December, 1972 75 cents (intro is Servicing. · 2019-07-17 · LSG-231 FM MULTIPLEX/ STEREO...

December, 1972 75 cents

A HOWARD W. SAMS PUBLICATION

(intro is Servicing.

Servicing horizontal sweep

Zapping transistors

RF devices in medical electronics

transistor tester1

Connect the Tester to your scope and Rapid Readtransistors, diodes. capacitors and resistors

No unsoldering of components

Complete with all leads and test prods

110 VAC operation. no batteries required

Amplified trace for better definition

Ease of operation with simple instructions

ALPHA ELECTRONICS3036 N. ASHLANDCHICAGO. ILL.E D. I.

4900 N. ELSTON AVE.CHICAGO, ILL.JOSEPH ELECTRONICS1733 N. HARLEM AVE.CHICAGO. ILL.C. B. CENTER OF AMERICA3431 W. IRVING PARK RD.CHICAGO. ILL.BB 8 W2137 S. EUCLIDBERWYN, ILL.WARREN RADIO800 S.W. JEFFERSON ST.PEORIA. ILL.KLAUSS RADIO INC8400 N. PIONEER PARKWAYPEORIA. ILL.

-4C1Fpower converter

Fleet CommanderMODEL F 40

aae S

17v NM UTPIAL 110V OC

CAR TOOL

2

Completely safe converter that provides 4000 watts ofpower from cars. trucks. tractor or stationery engines

Can operate heavy duty drills. portable saws. impactwrenches, lights, coffee makers, heaters or any brushtype motor

Recharges batteries in 3-5 minutes

Operates AC / DC TV

Power to weld up to 1/8 steel

Gives you 110VDC power where you need it

Really easy to use

Full line of accessories

EC -25 Heavy Duty 25 ext. cordBC -10 Battery chamber & welding cablesTC-3 Throttle CableC-35 Trickle charger/oil heater adapterVM-20 Volt meter adapterAC -60 1 10V - 60 cycle 2000 watt AC adapter

our distributersLAFAYETTE RADIO ELECTRONICS111 JERICHO TURNPIKESYOSSET. L.I.. N.Y.LAZAR ELECTRONICS4231 LANCASTER AVE.PHILADELPHIA, PA.ALMO ELECTRONICSROOSEVELT BLVD. AT BLUE GRASS RD.PHILADELPHIA. PA.G.B.N. CO.BOX 605COUNCIL BLUFFS. IA.AMERICAN MERCANTILE CO.2418 1st ST.SEATTLE. WASH.CEN-KAN SUPPLY CO.757 JEFFERSONGREAT BEND. KAN.REM ELECTRONICS SUPPLY CO INC.264 W. MARKET ST.WARREN. OHIO

RADIO SUPPLYENGINEERING CO.. INC

85 SELDEN AVE.DETROIT, MICH.WAIBLE ELECTRONICS1215 N.E. JEFFERSON ST.PEORIA. ILL.ACME RADIO510 N. BROADWAYMILWAUKEE. WISC.WILSON BROTHERS CO.THIEF RIVER FALLS. MINN.A & B SUPPLY CO.DETROIT LAKES. MINN.GIFFORD BROWN. INC.14th & WALNUT ST.DES MOINES. IA.RADIO EQUIPMENT CO.625 N. 18th ST.OMAHA, NEBR.

S 8 S ELECTRONICS INC.503 N. 7th ST.FARGO. N. DAK.CENTRAL DISTRIBUTORS955 N.E. UNION AVE.PORTLAND. OR.

FULTON RADIO SUPPLY CO.1208 GREENWOOD AVEJACKSON. MICH.HARRY STARK'S INC.112 3rd AVE. NO.MINNEAPOLIS. MINN.AL STEWART CO.711 BROADWAYTACOMA, WASH.UNITED RADIO SUPPLY123 N.E. 7th AVE.PORTLAND. OR

advanced applied electronics- 1000 SOUTH MAIN STREET COUNCIL BLUFFS. lOWA 51501.17121 328-8625For More Details Circle (1) on Reply Card

The more

you see

...The more

you believe.

Send for yourcopy o the new1972-73 Leader

catalog. Featuresnew "Leadership" per-

formance productsaccessories

unmatched in every way.

LeaderLBO -505DUAL CHANNELDUAL TRACE5'" OSCILLOSCOPEOutduals them all! Solid stateaccuracy. performance. Hastriggered & auto sweep: AC orDC coupling per channel: 15MHzbandwidth: 100nanosec cm max.speed (10Xmag.): 10MVp-p'cm

rt. sensitivity: cont. scale il-lumination w I ront panel control;Sep. or simult. display of 2 signalsto compare input -and -output.for color. B&W. audio & more.Checks gain. loss. distortion.phase shift. I req. Complete withprobes, adapters. leads.

LTC -905CURVE TRACERTest Transistor. Triac. SCR.Diode. FET & MOSFET quality...in -or -out of circuit, with precisevoltage or current steps. Has ex-clusive. variable lengthadjustment to 100V sweep. Placesentire h'z't'l trace on all scopefaces. Sweep Voltage is 8 stepsselectable. An all IC timesaverthat checks for opens. shorts.leakages. Complete with specialprobes and leads.

LSG-231FM MULTIPLEX/STEREO GENERATORSolid state stability that has noequal for Multiplex testing andservice. Compact, easy to use.Checks separation, balance.alignment. 19KHz pilot signalfreq. has 2Hz accuracy. The1KHz audio signal freq. has 1

accuracy. Signal separation is1972 50dB. 0-3Vrms output. cont. vari-

able. It's so accurate you may notwant to use a scope! With handytilt -stand.

The more you see ...the more you believe.

LSB-41RC SUBSTITUTION BOXThe quick, easy way to obtainresistor and capacitor values. Nomore "scrounging" through smallparts bins, no more struggleswith unmarked or illegible colorcoding. Has 24 EIA standard.10'0, 1W resistor subs, from 1012to 10M:. Selects any of 22 stan-dard capacitor subs. Lightweight,compact.

5559.95

S119.95

1 e.,41 (6 I.

ILHadlir

5229.95

S59.95

INSTRUMENTS CORP.37 27 Twenty -Seventh Street,Long Island City, N.Y. 11101 (212) 7297410

For More Details Circle (4) on Reply Card

December, 1972/ELECTRONIC SERVICING 1

EDITORIAL

RONALD N. MERRELL, DirectorCARL H. BABCOKE, Managing Editor

Diane M. Kelley. EditorialAssistant

WEBB G. STREIT, Graphic Designer

December 1972 Volume 22, No. 12

Electronic Servicing®

16 The Anatomy Of A Sweep Failure- A professional TV technicianfollowed the rules of good servicing and repaired an unexpectedfailure in his own color receiver-John S. Hanson.

20 Troubleshooting Tips For Flybacks... And other Defective compo-nents- Use these methods for faster diagnosis of horizontal sweeptroubles-Morris Moses.

24 Find Horizontal Sweep Defects By Signal -Subbing- Break the vi-cious circle of closed -loops by using signal-subbing-Forest H.Belt.

28 Checks... Do The Benefits Exceed The Dangers?- learn the dan-gers and precautions of using checks-Robert G. Amick.

32 Let's Zap A Few Transistors... It's Fun!- Tongue-in-cheekSuggestions that insure extra transistor failures-Bruce Anderson.

36 RF Devices Used In Medical Electronics- The Diathermy andElectrocautery machines used by doctors are specialized RF trans-mitters-Joseph J. Carr.

44 Some Answers From The June Survey- Facts and figures mostrequested by our readers.

IDEPARTMENTS

Electronic Scanner 4 Test Equipment Report .. 47

Symcure 8 Product Report 45Readers Exchange 12 Audio Systems Report 49

Service Bulletin 10 Book Review 53

Service Associations 14 Antenna Systems Report . 51

Catalog & Literature 46 Advertiser's Index 54

Second class postage paid at Kansas City. Mo. and additional mailing offices. Pub-lished monthly by INTERTEC PUBLISHING CORP., 1014 Wyandotte St., Kansas City,Mo. 64105. Vol. 22, No. 12. Subscription rate $6 per year in U.S . its possessions andCanada: other countries $7 per year.

Copyright, 1972, Howard W Sams & Co , Inc All rights Reserved Material may not bereproduced or photocopied in ary form without written permission of publisher

CONTRIBUTING AUTHORS

Bruce AndersonJoseph J CarrWayne LemonsRobert G Amick

TECHNICAL CONSULTANT

JOE A GROVES

EDITORIAL ADVISORY BOARD

LES NELSON, ChairmanHoward W. Sams & Co., Indianapolis

CIRCULATION

EVELYN ROGERS, Manager

ADVERTISING SALES

Kansas City, Missouri 64105Tele: 913/888

4664E. P. LANGAN, Director

R. JACK HANCOCK, ManagerJAKE STOCKWELL

MIKE KREITERAida Casanova. Production

REGIONAL ADVERTISING SALES OFFICES

Indianapolis. Indiana 46260ROY HENRY

2469 E. 98th St.Tele: 317/846-7026

New York. New York 10017George W. Fleck

Room 122760 E. 42nd St.

Tele. 212/687-7240

Los Angeles, California 90005RICHARD BOHEN

3600 Wilshire Blvd., Suite 1510Tele 213/383-1552

London IV, C. 2, EnglandJOHN ASHCRAFT & CO.

12 Bear StreetLeicester SquareTele: 930-0525

Amsterdam C. HollandJOHN ASHCRAFT & CO.

W. J.M. Sanders, Mgr.for Benelux & Germany

Herengracht 365Tele: 020-240908

Tokyo. JapanINTERNATIONAL MEDIAREPRESENTATIVES LTD.

1. Shiba-Kotohiracho, MinatokuTele: 502-0656

ELECTRONIC SERVICING (with which is corn-bired PF Reporter) is published monthly byIntertec Publishing Corp., 1014 WyandotteStreet, Kansas City. Missouri 64105.

Subscription Prices: 1 year $6.00, 2 years -$10 00, 3 years -913.00, in the U.S.A., its pos-sessions and Canada.

All other foreign countries: 1 year-$7.00,2 years-$12.00, 3 years -916.00. Single copy75c; back copies Si.

Adjustment necessitated by subscriptiontermination at single copy rate.

Robert E. Hertel, Publisher

Intertec Publishing Corp.Subsidiary of Howard W. Sams & Co., Inc.

2 ELECTRONIC SERVICING/December, 1972

IfNEW RATINGS (11:20'::d) ADDEDto world's broadest line of dipped tubulars!

SPRAGUE DIFILM' ORANGE DROP CAPACITORSSPRAGUE

600DC.

Designed to provide the electronics industry withcompact capacitors with outstanding dependabilityunder conditions of high heat and humidity.

Dual dielectric -combines the best features of bothpolyester film and special capacitor tissue.

Impregnated with HCX', an exclusive Spraguesynthetic hydrocarbon material which fills every voidin the paper, every pinhole in the film Wore it poly-

merizes, resulting in a solid, rock -hard capacitor section.

Double dipped in bright orange epoxy resin formoisture and mechanical protection.

Leakproof -because impregnant is solid, there isno oil to leak, no wax to drip.

Designed for operation at temperatures to 125 C.

Capacitance tolerance, ± 10%.

Sprague Sprague SpragueProducts Products Products

liF D. x L. Cat. No. FF D. x L. Cat. No. i8F D. x L Cat. No.

