .20 .25 .30 2561760 .65 .75 .85 251134 .45 .55 .6050609 3.65 4.05 4.50 UPC574C 1.00 1.08 120 258463 .80 1.00 1.10 256839 .25 .30 .35 2561775 .30 .35 .40 25041 .50 .55 .60

50613 5.20 5.40 5.95 U PC 575 C2 1.25 1.40 1.55 258474 .60 .70 .80 25C867A 3.10 3.30 3.60 25[1816 1.35 1.60 1.80 25055 .60 .65 255M5104 6.68 7.42 8.01 UPC576H 1.85 2.05 2.35 258507 70 .80 .90 25C900 .20 .25 .30 2501908 .25 .35 .40 35K22V 1.35 1.55 1.75STK011 3.55 3.80 4.30 UPC592H2 .65 .75 .85 250511 .60 70 .85 256930 .20 .25 .30 2501909 1.60 1.80 2.10 25035 1.20 1.30 1.505211013 7.40 7.80 8.60 UPC1001H21.85 2.05 2.35 258557 1.60 1.85 2.30 25C945 .20 .25 .30 2501945 4.30 4.80 520 351137 1.70 2.00 2.30STK015 4.00 4.20 4.70 UPC 1008C 4.10 .430 4.80 256183 .30 .40 .50 25C1000BL .30 .40 .45 2561957 .50 .60 .70 351140 1.05 1.155111050 23.10 25.98 28.86 UPC7020H 1.85 2.05 2.35 256184 .30 .40 .50 2561013 .50 .60 .65 25[1969 3.40 3.80 420 35841 1.25 1.40 1.55510415 7.10 7.60 8.10 UPC 3025H 1.85 .205 2.35 256372 .18 .25 .28 25[1014 .45 .60 .65 2501973 .60 .70 35045 1.25 1.40 1.55510435 4.40 4.90 5.50 UPC 1028H 1.40 1.62 1.80 756373 .20 .25 .30 2561018 .50 .60 .70 2561974 1.20 1.60 1.80 351148 3.30 340 3.70518439 7.60 7.90 8.30 UPC1031H 2.52 2.74 2.98 256380 18 .25 .28 2561030 1.70 2.00 .230 25[1975 120 1.60 1.80 351349 125 1.40 1.55TA7045M 1.90 2.10 2.40 UP01152H 2.90 3.10 3.30 256382 .30 .35 .40 2561056 4.30 4.50 4.70 2562009 70 .75 .80rA70550 1.90 2.10 2.40 UP6115659 1.85 2.05 2.35 25C387A .27 .35 .40 25C 1060 .65 .75 2502021 .50 .55 .60i n 7060P :65 .75 .85 UPD2r7C 8.70 8.90 9.10 256394 .18 .23 .27 25C1061 .65 .75 .85 25[2028 .45 .50 .55

Minimum Order $10.00 - N..I. Residents add 5% Sales Tax.We pay postage for prepaid orders of $50.00 or more,

Under $50.00, add $1.00, Canada $1,50.Quantity Discount Prices - Ask for our complete price list -

Manufacturer inquiries welcome - All parts guaranteed.Prices may change without notice. C.O.D. orders welcomed.

TOLL FREE TELEPHONENationwide 800/631-1250 Local 201/748-5089

In New York 212/7321376

IMMEDIATE DELIVERY WITHIN 48 HOURSON ALL PARTS IN STOCK

NEW -TONE ELECTRONICS INTERNATIONALP.O. Box 1739, Bloomfield, N.J. 07003

New Jersey Phone: 201/748-5089Monday thru Friday 8:30 to 5:30

Circle (9) on Reply Card

Haven't you wanted and waitedlong enough for your SencoreVA48 TV -Video Analyzer?

"I'm eriou : bout wanting to h = ouincrease your service by isolating trouble tospecific TV stages in minutes."Rich Brockway, Technical Cu: mer ervice Director

CHANNEL VIOEO P»tERN

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VirlErfMETER RINGRING N

Your VA48 is practically jumpin' out of the box in the Sencore stockroom, anxious to help you increase your colorTV, black and white T'!, VTR, or closed circuit TV service byas much as 50 percent. The VA48 will help you double yourshop income next year and build 3 service reputation thatwill never go away.

How can I help you and your VA48 get together? Just drop anote to the Sencore Customer Service Department or callour toll -free WATS number 800-843-3338 today and ask forRich Brockway. I will see that your VA48 is delivered to youimmediately, on a 30 -day money -back guarantee that it willdo just what we say i- will do. How can you lose? The onlyway you can lose is bi not picking up the phone right now.Need financing? Perhaps I can help you there.

Video Bars

The VA48 TV -Video Analyzer is like having a miniatureTV station at your fingertips for troubleshooting.The VA48 provides all phase -locked signals for fast signal injection troubleshooting into every singlestage of every TV, video tape recorder, MATV, CATV, or closed circuit TV. Makes all TV systems look alikefor simplified IC troublshooting

Patented Bar Sweep 3atterns enable you to align all RF, IF,and Chroma stages frcm top of chasss. Cuts aligning andtroubleshooting time in these secticns to less than one half.

Crystal -controlled trap frequency markers equip you to setall traps from top of chassis withou: renoving a single nut orbolt. What a time-saver" Phase -locked color bars, crosshatch, and dots speeds upyour convergence, troubleshooting, or alignment of any colorcircuit. No more running color patterns and no more guessworkas the entire TV stays locked in. Scope waveforms stay in syncfor comparison of any stage to another stage, anywhere in theTV.

IN Only TV analyzer that provides all var able drive signals fortube, transistor, and SCR TV sets as well. All drive signals aremonitored on peak -to -peak meter for accuracy and to helpdetermine defective stages.

Provides highly filtered 0 to 35 Volt power supply 'or bias,troubleshooting automatic circuits, powering circuits withhorizontal sweep derived voltages, and SCR checks

.

One-third the cost of equivalent instruments that have up to60 separate test leads and non -synchronized signals. TheVA48 is all p -lase -locked and all signals delivered frcm threecircuit -matched test leads for only $975.

3200 SENCORE DRIVE, SIOUX FALLS, S.D. 57107(6051 339-0100


Reader's exchange

model 440. Must be in good working condition; quoteprice. Vernon Oester, Box 243, Garrett, PA 15542.

Needed: B&K-Precision 1077B analyst and 467 CRTrestorer/analyzer. W. Kohler, 1441 Carol Lane,Deerfield, IL 60015.

Far Sale: Most Photofact folders before number 800.Mrs. B. Lawrence, RD -1, Delta, PA 17314.

Far Sale: Sencore TR151 transistor checker, withpapers, excellent condition, best offer. B. Longwood,56 N. Broadway, Yonkers, NY 10701.

For Sale: Model 23A Hickok Cardamatic tube tester;B&K-Precision 700 tube tester; Millen grid -dip meterwith 1 coil; RCA WV -98B VTVM; General Radio wavemeter; B.R. noise detector; 50 -MHz frequency counter;

and miscellaneous tubes. Trade for B&K-Precisionmodel 415 sweep/marker. Allan V. Eisenhaur, 9

Rachel Carson Lane, Centerville, ME 02632.

Needed: Schematic for a B&K-Precision 360 VOM.K.E. Lee, Route 1, Box 44, Big Rock, VA 24603.

For Sale or Trade: Rider's radio & TV manuals. Also,OlA, 5Z3, 6J6, 011A, 112A, UX200, 199, U864, 120,2A3, 25B8, VR150, 19T8, 71A, 117L3, 117M7 and 83tubes for old radios. G.C. Goodwin, c/o Odd FellowsNursing Home, Mattoon, IL 60960.

For Sale: Photofacts 173 to 419, old shop manuals,radios, record players and early -model TVs, PFReporter and Electronic Servicing from 1967 to 1978,Radio -Electronics from 1971 to July 1978, many oldbooks, used yokes, hundreds of good used tubes and

INEGARD 1KS...

old test equipment. Make an offer. Ray Otto, 205Lake, Menasha, WI 54952.

For Sale: Two file cabinets full of older Photofacts,$350. F. Swartz, 2050 Espanola, San Pablo, CA 94806.

For Sale: Some copies of Radio News dated 1939, 1940and 1941. Harold Homes, 1687 Greenwood Road,Alger, MI 48610.

For Sale: New Heath IG-57A, $135; IG-28, $75; IG-18,$75; and Sencore FC45, $300. All with manual andleads. Bill Becktold, 7429 Frederick St., Omaha, NE68124.

For Sale: B&K-Precision 1801 frequency counter, B&K1403A scope, B&K servicemaster and Hickok 25640 -channel CB RF generator. All CB equipment usedjust a few hours, in cartons with all probes and

manuals. Cost wasMichael Harlinski,MA 01109.

Needed: Schematicbuy, or copy andDrive, Humbolt, IA

Needed: Operatingsignal generator.Neptune, NJ 07753.

$950, sell for $700 or best offer.180 Cherokee Drive, Springfield,

for a Galaxy V transceiver. Willreturn. Steve Stein, 10 Rainbow50548.

manual for a model 610A HickokJ. Di Franco, 518 Glenmere,

For Sale: Volumes 7, 10, 11, 12, 13, 14, 15, 16 and 17of Rider's radio troubleshooters manuals with indexes.Also, numerous technical books, some now out ofprint. Write for a list. Macario Garnica Balbuina,Libertad #2208 Ote., Col. Moderna, Monterrey, NuevoLeon., Mexico.

in the Public Schools.Now it's readin; 'ritin'... and trainingthrough television.

Educators in Montgomery Coun-ty, Maryland, believe strongly in theeffectiveness of television as a class-room teaching tool. Each of theCounty's 186 schools is equippedwith a TV distribution system forboth off -the -air and closed-circuitprogramming.

Though the school system doesnot have over -the -air broadcastingfacilities, it does have a completestudio with commercial quality colorcameras, lighting and props. Gen-eral and custom-tailored classroomprograms are produced there on 1 -inch video tape, then reproduced on1/2 -inch reel-to-reel and video cas-settes for distribution to the schools.

There are several schools thathave TV studio facilities, too, forproducing their own black and whiteclosed circuit programs. Interested

FLOWER VALLEY SCHOOL

students are trained in various phasesof television production, and manygo on to careers in the TV industry.

A few years ago, the Marylandpublic broadcasting network begantransmitting on UHF channel 22.Few of the Montgomery Countyschools were equipped for adequatereception of this important educa-tional channel, so the decision wasmade to begin modernizing theantenna systems. MATV contractor,Don Morar, of Woodbine, Mary-land, was awarded the bid. To assuremeeting reception specifications,Morar selected various combinationsof Winegard antennas and pream-

plifiers to fit each reception location.A favorite combination Morar usesfor difficult UHF reception areas isWinegard's CH -9095 antenna withan AC -4990 preamp. "I have foundthis setup does an excellent job,"Morar said, "and as we all know,nobody makes a more reliable an-tenna preamplifier than Winegard."

It is interesting to note that moreand more educators are using TVas a positive influence and valuableaid at all levels of education withinour nation's school systems. AndWinegard reception products are atwork to help them achieve bettereducation from coast to coast.

WINEGARD WORKS... Everywhere!

V5'WINEDARDThe Winegard Company 3000 Kirkwood Street Burlington, Iowa 52601Don Morar, MATV Contractor


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-YOURS FREE.32 -pages of test instruments - from thelatest digital multimeters to the famousEICO scopes. Security systems. Auto-motive products. Kits and assembled.EICO quality. EICO value. For FREEcatalog, check reader service card orsend 750 for first class mail.

108 New South RoadHicksvillle, N.Y. 11801

JCircle (20) on Reply Card

troubIeshootíouil

Loss of horizontal lockingTruetone WEG2887A17(Photofact 1160-2)

Adjustment of the horizontal -hold coil could bring the horizontalto zero beat, but there was nolocking. Usually, a new duo -diodephase detector will cure this symp-tom. However, neither a replace-ment duo -diode nor a new oscillatortube helped the operation.

6GH8A 6GHBA

After the TV was brought to theshop, I checked the oscillator andphase -detector voltages. No dc vol-tage was measured at the plate ofVSOIA (the AFC tube) and R509checked open. Additional resistance

measurements proved R514 andR533 were about 35% -low, whileR507 measured only about 5K.

Replacement of these four resis-tors restored correct operation.Notice that Singer model HE -8060S-1280 and Coronado model TV2-6634 S-1157 have the same circuit.Check these resistors first, if nolocking or loose locking is thecomplaint with those models.

Charlie JacksonBuckner, Illinois

Smoked, no volumeAcme 8 -track tape player(no Photofact)

This nearly -new tape player hadsmoked and gone dead, accordingto the customer. I connected mybench power supply and test speak-ers, then inserted a tape. There wasno sound or smoke and the supplymeter showed zero current drain.The fuse in the in -line holder was a30 -ampere automotive type and itwas blown.

I removed the case and saw

RCA Receiving Tubes Mean Business!You can get 211 the receiving tubes youneed from your RCA Distributor . . .

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promote your business ... Tube Cad- Receivingdies, service tools, technical literatureand a wide assortment of in-store signs Tubesand displays.See your RCA Distributor for all yourtube needs.RCA Distributor and Special ProductsDivision, Deptford, N.J. 08096.


Surprised? Don't be. Becausetoday, Ungar has one of the broad-est, most complete lines of sol-dering and desoldering equipmentand accessories in the business.Product by product, you'll findapplication -oriented designs thatlet you neatly handle any job thatmay come along.