200 VOLTS D -C

.02

.022

.047

.05

.1

.15

.2

.22

.25

.33

.47

.5

29/u x1%62944 x 1%6

3%4 x'%16

3%4 x'961%4 X 1%1

5/8 x 11/443/64X

4%6X 1%11/44 X 1 9/8

1%6 x 1%4644 x 111/16

19/64 x 111A6

2PS-S202PS-S222PS-S472PS-S502PS-P102PS-P152PS-P202PS-P222PS-P252PS-P332PS-P472PS-P50

400 VOLTS D -C

.01

.015

.02

.022

.025

.03

.033

.04

.047

.05

.056

.068

.075

.1

.15

.2

.22

.25

1%2 x 3/4

3%4 x %31/64 x 1%6

31%4 x 1%6

31/44 x 1%6

'74z x 1%61y32 x 1%6

4144 x 1'/a41/64 x 13/443i4 x 111/16

494 X 1 11%643/64 x 1 114

4PS-S104PS-S154PS-S204PS-S224PS-S254PS-S304PS-S334PS-S404PS-S474PS-S504PS-S564PS-S684PS-S754PS-P104PS-P154PS-P204PS-P224PS-P25

600 VOLTS D -C

.001

.0012

.0015

.0018

.002

.0022

.0025

.0027

.003.0033.0039.004.0047

25/64 x 3/4

25/64 x 3/4

25/64 x 3/42544 x 3/42544 x 3/4

25/u x 3/4

2744 x 3/4

2744 x 3/4

2744 x 3/4

2244 x 3/4

2%4 x 3/4

2%4 x 3/42%4 x 3/4

6PS-D106PS-D126PS-D156PS-D186PS-D206PS-D226PS-D256PS-D276PS-D306PS-D336PS-D396PS-D406PS-D47

600 VOLTS D -C (cont.)

.005 29/u x 3/4 6PS-D50

.0056 15/32 X 3/4 6PS-D56

.006 17/32 x 3/4 6PS-D60

.0068 132 x 3/4 6PS-D68

.0075 15/32 X 3/4 6PS-D75

.008 29/4 x'36 6PS-D80

.0082 29/44 x % 6PS-D82.01 21/66x 13/46 6PS-S10.012 314 x'745 6PS-S12.015 31/64 X 1%6 6PS-S15.02 35/64 x'36 6PS-S20.022 35/64 x'%6 6PS-S22.025 35/64 x 1%6 6PS-S25.027 yin x 11/4 SPS-S27.03 0/32 x 11/4 6PS-S30.033 1%2 x 11/4 6PS-S33.035 I7/32 x 1% 6PS-S35.039 19/2 x 11/4 6PS-S39.04 142 x 1% 6PS-S40.047 19/32 x 11/4 6PS-S47.05 1%2 x 13/4 6PS-S50.056 41/44 x 1'/4 6PS-S56.06 4/44 x 11/4 6PS-S60.068 41/64 x 1% 6PS-S68.075 11/64 x 1% 6PS-S75.082 11/6 x 13/s 6PS-S82.1 11/6 x 1% 6PS-P10.15 47/64 x 1% 6PS-P15.2 22/323 111/6 6PS-P20.22 27/32 x 111/6 6PS-P22.25 2%2 x 111/16 6PS-P25.33 59/64 x 111/6 6PS-P33.47 1V64 x 1% 6PS-P47

1000 VOLTS D -C

.001

.0015

.002

.0022

.003

.0033

.004

.0047

.0050068

.01

.015

2%4 x 3/4

1%2 X 3/4

%6 X 3/42/14 X 3/4

Y16 x 1%6

7/16 X 1%6

1%2 X 1%6

16/32 31%6

'/32 X 1%631/64 x 1%6

1%4 x 1%6

17/32 X 1 1/4

10PS-D10lOPS-D15lOPS-D20lOPS-D22lOPS-D30

10PS-D33

lOPS-D40

lOPS-D471 OPS-D50

1OPS-D68

10PS-S10

10PS-S15

1000 VOLTS D -C (cont.)

.022

.033*.039

.047*.056

.068*.082

.1

3%4x 13/241%2 x 13/4

4%4 x 13/e43/64 x 1%4744 x 11%

4%4 X 1"/6x

19/64 x 11VB

lOPS-S22lOPS-S33lOPS-S3910PS-S47

lOPS-S56lOPS-S68lOPS-S8210PS-P10

1600 VOLTS D -C

.0005

.001

.0015

.002

.0022

.003

.0033*.0039

.004

.0047

.005

.006

.0068

.007

.0075

.008

.01

.015*.018

.02

.022.03.033.04.047.05

1/2 x 2/81%2 x 7/11

Y16 X 7/8

1/2 x 7/8

1/2 x 2/8

3/46 x 11/2

/I6 x 11/4314 x 11/93144 x 1 V8

1%4 x 11/431/64 x

22/32 x 11/4

'%32x111817/32x 11/4

1%2 X 1%5/8 x 1742

% x 1%22V32 x 1194%xi%

x119/4x119/4x 139/64

x 139/64

21/32 X 139/4

27/32 x 13%422/32 X 179/4

16PS-T5016PS-D1016PS-D1516PS-D2016PS-D2216PS-D3016PS-D3316PS-D3916PS-D4016PS-D4716PS-D5016PS-D6016PS-D6816PS-D7016PS-D7516PS-D8016PS-S1016PS-S1516PS-S1816PS-S2016PS-S2216PS-S3016PS-S3316PS-S4016PS-S4716PS-S50

2000 VOLTS D -C

.001

.0015

.0022

.0033

.0047

.0056

.0068*.0082*.027

x 11/a27/44 x 1/8

1%2 X 11/2

33A4 X 11/2

'/2x1%3144 x 1%3%64 x 1%

3){;4x 13/e5%,4x

20PS-D1020PS-D1520PS-D2220PS-D3320PS-D4720PS-D5620PS-D6820PS-08220PS S27

*New rating

MEMBER

For information on Sprague's broad line of components for the servicetrade, get Catalog C-620 from your Sprague Distributor or write toSprague Products Co., 105 Marshall St., North Adams, Moss. 01247

6, 7THE BROAD -LINE PRODUCER OF ELECTRONIC PARTS

For More Details Circle (5) on Reply CardDecember, 1972/ELECTRONIC SERVICING 3

SPRAGUETHE MARK OF RELIABILITY

milgll sca in ornews of the indus ry=NIL_

Gas ranges manufactured by the Caloric Corporation are to have an electric ignitionsystem, according to a recent article in Home Furnishings Daily. Each burner has a1.5 -watt electric element which ignites the gas within 2 seconds of turn -on. Theseignition coils glow continuously but don't produce as much heat as the conven-tional pilot light. Some previous attempts to develop electric ignition failed be-cause the coils in time became brittle. According to Caloric, they have solved theproblem by using coils made of a material called Kanthal.

Jerrold Electronics Corporation currently is running both basic and advancedschools for MATV. These are technical meetings, and there is no charge for at-tendance. For further details, write to: Training Director, Jerrold Electronics,P.O. Box "A", 401 Walnut Street, Philadelphia, Pa., 19105.

Ceramic cookware utensils now can grill or brown foods cooked in a microwaveoven. Previously, one of the serious limitations of the system of cooking foods inmicrowave ovens has been the difficulty in browning, grilling, searing or fryingfoods. Some ovens have included conventional electric elements for these purpos-es. The Atherton Division of Litton Industries, according to Home FurnishingsDaily, is now taking orders on a steak grill and a skillet, called Micro-Browners,for browning food at the same time it is cooked from inside -out by microwaves.These utensils sell for $19.95 each, and are made of specially -designed ceramicmaterial that heats when exposed to the microwave field.

A condenser -type phonograph cartridge which uses an electret for a voltage sourcehas just been introduced by Toshiba America, Inc. The low -mass of the cantileverarm of the stylus is one plate of the condenser (capacitor), and built-in IC's ampli-fy the tiny signals at the source. The manufacturer claims a dynamic range of 100dB, and a frequency response up to 35.000 Hz for the C-40 IS cartridge with aSZ200 matching equalizer.

SMus assertiblr

,Courtesy of Toshiba America. Inc )

'Cs

Coortectcs

Electret electrode

Stylus cow

&crow Darnoe,antsewt

"- Sirius rv,

Structure of C -401S

(Continued on page 6)

1111.1111111011111111111111.1.111=1

4 ELECTRONIC SERVICINGDecemper, 1972

PROVIDES YOU WITH ACOMPLETE SERVICE FORALL YOUR TELEVISIONTUNER REQUIREMENTS.

VHF Or UHF Any Type $9.75.UHF/VHF Combo $15.00.

In tiis price all parts are included,tubeE, transistors, diodes, and nuvistorsare charged at cost.

Fast efficient service at our 8 con-veniently located service centers.

Replacement Tuner $9.75.

This price buys you a complete newtuner built specifically by SARKES TAR-ZIAN INC. for this purpose.

All shafts have a maximum lengthof 12" which can be cut to 11/2".

Specify heater type parallel andseries 450mA or 600mA.

CUSTOMIZE ill*Customized tuners are available at

a cost of only $15.95.

All tuners are cleaned inside and Send in your original tuner for corn -out, repaired, realigned and air tested. parison purposes to:

TUNER SERVICE CORPORATIONTUNER .LRVIC:

Backed by the largest tuner manufacturer in the U.S.-Sarkes Tarzian, Inc.

INDIANA . 537 S. WALNUT, Bloomington, Indiana 47401 TEL: 812-332-7251(Headquarters

817 N. PENNSYLVANIA ST., Indianapolis, Indiana 46204 TEL: 317-632-3493

NEW JERSEY. 547-49 TONNELE AVE., Jersey City, New Jersey 07307 TEL: 201-792-3730

VIRGINIA... 4538 PRINCESS ANNE RD., Norfolk, Va. 23502 TEL: 703-855-2518

GEORGIA . 938 GORDON ST., S.W., Atlanta, Georgia 30310 TEL: 404-758-2232

KENTUCKY. 2920 TAYLOR BLVD., Louisville, Kentucky 40208 TEL: 502-634-3334

FLORIDA .... 1505 CYPRESS St., Tampa, Florida 33606 TEL: 813-253-0324

CALIFORNIJ SARKES TARZIAN, Inc. TUNER SERVICE DIVISION10654 MAGNOLIA BLVD., North Hollywood, Calif. 91601 TEL: 213-769-2720

WATCH US GROWFor More Details Circle (6) on Reply Card

news of the industry (Continued from page4)

Just as this issue was going to press with an article called "Be A 'Good Guy' AndBrighten Your Image", the editor noticed an article in the Wall Street Journal enti-tled "Corporate 'Good Guys' Get To Tell Their Side Of Consumer Story". SenatorFrank Moss (D., Utah), who is chairman of a Senate Consumer sub -committee, afew months ago wrote to the largest companies and invited them to detail their vol-untary efforts to help consumers. The 181 replies from corporation executives,who are harassed by consumer activists and unappreciated b' both the press andthe public, fill a 466 -page Senate document. It seems that TV servicemen are notthe only ones who have received a bad press.

The sounds of Big Ben's chimes mark the hour am half-hour near London Bridge atLake Havasu City, Arizona. Big Ben has rung o t the hours to Londoners since1858, and now by means of special audio tapes Es Aiding atmosphere for the enjoy-ment of tourists visiting the transplanted bridge. Equipment and tapes were sup-plied by Tape-Athon Corporation of Inglewood, California, and the music systemwas engineered and installed by Hollywood Sound Systems.

(Courtesy of Tape-Athon Corp.(

Color TV has been introduced in Italy, according to Radio & Television Weekly, butnot without much technical and political dissent. The Olympic games from Mun-ich were broadcast in Italy using both the French SECAM and the West GermanPAL systems. Proponents of the two systems are battling for control of the Italianmarket. In addition, leaders of the minority political party are against the start ofany kind of color broadcasting because they say the money is needed for betterschools and hospitals.

A thin -panel TV display was demonstrated by Zenith engineers at a recent Instituteof Electrical and Electronic Engineers (IEEE) conference, as reported in Home Fur-nishings Daily. The experimental "picture tube" was a Burroughs Self -Scan panelusing the gas -discharge principle, and showed only a portion of the TV picture.Dr. Robert Adler, Zenith vice president of research, is quoted as saying: "TheZenith thin -panel display is the first matrix devIce to produce a TV picture of suf-ficient quality to warrant comparison with a CRT."

6 ELECTRONIC SERVICING December, 1972

Introducingthe expensive digitalmultimeter thatdoesn't cost a lot.

The B&K Precision Model 281. A solid-state, lab -quality portable instrumentthat measures AC/DC voltage, current and resistance.

The state-of-the-art Model 281 shows readings on a large, clear,21/2 -digit numeric display. It also has positive over -range and reve-se-polarity indication. There's no need to switch leads. You can reverse polarityat the flick of a switch.

Model 281 readings are faster and more accurate than analog -typemeters. Unlike hard -to -see needle indicators, you can read the large,illuminated numerals-including the decimal point-from a distance.

Featured are 26 ranges: five DC voltage, 100mV to 1000V, with 1%accuracy and 10 megohms input impedance; five AC voltage, 100mV to 1000VRMS, five DC current, 100rt A to 1A; five AC current, 100P- A to 1A; and sixresistance, 10 ohms to 10 megohms.

With built-in protection, the 281 can't be harmed by overload. And forsafety's sake, it has a three -line AC grounded cord.

Everything about the 281 says expensive-except the pirce.Call your B&K distributor.

Or w re Dynascan Corporation.

Very good equipmentat a very good price. 16995

.

Product of Dynascan Corporation, 1801 West Belle Plaine Avenue, Chicago, Illinois 60613



CureSymptoms and cures compiled from field reportsof recurring troubles

Chassis-Panasonic Models CT -601, CT -602and ('T-603PHOTOFACT-1211-2

+34V

OPEN

TRgo) REG

3.30 C

+24V

Symptom-No sound and no rasterCure-Check TR801 regulator transistor, andreplace if open

Chassis-Panasonic CT -98PHOTOFACT-1179-2

OPENS

HORIZ AFC

CIA 9JW8

DRIFTS

-.001 .0033

Symptom-Horizontal frequency drifts withheatingCure-Replace C504 (.0033)

L

Chassis-Panasonic Models CT -95, CT -97 andCT -98PHOTOFACT-1115-1, 1153-2 and 1179-2

HV

132M

28M

CHANGED10M

VALUE

HV

TO

CRT

FOCUS

Symptom-Poor focusCure-Check R527 and replace, if it is out oftolerance

Chassis-Panasonic CT -97PHOTOFACT-I 153-2


HORIZ AFC

OA 9JW8

Symptom-Intermittent horizontal lockingCure-Replace C503 (.001), if it is open inter-mittently

3RD VIDEO IF AMP

0 6E17

DEFECTIVE

Symptom-Vertical rolls for several minuteswhen turned onCure-Replace the 6EJ7 3rd video IF amplifiertube


HORIZ OSC

Oa 9JW8

R508

270KOPEN

Symptom-No high voltage, horiz output tubeoverheatsCure-Replace R508 (270K), if it is open or in-creased in value


There must be an easier way...

There is: Sylvania's Chek-A-Color test jig.

TV servicemen were never meant to bemovingmen.

But, that was before antique, modernand French Provincial units chat includedhi-fi, tape decks and record players werebuilt around a large -screen color TV set.

Getting those units to the shop can bea big job.

That's why we developed our two Chek-A-Color test jigunits. One, our full -house model, gives everything you needto test a chassis. The other is a basic unit that practically letsyou design your own test jig.

All you have to take back to the shop is the electronic gutsof the TV monsters.

Regardless of the size of the original picture, Chek-A-Colorlets you see it on a benchtop 14 -inch n74 SYLVANIA 100 First Avenue, Waltham, Mass. 02154

(diagonal) screen. It adapts to both highand low focus voltage sets and a full lineof adapters lets you test over 5,000 dif-ferent models.

A front -panel switch controls a yokeprogramming system that gives you arange of impedances and/or deflection

voltages to closely match both tube and solid-state systems.

For actual testing, a convenient meter lets you measure an-ode voltage and a speaker lets you check sound performance.

Since Chek-A-Color handles tube, hybrid and solid-statechassis, there won't be many complete cabinets to lug.

With a Chek-A-Color test jig all you have to take is thechassis. Get the picture? Sylvania Electronic Components,

service^ ^

a digest of information from manufacturers

Video -IF oscillationSony Model KV-1210U

Symptoms of ringing or black horizontal bars duringstrong -signal reception with the Sony KV-1210U

might be caused by an open sound -reject potentiome-ter, VR-203.

For a fast diagnosis. parallel VR-203 with a 330 -ohmcarbon resistor. If a normal picture results, it is certainthe control is open. and should be replaced.

After the control is replaced, align the sound trap(T205) and VR-203 for minimum signal when a modu-lated 41.25 -MHz marker signal is fed to the input ofthe I F's.

Pads for mounting the yokeRCA CTC59 Chassis

In these models, the housing of the deflection yokeis attached to the picture tube by four adhesive mount-ing pads.

Replace these pads with new ones, if removal of thehousing becomes necessary.

The RCA stock number for the pads is 135645.

Excessive brightnessSony Model KV-1710 and KV-1720

Symptoms of high brightness and vertical retracelines when the brightness control has little effect might

20 HFSO-

0608 I

C805

L607 3.30410

3.304 32

23

D609 122

Courtesy ofSony Corp.

C804100p211V

(0.65A112

180F. ELT

-JR810 5 (0.65811_ _

be caused by an open 5 -ohm fusible resistor (R811).This resistor protects D609 and the +170 supply,

and it is mounted on the flyback transformer.First, check the resistor with an ohmmeter. If a

normal reading of 5 ohms is obtained, suspect the pic-ture tube. To check the picture tube, disconnect thecathode leads of the picture tube at terminals 34, 35and 36 on the SC board. If the picture is still bright, thepicture tube is defective.

Don't operate the picture tube at such a high bright-ness level for very long, otherwise it might be damagedby the excessive internal heat.

Got a

TroubleshootingTip?

If you've recently run across an unusual trouble symptomand have determined what caused it, why not pass the infoon to the other readers of ELECTRONIC SERVICING. You'llnot only be saving other service technicians valuable trouble-shooting time, you'll also be making a little extra change foryourself. Send a thorough description of the trouble symptomand the solution along with a brief discussion of your trou-bleshooting technique to:

Troubleshooting Tip, ELECTRONIC SERVICING1014 Wyandotte Street, Kansas City, Missouri 64105

10 ELECTRONIC SERVICING December 1972

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Need a not -available schematic." Need an obsolete parr.' Have anunusual service problem and want help? Send information and fullmailing address to ELECTRONIC SERVICING. Other ES read-ers should send replies with their offer of help direct to the writer.We reserve the right to edit and print all letters sent to this column.Let us help one another.

Needed: A "Combo- tuner 111F-IIIIF, Sears partnumber T95-44, her a .Silverion Chas.sis number 528-33500.

Ja.sper Mazar10 Brook Ave., R.D. 4Binghamton. N.Y. /3901

Needed: Power transformer .for a Delmonico, ModelE.M.U. 932. The translOrmer has no part number buthas markings S TA'.

Philip Bonsi,gnora3217 Pelham Ave.Baltimore, Maryland 21213

Needed: .S.chematic calibration data fOr a Pyramidcapacitor -resistor analy;:er, Model C RA -2.

Larry JanzenMinilabP.O. Box /63Neosho Rapids. Kansa.s. 66864

Needed: Schematic or a service manual for an antique"Freshman" table radio. about 1923. The serial num-ber is 152771, it was manufrictured in Chica,go.B.R.C.

Stephen A. Hash, Jr.231 G ladstoneCampbell. Ohio 44405

Needed: Operating manual fur the Hickok. Model188X signal generator.

John Rudiak1360 Well RoadSomerville. N.J. 08876

Needed: Schematic and operating instructions for aDoss -1)/50. transistorized flyback yoke tester.

George Su:uki4545 A liikoa St.Honolulu. Hawaii 9682/

Needed: Schematic and technical infOrmation fin. thedynamic transistor tester developed by Ily-Tronix In-strument Alodel 900.

Rudy's TV6002 LibbeyHouston, Texas 770/8

For More Details Circle (8) on Reply Card12 ELECTRONIC SERVICING December. 1972

Needed: Schematic of a power supply to furnish both+50 and -50 volts at 3 amperes, and +29 volts wellisolated from the other voltages.

R. L. Wesely585 F St.Lebanon, Oregon 97355

Needed: Schematic and operating manual fin. Tiro.Model 677 tube tester.

A. Bochichio45 Andrews St.Staten Island, New York 10305

Needed: Suggestions for restoring vertical sweep in aMagnavox T935 chassis. All the resistors hare beenchecked and all capacitors replaced.

Jasper D. Grant280 Leslie St.Newark, N .J.

Needed: To help underprivileged kids in high schoolelectronics courses: scopes; color test jigs, and, mis-cellaneous components. Write to me for details.

Charles Prime rand3509 Rogero Rd.Jacksonville, Florida 32211

Needed: Service information on Lafayette communica-tions receiver, Model HA -600A.

Jimmie BriggsRoute 2Happy, Texas 79042

Needed: C-40 adapter for a Model 350 or 400 CathodeRejuvenator Tester; a schematic and operating man-ual for a Philco Dynamic Mutual Conductance TubeTester. Model 9100.

Steve Hermanson102 South St.Lebanon, Illinois 62254

Needed: Up to date tube testing data for a PrecisionTube Tester, Model 660 and adapter Model G-140.

Robert Ralston110 Chestnut St.Westernport, Maryland 21562

Needed: Schematic and operating instruction for Audi-tion radios.

F. WegenerP.O. Box 3556Ponce, Puerto Rico 00731

For Sale: One Model 1077B TV Analyst, (used 6times); one Heath Kit 5 -inch scope; one Heath Kitelectronic switch.

Jacob P. Pettner1624 Second Aye.Conway. Pennsylvania /5027

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For More Details Circle (9) on Reply CardDecember, 1972 ELECTRONIC SERVICING 13

News from the

SERVICE ME n.

At the joint NEA/NATESA convention in NewOrleans, Morris L. Finneburgh, Sr. offered to take a

leave of absence from his company duties to help themerger. This offer has been made official in an an-nouncement from his company. "The Finney AntennaCompany is highly honored by the unanimous electionof its senior officer-M. L. Finneburgh, Sr.. E.H.F.-as Moderator -Chairman of the all-importantNATESA/NEA Merger Committees. The FinneyAntenna Company Board of Directors-recognizing

that the future security of independent TV service isseriously involved-has taken the following action:'Morris L. Finneburgh, Sr., E.H. F. has been tempo-rarily relieved of certain important company adminis-trative responsibilities in order to invest his maximumtime, efforts and guidance in behalf of the TV serviceindustry merger project.' The Finney Antenna Com-pany knows no ethically better way of continuing toearn the respect, confidence and patronage of our in-dustry."

Members of theNATESA/NEA MergerCommittee present atthe September meet-ing were: (back row.left to right) CliffordShaw. Gerald Hall.Paul Dontie, EdwardGorman. GeorgeWeiss and EmmettHughes: (front row.left to right) CharlesCouch. Leroy Rags-dale, M. L. Finne-burgh. Sr., NorrisBrowne. and VirgilGaither.

NEA NATESA MERGER

A giant step towards merger of NATESA and NEAwas taken at a meeting September 29th and 30th by theJoint Merger Committee. The committee. under thechairmanship of Morris L. Finneburgh, Sr., tentative-ly selected the name National Electronic ServiceDealer Association (N ESDA).

By unanimous agreement, Frank Moch (NATESA)and Richard Glass (NEA) would be elected to thepositions of Executive Vice -Presidents for the newassociation. A sub -committee at a later time will

present an outline of their specific duties. It wassuggested that Frank Moch assume the responsibili-ties of public relations, governmental contacts andpublicity, and Richard Glass would be in charge ofinternal and administrative affairs.

The next joint meeting will be held in Denver,Colorado the first week of December, 1972. At thatmeeting, the question must be answered about an earlyratification of the merger or waiting until the August,1973 convention in Kansas City.


NESA FALL CONVENTION

Members of the Nebraska Electronic Service Asso-ciation (NESA) met in their fall convention October6th. 7th and 8th at the New Paxton Hotel in Omaha,Nebraska. Five sessions of a Business ManagementSchool were held; Carl Babcoke, Managing Editor ofELECTRONIC SERVICING presented a three-hour technical seminar: Ron Crow gave a report onthe ISCET program and gave the CET test to several

Fred Marti-, who teachessalesman3-ir at the OmahaTechnical Cc lege. s shownlecturing 3It c ie of the fiveBusiness Vka -agerrent sess ons.All the sess cols werewell-attenc

technicians; and the keynote address was by PhillipDahlen, editor of Electronic -Technician Dealer.

A total of 208 persons attended some part of theactivities. Twenty-six distributors and manufacturersfurnished exhibits for the trade show. Bob Royce,regional vice-president, made most of the arrange-ments.

December 1972 ELECTRONIC SERVICING 15

The anatomy of a sweep failure

By John S. Hanson

A step-by-step account of how aprofessional TV technician fol-lored the rules i)f good sericingand repaired an unexpected failurein his OH' color receiver.

One Saturday evening as I

watched the antics of Archie Bunk-er. the circuit breaker in my porta-ble color set went "snap" and thepicture disappeared. When I resetthe breaker, sound and picturecame hack. but left again about ISminutes later. There seemed littlepoint in trying the breaker again.obviously I was faced with a TVmalfunction.

I had been wanting to try someof the techniques presented in theRCA No. 8 and No. 9 workshopprograms. which are about trouble-

shooting the RCA XL -I00 solid-state receivers. So my momentarydisgust at the prospect of an eve-ning without television faded intoan interest in trying some new trou-bleshooting. I brought into the liv-ing room some of my test equip-ment, a schematic. and a powercable.

Testing The SCR CircuitsNly receiver is an I8 -inch porta-

ble using RCA's CTC49XA chas-sis. A simplified schematic of thehorizontal sweep circuit is shownin Fig. I. This is a modified versionof the pioneering CTC40 horizon-tal circuit.

First. I measured the resistanceto ground from the anode (case) ofeach SCR. Retrace SCR 102 readabout 20K ohms and trace SCR101measured about 4K ohms: bothreadings were within tolerance. I

reset the breaker which promptlyclicked -off again. Rapidly turningoff the power switch. I measuredbetween the anodes of the twoSCR's, and was rewarded with alow -resistance reading. Only thecommutating capacitor (C413 andC414 in parallel in this model) isconnected between these twopoints, so it is the only componentthat could give such a reading if itshorted. Removing both capaci-tors. I found C4I4 (.06 mfd 5 per-cent) was shorted.

Luckily, I had an exact replace-ment capacitor in my parts kit, andquickly installed the new one. Thepicture came on and I settled hackto watch, hut this time I left off theback, just in case more repairswere needed.

After a few commercials, I real-ized the width was excessive, andthe side -pincushion correction

To

HV REG

4CRIO2

RETRACE

SWITCH

C

RETRACE

A DAMPER.075

RETRACE

.4 --

SHORTED 5%

TRACE--

(CR101) TRACE

SWITCH

A

c CR101

TRACEA DAMPER

YOKE

TO HVTRANS

TO HV

ADJ

Fig. 1 This is the basic horizontal sweep circuit of the RCA CTC49XA chassis. Deflection is by ringing the re-trace circuit at its high resonant frequency and ringing the trace circuit at a lower resonant frequency. Thisavoids harmful switching transients and the circuit operates at a low impedance so the yoke and high -voltagetransformer can be driven in parallel.