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Troubleshooting tips

charred wires that connected thepower socket to the on/off switchand to the track -changing solenoid.Something had drawn a lot ofcurrent. Because I had no schemat-ic and couldn't be sure of where thewiring connected on the board, Iset the current -limiting feature ofmy power supply for 2 A with adead short. When I touched thepositive lead to the solenoid, thesupply voltage dropped to nearlyzero and the current was 2 A. Thisindicated a dead short. A B+ wireran from the solenoid to the PCboard. I disconnected the wire atthe board and touched my positivesupply lead to the wire. It wasshorted to ground.

After checking the wiring, Ifound the motor was fed by powerfrom the circuit board, so Idisconnected the motor's B+ lead.This time when I applied power tothe previous point, the currentdrain was less than 50 mA, and Icould hear the normal backgroundnoise coming from the test speak-ers. Touching the supply probe tothe motor wire proved the motorwas shorted.

Thinking the motor had ajammed rotor, I began to remove itby taking out three Phillips -headscrews. When I lifted out themotor, I noticed that the B+ leadhad been pinched against the case,causing a dead short to ground. Iapplied power to the motor. Itrotated, and the drain was less than100 mA.

Apparently the wire had beenpinched during installation at thefactory. Installation of new wires toreplace the burned ones plus tapingand rerouting of the motor's B+wire completed the repair.

Never before have I had a motorlead pinched, but I have foundwires of dial lamps in CH radiospinched before. Of course, the fuseblew each time.

To minimize the cost of fusesblown during troubleshooting andto allow faster troubleshooting with-out danger of ruining more compo-nents, I usually set my bench powersupply for a certain maximumcurrent. It is quicker and moreaccurate than using an ohmmeter.

Mark HughesKings Mountain, NC




THE FASTE Y TO ORDERGENERAL ELECTRIC PARTS IS FM:

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ES -74

Name

Service Company

Address

City State _ Zip

GENERAL ELECTRIC

Video and ABLcircuits and servicing

Servicing GE 13"color TV, part 6

Video circuitsSome technicians believe video

circuits are simple, and that theyare included only to provide suffi-cient contrast. Perhaps this wastrue in tube -type black -and -whitereceivers, but certainly it's not thecase with modern solid-state colorreceivers.

For example, the General ElectricAA chassis has a total of seventransistorized stages between thevideo preamplifier and the picturetube. In addition to amplificationof the video signal, these stages alsoremove the 3.58 -MHz color signals,allow the adjustment of brightnessand contrast, have vertical and

Figure 1 A white arrow marks theapproximate location of the video andautomatic -brightness -limiter circuits inthe General Electric AA chassis.

By Gill Grieshaber, CET

horizontal blanking inserted, andare connected to the Automatic -Brightness Limiter (ABL) circuits.

Correct clamping to the properblack level is provided by acombination of direct coupling anddc restoration.

Defects in these video stages aremore likely to affect the brightnessthan the contrast. Also, trouble -

Figure 2 Major video and

shooting is more difficult withdirect -coupled stages. Therefore,modern video stages are very im-portant, and we urge you to studythem before you are forced torepair them.

Figure 1 shows the general areaof the video and ABL circuits in theGE AA chassis, while Figure 2 andFigure 3 have arrows to show

ABL components are identified by arrows.

02100215

0270 "'25

0230

Y220

0240

FRONT


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General Electric

transistor and diode locations onthe main module and on themodule that includes the picture -tube socket.

Analysis of video circuitsA schematic of the first five video

stages is given in Figure 4, andFigure 5 has the correspondingwaveforms.

When the receiver is tuned to anyTV station, both the video ampli-tude and the dc voltages varyconstantly according to the picturecontent. These are large changes,and they prevent correct readings ofboth peak -to -peak and dc voltages.

Therefore, to eliminate these varia-bles during waveform photos andvoltage measurements, a gray -quadpattern was used from an ATC-10American Technology generator.

0205 operationExcept for two items, the 0205

second -video stage is ordinary.First, the emitter resistor is notbypassed, and the collector loadresistances together are low, about1300 o. Because of these conditions,the base -to -collector gain is lessthan 2 (see Figure 4).

Also, between the emitter resistorand ground is a tuned circuit (L214

and C214) that resonates at about3.58 MHz. Any emitter signal issubtracted from the base signal.Therefore, any signal at L214/C214reduces the gain of the transistor.In other words, the L214/C214tuned circuit is a trap that reducesthe Q205 gain around the 3.58 -MHz frequency. This action isshown by the color -bar waveformsof Figure 6. L214 is not adjustable.

Delay lineL210 provides the usual time

delay of the luminance signal so itis in register with the chroma signalat the picture tube.

VIDEO

FROM

Q200

3V PP

TP3

+37V

5V PP

Q205

2ND VIDEO

16 IV

29V PP31V

R206 820

C214 I 200 pF

IV PPOV DC

DELAY LINE

L210

(OOOl

R208

2700R209

,212V

oio

T700r_FLYBACK

TO

HV RECT

ó 12 +178V

W4

L214

53VPP

45V

R2I2 ? 3300

3300

2700

IPNPI

Q210

3RD VIDEO

16.3 V

+17V

C213 68 pF

R210

R213 1500

+21.2V

3.6V PP

W6

Q215

/VIDEO

+20.5V

+38V

R214 1800

R215

IPNP)

Q240 ABL

R240 / 1100

+212V

R242

5000

CONTRAST

100K


Figure 3 Three color matrixing power transistors and onevideo driver transistor with associated components aremounted on the picture tube socket module. Allconnections are made through polarized plugs and

sockets so the assembly can be removed or replacedeasily. Picture A is the front side which has thecomponents, and picture B shows the wiring side asviewed from the rear of the TV.

R217

R245 i 510

+235V

EMITTER

FOLLOWER

Q220

+ 20 V C220

36VPP g µF

R218 2200

R247 100

Q245

ABL EF

+70V

R248

C244 I=, 4 7µF

7500

+211V

467V

R220 39K

36VPP

57V

R219 2/00 Y220

67V

ioL220

io

R226

R224 2000

C222 t- 1µF

+ 12V

Q225

EMITTER

FOLLOWER

.51VR230

21 2

95VPP

I I

HORIZ

3 66 PP 1000

R228 1000

+2.4V

R227

68V

HORIZ R231 150016V PP

Q230

IPNPIBLANKING

2500

BRIGHTNESS

89V

+212V

NY230

215V

C233

160VPP TP23 22

R233 C324

HORIZ -+ +-n/y- - (25V PP 396 068

W9

1200

R234

VERT

10K

TO Q404

VIDEO DRIVER

R232 91K


--- r-- W3r----

r._._

ifr+-.1."..140"4.""11,40"'W4

-- W5r-lr ro.....~~.

r.'------ =--- +--W6

Figure 5 These waveforms are keyedto the "W" numbers in Figure 4.

General Electric

For troubleshooting, rememberthat an open delay line eliminatesall video in downstream stages andalso produces a black raster.

An open of the common L210connection (that is tied to B+) willcause severe ringing which resem-bles ghosts. Also, an open R208or R209 will cause the sameringing, because of improper termi-nation at the input or output of theline.

Test for a defective delay line byremoving the component, turningdown the color control, and con-necting a short piece of wirebetween the collector of Q205 andthe base of Q210. The pictureshould have normal sharpness butwithout any ringing. If this testremoves the ringing, the delay linemust be bad, or one of the loadingresistors is out of tolerance.

Three stagesThe next natural break in the

circuit occurs at C220, the first andonly coupling capacitor. Therefore,the Q210, Q215 and Q220 stagesare explained together.

Q210 is connected as a normalcommon -emitter amplifier (signalenters at the base and leaves at thecollector). This provides a phasereversal (see waveforms W2 and W5in Figure 5). The emitter resistor isbypassed partially to high frequen-cies by C213, while R213 limits theamount of HF boost. Gain of Q210is about unity. Q210 is a PNP-po-larity transistor, so the B+ enters

at the emitter and exits at thecollector where it becomes the basebias and signal for Q215.

Q215 functions as a common -emitter amplifier. However, its gainusually is less than unity because ofthe large unbypassed resistance inthe emitter circuit. A part of thisresistance is the contrast control.Higher resistances decrease thegain, and lower resistance adjust-ments increase the Q215 gain bythe principle of degeneration (cur-rent feedback). Of course, adjust-ments of the R215 contrast controlchange the collector voltage (andthe base voltage of Q220, the nextstage), but this does not change theactual picture brightness because ofC220.

Q220 is wired as an emitterfollower (signal is applied to thebase and is taken from the emitterwhile the collecter has only B+)that drives the dc -restorer circuit inthe next stage. Both the do and acvoltages at the emitter change instep with picture variations andwith contrast -control adjustments.

DC restorerC220 is the coupling capacitor

between Q220 and Q225. Anycoupling capacitor eliminates thevital do level of the video signal,but the do relationship can berestored by a diode circuit thatclamps the waveform properly.

Diode Y220 and coupling capaci-tor C220 form a shunt -type peakreading rectifier circuit that pro-duces a negative do voltage at the

Figure 6 Color -bar waveforms prove L214 and C214 (in Q205 emitter circuit)function as a tuned trap to minimize color signals at the collector. Basewaveform (W1) has sync pulses, black bars between the color bars and a normalamplitude of 3.58 -MHz signal on top of the color -bar spaces. The collectorwaveform (W2) shows inversion and less color amplitude. The W3 (emitter)waveform is identical to that of the base. W4 (L214/C214 trap) shows only the11 color bars without sync or blanking pulses.

prfaÍS

w 44i y' ti1YY ¡,W2

019;gggfig$ 100,10r00000 MM. uiwtuwí`ctl b+.4.4

. Ü L

W4


A ti

Y220 anode when the video signalis rectified. The junction of C220and Y220 is connected to the baseof Q225. Therefore, when the videosignal there has increased ampli-tude, the base becomes less positive(which makes the picture brighter,as we shall see). Conversely, areduced video level allows the baseto become more positive, and theoverall picture is less bright. (Thisprevents a gray background duringlow -contrast dramatic scenes whenthe background should be jetblack.)

Notice that the true brightness ofthe picture is not changed, becausethe diode clamps the shoulder ofeach blanking pulse to the dcvoltage that's present at the cath-ode of Y220. This operation shouldbe clarified by the waveforms ofFigure 7.

Defective Y220When the video amplitude is

normal and Y220 is not defective,the anode of Y220 measures about0.8 V less positive than its cathode(from the clamping rectification). Ifthe same dc voltage is measured atboth ends of Y220, the diode isopen or shorted. Therefore, eitheran open or a short reduces thebrightness by eliminating that 0.8 Vof opposing voltage. Other symp-toms, however, are different.

An open Y220 probably smearsthe picture sharpness slightly, butthe difference is not noticeable. Theloss of brightness is the mainsymptom.

A severe degradation of picturequality occurs when diode Y220 isshorted, in addition to the largereduction of brightness. In thiscase, L220 is the only load for thesignal coming through C220, sooverpeaking and waveform distor-tion occurs. Figure 8 shows awaveform and a TV picture fornormal operation plus (for compari-son) another waveform and TVpicture when Y220 was shorted.The TV picture when the diode wasshorted is difficult to describe. Oneof the effects resembles whitecompression. But another showssmears along the trailing edges.

0225 emitter followerQ225 is connected as an emitter

follower whose high -impedance in-put does not interfere with theC220/Y220 dc restorer operation,and whose low -impedance outputfrom the emitter is adequate forsupplying the video -driver stage.

Input to Q225 consists of thevideo that comes through C220 andthe sum of the Y220 rectifiedvoltage plus the do voltages fromthe brightness control and the ABLcircuit.

Output of Q225 is video mixedwith a dc voltage that varies withbrightness -control adjustments(which don't change the videoamplitude).

At the output of decouplingresistor R230, the blanking signalsfrom Q230 are added before thecombined video and blanking issent to Q404.

Figure 7 Video coming through C220 is clamped by diode Y220 to a selected dclevel. Waveform A (at the Y220 anode) shows the relative positions of video andthe zero -voltage line. Clamping by diode Y220 occurs at the blanking shoulders.The line at the blanking shoulders in the top trace of B marks the dc voltagesupplied to the Y220 cathode. After the video level was reduced (bottomwaveform of B), the blanking shoulders still were clamped to the dc voltage.Therefore, the blanking shoulders remained at the selected dc voltage althoughthe video amplitude changed. Thisholds the cut-off point of the picturetube at the same fixed dc voltage(regardless of video changes) in ex-actly the same way as if dc couplinghad been used through all of the videostages.

11~1111111.., +

r-

Figure 8 A serious picture degradationoccurs when diode Y220 shorts. In A,the top trace is the normal generatorvideo at the Y220 anode. Lower traceshows the distortion caused by a

shorted Y220. TV picture B is a normalone, while picture C shows the sameTV picture after Y220 was shorted.There Is a compression of mostshades of brightness plus a trailingsmear and the picture was muchdarker.

wiliormipmee 11~11


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General Electric

Blanking

Horizontal -sweep pulses and ver-tical -sweep waveforms are both fedto the base of Q230 through C324.In addition to operating as acoupling capacitor, C324 has avalue that removes the tilt from thevertical waveform. (If this diagonalline between vertical pulses is notleveled, the top of the picture wouldbe brighter than the bottom.) R232applies a small forward bias to thePNP transistor, while the negative -

going peaks of both horizontal andvertical signals produce B/E cur-rent (and thus amplification). Thepositive peaks are conductedthrough Y230 to prevent peak -read-ing base rectification, which couldproduce a positive base voltage thatwould allow only the tips of theinput waveform to be amplified.(Therefore, an open Y230 wouldcause insufficient blanking, withvisible retrace lines. And a shortedY230 would eliminate all blanking.)