16 ELECTRONIC SERVICING December. 1972

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Fig. 2 Normal waveform at SCR102 (re-trace) is the one above, and below is thewrong waveform found when the high -voltage regulator was inoperative Normalringing frequency of the charging circuitis about 12.000 Hz. while the wrong fre-quency was about 7800 Hz.

wasn't working. Previous to thisfailure, the picture had been per-fect in convergence and pincushioncorrection. In fact, I recently dem-onstrated the excellent setup to afriendly competitor.

At that point. I decided somewaveform analysis was needed.and started with the low -capaci-tance probe applied to the anodesof the SCR's. The pulse at SC R 101(trace) was okay. just the normal

sharp spike of approximately thecorrect 500 volt p -p amplitude.

But at the anode of the retraceSCR. the waveform was abnormal(see Fig. 2). Instead of a roundedtop, it ascended more like a saw -tooth or ramp. This is the type ofwaveform produced by too long atime constant.

When I tried to adjust the highvoltage. R41 I (schematic in Fig. 3)had no effect. Also, the side -pin-cushion adjustment was inopera-tive.

Normal High -VoltageRegulation

A short review of the designgoals and normal operation of thehigh voltage regulation should behelpful at this point.

The amplitude of voltage at theanode of SC R102 in the retrace cir-cuit at the time retrace SCR 102conducts determines the amount ofhigh voltage and the width of thepicture. This is done by ringing thecharging circuit so the voltage ar-

riving through T402 and T403windings in parallel reaches a maxi-mum and then starts down to alower voltage before SCRIO2 con-ducts. The amount of voltage need-ed at any particular time is suppliedby the control circuit whichchanges the inductance of T402(Fig. I) to vary the resonant pointof the charging circuit. When theSCR conducts, the charge in C4I3and C4I4 is available to power thetrace part of the circuit.

The higher this voltage is at thetime SC R102 conducts, the widerthe scan and the greater the highvoltage. Also, the reverse is truewhen the voltage is reduced.

T402 is a saturable reactorwhose inductance decreases whenthe current through its controlwinding is increased. Minimumcontrol current drawn by the HVregulator transistor. Q401, duringtimes of maximum brightness, pro-duces a large inductance in thewinding of T402 (see the schematicin Fig. 3) which is in parallel with

FROM

YOKE

FROMVERT

SWEEP

HV ADJUST

2200

4700

0 SIDE PINCUSHAMP

100K

-.01

SIDE lmeg

PINCUSH

3900

TP-2

5.6mfd

SHORTED

C)I HV REG

giD04

6.8V

0 10000

CD

.-o 1403

B+

)

Fig. 3 The side -pincushion -correction waveform is added at TP-2 to the waveform from the cold end of thehorizontal yoke winding Both signals normally affect the width and high voltage. but at different points of thepicture.

T


the winding of T403. Therefore,this large combined inductance istuned by C4I2, C413 and C414 to alow frequency of about 10,000 Hz,as shown in the lower waveform ofFig. 4. The moderately -high volt-age present when the SCR con-ducts maintains the normal highvoltage even with the extra load ofmaximum picture -tube current.

Operation with a black rasterreverses these conditions. Controlcurrent through T402 is at maxi-mum, and this decreases the induc-tance of the winding parallelingthat of T403. The smaller total in-ductance is tuned by C412, C413and C414 to about 13,000 Hz.Therefore, as shown in the upperwaveform of Fig. 4, ringing hasproceeded farther and there is amuch lower voltage available whenthe SCR102 conducts. Lower volt-age means less high voltage andnarrower width which cancels theeffects of the lighter picture tubeload. Of course, operation at nor-mal brightness produces conditionsin between these extremes with aringing sine -wave frequency ofabout 12,000 Hz (shown in theupper waveform of Fig. 2).

When decreased picture tubecurrent or increased line voltageproduces more width, the horizon-tal sweep current through the yokealso increases. This larger currentcauses more amplitude of the para-bolic voltage (lower waveform ofFig. 5) dropped across C408 andC409 (see Fig. I). This voltage isreduced and regulated by the ac-tion of zener CR404, and the re-mainder (upper waveform of Fig.5) is applied to the base of Q401,the HV regulator transistor. Q401has no forward bias except this sig-nal. Therefore, it can conduct onlyduring the positive -going tips whencollector current is needed to de-termine the inductance of T402.CR403 is added in parallel withT402 to damp any ringing of thatwinding, and current from thedamping conduction adds to that ofQ401 to increase the efficiency ofthe H V and width regulation.

Pincushion correctionIn the RCA CTC49 chassis.

side -pincushion correction is in-serted into the high -voltage regula-tion. Most of the other SCR -sweepcircuits don't have this tie-in. And.instead of narrowing the picture atthe top and bottom to remove thepincushioned effect at the right andleft edges, the CTC49 widens thepicture in the center.

Q402 (Fig. 3) amplifies a filteredvertical sweep waveform and ap-plies it through CR405 to the samezener (CR404) used in the high -voltage regulator. This increasesthe amount of width and H V whenthe vertical sweep is near the cen-ter of its scan. Obviously, somehigh -voltage regulator defects alsoeliminate the side -pincushioncorrection. And both circuits affectthe width.

Finding The Source Of TheWrong Retrace Waveform

According to the theory of oper-ation, the abnormal waveform atthe anode of SCRI02 (lower wave-form of Fig. 2) indicates the charg-ing circuit is ringing at about 7800Hz. This is such a low frequency itsuggests T402 might have zero con-trol current or have an open wind-ing.

The scope showed no signal atthe base of Q401, the H V -regulatortransistor. Moving the probe to theother end of CR404 (TP-2), I couldfind no waveform there, either.Without these waveforms, therecan be no H V regulation.

Because both the H V -regulatorand pincushion -correction circuitsaffect the width, and both signalsshould appear at TP-2, I decided toseparate them at that point for test-ing. When CR405 was disconnect-ed, a normal H V -regulator wave-form was obtained at TP-2. Andwhen I tried it, the H V Adjust con-trol changed the high voltage.

Next, I suspected thepincushion -amplifier transistor,Q402, might be defective, but itwas okay.

Just a few ohmmeter measure-ments later, I found C415 wasshorted. The value of C4I5 can'tbe too large, else there will be in-

CR'ONDUCT I ON

.11611 4=1111.1

Fig. 4 The top waveform is normal foroperation with the brightness turneddown. Frequency of the charging -circuitringing is about 13,000 Hz,so the voltageis fairly low when SCR102 conducts. Like-wise, the lower waveform is normal forhigh -brightness operation when the fre-quency of the charging circuit is about10,000 Hz. This gives a fairly high SCRvoltage to maintain good high voltageunder the heavy drain of the picture -tubecurrent.

4keiNetheeNeop.\(

I V \Fig.5 Normal waveform at the base of theregulator transistor (0401) is shown atthe top The bottom waveform is the nor-mal 6 volts p -p at TP-2.

sufficient side -pincushion correc-tion. After measuring two or three4-mfd capacitors, I found one ofabout 5 mfd. I installed it, reset theside -pincushion control for straightvertical lines at the extreme leftand right edges of the picture,turned the brightness down andadjusted R41 I for 26.5 kilovolts,and the picture looked fine again.

A Happy EndingWhy had there been two sepa-

rate parts failures? Perhaps C415shorted first and the resulting ex-cessive width escaped my attentionuntil the overload found a weak-ness in C414 and shorted it also.

My color receiver was operatingexcellently again, but I had missedthe news and had to settle forwatching the late, late show. 0


Troubleshooting tips for flybacksand other defective components

by Morris Moses

zi high -voltage transAmner inflames is a spectacular sight, butnot all component fidlures in thehorizontal sweeplhigh-voltage cir-cuit provide dramatic evidence.One of the following methods oftesting is sure to spot those otherhad parts.

Component failures in thehorizontal-sweep/high voltage cir-cuits are so common we mightthink the job of finding them wouldbecome a dull routine. That's nottrue, because there are defectswhich can cause many differentsymptoms. It's not surprising.then, to learn that more than onetype of test is necessary to find allof the had components.

To start. let's assume there is noraster because there is no high vol-tage, and this has been proved byuse of a high -voltage probe andmeter connected to the anode but-ton of the CRT and to ground. Avisual inspection of the flyback andthe horizontal sweep tubes shouldhe done first.

Visual TestsMy best ads ice is to look, look

and look even more. Use a magni-fying glass if your vision is lessthan 20/20, and examine carefullyall areas where flyback or high -voltage troubles can lurk.

Here are some specific defects towatch out for: A burned spot on a flyback wind-

ing. (Usually proves it is defec-tive.)

Broken leads at a lug of the fly-back. (Often can be repaired.)

An excessive amount of waxunderneath the winding of theflyback. (Many flybacks dripsome wax: learn from the onesstill working how much is nor-mal.)

A pinhole in the insulation of thesingle -turn HV-rectifier filamentwinding permitting an arc to thetransformer frame or to ground.(Often this can be repaired byinstalling a new wire.)

A path of carbon across the sock-et of the HV rectifier tube. (Re-pair by installing a new socket.)

Cracked glass or a white getter -

HORIZONTAL

OUTPUT iAH F.

750V

WIDTH

-o

HV

HORIZ SIN

HORIZYOKE

B+

-6- AGC

B BOOST

area inside a tube. (Replace thetube.)

A blue glow inside the plate.(Replace the tube, it's gassy.)

A red area on the plate of thetube. (Usually not a defectivetube, but indicates trouble else-where.) It's surprising how manytroubles can he found by watch-ing for these symptoms.

Testing By Tube ReplacementChecking horizontal -sweep

tubes by use of a tube tester is notaltogether satisfactory. The DCand AC voltages in any type oftube tester can't be as high as thoseencountered in the receiver. There-fore, many arcs, slight leakages.borderline weak emissions or tend-encies toward gas will not be foundby that method. Replacement witha known -good tube often is theonly satisfactory solution.

Even the replacement of tubesmust be planned with some care.for such common conditions asdouble -troubles can give false re-sults. For example, suppose theoriginal trouble was an open hori-zontal oscillator coil. This kills the

FROM HORIZOSC

CHECK DC AND AC

GRID DRIVE

CHECK CATHODE

CURRENT

HORIZ

CHECK SCREEN

VOLTAGE

Fig. 1 This schematic is typical of many b -w horizontal -sweep and Fig. 2 Open the cathode circuit, then check the cathode current,DC and AC grid voltages, and the screen -grid voltage to obtainsome helpful readings.

high -voltage circuits.

20 ELECTRONIC SERVICING/December. 1972

oscillation; and loss of drive to theoutput tube is the original trouble(the only one). But it never stopsthere. No customer ever turns offthe receiver soon enough to avoiddamage. In fact, many of themcontinue running the set all eveningso they can follow the programs bythe sound alone!

Of course, after the horizontalsweep has operated for a time with-out oscillator drive, the output tube(and probably the damper) hasbeen weakened or ruined. Thenregardless of which tube -replace-ment method you use (one by oneor all at once), there is a possibilityyou'll ruin one or more of your newtubes before deciding that tubes arenot the main problem.

My own answer to this dilemmais to replace the tubes one by one.but also to monitor some sweepvoltage and keep a sharp watch forvisual symptoms. Two DC vol-tages give us the most informationfor this test. One is the B -boostvoltage, and the other is the screenvoltage of the horizontal outputtube. Analysis by the screen vol-tage was given in the May, 1972

issue of ELECTRONIC SERV-ICING, starting on page 57, andwill not be repeated here.

An alternate method is to installall new sweep and high -voltagetubes at the same time, and watchcarefully for red plates during thefirst minute of operation. If thenew tubes restored normal opera-tion, re -install the old tubes one ata time until there is no raster. Thelast tube replaced will be the badone. Unless, of course, there'stwo!

Diagnosis In The ShopPreviously, I mentioned moni-

toring a DC voltage while changingtubes. If the B -boost in Fig. I mea-sured +350 when a bad tube wasused and the voltage shot up to+800 when a new tube was in-stalled and given time to heat, thereis no doubt about the need for thenew tube. But there are many morecases in which the B -boost voltagehelps diagnosis.

For example, when the receiverwas turned on from a cold start, the

B -boost started at zero and at theend of a minute was only 200 volts.Diagnosis: The damper tube isweak. Or, the B -boost came up to+350 after 45 seconds of operation,and the plate of the output tube hada red glow. A loss of oscillatordrive, bad flyback, shorted boostcapacitor (C3 or C4), or other de-fects which load the output stagecould be the culprit. Then, if youdisconnected the horizontal yokecoils, and the B -boost went to+1000 volts, it is certain the yokehas shorted turns.

Checking horizontal driveand plate current

Any horizontal -output tube willdraw an excessive amount of platecurrent if the horizontal drive fromthe oscillator is missing or reducedin amplitude. The schematicsusually show a typical DC voltagefor the control grid. This voltage isproduced by rectification of theAC signal from the oscillator bythe grid -cathode circuit of the out-put tube. So, remember the outputtube must be in the socket, have acomplete circuit through the cath-ode to ground, and the tube mustbe capable of drawing grid currentbefore this voltage can be generat-ed.

In most cases, the DC reading isan accurate indication of theamount of AC signal there. But thiscan be misleading where leakages(through capacitors, for example)can increase or decrease the DCvoltage without materially affectingthe AC drive from the oscillator.

Anyway you look at it, a low DCreading there means trouble andexcessive plate current.

After you have checked (andcorrected, if needed) the control -grid drive, it is recommended thatyou break the cathode circuit of theoutput tube and install a milliam-meter between the cathode andground as shown in Fig. 2. Becareful that you don't also open theheater ground circuit; often the twoare grounded at the same spot.

If normal cathode current forthat model should not exceed 220

mills, but the meter shows 350,

don't operate the chassis very long

COIL OR

TRANSFORMER

Fig. 3 Circuit used to check inductancesby the ringing method. The test frequencyand the value of the series capacitor arecritical for best results.

Fig. 4 Waveforms obtained byflyback transformer.(top) Normal waveform when the induc-tance has no shorted turns.(center) Reduced amplitude when severalturns are shorted.(bottom) Nothing but the ringing pulseshows when many turns are shorted.

ringing a

Fig.5Waveforms obtained by ringing withand without the yoke in the sweep circuit.(top) Normal waveform of the entire hori-zontal sweep circuit, when the capacitoris connected to the plate cap of the out-put tube.(bottom) Normal waveform (withoutchanging the test conditons) when theyoke was disconnected. Ringing occursat a lower frequency.


at a time because the tubes can bedamaged. Such a reading indicatesa large overload in the plate circuitof the output tube. Remove theplate cap of the H V -rectifier tube.Reduction of the cathode currentto normal indicates the rectifiertube is gassy or shorted, or there isan excessive load on the DC out-put of the high voltage.

Using the cathode current as anindicator shows when the overloadhas been eliminated, even when thetemporary test you used to reducethe current also eliminated the H Vor the raster.

When you have to dig deeper forthe defect, monitor the cathodecurrent as you disconnect parallelloads, such as focus coils or pin-cushion transformers in color sets,or width coils in b -w chassis. Thecircuit which reduces the plate cur-rent when you disconnect it un-doubtedly is the one producing theoverload. If you have opened allthe circuits that load the flybackand the cathode current is stillhigh, it is likely the flyback hasshorted turns.

Checking the flybackIt's good technique to test the

easy things first. With flybacks,that means to try ohmmeter read-ings first. An open winding is easyto spot because most modern fly -

backs measure continuity betweenall lugs (except pulse windings onsome color sets).

Checking for shorted turns ismore difficult. Of course, if theH V -tertiary winding is supposed tobe 600 ohms and measures 80,there's no doubt about that read-ing!

Ringing tests using your scopeFigure 3 shows how to check any

inductance by ringing it with apulse from the deflection circuit ofyour scope. Some scopes have aterminal on the back panel for thispurpose. Or you can open yourscope and add a terminal and a wireto the best point.

Two conditions are critical in aringing test. The frequency must benearly optimum for the inductance,or the ringing will continue too longor die away too soon for an accur-ate test. (When you use your scope

for the pulse, you select the fre-quency by adjusting the coarse andfine horizontal -frequency knobs.)

In addition, the value of the ca-pacitance between the source ofpulses and the inductance is criti-cal. Values between 100 and 200 pfusually work best with componentswhich are part of horizontal sweepcircuits.

The results of ringing tests canbe quite accurate, but only if anoth-er identical but normal inductanceis available for a comparison. Se-lect a frequency and a capacitancevalue that give ringing similar tothat in the upper waveform of Fig.4. Then test the suspected induc-tance.

The waveform in Fig. 4 is proba-bly ideal for ringing tests. When afew turns of the inductance areshorted, both the amplitude and thenumber of cycles before it decaysto zero are reduced, as shown inthe center waveform. The bottomwaveform shows the results ofmany shorted turns.

Ring the entire sweep systemBecause there are so many sepa-

rate inductances in any horizontalsweep circuit, it is faster to do apreliminary ringing test of the en-tire system. If the results are nor-mal, the whole circuit is certain tohave no shorted inductances. Thencheck the individual inductances, ifthe test shows a heavy load.

Just connect the capacitor be-tween the source of the pulse andthe plate cap of the output tube(and ground the scope to the re-ceiver chassis, of course).

A normal ringing waveform isshown at the top of Fig. 5. Whenthe yoke coil is disconnected, theringing operates at a much lowerfrequency, as shown by the widersine waves in the lower waveform.

Square waves from an audiogenerator can be used also for ring-ing tests. The advantage is the bet-ter accuracy with which the fre-quency can be reset each time.

Installing A New FlybackMy advice is to obtain an exact

replacement flyback. This is partic-ularly important with color TV'sbecause of the many extra pulsewindings and other differences.

Sometimes, as with some Zenithparts, the original -replacement fly-back comes with many of thesmaller components alreadymounted and wired. This savesconsiderable time.

One situation we techniciansdon't like to talk about, is the pos-sibility of incorrectly wiring thereplacement transformer. Thereare several methods of avoidingthis problem. I always make asketch which includes the colorcode and terminal numbers plusextra notes like: "Don't forget toinstall the rubber grommet on the6JE6 plate lead". Another tip is toclip the old wires leaving about 1/4inch of insulation at the terminalsof the old transformer. This givesan extra check of the color codes.Also, it's better to strip the insula-tion and make a new end on thewire before soldering.

Speaking of soldering, sharppoints of solder or tips of the wirescan draw arcs, so make sure theends of the wires are down againstthe lugs and the solder flows onsmoothly.

Dress all wiring around thetransformer very carefully. Useany of the original clips or ties tohold it in place. It's easier to pre-vent future arcs and callbacks thanto repair them later.

Adjusting The Sweep CircuitMost color TV's have two ad-

justments in the horizontal sweepcircuit: a high -voltage adjust con-trol and an efficiency coil. Thesetwo adjustments affect each otherand, therefore, should be adjustedalternately several times. Checkthe service data for the method foreach model.

Remember that a loss of high-

voltage regulation might have beenthe cause of the flyback failure,because this permits excessive highvoltage and width during times thescreen is dark. The only way to becertain the high -voltage regulationis operating normally is to adjust itand test it.

If the high -voltage regulation isworking okay and the cathode cur-rent of the output tube is withintolerance, there's a very goodchance there will be no call-backson that repair.


TO A PRO,TIME IS MONEYSo take time to read about the BUSS° Kolor Kit of replacement fuses

The mark of a professional Certified Electronic Technician is efficiency.He's got the ability to locate a problem quickly, repair it quickly, andget on to the next job.

One of his secrets is that he always has the part he needs when he needs it.That's where the BUSS Kolor Kit of replacement fuses for domestic andforeign TVs comes in.

The Kolor Kit comes in two sizes, the No. 140 Kolor Kit containing 120fuses, and the No. 240 Deluxe Kolor Kit containing 240 fuses plus four setsof twin clips. With a BUSS Kolor Kit in your tube caddy, you'll alwayshave the fuse you need when you need it. Ideal for servicing both color andblack and white TV's.

BUSS Kolor Kits are available from your local BUSS Distributor.

0

Bussmann Mtg. Division, McGraw -Edison Co., St. Louis, Mo. 63107

December. 1972/ELECTRONIC SERVICING 23

Find horizontal sweepdefects by SIGNAL -SUBBING

By Forest H. Belt

The second step in troubleshootingis to find which stage of a basic cir-cuit hides a defect. Signal -Subbinghelps you locate this stage -fast!

Troubleshooting any type of hor-izontal deflection system in a TVreceiver is loaded with difficulties.One reason for this unhappy stateof affairs is that sweep circuits con-tain one or more "closed loops"(see Fig. 1). A defect in any link ofa loop upsets the rest of it. makingit hard to know where to startchecking.

Perhaps you have your own petway of curing that kind of trouble.My method starts by opening theloop. Then I check the stages bysignal -substitution just as if theywere a series of amplifiers.

Signal -Subbing In The OutputStage

Suppose there is no high voltageor raster. Open the flyback/output-tube loop by removing the cap from

the horizontal output tube andconnecting an external horizontal -output signal to the cap. I use theplate drive from my B&K model1076 TV Analyst for this step. Ifthe high voltage doesn't return.suspect the flyback transformer,boost capacitor, damper tube oryoke. Disconnect the Analyst andreconnect the plate cap.

Disconnect the yoke and see ifthe high voltage returns or if theboost voltage rises to a value high-er than normal. If so, the yoke isshorted.

Check the B -boost voltage. If itis equal to or higher than the B -plussupply, chances are the dampertube is okay.

However, if the high voltage re-turns when you use the drive fromthe Analyst, the trouble is in thehorizontal oscillator, or in the grid.cathode or screen circuit of theoutput tube.

Next, inject a grid -drive signal atthe grid of the output tube. A rasterand the return of high voltageproves the problem is in the hori-zontal oscillator stage or in thecoupling to the grid.

Signal -Subbing The OscillatorOne way to service the oscillator

is to break the positive feedbackloop and treat the stage as an am-plifier. Inject a grid -drive signal atthe output. in the middle (if thereare two stages), and at the input ofthe oscillator. By noticing whichpoints give high voltage and whichdo not, you can find the stage withthe defect.

Or, if the problem involves hori-zontal locking, you can substitutethe grid -drive signal for either thehorizontal sync or the sample ofsweep from the flyback to see if theAFC is controlling the frequency.And because the output of theAFC stage is DC voltage, you canuse a variable DC supply. varyingthe voltage to see the effect on thefrequency.

These are the condensed proce-dures in signal -subbing horizontaldeflection in tube -type televisionsets.

Signal -Subbing In TransistorOutput Stages

Unfortunately. when I tried us-ing these methods with my model

HOR A,

CONTROL

FEEDBACK

FEEDBAL

HOR

OUTPUT

AMP

BOOST

VOLTAGE

(DAMPER)

FLYBACK

TRANS-

FORMER

HIGHVOLTAGE

Fig. 1 Horizontal sweep section actually contains several closed loops Best way to check is by opening themand substituting signal at appropriate points


HORIZ I VERTSWITCH

WINDING ONFLYBACK

.:4,4

SOLID STATE

HORIZ DRIVE

10000 50 mld

I.50 nit (1

50V 50V27K

Fig. 2 Low -impedance circuitry in the B&K model 1077B supplies a signal that can drivesolid-state sweep stages in transistor TV sets.

4

If

(A) (B)

Fig.3 These sweep waveforms are supplied by the B&K model 1077B "A" is for solid-state substitution "B" is for :ubes

(1)

HCFR I I

S "NC

HORIZAFC

FEEDBACKFOR

CONTROLONLY

HORIZOSC

0HORIZDRIVER

BREAK

FOR 6 AND Ti

BREAK IF OR 2 3. 4 AND 51

HORIZOUTPUT

AMP

TO

HORIZ DRIVER

HV

XF MR

YOKE

Fig.4 Signal -substitution sequence in a typical transistorized monochrome televisionreceiver Oscillator is a closed -loop circuit within the section, and is tested accordingly.

Fig. 5 Inductance -test lack and knobs onmodel 1077B for checking yoke andtransformer when substitution won twork

1076 Analyst and solid-state sets, Ifound it wouldn't work. I had toupdate my equipment. Now I havethe new B&K model 1077B Ana-lyst. It has a Solid -State SweepDrive jack. Figure 2 shows thecircuit used to drive transistorizedhorizontal sweep stages. The signalcomes from the same flyback thatsupplies deflection for the flying -spot scanner. Impedance is low,hack -to -hack electrolytics are usedas couplers, and a potentiometer isprovided for amplitude adjust-ments.

Waveforms of the pulses for usewith solid-state and with tubes areshown in Fig. 3.

The block diagram of Fig. 4shows the horizontal -sweep sec-tion of a transistorized monoch-rome TV. Numbered points showwhere to use signal substitution toisolate troubles.

There's one important differencebetween most transistor horizontalsweep systems and their tube coun-terparts: The yoke is driven direct-ly from the output transistor.Horizontal -output transformerssupply a stepped -up signal for high -voltage rectification, and pulses oflower amplitudes for other purpos-es.

The only feedback loop is for thecontrol of horizontal frequency.Pulses from the output stage arefed back to the horizontal AFCcircuit.