The negative -going sweep signalsare inverted in Q230, and thepositive -going collector signals aresent through R231 to join the videoat the output of R230. Then bothblanking and video go to the baseof Q404, which is on the modulethat includes the picture -tube sock-et.

Notice that a negative -going sig-nal (such as a reduced dc voltage)at the junction of R230 and R231increases the picture brightness.And an increased do positive vol-tage or a positive -going video signal(see W7 in Figure 5) at R230/R231decreases the picture brightness.Therefore, the positive -going tips ofthe blanking signals at R230/R231will reduce the brightness (blankthe picture tube).

Keep these statements in mindwhen you measure dc voltagesduring troubleshooting.

Next, the ABL circuit will beanalyzed before the remainder ofthe video circuit is discussed.

Automatic -brightness limiterHigh -voltage current from the

picture -tube guns travels throughthe video -output transistors toground. From ground, this currentflows through resistor R702 (seeFigure 4) to the low end of theHV-rectifier winding of the flyback.

TESTPOINTLOW

BRIGHTNORMALBRIGHT

HIGHBRIGHT

Q240 base 19.4 18.2 17.80240 emitter 18.3 17.9 17.7Q240 coil 7.5 6.3 7.20245 emitter 8.1 6.8 6.50225 base 7.1 5.9 5.70404 base 6.8 6.9 6.7Q420 coil 138 110 1020400 coil 138 113 1080410 coil 137 110 104

Table 1 These key dc voltages were measured

Therefore, the flyback end of R702will have a negative voltage thatvaries directly with the picture -tubebrightness.

Well, it would be negative exceptfor a positive voltage brought fromthe +21.2-V source throughR244. After this bucking positivevoltage is added, the dc voltage atR702 becomes less positive withincreased brightness. Variations ofthe positive voltage are used tooperate the automatic -brightness-

level (ABL) circuit.C246, R246 and C240 filter the

horizontal ripple from the R702 dovoltage before it is applied to thebase of Q240, a PNP-polaritytransistor. Voltage dividerR240/R241 applies a positive vol-tage to the Q240 emitter. Thisvoltage is approximately equal tothe base voltage. Therefore, Q240does not have enough forward biasto conduct when the picture -tubecurrent is not excessive. In otherwords, over the normal brightnessrange, Q240 is cut off and doesnothing. Q240 drives Q245, soQ245 also does not conduct, andthe de voltage applied to Y220 andthe Q225 base voltage is notchanged. The ABL circuit does notoperate at any normal brightness.

If the brightness becomes exces-

at different brightness levels.

sive for any reason, the Q240 basevoltage becomes less positive, andQ240 conducts, thus increasing thepositive voltage at the Q245 base.In turn, Q245 conducts and bringssome of the positive collector vol-tage to the emitter, where itincreases the de positive voltageat the base of Q225. As statedbefore, a higher do voltage herereduces the brightness.

Therefore, the ABL circuit worksto cancel most excessive brightness.The figures in Table 1 should makethe operation more clear.

One factor is not accounted forin the de voltages. The filter at theQ240 base removes the horizontalripple, but it does not eliminate thelow -frequency 60 -Hz ripple that isproduced by the alternate high andlow picture -tube currents that occurduring vertical trace and retrace.These waveforms are forward biasfor Q240, and they cause conduc-tion that does not seem to bejustified according to the de volt-ages alone.

Video and chroma matrixingAt the neck of the picture tube is

a combination CRT socket andmodule that contains one video-

driver transistor and three colorpower amplifier transistors that


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+7.40V0.6 V PP

GREEN

Q420

R424

330

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8426 2 47

C426

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+7.4200.6 V PP

1404

330

+6BV0.7 V PP

8421

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8406247

C406

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9.5V PP+6.8V

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R453

1500

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GREEN CATHODE

95V PP+ 104V

8450TO CRT HEATER

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(000') R451 PTO CRT PIN 11

1401 1500 \ BLUE CATHODE

R400100

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R411

6800

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R410

8415 240+ 145V

100

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VIDEO DRIVER

PNDP f-

C404T10pF

Y400

0410

+ 6.0V 8440

rn1500

C4027.820 pF

MATRIXING

2.8VPP+ 6.8V

R457

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+109aV

TO CRT PIN 4

RED CATHODE

95V PPr 106.8

GROUND FOR

SCREEN AD1.

Figure 9 Luminance video and demodulated chroma signals are matrixed insideQ420, Q400 and Q410. Chroma signals are applied to the bases, and luminancesignals are applied to the emitters. These four transistors are mounted on theCRT -socket module of Figure 3. Voltages and waveforms were measured duringreception of a generator B&W signal, therefore, no chroma signals were there.

drive the three picture -tubecathodes. Figure 9 gives the entireschematic, and Figure 10 shows theluminance waveforms when video issupplied by a generator.

0404 operates as another emitterfollower. Video from the emittergoes through R425, R405 and R415to the emitters of the three color -output transistors. Neither com-mon -base amplifiers (where thesignal enters at the emitter andexits at the collector) nor emitterfollowers invert the polarity. There-fore, the video (plus blanking) ispositive -going through these stagesand at the CRT cathodes. Ofcourse, a positive signal to a CRTcathode decreases the brightness ofthat gun, so the polarity at theCRT is correct.

Matrixing of the G -Y, R -Y andB -Y demodulated chroma signalswith the luminance occurs insideQ420, Q400 and Q410. Thesechroma signals enter at each base(so the collector polarity is in-verted), the luminance signal entersat each emitter (this signal is notinverted), and the combined colorand luminance signals come out atthe collectors.

Chroma waveforms for thesesame stages are very different. Theywill be shown and explained nextmonth.

One unusual characteristic of thistype of matrixing is that thechroma signal appears at the base,the emitter, and the collector ofthese color transistors. Signal isfound at the emitters because theyare not bypassed. In the same way,the luminance signal can be scopedat base, emitter and collector ofeach color amplifier. When theluminance is fed to the emitter,some of the waveform appears atthe base because it isn't bypassedand there is conduction betweenemitter and base at all times. Thesewaveforms can be very confusingunless you know the facts. Aluminance signal fed to a tubecathode does not appear at theunbypassed grid. This is one of themany differences between transistorand tube circuits.

TroubleshootingVideo -circuit troubles might in-

clude insufficient contrast, smearedpictures, excessive brightness, dark


General Electric

~44fra=m211/1"

Figure 10 These waveforms were madewhen a video generator supplied thesignal. The W numbers correspond tothose of the Figure 9 schematic,

r4----Jils=fetZmiir

__1I___ ....

1111..1..

or blanked -out pictures, or wrongraster colors (bad gray scale).Probably the most common symp-tom will be wrong brightness.

In general, video troubleshootingshould be done in sections. Q205,Q210, Q215 and Q220 comprise thefirst section. Preliminary analysisshould be done as though thesefour stages were just one. Checkinput and output signals first. Ifyour scope shows the proper wave-form at the Q220 emitter (and ifthe dc voltage there is withintolerance), probably this section offour stages is working correctly.

Here's a valuable tip: No defectin this section of the video circuitcan eliminate the raster. That'sassuming the defect doesn't affect apower supply which is common toother circuits. Defects here caneliminate the video, weaken it ordegrade it. And a loss of video willdarken the raster. For example, if ablob of solder shorts the Q215 baseto ground, the downstream dovoltages will change drastically, butC220 isolates the disturbance. Youcan turn up the brightness controlslightly and obtain a blank raster.

By contrast, serious defects in thelast section of the video circuit fromQ225 to the picture -tube cathodesoften cause excessive brightness ora dark picture. The driver transistor(Q404) is the only one that theoreti-cally could reduce the contrast.However, Q404 is an emitter follow-er, and they seldom have defectsthat reduce the output signal. Thenext stage has three power transis-tors that drive the CRT cathodes,and a defect in just one wouldchange the B&W screen color morethan it would the contrast.

If a defect reduces the +145-Vsupply (scan rectified from thehorizontal sweep) for the coloramplifiers, the raster and picturewill be too bright. Sometimes thebrightness is so great it kills thehigh voltage. A C/E short in Q404driver transistor also causes tremen-dous brightness and possible loss ofHV.

On the other hand, an open inQ404 would bias all three coloramplifiers (Q420, Q400 and Q410)to cut off. They in turn would applyan increased positive voltage to theCRT cathodes, and no raster couldbe seen.

T P40

At the lower corner of themodule containing the CRT socketis test point TP40, which is usedduring the gray -scale adjustments.There is no service/normal switch.Therefore, the brightness and con-trast controls are turned downcompletely, TP40 is grounded andthe three CRT screen controls areadjusted for a dim gray raster.Then the contrast and brightnessare turned up to normal and atouchup made on the screen con-trols (if the B&W picture has atint).

This test point can be usedduring troubleshooting. If you canfollow the sequence for setting thescreen controls and are successfulin obtaining a dim raster, thisproves that any problem of a dimor blacked -out picture is caused bythe Q404, Q225, or Q230 stages.

Servicing direct -coupled stagesAnalyzing direct -coupled stages is

quite difficult, and most methodshave some snares and dangersbecause the signal and do voltagesof each stage depend on conditionsof upstream stages. Even simpletests (such as shorting base toemitter to turn off a transistor) canproduce severe overloads on transis-tors that are several stages down-stream from the one being tested.

You can substitute for wrongvoltages by applying power from anadjustable -voltage supply through alimiting resistor to a bad stage.But this must be done with carewhile monitoring the effect on thestages that follow.

DC voltage analysis perhaps isthe safest and most simple method.At least this should be done first.Most transistor defects are shorts oropens, so write down the measuredvoltages and then use logic todecide which defects might accountfor the readings. Then remove thetransistor or other component forout -of -circuit testing. The AAchassis GE has all video transistorssoldered to the circuit board, so tryto be accurate in your diagnosis.

Next monthChroma circuits of the AA -

chassis General Electric, includingthe Color Monitor, will be discussednext month.

30 Electrcnic Servicing February 1979

Quick TV Tips G1Se «theBy Wayne Lemons, CET

SymptomsBoth horizontal and vertical sync

disappeared intermittently in thisAdmiral TV receiver. Scope wave-forms isolated the intermittent sig-nal to the output of sync amplifierQ2 (see the partial schematic). Noloss of sync occurred in the videochannel, and the picture sufferedno apparent change.

Although the problem was veryerratic, the TV sometimes wouldremain without sync for severalminutes. Therefore, we were able tomeasure all dc voltages and look atthe scope waveforms.

Actually, the waveforms of Q2were not helpful. Q2 was saturated(collector and emitter voltageschecked about the same) and didn'tamplify. But, the big question wasthis: Why was Q2 saturated?

No defective parts?Each resistor shown in the sche-

matic was unsoldered at one endand individually tested for resis-tance. Unfortunately, all were with-in a 5% tolerance. Q1 was notdefective, it had the correct biasand was amplifying normally. Q2checked okay, and a new transistoroperated in the same intermittentway.

Bias and video for the Q2 basewere supplied by a voltage dividerthat paralleled the Q1 collectorload resistor. Therefore, we rea-soned that the defect must be inthat area. An in -circuit resistancetest across resistor R1 gave areading of about 2300 0 . Thisseemed about right since the3300-0 121 was paralleled by about75000 from the series -connected R2and R3.

All information necessary for us(and you) to identify the badcomponent has been given. Thinkabout the problem before you readthe answer.

The solutionAn in -circuit reading of 2300 0

Peat* sYneThis is a case history that baffled twogood technicians for about an hour.All important clues are given here.Can you solve it faster than they did?

QIVIDEO AMP

READS

2300 OHMS

ACROSS Rl

IN CIRCUIT

DLI DELAY LINE

RI

3300

VIDEO OK

T_ Q2

R2SYNC AMP

6800

+23IV

R3

680

+ 25V

+ 23.70

+ 23.8V

R4

120

5600

+ 25V

C2

VIDEO

AMP

LI

R6

2200

CITO SYNC

I

02

\SEP

NO VIDEO

WHAT DEFECT PREVENTSA2 FROM AMPLIFYING?

across R1 should have been enoughfor us (and you) to find the oneintermittent component. Notice thatnot only is Rl paralleled by thesum of R2 and R3, but also Rl isparalleled by R6 (through the delayline and Ll). The reading shouldhave been about 1100 0

The delay line must have hadcontinuity constantly, since a pic-ture was on the screen. Also, allresistors had been checked out -of -circuit. Therefore, either L1 wasintermittently open, or R6 had abad soldering joint that was open-ing the Li circuit. Ll was openingerratically!

When Ll opened, the Q1 collec-

tor load resistance went up fromabout 11000 to about 23000 , thusincreasing the voltage drop acrossRl. In turn, Q2 was biased intosaturation and loss of gain by thelarger R1 voltage.

CommentsLooking back after the problem

was corrected, we remembered thatthe picture showed some "ghosts"which are typical for an incorrectly -terminated delay line. But ofcourse, we were looking for a synctrouble, and intended to check theghosts later.

Could you have found the defectin less time than we did? E


TypicalRadio

Repairs0022

SHORTED

RE AMP

TR4

.9V

TO AVC

+26V

30

047-r

1000=

Figure 1 Audiovox model AMF-15 hadno AM -band operation.

By Homer Davidson

Although no single article can describe all possibledefects in car radios and tape players, these casehistories should help you solve many similar problems inother models. Also, suggestions are given for trouble-shooting tests and general methods.

Solid-state auto radios are notvery difficult to repair. Some cir-cuits are in cramped corners, andthere are some accessibility prob-lems. Also, many machines willrequire removal of dust and dirtbefore you can see the components.Other problems should be no moresevere than those in home radios.

The following case historiesshould help you anticipate some ofthe typical troubles.