More detail of the horizontal os-cillator is shown in the inset. Thenumbers correspond with the samenumbers on the main block dia-gram. Positive feedback to sustain

December. 1972/ELECTRONIC SERVICING 25

HORIZ=iSYNC

HORIZAFC

FEEDBACKI OR

CONTROL

NOR IL

BLOCKINGOSC

RETRACE

SWITCHAND

DIODE

BREAK

(FOR b AND 11

BREAK

IFOR ? F 4i

FROM

HORIZAFC

DC

FREQ

ANDHOLD

NETWORK

SOV

C

TRACE

SWITCHAND

DIODE

OUTPUTXFMR

YOKE

- HV RECT(OR MULTI

- FOCUSISOME CHASSIS)

- HV REG

- BRT LIM

- CONV

CHROMABLANKING

- ETC.

Fig. 6 Horizontal sweep system unique to RCA color chassis CTC40 and CTC44. Uses silicon -controlled recti-fier switching. with diodes to keep sweep currents in right paths.

oscillation comes from the lowerend of the collector transformerwinding hack to the base through acapacitor and a resistor.

To inject the drive signal into theoscillator, break the feedback cir-cuit. as shown. Injection at point 2checks out the driver and thestages that follow. A signal subbedat point 3 tells whether or not thetransformer is okay.

If the drive signal applied topoint 4 produces high voltage and araster, the oscillator transistormust he normal. And if the signalcomes through when applied topoint 5. the feedback capacitor andresistor are okay.

Testpoint DC is the place toapply a variable DC voltage fromthe Bias -DC outlet on the Analystto check how well the oscillatorfrequency can he controlled. if lock-ing is the problem.

Points 6 and 7 are for checkingthe AFC feedback loop. Pulsesinjected here will not permit hori-

zontal locking unless you use theRF test pattern from the generatorapplied to the antenna terminals ofthe set.

The 1077B solid-state sweepdrive works fine for points I. 2, 3, 4and 5. Also at points 3, 4 and 5 ifyou turn down the amplitude at bit.Use the Keying Pulse for points 6and 7.

Testing The High -VoltageTransformer

One question rye heard fromtechnicians who try these methodsof subbing is how you can directlydrive the high -voltage transformerwith the Analyst. The answer is:you don't. There just isn't enoughpotter to drive both the yoke andhigh -voltage transformer. It's onlypractical to inject the horizontal -

drive signal at the base of the out-put stage. However, inductancetests can he made with the FlybackYoke Test Signal (see Fig. 5).

Testing SCR -Sweep CircuitsYou can use the 1077B Analyst

in testing the horizontal oscillatorof RCA TV's which use twoSCR's for horizontal deflection.But don't hook the Analyst into theanode circuits of the SCR's, or it'slikely the back-to-back electroly-tics inside the Analyst will explodefrom overload! Later, I'll tell youabetter way of servicing that portionof the circuit.

The block diagram of the hori-zontal sweep circuits of the RCACTC40 and CTC44 is in Fig. 6.Both the retrace and trace sectionsinclude a SCR and a diode: all fourare used for switching.

The inset of the schematic showshow the blocking oscillator can heopened up for testing by injectionof horizontal pulses. In this case.you start by injecting the pulses atpoint "G" (see Fig. 7A) which isconnected to the gate of the retraceSCR. If the raster and high -voltage


appear, the horizontal oscillator isdead.

Oscillator subbingInject the solid-state drive pulses

at the collector of the oscillatortransistor, and then at the base.Lack of high voltage tells youwhich circuit is dead. If both pointsproduce high voltage, break thepositive feedback path at the ca-pacitor which is between the oscil-lator transformer and the hold con-trol network. Try injecting thedrive at either end of the capacitor.

Horizontal locking can be testedusing the variable -DC -voltagemethod by connecting the supplyto point "DC".

Testing the SCR'sHowever, if the horizontal -drive

pulses applied to point "6" did notgive high voltage and sweep, testthe SCR's.

Remove two screws from eachSCR (Fig. 7B) then use a fingernailto lift them away from the micawasher and the socket. Caution:mark the SCR's or remove themone at a time, because they are notinterchangeable (one is rated formore current).

In nearly every case, an ohm-meter test will be sufficient. Thegate -to -cathode resistance shouldbe low, about 300 ohms for those inCTC4O chassis, or less for theCTC44 version. There's no diodeaction; resistance is nearly thesame regardless of polarity. Theanode -to -cathode resistance shouldbe very high (say above 10 meg-ohms) with either polarity.

Types of defectsDefects in the SCR sections can

be classified into two types: theones that trip the circuit breakers,and the ones that do not.

A dead oscillator merely stopsall SCR and diode conduction, andthey feel cold relative to the normalslight warmth.

The breaker tripsSuppose the breaker keeps trip-

ping when reset. Turn off the set,and connect a jumper lead from theanode of the trace SCRIOI (Fig.9B) to chassis. This prevents thetrace section from operating. Resetthe breaker and apply the power. Ifthe breaker trips again, the over -


(A) (B)

Fig. 7 (A) Test point "G" for subst luting sweep trigger (B) Two screws hold each SCR inits socket.

lOmeg

OR HIGHER

BOTH WAYS'

100 10000BOTH WAYS)

ANODE 'CASE'

:0 mey

OR HIGHER

100'H WAYS'

Fig.8 Method of checking SCRs with an ohmmeter.

(A) (B)

Fig. 9 Some of the tests to make if substitute trigger doesn't start SCR sweep working.(A) Test diodes. (B) Ground anode of trace switch SCR to isolate cause of overload thattrips circuit breaker.


CHECKS... Do TheBenefits Exceed The Dangers?You know the advantages Id using checks. ,Vow learnthe dangers and precautions.

Checks help make doing business easier, safer andfaster. Instead of taking in or paying out cash in thenormal course of business, you receive or pay outchecks. You don't need to keep large sums of cash onhand, nor must you make a trip to the bank before pay-ing a bill. But where there is money, or a negotiablesubstitute for money, the crooks will not he far behind.

Crooks Are VersatileIn the days before banking became widespread,

robbers and burglars preyed on couriers who carriedcash between businesses. Use of checks and creditexchanges have reduced that hazard. But crime is aninventive man's business, and we find the highway-man has been replaced by the forger, had -check artistand "paperhanger."

So, although there are so many advantages to usingchecks, you should know the hazards, and how to pro-tect yourself from losses.

Properly Draw Up Your ChecksA sample of a properly -drawn check is shown in

Fig. I. Notice that it contains all of the legal require-ments: date, payee, drawee, amount to he paid, andthe signature of the maker. Also, the payee is named,not just mentioned as "Bearer". The amount to bepaid is given both in figures and words. Since thischeck is handwritten, the words and figures are care-fully placed to eliminate any spaces that could be usedto alter the amount. Notice that insertion of a wordand a number could "kite" your carelessly -drawncheck from $20 to $120 or $200.

You must he sure you have enough credit in your

DON'TI/ AVE SPACE

MIDTOWN RANK t TRUSTAny town, USA

FAIN' 111 AVE SPAt

,_1171,

el"A,,,tK ./ 'Z

W.4.<7see.

USE BANK SIGNATURE

F III INUNUSED SPACE

Fig. 1 Details of a properly -drawn check.

account to cover all your checks. A check drawnagainst a hank where you don't have an account is a"No Account" (NA) check. One drawn against abank where you do have funds, but not enough to cov-er the amount of the check, makes it a "Not SufficientFunds" (NSF) check. Both NSF and NA checks aregrounds for prosecution in most areas of the nation.The law, recognizing the crucial importance of credit,protects the trustworthiness and collectibility ofchecks.

EndorsementsFigure 2 illustrates "Blank", "Restrictive" and

"Full" (or "Special") endorsements. It's handy toknow what each does and means.

A Blank endorsement actually turns the check intoone that can be used by anybody possessing it, justlike a check made to "Bearer". The danger here isthat-after the first endorsement-it can he passedwithout further endorsements, making prosecution ofa bad check very difficult. Minimize the danger whenaccepting a third -party check by requiring an endorse-ment by the one presenting it to you.

Remember the old riddle about the check that waspassed several times from one person to another be-fore it was found to be worthless? The riddle asked fora mathematical solution as to who lost. Legally, thelast person who holds the check-the fellow who pres-ents it to a bank for payment-is the loser.

Holders In Due CourseThis last man of the chain is called a "holder in due

course" and he has special protection under the law,with the right to collect from the prior endorsers, thepayee, or the maker. If the original check was legal,nothing takes precedent over his right.

Fig. 2 Three examples of common forms of indorsement (on theback of the check). From left to right. Blank Endorsement, Re-strictive Endorsement and Full (special) Endorsement.


Tips for safer check cashing

By Robert G. Amick

Obviously, any lack of intervening endorsementsreduces the number of people against whom you cantake action. The cost of recovery of a small -amountcheck is much too high to he practical. Prevention isthe best solution to the problem.

Restrictive EndorsementsA safety device you should use is the Restrictive

Endorsement which restricts further negotiations ofthe check. When you endorse a check "For Deposit".your hank, but no other, will accept it.

Full EndorsementsFull Endorsements make transfer of a check specif-

ic, but allows it continued negotiability. This helps inquestions about whether or not payment was actuallymade, but doesn't make any easier the tracing of a hadcheck.

How To Avoid TroubleDon't compete with your neighborhood bank for the

check -cashing business! Especially when cashing re-quests come from pleasant -appearing strangers withplausible stories of "emergencies". Occasionally, oneof your customers, or someone who's known to you,will have a real need and ask for help after bankinghours. If you have a "No Checks Cashed" rule. thiscould be a worthwhile exception. But, be careful of theothers.

It's likely you'll receive a few NSF checks fromyour regular service customers, even when theamounts are small. Most will be from people who tryto race the check to the bank and will cause you fewproblems. The dangers from real crooks occur whenyou get into higher -ticket rentals or sales. Also, you'remore vulnerable when doing walk-in business, be-cause there are no hints about the permanence of thehome location.

Your best protection, when cashing checks, is toexplain that you do very little cash business, and keeponly a small amount of petty cash. That lets you out ofany request over (say) $10 or $15.

What kind of checks should you look out for? Everycheck! Even paychecks are not necessarily what theyseem. Rolling drunks on payday isn't profitable for thecrook just because of the cash. The thief usuallygets-in addition to the victim's check-many identifi-cation cards with samples of signatures.

Avoid Counter and Universal ChecksCashing two forms of checks definitely is out:

Don't cash any check showing alteration. Don't cash any check written in pencil. Don't cash checks for juveniles. Don't cash bank -counter checks.or universal checks. Don't cash checks signed withrubber stamps, unless you know all thepeople involved. Don't cash checks for strangers unlessthey have positive identificationfrom local references. Make the person presenting the checkindorse it in your sight (even if it isalready signed) and compare the signatureagainst those on other identifications. Don't cash "third -party" checksunless all persons are known to you. Don't cash checks on out-of-townbanks or businesses unless you are certainthe companies and checks are valid. Don't be too embarrassed to askquestions about any check details thatbother you. It is. after all, yourmoney, and you are being asked toconfer a favor. Call the bank (if within bankinghours), give your business name, the accountnumber from the check that is inquestion, and the amount of the check. Thebank will tell you whether or notthere is sufficient money in the accountto cover the check. Immediately deposit into your bankall the

Counter Checks and Universal Check Blanks. Count-er checks are intended for use inside a hank by aperson who has an account but didn't bring his owncheck book. Unfortunately, these forms are availableto anyone who walks into the lobby of the hank. TheUniversal check has a space for the name of the hankto be written in. Neither type of check can be handledby high-speed automatic check -sorters. They won't heaccepted for transfer by clearing houses, and manybanks will not honor them, even at the hank counter.Refuse to cash any of these checks.

Avoid Post -Dated ChecksAlthough post-dated checks are not illegal, the hank

won't accept one, or it may not place a "hold" on theamount until the date on the check. This gives the cus-tomer time to get his deposit in before the check isdue. Unfortunately for you. it also gives him time toclose his account and move away.

Be Alert For "Kiters"Check "kiters'' alter the amount on the check. The

successful ones change the spelled -out amount, be-cause most banks give priority to this over any amount


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IT SPRAYSUP

GOLDENFOAMCORRECTSTUNERPROBLEMSLIKE

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in figures. If one of your checks is altered in this way,you legally are responsible for the original amount ofthe check. On the other hand, if you cash a "kited"check, you lose any amount in excess of the original.

Watch For ForgeriesForgers work on the signature, or on the endorse-

ment. The mugger who rolls a drunk also commits for-gery if he endorses and cashes the check. That's whyyou can't trust even legitimate payroll checks. Some-times whole blocks of payroll checks are stolen byburglars, who then cash as many of them as possiblebefore moving out of town.

Ordinarily, an incomplete negotiable instrument(unsigned or incompleted check) doesn't become le-gally valid when filled out by a thief. But it makes a lotof trouble, and you just might be stuck for the amount.

A few versatile, imaginative criminal groups evenprint their own checks-on nonexistent banks orcompanies-and their own identification. And, I heardof one creative loner who cashed his valid paycheck atthe bank, and then went to a neighborhood grocerystore where he cashed the voucher half of the samecheck!

There's Danger Both WaysBy now, you're aware of many ways you can lose

money at both ends of the check business: either byaccepting checks from others, or by issuing them your-self.