Dead AM receptionNo sound could be heard on

either the FM or AM bands.Voltage measurements around thepower section of the circuit boardrevealed that no voltage was reach-ing any circuits. While tracing thesupply voltage from the on/offswitch to the filter capacitors, Ifound an open in the printedwiring.

The open wiring was bridged bya piece of hookup wire solderedover the printed wire. The FMradio operated on all the usualstations, but the AM function wascompletely dead.

Now, the IF transistors are

common to both AM and FM, so itwas obvious that the problem mustbe around the AM input stages,such as the RF or oscillator.

An in -circuit test of RF transistorTR4 showed a beta reading withoutany opens. Voltage readings, too,were quite normal. But when any ofthe transistor leads was touched,strong local radio stations could beheard. Obviously, the defect was inthe RF stage.

A generator signal was injectedat the base when the radio wastuned to 1400 kHz and the gainseemed to be normal. The samesignal applied to the input jackcould not be heard. The signal wasinjected in turn to each end of the.01 coupling capacitor, and it gavenormal volume.

The defect had to be between theinput jack and the .01 couplingcapacitor (Figure 1). Ohmmetertests of the few components foundthat the .0022 bypass capacitor wasshorted. A new capacitor restoredcorrect AM sensitivity.

Motorboating and oscillatingA mixture of oscillations and

motorboating was the complaintagainst the model 706A Dodgeradio.

Most complaints of this natureare caused by open filters or bypasscapacitors. Occasionally, bad tran-sistors or improper alignment willdo the same.

All filter and bypass capacitorswere paralleled in turn by anothercapacitor of a larger value, but theproblems continued.

Generally, transistor testing andvoltage measurements are not effec-tive for locating components thatproduce oscillations. The squealingcould be heard as the radio wastuned across each station, so wesuspected a bad converter bypasscapacitor.

However, in making the tests, themeter probe was touched to theemitter of the RF transistor (Figure2) and the radio played weakly butwithout oscillations.

The .01 emitter bypass capacitorwas replaced, and the performancewas very good.

Intermittently weak receptionWhen the American Motors


model 2HT1413, radio became in-termittent, only two local stationscould be heard at all. However, theradio would rapidly alternate be-tween normal sensitivity and thisweak condition.

Because there was no overload oflocal stations during the weakperiods, we assumed the problemwas in the RF stage. Very low dovoltage was measured at the base ofQ1 (Figure 3) and none at theemitter. These readings indicatedthat Q1 was not conducting.

However, an in -circuit test of Q1showed a good beta reading and noopens. Sometimes an intermittenttransistor will "pop" on when atransistor tester is connected, so wealways make additional tests. Thesuspected transistor was replacedwith a universal SK3018. Unfortu-nately, within minutes, the intermit-tent began again.

After several unsuccessful tests,we measured the resistance of alltransistor leads to ground. Suchtests generally are not accurate withthe transistor still connected. But

Figure 2 Motorboating and oscillationsruined reception of the model 706ADodge radio.

OVEN

Figure 3 Intermittently, the model2HT1413 American Motors radio wouldbecome very weak. Only two stationscould be heard.

RF AMP

47µF

AVC INTERMITENT_ = SHORT

this test showed about 200 o fromemitter to ground and only about3 n from base to ground.

We replaced the 47 -NF base -return bypass capacitor and theintermittent was cured.

One local stationOnly the local 540 -kHz radio

station could be heard at the lowend of the dial, and nothing (noteven noise or static) was receivedabove about 700 kHz.

When only the low end stationscan be received, we usually find theconverter transistor is not oscillat-ing over the entire band. In thiscase, a replacement converter tran-sistor didn't solve the problem.

Analysis of the dc voltagesshowed a supply voltage of slightlyabove 6 V (it should have been 12V or higher). And the smallbench -mounted power supply wasrunning hot and buzzing. Wesuspected the audio power -outputtransistor, which has its mountingscrew located inside the dial assem-bly. After we unsoldered the tran-

sistor leads, the supply voltage roseto the normal 12 V.

Before the power transistor couldbe removed, it was necessary toremove four plastic inserts from thedial assembly. To remove eachinsert, take out the round centercore and then pry out the plasticinsert. Next, remove two metalscrews that hold the metal dialassembly. The mounting screw forthe transistor now is accessible.

After the output transistor wasremoved from the small circuitboard (see photo in Figure 4), aleakage test verified that the tran-sistor had nearly a dead short. Auniversal SK3041 was used toreplace it.

Before you solder the new leads,make sure the flat side of thetransistor is opposite the lead wires.Then, doublecheck the wiring. Yel-low wire goes to the emitter, theblue wire to collector and the greenwire to the base. After the transis-tor and small circuit board arefastened into position, a drop ofsilicone -rubber cement should be

Figure 4 Excessive current drain in the Philco-Ford model DOAA-18806indicated a shorted output transistor. In this model, part of the dial assemblymust be removed to gain access to it.


Radio repairs

added to prevent the board fromturning.

Severe noiseA model CYM62 Motorola had

very noisy reception, and occasion-ally the audio would stop for ashort time.

Generally, such noise is causedby bad transistors, worn volumecontrols, leaky IF transformers, andleaky RF or oscillator paddercapacitors. And sometimes a defec-tive ceramic capacitor or noisyresistor in the audio stages canproduce a similar noise. Of course,audio noises can be heard all thetimé, but RF and IF noises vary inloudness with the volume controlsettings. Thus, the volume controldivides the radio for test purposes.In this case, the noise originatedbefore the volume control.

One shortcut for finding noisytransistors is to short the base to itsemitter. Do this to each stage. Ifthe B/E short stops the noise, thenoise source probably is in somestage upstream. By using thismethod, we noise to theconverter stage.

Sometimes the circuit where theproblem originates will show afluctuation of dc voltage when thenoise is loudest. This was true ofthe converter emitter voltage, andwe concluded the defect was cldseby (Figure 5). Because nearly all ofthe supply voltage appears acrossthe oscillator padder capacitor, itwas suspected of erratic leakage.

When the capacitor was discon-nected, a varying high -resistancereading. was obtained across theterminals. Installation and adjust-ment of a new padder solved thenoise problem.

Low audio gainOnly one radio station could be

heard, and it had weak volume.These symptoms in a model 986846Delco might make you suspect anRF, converter, or IF problem. Thissuspicion was strengthened by anormal amount of buzz, when ascrewdriver blade and finger weretouched to the center lug of thevolume control.

Using a noise generator, thesignal was traced to the second -IFtransistor. When the signal was

262kHz

Figure 5 Severe noise in

a CYM-62 Motorola wastraced to a leaky paddercapacitor.

applied to the base, the sound wasvery weak, but it was loud whentouched to the collector. An in -circuit transistor test indicated thetransistor was open, and the instal-lation of a replacement restored theproper volume and number ofstations.

Broken volume controlThe complaints against the Craig

model 3521 radio and cassetteplayer were no sound and a loosevolume control.

A visual examination showed theframe of the volume control wasfirmly attached to the radio, butboth volume controls and theswitch were pushed backwards sothey rotated with the shaft. Thisimproper movement had broken thepower lead from the on/off switch.

Figure 6 Both volume controls and the switch were pushed backposition, and several wires were broken in the Craig model 3521 radio.

out of


AUDIO

AMP

+ 6V

187VI+14V

OPEN AUDIO

DRIVER

60K

124V

1+124VI 10012

+11 2V

68

AUDIO

OUTPUT

(+12 4V)+122V

47

(0V)+12V

+124V

TO

SPKR

Figure 7 No click or thumpcould be heard when thisinoperative Motorola TM7Awas turned on. Usually apower problem or a deadoutput transistor is re-sponsible.

The customer was ready to starthis vacation and there was no timeto order the special control assem-bly. Therefore, the control wasfastened together (with spots ofsolder strengthening the tabs), thepower wire and ground leads wereresoldered, and the radio workedfine except for the noisy volumecontrols (Figure 6). We ordered thevolume -control assembly for instal-

lation after his vacation.Some noisy volume and tone

controls can be restored by squirt-ing tuner spray inside and thenrotating the shaft several times.Other controls either don't becomequiet or the noise elimination lastsonly a short time. So, it's best toconsider cleaning as a temporaryremedy that might last until a newcontrol can be obtained.

Figure 8 A poorly -soldered joint produced one weak stereo audio channel in aSanyo FT872.

No soundWhen this Motorola model

TM7A was brought in, no stationcould be received and no click washeard when the radio first wasturned on. (If the output stage isoperating, most radios will have athump or click.) With these symp-toms, the output transistor usuallyis dead. We replaced it, but therewas no change (Figure 7).

An audio tone was injected at thevolume control, but not a soundcame from the speaker. Next, dcvoltage readings were taken in theaudio system. The emitter voltagewas zero, the base had 8.7 V, andthe collector measured the same asthe 14.2 V supply. There was noC/E current, and yet the forwardbias was 8.7 V. Obviously, the B/Ejunction was open. This was verifiedby an in -circuit transistor test, anda new transistor restored the goodperformance.

One weak channelOne channel of the Sanyo FT872

was very weak, but there was nodistortion. In this combination rad-io and Stereo -8 player, the audiostages are on a separate circuitboard, as shown in Figure 8.

Where two identical stereo chan-nels are used, a very effectivetroubleshooting technique is tocompare the voltages and signallevel of the bad channel against thegood one. Therefore, a signal froman audio generator was injected ateach stage of both amplifiers,starting with the output and work -


Radio repairs

ing upstream. Source of the weaksignal was found between the firstand second audio transistor.

When the signal was injected atthe input side of the 10 -DF couplingcapacitor, the sound usually wasweak, but at times it snapped backto normal volume. At first, wethought the capacitor was intermit-tent, but a loose soldering joint wasfound at one end of the capacitorduring the start of disconnecting it.

A good soldering joint stoppedthe intermittent and brought backproper gain to the weak channel.

Intermittent transistorAt first, we suspected an IC

audio amplifier in the model CKL-4019 Automatic radio. However,voltage checks and other testschanged our suspicion to the audiooutput transistor (see Figure 9).When the meter probe was touchedto the transistor leads, several timesthe sound would begin. There wasno noise and no stations when theradio was malfunctioning.

When the sound was not work-ing, the collector voltage was zero,the base voltage was 10 V and theemitter measured 12.8 (the supplyvoltage). These voltages indicate notransistor current and an openjunction. Replacement of the inter-mittent output transistor with anSK3041 transistor cured the prob-lem.

Both stereo channels deadBoth channels of the model

KID -565 Kraco radio and tapeplayer were dead. This is unusual.Usually the two channels havedifferent symptoms, even if bothhave problems. Of course, power -supply defects can kill both chan-nels at the same time.

In this case, the audio power ICsof both channels were nearlyshorted (Figure 10) and requiredreplacement. Shorted speaker wiresmight have caused the ICs to fail.

Before you remove any ICs,check for mounting arrows oridentification numbers. It's difficultto determine the right positionotherwise.

Loud shrieking noisesRadio stations could be tuned in;

however, volume of the sound was

CKL-4019 Automatic radio had intermittent volume.

Figure 10 Both stereo channels of the Kraco model KID -565 were dead; anunusual symptom, except for power -supply problems.


Figure An of the radio.Filter capacitors often cause this trouble.

not changed by the controls. Butthe most obvious symptom of themodel 7985773 Delco was theear-splitting shrieking noise.

Noises of this kind often arecaused by open filter capacitors(shown in Figure 11). Test for thepossibility by shunting a 1000-11F16-V capacitor across each filter inturn. If the test capacitor stops theshrieking noise, the capacitor it was

paralleling at the moment is theopen one.

Sometimes several capacitors arelocated in one container. If just onesection is open, it's best to replacethe entire assembly.

One filter capacitor was replacedand all abnormal noises were gone.

MotorboatingWhen the volume control of the

Delco model 01BP2 was advanced,the sound would develop a fastvariation of volume (often calledmotorboating). Also, the dc voltagesat the filter capacitors would varyin step with the motorboating.

Each filter was shunted by a testcapacitor. Paralleling the test ca-pacitor across one certain filtercapacitor stopped the motorboating(Figure 12). This was in a multiple -

capacitor can, so the whole assem-bly was replaced. All motorboatingwas eliminated.

CommentsAs you can understand from

these actual case histories, notmany auto -radio repairs are diffi-cult. As always, intermittent prob-lems bring additional complica-tions. But, the techniques of signalinjection and dc -voltage analysisusually can pinpoint the stage thathas the trouble.

Some defects are more likely tooccur than others. Capacitors oftenbecome intermittent; resistors sel-dom do. And symptoms vary ac-cording to the circuit having thedefect. You can save hours byknowing these facts.

Before you install the covers aftera repair, check the pilot lamps andreplace them if necessary. Usewindow spray to clean out any dirtor grease from the dial assembly.Adjust all pushbuttons correctly forlocal radio stations. These choresrequire very little time, but they willimpress the customers with yourhelpful attitude. U

+126V 9AMP

+12.2V

+48V

+2.5V

Figure 12 Motorboatingcommonly is caused byopen filters. This was trueof the model 01 BP2 Delcoradio. Several capacitorswere in one can, so thecan was replaced, ratherthan just the one badsection.


22m Wb 1©1 1©bnO© IOAVo000z.

\COUNTER GLITCHES/Jf

In the December Technical Note-book, I discussed three capacitorquestions that are difficult fortechnicians to answer. My theory isthat problems arise because theyare not taught how capacitorsactually work. Instead, they aretaught from incomplete models.

Keep in mind that this is mytheory. Here, as with other contro-versial subjects I discuss in Techni-cal Notebook, Electronic Servicingallows me to present my ideas. Ifyou disagree, then your quarrel iswith me, and not with the maga-zine.