Employ a few simple precautions to make thingsmore difficult for those who try to misuse your checks.Here's some examples:

Make out your checks so alteration is difficult. Bet-ter yet, use a check protector;

Don't pre -sign your checks;

Use a different signature for banking uses than forletters or legal matters;

Keep your checkbook and bank records locked up;

Endorse your checks "For Deposit Only" whensending them to your bank by someone else; and

Verify the amount of each cancelled check returnedwith your bank statement against the amount onyour check stub or book to determine whether or notit has been "kited".

SummaryAll things considered, it is safer to use checks than

cash. But you must use many precautions to avoidlosses.

Although the law is all on your side, conviction of a"kiter" or forger doesn't automatically restore yourmoney. Prevention is always better than any cure. 0



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Let's zapa few transistors. .

fun! By Bruce Anderson

Good Advice in reverse about thecare and feeding of solid-statecomponents.

When the first transistors ap-peared nearly twenty years ago, itwasn't much of a trick to blow outa handful of them in the course ofnormal servicing. Those early tran-sistors were point -contact devices,and were extremely sensitive toovercurrent and overvoltage, heat,and lead stress.

Nowadays, zapping a transistoris more of a chore. The voltage andcurrent ratings are higher, heat dis-sipation is greater, and tolerance totransients is better. Yes, transis-tors are plainly more rugged thanthey were a generation ago. Andyet, the enterprising repairman (notto be confused with technicians)still can ruin a fair number of tran-sistors by following the suggestionsoffered here.

Zapping By SolderingUnsoldering and resoldering

transistors is an excellent way toruin them, so this should be done atevery opportunity. After all, in -

circuit transistor testers have beenknown to be inaccurate in certainrare instances, so it's pointless touse one of them. Right? Better tounlimber the trusty old solderingiron and yank out that pesky tran-sistor. Then if its bad, half the jobwill already be done!

For killing these new, toughertransistors, a large -wattage irondefinitely is called for. If a 150 -wattiron is used, it usually is possible toheat the transistor leads enoughfrom the top of the board to meltthe solder underneath. This way, itisn't necessary to turn the chassisupside down to unsolder. Ofcourse, there's no way to solder inthe new one from the top, but wor-

. it's

ry about that later on.For those who insist on unsolder-

ing from the copper side of theboard, we suggest this little time-saver. Hold the iron on the transis-tor lead while you locate the deviceon the opposite of the hoard. Then,when you finally get hold of thecorrect lead the solder already willbe melted along with the copper -foil junction.

The soldering iron itselfshouldn't be overlooked, also, forit can add significantly to the num-ber of transistors that can bezapped. As noted before, it shouldbe plenty large. (This makes itmore useful for separating the cop-per foil from the circuit board-anadded benefit.) If it is equippedwith a three -contact plug. cut offthe ground connection. This willprove that you are not intimidatedby Underwriters Laboratories, theNational Safety Council. NationalBureau of Fire Underwriters, andother cautious types. It will alsokeep any stray electrical leakagebetween the heating element andthe tip from blowing a fuse or trip-ping a circuit breaker. As addedadvantages, removing the groundconnector will allow the iron to beplugged in either way, a time-sav-er, and the tingle you feel whentouching the tip is an assurancethat the iron is energized.

This electrically "hot" iron ismuch more effective if the chassisto be serviced is connected to ACpower. Especially when the chassisis a "hot" type, the AC from thetip of the iron can produce highcurrents in any transistors whichare touched. It may not zap everyone, but then, nothing is perfect.To help compensate for the transis-tors that survive, an occasionallow -voltage capacitor can be de-stroyed.

Zapping By Signal InjectionSignal injection and signal trac-

ing are probably equally good waysof troubleshooting. With properattention to detail, a fair number oftransistors can be destroyed witheither technique.

Since the hybrid chassis offerseasier opportunities for zapping,here is a good place to practice.Figure I illustrates the basic princi-ple. A reasonable way to startchecking a no -video problem is byinjecting a square wave at the plateof the final video amplifier. Ablocking capacitor is necessary toprevent the plate voltage fromdamaging the generator and thecapacitance has to be fairly high topass a low -frequency square wave.So, the result is a 1-mfd capacitorcharged to about 200 volts from theplate voltage. Now, what betterway to discharge it than throughthe base/emitter junction of Q1, atransistor video amplifier? Justremove the capacitor from theplate and touch it to the base. Thepeak current might reach severalamperes, but only for a very shorttime. If the transistor happens tosurvive, don't waste any more timetrying to blow it-pick an easierone.

After the technique has beenpracticed awhile, it can be adaptedto all -transistor circuitry. Simplycharge the blocking capacitor fromthe highest -available collector volt-age and discharge it through a basecircuit.

Zapping With MetersIt's a little difficult to damage

transistors with a scope or VTVMprobe, unless you use an oversizealligator clip. This will allow simul-taneous connection to the base andthe collector; or perhaps to a B+terminal and a transistor lead.


150V 300

VIDEOIll PUIMo

t ISO

E VIDEODRIVER

CHARGE CI 10MO V OlIS

AUDIO GENERATOR

0

TO CHASSIS

DISCHARGE 1.1 II)J BASE ES 01

Fig. 1 Charge the blocking capacitor which is between generatorand tube to a high voltage then discharge it by next injecting asignal at the base of a transistor. This method is guaranteed tozap any small transistor.

On the other hand, a "cheapie"VOM can wreck a transistor if youuse it properly. First, connect the1000 -ohms -per -volt meter to thecollector and check the DC volt-age. Next, decide to check for ACsignal at the collector, so switch tothe "output- function of the meterand scale down to the lowest range.say I volt. This charges the block-ing capacitor of the meter. Then.without discharging the capacitor.connect the meter to the base of thetransistor. The discharge currentequals the voltage across the ca-pacitor divided by the resistance ofthe meter and junction, which is it

little more than 10(X) ohms total.This allows an instantaneous cur-rent of 10 milliamperes. enough todamage some transistors. If thedevice happens to be a MOSFET,and this jolt is applied to the gate.chances are good that the device isruined.

Zapping With In -Circuit TestsAs mentioned before. there are a

lot of good in -circuit transistor test-ers available, but of course, theseare for "scientists." Any true"screwdriver and pliers- service-man knows that fancy test equip-ment is unnecessary, so he simplyshorts together the base and emit-ter of the transistor. This turns offthe device, and the collector volt-age will rise to B+ if the transistoris not leaky or shorted.

Usually. this technique will notdamage the transistor. So to do

B

INPUT INPUT

61 1A x200OR MA OHMS

Z NIA x?OR 70 OHMS

OUTPUT

20

01

BETA 100

1 BETA 12OR MO OHMS

2 OHMS

20

OUTPUT

Fig. 2 Removing the forward bias of 02 by shorting between baseand emitter also decreases the impedance of the base circuit of01. The resulting excessive base current might successfully zapthe base -emitter junction of 01.

maximum damage. use a test leadwith large alligator clips, preferablyone you have stepped on a fewtimes, and don't bother to turn offthe instrument while making theconnections. It is surprising howmany times it's possible to get thebase of .the transistor connected toB+ or to the collector. The blow-outs score is nearly 100 percent.

Even if the transistor under testsurvives the previous routine, it'spossible in some circuits to zap theone next to it. The circuit in Figure2 shows how it can be done. As ageneral rule, the base impedance ofa transistor is approximately equalto the value of the emitter resistortimes the DC beta of the transistor.

In the example. the base imped-ance of Q2 is about 200 ohms, andthis is effectively the emitter resis-tance of QI. Consequentl. thenormal base impedance of QI isbeta times 2(X), or 20K ohms. But.when the base of Q2 is shorted toits emitter, the base impedance ofQI drops to only 200 ohms. It isvery likely the base current of Q1will be increased well above therating of the transistor, causing it tooverheat and self-destruct. (Mis-sion Possible!)

Special Zapping Tricks For TV'sBecause of the high voltages and

pulsed circuits in a television re-ceiver, transistor zapping is a loteasier in TV's than it is in audioequipment, especially if one takesfull advantage of his opportunities.

One simple trick is to removeany defective spark gaps-andsimply leave them out. Many of thespark gaps look a lot like small disccapacitors, so a capacitor can beused to replace a defective sparkgap and hardly anyone will noticethe difference. Of course, the ca-pacitor will not protect the circuit,and sooner or later a transistor ortwo will be destroyed by a simplearc in the high -voltage system orthe CRT.

Replacing the original spark gapwith a capacitor is doubly ingen-ious. First, there is a delayed ac-tion, because the transistor mightnot blow for days, weeks. or may-be even months. Second, whoeverreplaces the transistor probablywon't notice that the spark gap hasbeen replaced by a capacitor.Therefore, the actual cause of thetrouble will not be suspected. andwill continue to zap. To get maxi-mum "mileage" out of this littleswap. avoid servicing the receiverafter the first time. Chances are.you won't be asked anyway.

Less subtle is the trick of replac-ing a CRT socket which has built-in spark gaps with one which doesnot. If a technician happens to ser-vice the instrument the next time,he is likely to notice the change andcorrect it.

Arcing the high voltage to thechassis has always been useful forimpressing customers. In solid-state receivers, they are impressedeven more when the set immediate -


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ly stops doing some of the goodthings it had been doing before.Although this is a good way to zaptransistors, it is recommended thatyou stifle the urge to draw thosepretty arcs of high voltage until thereceiver is in the shop and safelyaway from the inquisitive eyes ofthe set owner.

Leaving out grounding strapsand wires between various units ofthe chassis is another little trickwhich will zap an occasional tran-sistor. Many of these groundingconductors are used to preventhum or to reduce stray pick-up ofpulses from the horizontal -outputsystem. But some of them serve toinsure very -low -resistance currentpaths for the energy contained inarcs. Since it is difficult to tellwhich is which, eliminate all theconductors you can. In addition tokilling a few transistors, you alsocan degrade the performance of theset.

The SCR horizontal -deflectionsystem introduced by RCA a fewyears ago (and now in use in someother makes of receivers) offerssome unique opportunities for zap-ping. The system requires a yokehaving very low impedance, whichmakes it a cinch for you to blow theSCR's (and the diodes that go withthem) by connecting to the high-

impedance yoke of a wrong test jig.And if the clips which hold thediodes are too tight, spread them alittle with a screwdriver; the arcwhich results is sure to zap at leastone of the devices. As a matter offact, just about any intermittentconnection in the yoke or flyback -

transformer circuits can damageone or more of the devices, so do asloppy solder job, or operate thesweep with a couple of unsolderedconnections.

Zapping New TransistorsIf it has been difficult to achieve

the daily quota of zapped transis-tors, don't overlook the possibilityof shooting a couple of the newones. The tips which follow are notguaranteed always to work, butthey will help the dedicated zapper.

Slip -over heat sinks make attrac-tive decorations for the shop, so

neatly line them up over the bench.If you should decide to put some ofthem back on the transistors, avoidusing heat -sink compound-it'smessy, and also makes the heatsinks get warmer!

Don't take heat -sink compoundwith you on service calls. There isusually some left over around theedges of any bolted -down transis-tors you might replace in the home,and this can be wiped up daintilywith a finger and reused on thereplacement. If there just isn't anycompound at all on the old one,make a note to bring some on thecall-back, which should be about aweek later.

If there is a high -wattage resistorconveniently near a transistor,leave a little extra lead length onthe replacement so that it can besnuggled close to the source ofheat. This added warmth, we sus-pect, makes the transistor feel"wanted and loved. Thus it willsurely respond by conductingmuch more current than it would ifit were cold.

Some fussy technicians haveformed the habit of always graspingwith pliers the lead to be soldered.The idea is that the pliers will serveas a heat sink to conduct away theheat of soldering. A true transistor -killer knows that the pliers get inthe way, so he holds the body ofthe transistor or perhaps one of theother leads. He may get the ideathat a high percentage of new tran-sistors are defective: but on this heis either wrong or modest. Heshould take the credit: his ownefforts are wiping them out.

ConfessionJust to keep the record straight,

our personal preference is to makemoney servicing television. Wealso like to help our customers, andwe like to go to sleep at night withthe feeling that we have treatedeach of these customers honestly,efficiently, and professionally.Accordingly, our policy is againstzapping transistors. All my pre-vious suggestions were made"tongue-in-cheek". Invert them180 degrees if you will extend thelifespan of all solid-state compo-nents. 0

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December. 1972 ELECTRONIC SERVICING 35

RF devices usedin medicalelectronics

401611,!'

By Joseph J. Carr

Diathernq and Electrocauteryequipment used by medical teamsfeature circuits that will seem fa-miliar to anyone who has studiedradio transmitters. Only the strictrequirements Pr dependable oper-ation and patient sufrty make themunique.

For many years. the medicalprofession has been using radio -frequency (RF) energy in the treat-ment of patients. Electrocauteryinstruments cut and cauterize tis-sues, while diathermy heats by RFinduction. These machines are ofincalculable value to doctors andsurgeons. But they can and docause interference with broadcastservices.