Question of the unchargedcapacitor

A schematic for the last capacitorquestion of the series is shown inFigure 1. (I don't call it a circuit,but an arrangement, because acircuit has a complete path forcurrent flow. A capacitor does not.)

Question: What is the voltagebetween points A and B, if capaci-tor Cl is uncharged?

Answer: There is 100 V betweenA and B.

The reasoning is quite simple. Ifthe capacitor is uncharged, it can'thave any voltage across its termi-

Your comments or questions arewelcome. Please give us permissionto quote from your letters. Write toSam at:

J.A. "Sam" Wilsonc/o Electronic ServicingP.O. Box 12901Overland Park, Kansas 66212

By J.A. "Sam" Wilson

nals. Therefore, the same voltage isat each of the capacitor terminals.In other words, the voltage betweenA and B is identical to the batteryvoltage. These last two statementsare true because of the zero voltageacross the capacitor.

This question was used in anearly version of the CET test, and itbrought me more mail than anyother question in any test. Whyshould this simple arrangement ofcomponents be so difficult toanalyze? Perhaps it's because theusual capacitor model places exces-sive emphasis on the thought that

Figure 1Cl

100V

r A

B

WHEN CAPACITOR ISUNCHARGED, WHAT VOLTAGE

IS BETWEEN A AND B?

Figure 3POSITIVE

CHARGE

.++

NEGATIVE

CHARGE

tFORCE

I

UNLIKE CHARGESATTRACT

Figure 2

VI

CI

ELECTRON

FLOW ¡

R1 I DURING I R2

I CHARGE I

WHAT DOES Cl DO?

V2

Figure 2 Cl is called a coupling or blocking capacitor. Whatdoes it actually do?Figure 3 A charged capacitor has opposite charges at the plates.These attract; therefore, work is required to move the platesapart. This work accounts for the increased voltage that occurswhen the plates are separated more widely.

Figure 4

#22 SOLID COPPER WIRE

2"

HOW MUCH CAPACITANCE?


capacitors will pass ac but not dovoltages.

The circuit often used to demon-strate this idea is shown in Figure2. Capacitor Cl sometimes is calleda blocking or (more often) couplingcapacitor. Its purpose often isdescribed this way: the capacitorallows the ac signal to pass fromV1 to V2, but prevents the V1positive plate voltage from reachingthe grid of V2.

The explanation is not wrong,but it omits the initial chargingthat occurs when the circuit first isenergized. A dotted arrow showsthe electron path for the chargingcurrent. After the capacitor be-comes charged, the dc voltageacross resistor R2 has dropped tozero volts. The do voltage across thecapacitor then is equal to the B+minus the voltage drop across Rl.

Notice the similarity between theschematics of Figure 1 and Figure2. In both cases, the capacitor isconnected to a positive voltage.However, in Figure 1, the capacitoris uncharged, so the output dovoltage equals the supply voltage.In Figure 2, the capacitor ischarged, and its output voltage iszero volts.

Just as soon as a conventionalvoltmeter (which draws currentfrom the tested circuit) is connectedbetween points A and B in Figure1, the capacitor begins to charge.Eventually, the dc output voltagewill become zero volts when thecapacitor reaches full charge. How-ever, that is not a consideration inthe question, because the capacitoris described as being uncharged.

In a future issue, I'll presentsome comments from readers aboutthis capacitor series.

More comments about wortOne reader (who didn't give

permission for his name to bementioned) asked me to give addi-tional information about the in-crease of voltage across a chargedcapacitor when the plates aremoved apart. He asked why thevoltage went up when the plates aremoved farther apart but not whenthey are allowed to move towardeach other.

The answer is found in thisstatement: Voltage is a unit of

work. That is, work equals forcemultiplied by distance. When acapacitor is charged, one of theplates is positive and the other isnegative (see Figure 3). Like chargesrepel and unlike charges attract.Therefore, the plates of a chargedcapacitor are attracted to eachother. To move those plates apart,you must exert force through adistance.

Since the plates are attracted toeach other, they will move towardeach other without the need for anexternal force. So, it's not necessaryto expend work on the system tomove the plates nearer together.

When the plates are movedapart, energy is stored, and thisenergy is given up when the platesare returned to their original posi-tion.

Figure 5 These are corrected schematics from the October, 1978 IndustrialElectronics article in Electronic Servicing. The A schematic was Figure 1on page 32; B was Figure 2 on page 33; C was Figure 3 on page 36; Dis the binary counts of this Figure 5C; and E was Figure 4 on page 36.The capacitor added to all schematics cures an unexpected glitch.

E!

44 E

RES

IR 7476

43 C

Q 112 7476 In 7476

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COUNT Q Q READOUT DECIMAL NAND IN NAND OUT

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1127420

Technical notebook

Please, no phone calls1 try to answer all letters sent by

readers. Sometimes there's a longdelay because I have a busyschedule. But I do answer eventu-ally.

However, I don't have a tele-phone. (I'm waiting to see if theycatch on.) So, when people call theISCET/NESDA office, the maga-zine, or my place of work, theywaste their time and money. I neverreturn phone calls because it's toomuch trouble to find a pay phone.

Please write to me; don't call.

A strange capacitorI just can't resist one more

capacitor question. At the begin-ning, I must explain that I don'tknow of any practical applicationfor the answer.

Question: What is the capaci-tance of the piece of wire in Figure4? The answer is given at the end.

Glitch...that old demonMany readers have written about

the first four illustrations in theOctober, 1978 Industrial Electron-ics article (pages 32, 33, and 36).Those illustrations and the accom-panying text had too many errors toblame on the typesetters (our usualexcuse). (Three of the schematicshad NOR symbols when the gateplainly was labelled as a NAND. InFigure 3, the NAND inputs werewired incorrectly. Also, the Figure 8caption should have referred toFigure 4, not 3.) Corrected sche-matics are in Figure 5.

However, even after several read-ers recognized the mistakes andcorrectly wired the counters, wrongcounts were obtained.

With ripple counters, each flipflop is switched in sequence. Thefirst switches the second, the secondswitches the third and so on. Thesecounters are programmed to stop orrepeat the count when all fourNAND inputs receive logic 1 signals(highs). At that time, the NANDoutput should go low and stop thecount.

Figure 6 shows the NAND inputwaveforms for the October Figure1. The area of interest is the tinyslice of time between the 7 countand the 8 count. This point ismarked by an arrow. Notice thatsignals from the first, second and


fourth flip flops are changing tohighs, while the signal from thethird flip flop is switching to a low.

If these four waveforms switchedat the same instant, there would beno problem. However, if the thirdflip flop signal has the slightestdelay in dropping to zero, all fourNAND inputs will have logic onesfor a very short time before thecorrect states are established. Thisbrief transient condition producesat the NAND output a glitch that'ssimilar to the narrow negative pulseof Figure 7. Unfortunately, theglitch resets the four flip flops tozero before the counter reaches theprogrammed count of eleven.

A simple fixThe glitch can be eliminated by

the addition of a 0.047 microfaradcapacitor connected from theNAND output to ground, as shownin Figure 8 and the correctedschematics of Figure 5. The capaci-tor stores the narrow glitch but thevalue is too small to affect thecorrect NAND output logic states.With the capacitor added, thecounters work as intended.

Now, I don't recommend addingcapacitors to solve glitch problems,unless there is no other solution.For example, a 2 -input NANDcould be used to switch only twoadjacent flip flops. This greatlyreduces the effects of time delays.

Another design solution is to usea synchronous counter. I'll discussthat type next month.

Answer to wire capacitorA straight piece of solid wire has

an infinitely -large capacitance! Re-member that moving the capacitorplates nearer together increases thecapacitance. This is proved by thefollowing equation for capacitance:

C=k NA

d

In this case, k is the dielectricconstant, N is the number ofparalleled plates, A is the area ofeach plate, and d is the distancebetween the plates.

Therefore, if the distance betweenplates is reduced to zero, thecapacitance becomes infinitelylarge. Figure 9 shows how such acapacitor can be made from wire.

As I wrote earlier, I don't knowof any practical use for this curioustype of capacitor. Do you?

0 1 2 3 4 5 6 7 S 9 10 117 j1 L 1

2

3 NAND j'

/d .

SWITCHING DELAY OF *3PRODUCES HIGHS AT ALL NAND INPUTS

Figure 6 If the third flip flop signal is slow in dropping to zero at thebeginning of the eighth count, al NAND inputs will have highs for a verybrief time. However, this is long enough to procuce a negative -goingglitcn at the NAND output, and it stops the count prematurely.

BEGINN NG OF CÚUNT ,I Figure 7 A timedelay in the third

LOGIC 1

LOGIC 0

TIME DELAYGLITCF

flip flop cancause a glitch atthe NAND output.

_ GLITCH The gluch resetsthe counters be -

CAUSES fore the pro-grammed num-ber.

8 AFigure 0.047

NAND/

ADDS

ELIMINATE GLITCH

capacitor added

I047 to the NAND out-

put removes theglitch.

1-i

I1 INCH

LOW

d -1-- 1 INCH

CAPACITANCEFigure 9 S a msays this lowerwire has infinitecapacitance.--,

INFINITE CAPACITANCE

CAPACITANCE OF A WIRE

FeJrJary 1979 Electronic Servicing 41

Just a bad tunerHis RCA color TV that was

purchased recently in the Stateswould not receive one of the twolocal Bermuda channels unless heforced the channel knob to stay abit to one side of the number,reported one customer.

I informed him that corrodedcontacts inside the tuner probablywere causing the intermittent, andthat such defects are rare in newTVs. Because the receiver was inwarranty, I advised him to have thetuner sent to the selling dealer.

He agreed with my suggestion,and I removed the tuner. I took theprecautions of making a pictorialdiagram of the wires and connec-tions before I removed them, andthen clipped off the leads to theUHF switch (sometimes the switchwill melt if the iron is too hot dur-ing the unsoldering).

About five weeks later, the tunercame back, and I installed it in theTV. Both local stations were re-ceived in good fashion, and I wasabout to replace the back screwsbefore delivering it to the customerwhen I noticed that the picture wastoo narrow. About 1 -inch of blackshowed at the right and about1/2 -inch at the left.

When did it become narrow?Had the picture been narrow

before I worked on it? Could I havecaused the problem? Was my linevoltage low? These were some ofthe thoughts that flashed throughmy mind.

Difficult analysisof a narrow picture

By Frank Wolff, CET

With skill, perseverance and several good tips from ElectronicServicing articles, this -technician was able to find severalobscure defects in one TV receiver.

First, I checked my shop linevoltage, and it measured a volt orso above 120. The line voltage wasokay. I called the customer whoreported that the picture had beennarrow since he bought it, but thepicture was excellent and the nar-row picture had not bothered him.Well, it bothered me!

No schematicAgain, I removed the cabinet

back and carefully examined thechassis for a width pot or a widthconnector wire. Neither were found,but I did locate a width switch,which I started to slide. Then I sawthe precautionary notice to turn offthe power before changing theswitch position. I followed instruc-tions, but the switch must havebeen in the "wide" position before,because the picture was more

narrow now. I turned off the powerand moved the switch back to theoriginal position.

I was beginning to worry becauseI had no replacement parts for thismodel. If I were forced to orderparts (which require five weeks toarrive) and then found I haddiagnosed wrong, the customerwould be more than unhappy,. Thiscalled for careful and accuratetroubleshooting before any compo-nents were ordered.

To make the situation worse, theRCA had a CTC78 chassis but myPhotofacts stopped with the 1976models. I was not familiar with thistype of horizontal -output circuit.

The latest Howard W. SamsColor TV Field -Service Guide onmy bookshelf was volume S. Itcovered RCAs only to CTC66, and Ispent some time looking for similarchassis layouts before settling on a

FROM

HORIZ

OSC -I

.72 V

.150 V ---lXxxxxl _ j- 1CRI0, ®i .075

RETRACE

SWITCH FERRITEC% READ

CR402 C 33RETRACE AS TSWITCH

REG

3,90I0W

1200

1- -1 Ífd p .18

- Ers'3°33

FERRITEBEAD

.066

RETRACE TRACE

.50V

i,001

330

G(CRI01

-7.2 V ^'

4700

4.702W

CR401

E

SWITCH

TRACE

SWITCH

HV REG

1 A -1.4 V

YOKE

I 5yF

LAB AC K

300 0CR405

HV

7 T ADJUST

ZENER. 1000

7flI. 0047

330 0

Figure 1 Thishorizontal -sweepschematic of theRCA CTC58 colorTV is similar tothe one repairedby the technician.

270150 V

CTC58. It had SCRs for horizontaloutputs, and this reminded me of aseries about that model in theJanuary, February, March andApril 1976 issues of ElectronicServicing. I was glad now that I

had saved all of the old issues.

Suggestions fromElectronic Servicing

After a long review of thearticles, and fortified by severalcups of coffee, I returned to thereceiver with renewed confidence.

As the first step, I shorted TP1 toTP2 to find out if the over -voltageprotection circuit would operate tothrow the horizontal out of lock. Itdidn't. Igrounded TP2 to see if theprotection circuit was loading downthe horizontal sweep. Again, therewas no change.

A suggestion in the April articlestated that certain shorts or over-loads at some flyback taps willnarrow the picture without causingnon -linearity or foldover. I decidedto remove one circuit at a timefrom the flyback. Any circuit thatgave more width when disconnectedmust have the overload. Lifting onewire from the board disconnectedthe top/bottom pincushion circuit,but the width did not improve.Other flyback connections appearedto be very difficult to remove, and Idecided to come back to that test

,later.I suspected that a yoke problem

might narrow the raster, but theraster showed no distortion, and Idecided to test other things.

During the tests, I noticed thatthe picture widened to almostnormal width at low brightness, andthen narrowed as the brightnesswas increased. This pointed to poorregulation. The March article statedthat an open C407 causes poorregulation (see Figure 1). Thisseemed to be a good suggestion.However, an open C407 produceswrinkles in the SCR101 anodewaveform. There were no abnormalwrinkles, so C407 probably was notopen.

I was surprised to measure only15 kV of high voltage. Usually lowHV causes out -of -focus or darkpictures, but that was not true here.As I adjusted the HV control fromend to end the HV varied onlyabout 1 kV, and could not beadjusted above 16.5 kV even with adark picture. Also, pulses at the

0401 regulator collector changedvery little as the pot was adjusted.These symptoms appeared to pointto a regulator problem.

Finally, I remembered the sug-gestion that grounding the base ofQ401 would eliminate the HVregulation (which with a normal TVwould activate the protective cir-cuit). When I grounded the base,the HV shot up to 30 kV, and theHV protective circuit promptlyforced the oscillator far out of fre-quency. Next, I grounded the baseof 0402, the over -voltage protectivetransistor, and was relieved toobtain a bright and very widepicture. This was proof the narrowwidth was produced by excessiveHV regulation, and that the protec-tive circuit was operating normally.

Where in the regulator?The test proved even more: the

defect was not in the collectorcircuit of Q401 but was located atthe base, the emitter or the circuitsthat supplied them. With the baseungrounded, the emitter and collec-tor dc voltages were about right.Suspicion now was directed to thebase.

Perhaps too much amplitude ofhorizontal pulses was reaching thebase. To prove or disprove thistheory, I paralleled R411 with a100- 5-2 resistor which would permitless amplitude from the variablecontrol (Figure 2). With the groundsremoved from Q401 and Q402, thepicture had full width and goodbrightness, while the HV controlcould vary the HV from 20 kV to25 kV. Eureka! But, changing aresistor value is not a cure.

Perhaps the HV control or one ofthe resistors was out of tolerance.After I removed the pot from thecircuit, it and the two associatedresistors (R430 and R411) testedwithin tolerance. Another compo-nent must be bad.

Only one part remained to betested. I removed zener diodeCR405 and discovered the usualforward resistance but an abnormal5K reading with reversed polarity.The reverse resistance should bealmost infinity. There could be notdoubt, CR405 was defective.

Unfortunately, I didn't have a13-V zener in my stock, but I didhave two 6.3-V zeners which I

connected in series. After installingthé zeners and reconnecting theother components, I was rewardedwith a normal picture. I adjustedthe HV to 24.5 kV with a darkpicture, and measured a drop toonly 23.5 kV at high brightness.The regulation was operating asdesigned.

Test itIf you would like to duplicate this

problem, connect a S K resistor inseries with a 0.5 M control, andparallel them across CR405 in a TVthat is working okay. Adjust the potand notice the width change atlow -resistance settings.

CommentsAs soon as Photofact 1628-2 was

available, I obtained one and use itnow when repairing this sameCTC78 color TV. Also, I thank GillGrieshaber and Electronic Servicingfor helping me with this difficultrepair.

HORIZ

PULSES

R430 LEAKY

220 \CR405ZENER

HV

R412

loo

R411

430 C409

.012

C421 Q401HV REGULATOR

470pF

R435

l01

NARROW WIDTH

CR404

+18V

T402REGULATOR

Figure 2 The narrow picture was caused by excessive HV-regulator operation.CR405 leakage forced 0401 to conduct too much saturation current throughregulation transformer T402.


Most MATV systems are designed for adequate signal level ateach TV tap -off. However, many of them have too much snow inthe picture. On the other hand, any MATV system that hasexcellent signal-to-noise ratio will automatically have sufficientsignal level to each TV. Use these suggestions to minimize snowin the systems you design or repair.

These pictures illustrate three signal-to-noise ratios. The top picture has noperceptible snow for a S/N of about45 dB. Some snow at about 29 dB isshown by the center picture, while anunacceptable 22 dB S/N is pictured atthe bottom.

Excessive snow in a TV picturedispleases any viewer. It is evenmore intolerable if the sameamount of snow is present aftergoing to great trouble and expensefor an elaborate Master Antenna.for TV (MATV) system.

Unfortunately, such discourage-ments are not rare. Sometimes thesnow is stronger following installa-tion of a new MATV system. Whatwent wrong? The preamplifier israted for more than enough gain,and other parts were selected withcare. Of course, there could be adefect in the preamplifier, or thedownlead might have an open in it.In many cases, however, severalimportant MATV principles wereviolated in the design specifications.

Minimum snow can be obtainedonly by following several importantsteps. The signal-to-noise ratio isall-important. Total gain is secon-dary. Because very little has beenwritten about the subject, the basicprinciples, calculations and systemdesigns that are imperative forobtaining the best signal-to-noiseratio will be discussed here.

What is noise?Noise is any signal that exists in

the absence of the desired signal.According to that definition, noiseincludes the black or white dotsand lines from motor or power -linearcs, the picture flashes fromlightning or auto ignition, and theswirling lines from CB or FMinterference.

However, for this article, only thewide -bandwidth "white" or "pink"noises produced by various noisemechanisms in diodes and transis-tors, and by the thermal agitationof electrons flowing through resis-tances are being considered. These

gainversusnoiseBy James E. Kluge,technical editor,Winegard Company

noises cover almost all frequencies,appearing in TV pictures as snow,and in the sound as a constanthissing or frying.

Facts about noiseA few abbreviations used in

explaining or calculating noiseproblems are signal (S), noise (N)signal-to-noise ratio (S/N) and noisefigure (NF). Before they are dis-cussed, here are some fundamentalconcepts: An antenna in an electromagnet-ic field produces a signal voltage,but it does not generate anyappreciable noise. Thermal noise is added to thesignal by the resistive terminationat the input of a preamp, or at theend of the downlead. A 75- c -impedance antenna hasa theoretical noise voltage (acrossthe 75- S? termination resistor) of-59.1 dBmv (or 1.11 uV). In likefashion, noise at the 300- n termi-nation resistor of a 300- antennahas a minimum of -47.1 dBmv (or4.44 uV). (Because of the impe-dance ratio, both noise and signalin 300- S2 circuits are four timesthose in 75-0 wiring.) Signal-to-noise ratio equals thesignal power present divided by thenoise power. A marginal -quality TVpicture can be obtained with 25 dB,while excellent quality requiresabout 45 dB S/N. Noise figure of an amplifier is theamount of noise that's added to thesignal by the amplifier. S/N in dBat the amplifier input minus theS/N in dB at the amplifier outputequals the noise figure (NF). The signal-to-noise ratio of anyMATV system always is best at theantenna terminals before any pre-amplifier or downlead. In other


words, the S/N cannot be im-proved following the antenna.Therefore:the best way to improve the S/Nis to use an antenna that hashigher gain.

Everything done to the signal af-ter it leaves the antenna degradesthe signal-to-noise ratio by attenu-ating the signal or adding noise.This is true of the downlead, ampsor preamps, splitters and attenua-tors. If you use good techniques,however, the degradation can beminimized. The NF of passive devices (suchas splitters, downlead, filters andmatching pads) is equal to thepower -damping factor. For exam-ple, a 6 -dB (4 -to -I) attenuator has apower gain of 0.25, and a power -damping factor of 4, which in turngives a NF of 4.

In general terms, there are twosteps for obtaining a high S/N ateach receiver of a MATV system.First, achieve a high S/N at theantenna. And then minimize theaddition of noise by maintaining asufficient signal level at each pointof the system.

Antenna S/NOne limitation of the maximum

output signal from an antenna isthe strength of the signal that

surrounds the antenna. Thus, themaximum signal level that's availa-ble depends on the transmitterpower, frequency, distance from thestation, weather conditions, antennaheight and any obstructions in theline -of -sight signal path. Only thelast two conditions are controllable.The antenna can be moved horizon-tally to a more -favorable location,and a signal -strength meter can beused during tests at differentheights to find the one giving thestrongest signal.

Gain is determined partially bythe size and physical configurationof an antenna. Although no onecan judge gain merely by looking atan antenna, it's true that largerantennas generally produce moregain than smaller ones do.

Noise from an antenna and itsloading resistance can't be reduced.Therefore, to obtain an adequateS/N at the antenna, it's imperativethat a large enough antenna beplaced in a favorable location.

What is an adequate S/N? Asmentioned previously, a S/N of 45dB at the TV tuner will provide anexcellent picture without noticeablesnow. However, it's advisable tostart with about 60 dB at theantenna to allow leeway for thereduction of S/N that always occursbefore the signal reaches the TV.

Figure 1 Placing a low -noise preamp between antenna and coax can give abetter S/N than placing it between coax and the TV receiver. (A) This is theformula for calculating the total noise figure from two cascaded networks; (B)gives the gain and noise ratio of each network; (C) is the circuit and calculationof SIN with the preamp ahead of the coax; and (D) is the same but with thecoax before the preamp. The (C) wiring provides 4.85 dB improvement over the(D) circuit.

NFab - NE +

w here. NFab-

NFh I I AGa

overall noise-ligure ratio

\Nll-NN:\ I'Itl A\ll' IIXI It UF RG-59 I:B

NF,: network A noise-ligure rano (LVIN 31-11 115 )IHl `G:AIN" (1.311) iS dfi,NFh netoork B noise -figure rano NF 1.495 13 dB1 NE vi;)Via = network A Ir aer gain

INK I NI

ANTENNA

PR I :\ S1 I'

NF !WORK A

S N 35 dB >I LAIN = +15 dBNF = 3 dB

110 It RG-54 l' CNEI WORK B 01.' 1 Pl I NF

S IJ 1113

NFab = 1.995 + 3.16-I

31.6

GAIN - -5 dBNF = 5 dB

N- 31 ))4, dB

= 2.0613.í5 dB)

D100 ft RG-59N PREAMPNETWORK A NETWORK B OUTPUT Ni

INPUT NF

ANTENNAS)N-35dB GAIN -5 dB S N=30 dB GAIN = +15 dB S N = 27 dB

NF - 5 dB NF = 3dB

NFab = 3.16 + 1.995-1 = 6.31 IH dB)0 316

Now muchbetter offwould you be

II you had your1" Class FCC

License

Think about it. An FCC License is re-quired for certain jobs in Broad-casting and communications. And.even when a 1st Class FCC "ticket"is not a legal requirement for a job,it is Government certification of spe-cific skills and knowledge. That'sbound to impress any employer ofelectronics personnel! That's whyCleveland Institute of Electronicsoffers you a choice of professionalcareer courses designed to help youpass the government -administeredFCC License exam.

Learn from thespecialists.We know what the government ex-aminers require. We aim to makesure you get it. In fact, close to 4out of 5 CIE graduates who tookthe FCC exam got their licenses,according to our continuing sur-veys. Not surprising. CIE is thelargest independent home -studyschool in the world specializingexclusively in electronics.

Send for yourFREE CIE CatalogGet all the details on earning yourFCC License. Fast! Mail the couponright now for CIE's FREE schoolcatalog-plus a complete packageof independent home -study informa-tion. For your convenience, we'll tryto have a CIE representative contactyou to answer any questions youmay have. All CIE career courses areapproved for educational benefitsunder the G.I. Bill.

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Circle (16) on Reply CardFebruary 1979 Electronic Servicing 47

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MATV gain vs. noise

About 35 dB at the antenna(followed by minimum degradationof the S/N) is the bottom limit forsatisfactory operation. Any lesssignal or excessive degradation ofthe S/N will produce pictures thatare barely watchable.

An important question is this:how can the S/N degradation beheld to a minimum?

First amp limits S/NBoth practical experience and the

formula (for computing the NF ofcascaded stages) prove that theoverall noise figure of the MATVsystem depends primarily on thenoise figure of the first amplifyingstage. Nothing can remove noiseafter it is added to the signal;signal and noise together are ampli-fied by the same amount.

Therefore, when selecting anantenna preamplifier, choose onethat has the lowest noise inpreference to one having high gain.

Of course, if the NF of thefollowing network (downlead, filteror splitter) is very high, you mightrequire a preamp having high gainin addition to a low NF. (Remem-ber, however, that high -gain ampli-fiers usually overload at lower input

levels than lower -gain ones do. So,don't select a high -gain preampunless the additional gain actuallyis needed.)

Two examplesA typical installation calculated

both with the preamp ahead of thecoax loss and with the coax loss infront of the preamp (Figure 1) willhelp clarify the principle. Placingthe preamp ahead of the coax lossimproved the S/N by 4.85 dBcompared to the reverse.

Figure 2 shows the same kind ofcalculations for a MATV systemwith an antenna and 100 ft ofRG-59/U coax which fed the signalto a TV tuner. The first amplifierof the system was the tuner RFamplifier and mixer which have apoor 8 DB NF. Therefore, the 5 dBNF of the coax and the 8 dB NF ofthe tuner are added together toproduce an overall NF of 13 dB.

After the preamplifier was addedto give low -noise gain before thecoax loss, it becomes the firstamplifier. Therefore, the noise fig-ures calculated according to theformula, producing a total NF ofonly 6 dB (which is less than the 8dB of the TV tuner when usedalone).

Figure 2 A preamplifier between the antenna and the coaxial cable can reducethe S/N below that of the TV tuner alone. (A) The MATV system with antenna,coaxial cable, and the tuner of the TV provides an unacceptable 22 dB S/N,while at (B) a low -noise preamp reduced the noise figure to only 6 dB and gavea passable 29 dB S/N.

INPUT NF

ANTENNA

IIMI It RG.SU CNE ¡WORK .5

S \ 35 d6 GAIN 5 dBNi 5 dB

I.\. TUNERNETWORK B

S N pI iIB

NF I."8 + 2.51 - 1 4455113 dB)ah 1).552

GAIN N ANF 8 dB

AOUT PCT NF

S N 22 dR lY) 11 -Es

ANTENNA

S N=35 dB

PREAMP

IGAIN = +15 dB I S N 32 )111NF=3dB

IIMI II R3) -i9 L l A IL N'FSR

I GAIN -5 dBII` NF 5dB

S N 31.25 dBIS'

GAIN N

NF ri dB I

2.51 1

NF 1.538 _ . - 2.0I I5 dB OVERALL. NH1

B

2v d6 TO IF.

Circle (17) on Reply Card48 Electronic Servicing February 1979

Preamp requirementsAny preamp that is included to

prevent severe degradation of theNF because of heavy signal lossesmust have a very -low noise figure,of course. In addition, it needs gainwhich can be calculated by thefollowing formula:

Gain equals total losses indecibels plus 6 dB plus thenoise figure in decibels.

It is easy to see why the preampmust make up for the losses, butthat would only keep the NF thesame as it was originally if thepreamp had no noise. Therefore, tocompensate for the preamp NF andprovide a cushion for variations, theother two figures must be included.

For example, if the coax lossesare 5 dB and the NF of awidely -used preamp is 3 dB, thenthe required preamp gain = 5 + 6+ 3 or 14 dB. This matches thespecs of the preamp, so it would besuitable. On the other hand, anoth-er preamp with a gain of 15 dB anda NF of 6.4 dB would calculate thisway: 5 + 6 + 6.4 = 17.4. Thepreamp would not be suitablebecause it lacked 2.4 dB of havingenough gain. (In some applications,the higher NF also might make itunsuitable.)

SummaryEverything in a MATV system

(except the antenna) adds noise tothe signal either directly or indirect-ly. Preamplifiers and other amplifi-ers with transistors add their inter-nal noise to the signal as it passesthrough.

Passive devices (downlead, split-ters, filters and tap -offs) don'tgenerate noise themselves. However,they always are followed by activedevices (amplifiers or TV tuners)that have a fixed noise level whichcomparatively becomes worse whenthe input signal is reduced byupstream passive devices. That'swhy passive components have a NFrating.

These are the steps for reducingnoise and snow as much as possiblein MATV systems: Obtain all possible signal fromthe antenna. Choose an antennathat has more gain than theamount needed to supply only oneTV located at the antenna. Selectthe antenna location and orienta-tation with care, always trying toobtain maximum signal level withminimum ghosts and noise. Re-

member: the antenna is the onlypart of any MATV system that doesnot add any snow. Any antennaimprovement is all "gain" withouttradeoffs. Examine the picture on aportable TV connected near theantenna, and be certain there ismore than enough signal. Thesignal-to-noise ratio never will bebetter than it is here. At the headend location (orwhere the splitter of a small systemwill be located), again view thesignal coming from the downlead. Ifthe snow is worse than it was at theantenna, add an antenna -mountedlow -noise preamplifier in front ofthe coaxial downlead. Determinethe gain needed by the formula:

Gain =losses in dBs plus 6dB plus NF of preamp in dBs

If an amplifier or a preamplifieris needed to compensate for thedownlead or other distributionlosses (thus preventing a drop ofS/N), select one having a very lownoise figure. The S/N for thedownstream signal depends mainlyon the NF of the first transistorstage in the first amplifier. Thisstage is second in importance onlyto the antenna for minimizingsnow. At the antenna (or the antenna -mounted preamp) output, measurethe carrier strength of the weakestusable channel. Then, at all pointsdownstream, never allow the signalto fall below 6 dB above thisreading. This will preserve thesignal-to-noise ratio. Otherwise, thefirst active device following theweak signal will degrade the S/N. Ifthe loss that reduces the signalbelow the reference -plus 6 dB pointis in a long run of coaxial cable,then add amplifiers at intervals toprevent excessive signal loss beforethe next amplification. At each TV receiver of thesystem, the minimum level (withsome snow) should be 1000 uV (0dBmV). Of course, higher signallevels (up to 10,000 uV, or +20dBmV) are desirable. However,don't confuse signal level withsignal-to-noise ratio. A 10,000 uVsignal with a poor signal-to-noiseratio still has excessive snow (notsnow from the TV, but snow fromthe MATV system).

Follow these few principles andall of your MATV installationsshould provide minimum snow thatwill please your customers. E

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259 474 90 25D 12 10 UPC 1154 240259 495 .80 25D 234 10 UPC 14305 3.40256 507 1.00 250 235 -80 UPO 861 950289 5260259 595 1

250 261250 241

45 IMO 857 9m210 UPS 858 r00

25B 596 50 25D 313 PLL 01A 4 sZSD 315 w PLC 02A 5.90

2SC aso 325 .o PLL 034 e54]5D 421 225

DIODES25C 26, so 25D 525 I 20250 312250 373

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50280 300 30 FET IS 332 5

2SC 394 .30 1S 953 20

28C 458 .30 255 1991 60 1S 1001 as2SC 495 .60 255 23 .90 15 1209 4525C 509 45 255 30 50 15 1211 452SC 5154 100 245 33 1S 7555 25250 511 3.00 255 55 1S1546 as25C 535 40 356 221 1.m IS 1555 2028C 634* .45 38K 39 1.20 18 2016 25

29C 995 130 3. 40 1.20 15 2003 45260 710 .30 35K41 1.e0 18 2413 2028C 711 30 385 45 1.54 1N 3425C 730 3.40 355 48 3.90 114 80 15

25C 732 .30 355 49 1.54 100 1 10380 735 30 10D 1028C 154 2.09 IC v05625C 195* 2.00280 18 2.40 AN 2140 1.30 ZENERS25C 18425C 719

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2 401.952.00

MiSC2SC 953 )0 NA 1305W 2.50 SG 613 5 952SC 959 1.30 NA 1322 3.00 16105 028C 100061 .45 NA 1339 3011 MPS 031 1º0

IMMEDIATE SHIPMENT WITHIN 48 HOURSMinimum order 55.00 Add 51.00 postageQuantity discount prices - Mfg. inquiries Welcome

Ask For Our Complete Price Llsl

FUJI - SVEA ENTERPRISEa Division of Fuji -S vea Incorporated

P.O. Box 40325 Cincinnati, Ohio 45240

TOLL FREE Nationwide 800/543-1607TELEPHONE. Ohio 800/582-1630

Hours Mon. -Fri. 10-7, Sat. 11-5


¡Lt..:,)Il

P!k. _a-wlk . ,.,

,. ,..,

ONE arts book. For all brands: NOW...The Sperry Tech Pricing Book

places over 8,000 fast-moving partsright at your finger tips!...

ONE

ego1Over 3,000 direct factory replacementparts, including 17 major MFR's bothdomestic and off shoreOver 1,100 popular receiving tube prices*Complete universal parts listings...capacitors,circuit breakers, circuit boards, crystals,interlocks, rectifiers, resistors, sockets,tuners (rebuilt), batteries, fuses, pilot bulbs,tube brightners, etc.

750 picture tube prices (including a complete interchangeability guide)Manufacturers directory with names, addresses, and telephone numbers

When you appear on the job with -a professional parts pricing book you make the bestimpression on customers...cultivates repeat business. At the same time you can adjustprices in a manner that will compensate for obsolete parts in inventory you can't resell orreturn, so you can start realizing a profit from your parts sales.

When price changes occur you automatically receive an up -dated section reflecting newprices...this way you know your parts prices are always current.But that's not all...as part of our subscription service, parts usage is ranked by popularityand is up -dated each year...a vital factor in controlling obsolescence.

CALL TOLL FREE/800-228-4338.(Between 8:00 AM and 5:00 PM CST Monday thru Friday)

-and we'll send you a complete parts book, postage prepaid with the mark-uppercentage you feel is correct for your shop for only $24.50. You'll have the opportunity toexamine the contents before deciding on our automatic up -dating service

sperry tech inc. P.O. Box 5234 Lincoln, Nebraska 68505


BY POPULARDEMAND!

MS -215 Dual TraceMiniscope

With RechargeableBatteries & Charger Unit. $435 15 -megahertz bandwidth.

External & internal trigger.

Auto or line sync modes.

Power usage -<15 W. Battery or line operation.

2.9" H x 6.4" W x 8.0" D.

Non -Linear Systems, Inc.Originator of the digital voltmeter.Bon N, Del Mar, California 92014Telephone (714) 755.1134 TWO 910-3221132


NEW TUNERSNOT universal or customized. NOTseconds, culls, dogs, or oddballs. Only$29.95 for ANY new tuner. Over 5,000 instock including Philco TT192.

Call Toll Free 1-800-433-7124TEXAS TUNER SUPPLY

4210 N.E. 28th St., Ft. Worth, TX 76117


IT'S NO PUZZLE TO ORDER

OELRICH SERVICE FORMSFOR TV -RADIO Ü 2 WAY RA010 SERVICE LEGAL FORMS FOR CALIF. FLA.UTAH NOW AT YOUR PARTS JOBBER OR WRITE FOR CATALOG 864

OELRICH PUBLICATIONS4040 N NASHVILLE AVE. CHICAGO. ILLINOIS 60634


TUNER SERVICEAll oserhauls guaranteed two full year.,

Give us a try - you'll like theway we do business.

Call TOLL FREE 800-433-7124In Texas call 817-834-8201TEXAS TUNER SERVICE

4210 N E. 28th St.. Ft. Worth, TX 76117Circle (23) on Reply Card

Perform adeath -defying

act.Eat less saturated fat.

T.

test equipment

Portable DMMModel LX -303 from Hickok is a

pocket -sized battery -operated digitalmultimeter with a 3-1/2 digit LCDdisplay. Auto -polarity, auto -zeroingand automatic overrange are pro-vided. Accuracy of dc volts is±0.50/o of reading ±0.50/o of full-scale reading. Battery life is morethan 200 hours from a single 9-Valkaline battery. Several accessoriesare available, such as an acadapter, vinyl carrying case, dc -current shunt, 40 kV dc probe andan X10 dcv adapter that slips overthe probe.

Model LX -303 sells for $74.95.


Dual -trace delayed -sweep scopeOne unique feature of the model

D67A Telequipment scope is"mixed" sweep, with one sweeprate scanning the picture over partof the screen and another sweeprate working across the rest of thescreen. This delayed sweep can beadjusted according to need. Dual -trace operation permits viewing oftwo waveforms simultaneously byeither alternate or chopped mode.Conventional horizontal sweep timescan be selected between 40 ns and2 s per graticule division. A syncseparator is built-in to providestable TV vertical and horizontaldisplays.

Maximum sensitivity of each verti-cal channel is 10 mV, and minimumsensitivity is 50 V per division.Bandwidth is from dc to above 15MHz.

Price of the D67 Telequipment is$1325. (Telequipment is a subsidiaryof Tektronix.)



Small frequency counterContinental Specialties offers the

MAX -550 frequency counter whichcovers the 1 -kHz to 550 -MHz rangewith 1 kHz resolution on the 6 -digitdisplay. A carrying case, cablesand alternate power sources areoptional accessories.

MAX -550 sells for less than $150.Circle (32) on Reply Card

Portable VOMMeter protection and a mirrored

scale are two features of the Muramodel NH -63 VOM multitester. Sen-sitivity of the six dc ranges is 20,000ohms -per -volt, and it is 10,000 0 /Vfor the four ac ranges. In addition,

three resistance ranges and twocurrent ranges are provided.

The suggested price is $25.50.Circle (33) on Reply Card

dc

Dual -triggering scopeA new feature of the model 1032A

Ballantine Laboratories scope isindependent triggering of the dual -trace channels. Each channel hasits own trigger circuit, and anelectronic switch selects the triggerof the channel that's being dis-played. This allows non -synchronouswaveforms to be viewed simultane-ously. The CRT of the dc -to -20 MHzinstrument has an advanced mono -accelerator design which is said toprovide high brightness and a smallspot diameter on the 8 cm x 10 cmscreen. Twelve vertical ranges cov-er sensitivities between 5 mV and 20V/cm division. Calibrated horizontal

sweep times are between 0.5 and 1us per division plus an X10 magnifi-er.

Model 1032A sells for $895.Circle (34) on Reply Card

Function generatorContinental Specialties offers

model 2001 function generatorwhich has outputs of sine, triangle,square or TTL-square waveformsthat can be swept over a 10:1 to100:1 range.

Repetition frequency is selectedby a vernier dial and five pushbut-tons and cover 1 Hz to 100 kHz infive ranges.

Sine, square and triangle wave-form output signals can be variedover a 40 dB range, with amaximum level of 10 V peak -to -peak.The TTL output can drive 10 TTLloads with rise and fall times ofbetter than 25 ns. Sine waves aresaid to have less than 20/o distortion.

User price of model 2001 is$124.95.


Tiny DMMHeuer has announced a micro -

miniaturized digital multimeter,DMM 2000, for field -service mea-surements.

The instrument has a 3 -digit LCDreadout, providing four measuringranges for each mode: DC up to1000V and AC up to 700V, AC andDC current up to 2A, and resistanceup to 20 M ohm, with a typicalaccuracy of 0.50/o on DC ranges.

Two technical features of themultimeter are its true RMS (rootmean square) measurement of ACranges and shielding against RF. Upto 100 hour battery life is providedfor the Dmm 2000 by four 1.5Vwatch batteries.


Complete Line ofReplacement Parts for

CB - STEREO - TV

M«w 1,G 175AdeptsP1-259for um volt

WRGS CGeneabM

1 DryU.«

35

Ol,

ModelUG-176/UAdepto, forRG-59/UCeele

1.9 pry,o.« 01,

8.71Mt«1

RCA Shielded Plug

,Oryion Ole 17

t.Math

tStandard Stereo Phone Plug

with 1. phone plug. «n, IMninal

1.5 45

10001,

Moth

á Miniature 3.5rrlm Plug

1-9 01y19«0l, a

PL -259 lor RG9U Cable

4 Pin Mc Connector.0 ,

10 Ory

3 Pin M1c Connector

1 -ably lm1091 oh 110

Motel CO 554

Adept. PL -259 to Motorola plugor RCA lope phone let..1.1 017 loIo«Ol,

Model FS -157

00.Me. 1.111.90H100Ory

UHF/VHF Snider withMeletng Standen..

Separate f -5a gh

sod ring Included

>1

e1Í 30100 t.9 OryUHF 1/01 FM 10-n On

9O1b10'« Ory n

w1

YODEL /5 72

Heap Duty Clip LeedsTwo seen of 5 Wiener cob«22" long lip tO Hp

t.1100, 180

0.N Ory 1.

Matching Tranilorm«75-300 ohm

1/14F,UtM/FN ,5.30 eM .e1e1ee,.1Mw,4ew F- ha4 e1M,9e. Mo on.lelnOn1F0n. F4.Iar« lo. 4,eeru0eIse. ar a< inns. .,..e.e.,1-.le

1-0 00dY 1u«Ory 55

Aatel Lead Cpecllon90 MOD s 450 nits

10-« pry

100 MFD e 460 eo1M

1-1 O1,lp« pn 125

,w

310

511/

Emitter 0.atetor.0.5 new

1-101yte« 0h

t.1 0t7non Oh

1.90,0

to-« Oh

Foeu. RectllMr

IKY 6.5 In

1.0 Oh 10 1.101, 140

to -e o1r « 10«On 0

Lighter Plug

1-9 Ory. 70

10-aa Orr. 94

FuMMadsl

F«-1

Foe* ~der w49n 18- w r 411

M ..eteerd ,: hr.. W /2for

9 0ry. 4'lo-0Ory 00

tows Can be

used on panel.up to 5/16' thickNee b.n eTOet knob No screw driverrequired

90n;0-« On

Fuse N010Model FS

s3AG Fun. 1A.2A.3A.4A.SA.6A

13

IMMEDIATE DELIVERY WITHIN 48 HOURS

Minimum order 510.00 Add 51.00 postageQuantity discount preces Mtgr. inquiries Welcome

Ask For Our Complete Price List

FUJI - SVEA ENTERPRISEa Division of Fuji-Svea Incorporated

P.O. Box 40325 Cincinnati, Ohio 45240

TOLL FREE Nationwide 800/543-1607TELEPHONE Ohio 800/582-1630

Hours Mon. -Fri. 10-7; Sat. 11-5


ilimarketulaceFor SaleREPLACEMENT COLOR YOKES -DEALERS ONLY.

Zenith 95-2501-2532-2638-2667-S-89633 etc. 16.95,Magnavox 361380-1 18.95, Sylvania, GE etc. 14.95to 19.95. Request for price list on your Letter-head. David Sims Enterprises, Inc., 665 JerichoTurnpike, Huntington Station, N.Y. 11746.12-76-tf

TV & RADIO TUBES 36c EA!! Free color catalog.Cornell, 4221 University, San Diego, California92105. 8-76-tf

ELECTRONIC SURPLUS, CLOSEOUTS, LIQUIDA-TIONS! Parts, equipment stereo, industrial,educational. Amazing values! Fascinating itemsunavailable in stores or catalogs anywhere.Unusual FREE catalog. ETCO-011, Box 762.Hattsburgh, N.Y. 12901. 6-78-tf

MOVING TO FLORIDA? TV SERVICE AND RENT-AL BUSINESS FOR SALE ON FLORIDA'S WESTCOAST. DOING $40,000-$50,000 PER YEAR. ALLREASONABLE OFFERS CONSIDERED, ALSOBUILDING AVAILABLE. CONTACT: MR.SOTHERN, 1-813-535-2028 AFTER 7 PM ORWRITE: 1834 SUNRISE BLVD., CLEARWATER,FLORIDA 33520. 9-78-tf

SENCORE VA48-Like new, all probes, instruc-tions, $700 firm. HUME, 108 Hillcrest Circle,Greenville, S.C. 29609. 2-79-1í

TELEVISION SALES AND SERVICE. Establishedseven years, two -man shop. Excellent clientel infast growing suburb of Phoenix, Arizona. RCAauthorized servicecenter. For information:Taylor's T.V., 12833 N. Cave Creek Road,Phoenix, Arizona 85022. 2-79-1t

TV SALES AND SERVICE business established23 years. Building available. 109 W. Center St.,Bellevue, Ohio 44811. 2-79-21

ad index

For Sale (Cont.)TUBES -RECEIVING, Industrial and Semiconduc-tors Factory Boxed. Free price sheet includingTV, Radio and audio parts list. Low, low prices.Transleteronic, Inc., 1365 39th St., Brooklyn,

New York 11218. Telephone: (212) 633-2800. Tollfree: 800-221-5802. 5-78-12t

1077B B&K ANALYST NEW, 520B TransistorTester new, 415 Sweep/Marker used in originalboxes. $785.00 for all. Ralph Dorough, 117 PecanSt., Terrell, Texas 75160. 2-79-11

Business OpportunityMECHANICALLY INCLINED INDIVIDU-ALS-BUILD ELECTRONIC DEVICESIN YOUR HOME. GET STARTED INYOUR SPARE TIME. $300 TO $600/WKPOSSIBLE. EXPERIENCE NOT NECES-SARY. WRITE FOR FREE LITERA-TURE. ELECTRONIC DEVELOPMENTLAB., BOX 1560A, PINELLAS, PARK,FLA., 33565.

8-78-tfWANTED FOR CASH! We buy scrap electronicparts containing gold, silver, platinum! Immedi-ate top dollar cash offer by return mail. Ship to:American Metals Co., P.O. Box 30009, Dept. ES,St. Andrews Branch, Charleston, SC 29407

11-78-t f

MEN/WOMEN FOR FUN! Shaklee WholesaleDistributors earn $200-$5,000 monthly. Bonus,New Car. Etc. Details, Golden, RT2, Box 392ES,Fair Grove, MO 65648. 12-78-3t

WantedTECHNICIANS WANTED: Television -Audio -Com-munications. Excellent fringe benefits, salarydepends on experience. Miller's Electronics, 801Texas, Goodland, Kansas 67735. 2-79-2t

B & K Precision, Dynascan Corp 7

Cleveland Institute ofElectronics 47

Channel Master 21

The CooperGroup Inside Back Cover

Dynascan Corp., B & K Precision....7

EICO 16

Enterprise Development Corp 18

John Fluke Mfg. Co.,Inc. Inside Front Cover -1,5

Fuji-Svea Enterprise 49, 51

Gamit Enterprises, Inc 18

General Electric Co., TelevisionBusiness Div. 19

National Camera, Inc 48

New -Tone Electronics Intl. 12

Non -Linear Systems, Inc. 50

Oelrich Publications 50

PTS Electronics, Inc 26-27

RCA Distributor andSpecial Products 16

Sencore, Inc. 13

Sperry Tech, Inc. 50

GTE Sylvania ECG/CR 3

Texas Tuner Service 50

Texas Tuner Supply 50

Thordarson Meissner, Inc. 12

Ungar 17

Universal Enterprises,Inc 18

Winegard Co. 14-15

Zenith Radio Corp. 4 Back Cover

Help WantedELECTRONIC TECHNICIANS-MOTOROLA, lead-er in two-way radio communication, presentlyhas openings throughout the U.S. for techniciansand supervisors experienced in the installationand maintenance of communications systems(two-way, paging, microwave and CCTV). Ifinterested in good salary and excellent fringebenefits send your resume and geographicalpreference to: BOB CLENDENIN, MOTOROLA,COMMUNICATIONS & ELECTRONICS, INC., 1821N. Office Square, Room 200C, Schaumburg, IL60196. Equal employment opportunity/affirmativeaction employer. 2-79-3t

TELEVISION TECHNICIANS-Experience neces-sary, top pay, medical benefits, paid vacations.Enjoy a new "Life Style" in a beautiful, friendly,smog free, full service desert community. Sendyour resume to 225 E. Ridgecrest Blvd.,Ridgecrest, California 93555. Telephone 714-375-1361, ask for Service manager. 1-79-3t

Education -InstructionREPAIR TV TUNERS-High Earnings. CompleteCourse Details, 12 Repair Tricks, Many Plans,Two Lessons, all for $2. Refundable. FrankBocek, Box 3236 Enterprise, Redding, Calif.96001. 8-76-tf

Advertising ServicesTERRIFIC SWAP OFFERS NATIONWIDE! Next 5issues $2. "Electronics Trader," Box 73 -ES, FollyBeach, SC 29439. 1-79-TF

Professionals AccreditedPROFESSIONAL DEGREES (Bachelor, Master,Doctor) earned with Professional Experience inElectronic Business Management, Sales, orServicing. WORLDWIDE SERVICE. Free Details.EBERT PROFESSIONALS INSTITUTE, Box 1651,Dept. R, Columbia, Missouri 65201. 1-79-4t

Electronic ServicingAdvertising Sales Offices

NATIONAL SALES MANAGER/CHICAGOJim Reilly, 1011 E. Touhy Ave., Suite 245,Des Plaines, IL 60018;Phone: (312) 299-2601

KANSAS CITY, MISSOURIHelen Hull, P.O. Box 12901,Overland Park, KS 66212:Phone: (913) 888-4664

NEW YORK, NEW YORKJoe Concert, One Penn Plaza, Suite 2532,New York, NY 10001;Phone: (212) 564-8454

FT. LAUDERDALE, FLORIDABrinker and Brinker2240 N.E. 53 StreetFt. Lauderdale, FL 33308Phone: (305) 771-0064

SAN FRANCISCO, CALIFORNIAJohn MacKay, 703 Market St., Room 1109,San Francisco, CA 94103Phone: (415) 546-1040

LONDON, ENGLANDJohn Ashcraft & Co., 12 Bear St.,Leicester Square, London, WC2H 7AS,England; Phone: 930-0525

AMSTERDAM, HOLLANDJohn Ashcraft & Co., John J. Lucassen,Sloterweg 303, 1171 VC-Badhoevedorp,Holland;Phone: 2968-6226

TOKYO, JAPANInternational Media Representatives, Ltd.,2-29, Toranomon 1-chome, Minato-ku,Tokyo 105, Japan;Phone: 502-0656


If you don't see your Kind ofelectronic pliers here,

collzXcelite makes them all.Xcelite, long acknowledged as the world's first family of electronic hand tools,now includes a greatly expanded line of solid joint pliers and cutters. All the pliersyou'll ever need, and more. Because new designs are continually added as newelectronic products are born.

The present range extends through 38 patterns and sizes including 13 newmodels for miniature electronics. Made in U.S.A. by the latest technologyand quality controls, in one of the world's most modern electronic hand toolsplants, Xcelite pliers set the standards for the industry. Yet the same.advancedproduction techniques make them competitively priced.

Typical of the features that single out Xcelite quality are coil spring openers,polished heads, cleanly milled and perfectly aligned jaws, hand -honed and matedcutting edges, exceptional strength and performance provided by forged alloysteel construction, precision machining and scientific proportioning. Handles aredesigned for maximum leverage and convenience, with plastic coated"Cushion -Grip" for added comfort.

Styles? What else could you possibly need: standard, midget, and taper nose diagonals;standard, very fine and extra thin needle nose; long and short nose; long, short and midget chainnose, with and without side cutters; side cutting; short flat nose; round nose; tip cutter wiring;cutting and looping; short nose tip cutting; thin bent nose; midget semi and full flushcutting; diagonal full flush cutting; and stainless diagonal cutting.

You don't know what you can do with pliers until you knowwhat Xcelite pliers can do for you. See your distributor and lethim update you.

Y

TheCooperGroupElectronics Division

WELLER" . WI55" XCELITE"BOX 728, APEX. NORTH CAROLINA 27502. 919/362-7511


11

There's no waitingor turn -around timewhen you bring Zenithmodules, tuners orsub -assemblies needingrepair to your Zenithdistributor.

That's bench strengthfor you-as deep, depend-able, and easy to draw onas any you'll ever know.

Not only will the faultycomponent be replaced, butthe replacement modulewill have been up -dated toincorporate the latest factorytechnical improvements.

And it's an over-the-counterexchange. You walk out witha Zenith factory repaired andre -conditioned replacementserviced by the same peoplewho made the original.

So it simply makes goodsense to exchange your modules,tuners, and sub -assemblies withthose from the original source.

That's with your Zenithdistributor, of course, for modules,tuners and sub-assemblies...anda bench that never quits!

For your own reputation and in your customers'best interest, always specify Zenith exact

replacement parts and accessories.

7(THNliry goes in Deloie Elity goes in before the name goes on-

Zenith Radio Corporation /Service, Parts & Accessories Division /11000 Seymour Avenue/Franklin Park, Illinois 60131


Thereare timeshe'd giveanythingto drawon a

bench asconsistentlystrong,deep, andversatile asZenith's! I

Notre Dame basketball coach,"DIGGER" PHELPS

February, 1979 Electronic servicing - RADIO and ......Radio Supply Co., Inc. (316) 267-5216 MARYLAND...

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Transcript of February, 1979 Electronic servicing - RADIO and ......Radio Supply Co., Inc. (316) 267-5216 MARYLAND...