Just ask any Citizens -Band oramateur radio operator what adiathermy machine can do to hisreception. It's likely his answerwill be unprintable! Remote model -control and Class -D CB servicesmust share the 11 -meter band withdiathermy equipment which is not-ed for causing interference thatseems out of all proportion to thesmall amount of energy actuallyradiated.

V

'a.

Photo courtesy of theNebel-Flarsheim Divisionof the Ritter CompanyRochester. NY

Typical of electrosurgery machines is this Bovie unit.

Diathermy MachinesA block diagram typical of mod-

ern diathermy machines is shownin Fig. I. You transmitter buffs willrecognize it as the old-fashioned"master oscillator/power ampli-fier" (MOPA) type of circuit. The27 -MHz oscillator usually is crys-tal controlled, and the "antenna"is a coil inside the patient's heatingpad. RF currents heat liquids in thetissues during typical usage.

Fig. 1 This block diagram of a simple -typeof diathermy machine is similar to aMOPA transmitting station.

In many cases, an unfiltered DCvoltage is supplied to the final oroutput stage. Some early -designedmachines actually fed raw high -voltage AC to the plate circuit ofthe final amplifier. It is the unfil-tered DC or raw AC in the finalamplifier that accounts for the rau-cous, buzzing sounds radiated onthe I I -meter band by medical and

industrial diathermy induction -heating equipment.

Electro SurgeryRF-powered machines enabling

surgeons to perform electrosurgeryand electrocautery C'stops bleed-ing") are variously called "electro-cautery machine", "electrosurgi-cal apparatus" or "Bovies". Ac-tually, the word "Bovie" is a pro-prietary brand name for any suchapparatus manufactured by theLiebel-Flarsheim Division of theRitter Company. Because Boviemachines were so prominent in thepioneering days of the 1920's,many medical people mistakenlycall all electrocautery machines bythe generic term of "Bovie".

Surprisingly, many of the basicspark -gap principles are still usedin modern electrocautery equip-ment. One of the less -desirablecharacteristics of any spark -gaptransmitter is that it generatesmany harmonics, plus other signalsnot harmonically related, in addi-tion to the fundamental frequency(itself a broad signal because ofsome FM action plus jagged modu-lation). Although, the circuitry isostensibly shielded, the high levelof Electromagnetic Interference


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(EMI) around nearly any hospitalis evidence of the difficulties incontrolling such unwanted radia-tion.

Occasionally signals from thediathermy or electrocautery equip-ment will enter ECG or EEG ma-chines and cause an interference onthe scopes or strip paper read-outthat is descriptively called "base-line grass" or "baseline artifacts".If you are called on to eliminatesuch interference, it's wise tocheck against the use of diathermyand electrocautery machines.

The partial schematic of Fig. 2 isfrom a Philips Medical ElectronicsCompany Model ES3 electrosurgi-cal apparatus. The high voltagewhich arcs across the points of thespark gap is raw AC from a step-uppower transformer. Spark -gap cur-rent also passes through the pri-mary of the RF-oscillation coil,L2A. A tuned circuit, consisting ofL2B and the three paralleled .001capacitors, forces the spark -gapcurrent to flow in resonance withit. Matching to the electrodes usedfor cutting human tissues is by thestep-up coil, L3. The amplitude ofthe cutting voltage is determinedby selection of a tap on L2B.

A good example of things thatcause confusion between medicalmen and electronics men also isfound in Fig. 2: differences of jar-gon. Notice the lead going to thepatient plate that is called "indif-ferent electrode". To electronicsmen, such a label is meaningless.Medically, it means an inactiveconnection; which is far from cor-rect! The wire lead connects to an"electrode" consisting of severalsquare feet of metal fabric onwhich the patient is placed while onthe operating table. Such a largearea is necessary to spread or dissi-pate the current. If a bony part ofthe body (such as an elbow) press-es too hard and significantly re-duces the resistivity at that one

110VA,,b0.4:

0.001 0.001

0.001 0.001

Out PUT

0 001

1 001

0.001

0.001

INDIFFERENT

FIECTRODT

10 PATIENT RATE

ACTIVE

ELECTRODE

Fig. 2 Spark -gap oscillators still are being used in electrocautery equipment. This circuitis from the Philips Medical Systems, Inc. Model ES3.

(Al

(C)

(E)

Fig. 3 Waveforms available from the Bovie brand of electrocautery machine. (A) A near -

sine wave gives maximum cutting and minimum hemastasis. (B) Cutting with moderatehemastasis. (C and D) Cutting with increased hemastasis. (E) Minimum cutting withmaximum coagulating and fulgarating effects.


0.001

PULSATING DC INPUTA

Fig. 4 Circuit of the vacuum -tube oscillator in the Philips Model ES3 electrccautery ma-chine.

Photo courtesy of the Liebel-Flarshetrr Division of the Ritter Compiny. Rochester. NY

Fig. 5 An interior view of the Bovie electrocautery mach re.

ADJUSTABLEPERIOD

MV

GATE

500 kHzADJUSTABLE

MV

ik 0_CU-TING WITH CUTTING ONLYCOAGULATION

0 /0VDC

POWER

COW

PULSE

SHAPINGAMPLIFIER

POWER

AMPLIFIER

UNFILTERED

DC SUPPL1,

Fig.6 This block diagram is of the solid-state model Boyle..

point, a painful burn could developthere.

Of course, two electrodes arerequired, and you might reasonablyexpect the cutting electrode to bejust opposite in characteristicsfrom the "indifferent" one (and itis). The small cutting electrode hasa point which concentrates all ofthe RF energy at one tiny area,resulting in a combination of cut-ting and burning (cauterizing) ofthe tissues. This ability to cauterizeand thus control bleeding is one ofthe major advantages of electro-cautery over the scalpel.

The ratio of the degree of cuttingversus the amount of burning isdetermined largely by the wave -shape of the RF current. Some ofthe waveshapes available from aBovie are pictured by the drawingsof Fig. 3. Generally speaking, apure sine wave produces more cut-ting and less hemastasis ("stopbleeding"), while a pulsed signalwhich is allowed to ring causesmore hemastasis and fulgaration(deliberate destruction of tissues)and less cutting.

Tube -Powered ElectrocauteryMachines

Waveforms with pulses and sinewaves indicate that there must bemeans other than spark gaps forgenerating the RF current for elec-trocautery uses. Most modernelectrocautery units use vacuumtubes, or tubes plus a spark gap.

Figure 4 shows the Hartley -typeself-excited oscillator used in thePhilips Model ES3 electrosurgicalmachine. Low RF frequencies ofunder 1 MHz are necessary to min-imize general heating of the tissues.Notice that the power for this stageis unfiltered pulsating DC voltage.Energy from a spark gap can bemixed with a signal from the tubeto produce the variety of currentwaveforms needed by the surgeon.

An inside view of Ritter Compa-ny's Bovie electrosurgical unit(Fig. 5) shows the push-pull oscilla-tor tubes and the massive switch.Sizes of these components shouldgive us an appreciation of the largepowers involved.

40 ELECTRONIC SERVICING December, 1972

AccessoriesOne important accessory for use

with electrosurgical machines isthe footswitch. These switches arecalled "explosion proof', but arein reality "arc proof' because theequipment is usually used in oper-ating rooms which also contain rawoxygen and explosive gases usedfor anesthesia. It is imperative thatthe gas -proof integrity of theseswitches be maintained at all times.

A Solid -State BovieSolid-state components have

invaded the medical field, althoughmany tube -powered units also arebeing sold. The block diagram (seeFig. 6) of a Ritter Bovie usingtransistors starts with a 500-KHimultivibrator whose output is fedto a number of potentiometers thatcontrol output power by reducingthe drive to the power amplifiers.The final power amplifier (and onlythat stage) is supplied with unfil-tered pulsating DC voltage.

A gating circuit (shown in Fig. 7)modifies the signal from the 500-KHz oscillator so ringing can occurafter the oscillator is cutoff, when-ever coagulation is required.

Switch -selected timing resistorscontrol the amount of time the asta-ble multivibrator conducts so theoutput of the 500-KHz oscillator isin pulses or bursts of energy.

A partial schematic of the poweramplifier stage in the solid-stateBovie is shown in Fig. 8. Two tran-sistors are paralleled in a uniquecircuit that has a special combina-tion input-output transformer,diodes to stabilize the bias, andzener diodes to clip any transientvoltages that might damage thetransistors.

Patient SafetySafety for both the patient and

the operating -room personnel is ofparamount importance in medicalelectronics. The equipment manu-facturers take great pains to designsafety into the units. Any repairwork must maintain this safety.

Safety precautions are groupedinto three basic areas: electrical,mechanical, and the prevention of

ADJUSTABLE PERIODASTABLE MULTIVI ORATOR 5013.012 MUllIVIBRATOR

1800 2700

OUTPUT

Fig. 7 Schematic of the 500-KHz and adjustable -period multivibrators used in the solid-state Bovie.

INPUTFROA1

DRIVER

INPUT OUTPUTTRANSFORMER

RF OUTPUT

40 ®oI

1_

Fig. 8 Schematic of the final RF power amplifier of the solid-state Bovie.

110VAL,

604-17

JBUZZER

Dl

WARNINGLAMP

IGO)

TOPATIENTGROUND

PLATE

0 0022

iCourtesy of the Ritter Company)

Fig. 9 This open -ground protector circuit removes power to the Bovie if the ground cir-cuit becomes open.


explosions. Mechanical safety isseldom the concern of electronicsmen. But the prevention of explo-sions is so important that mostelectrocautery equipment ismarked clearly "Do not use in thepresence of explosive gases".

Sometimes electronic and me-chanical safety procedures mustwork together. For example, thepower plugs that pull out all tooeasily, or make intermittent con-tact, so that critically -needed ma-chine (perhaps a monitor or a defi-brillator) is out of service just whenit is needed most. Only the highesttype of servicing craftsmanship canbe permitted.

Ground CurrentsA minor g,iound loop that might

cause only a faint buzz in a hi-fiamplifier could cause a killing cur-rent to flow through a patient. Be-fore you dash off to refer to the"lethal currents level" in someelectrical safety book which says200 or 300 milliamperes are re-quired to kill, remember that thosefigures are correct only for intact

skin touching both conductors. Insurgery, however, the electricalcondition is vastly more criticalbecause the patient's body mightbe opened by surgical incision orby means of a catheter placed inthe vein of an arm. It is the currentdensity through the heart that is thedanger. A current as low as 20microamperes at the heart mightkill the patient. Voltages thatcouldn't even he felt by the operat-ing room personnel might be fatalto the patient.

In the solid-state Boyle, there isa circuit (Fig. 9) that disconnectsthe AC power to the equipment ifthe ground lead is broken. TheSCR normally is biased "off" be-cause the ground wire shorts outthe forward bias at the gate. If theground wire opens, the currentthrough the 1000 ohm resistor bias-es the SCR "on" and it removesthe voltage from the relay coil,cutting off the voltage to the Bovieand applying it to a buzzer and awarning light.

By the way, some operating

room people have been known,incredible as it may seem, to dis-connect the buzzer because it keptsounding!

The Future Of Electronics InMedicine

Data about symptoms and read-ings from many types of patientmonitors now can be stored incomputers. In fact, there are ru-mors that computers might be usedto give tentative diagnosis.

It seems more than likely thatthe most helpful of future machinesused in medicine will be electronicin nature. Therefore, more repairsto these instruments must be doneby electronic technicians and lessby doctors or medical aides.

The repair of electronic medicalequipment appears to be a veryneeded and promising field for anyof you who would want to enter it.But we must emphasize: Preparethoroughly for this type of work.Remember that human lives candepend on the quality of your work-manship. (71

NEW EICO TR-410Solid -State'TriggeredSwear I0 MHzOscilloscope$37995

Never before has so muchbeen built into a low costsolid state triggeredsweep scope!

INCLUDES EXCLUSIVEDUAL PROBE

o

EICO introduces the first laboratory quality, high performance,wideband Triggered Sweep Oscilloscope, at a price you canafford!Use as Vectorscope for Color TV Servicing 3 calibrationvoltages (2, 5 and 10) Quick connect BNC connector atVertical Input Front panel adjustable Horizontal and VerticalDC Balance Controls Vertical and Horizontal selection of ACor DC modes of amplification Sweep synchronized Gate Out-put Flat faced CRT Z Axis input Rear panel astigmatismcontrol Edge lit calibrated screen Operates on a standard120 volt, a low 100 volt or a 220-230 volt line.

FREE 1973 EICO CATALOGFor name of nearest dealer and free catalog check re-order service card or send 254 for prompt first class mail E/C04service. EICO-283 Malta St., Bitlyn, N.Y. 11201

Pioneering again Castle presents a sensational NEWTimesaver for the Professional TY Service Technician

TV TIMER SUMER.

Transistorized Test Unit substitutes the tuner in defective TV Receiver to prove whetheroriginal tuner is good or bad. Performs tests normally made using elaborate and expen-sive signal generating equipment and oscilloscopes . but much more simply, witheasily understood results. Tests that are, in fact, so simple that they can be made rightin the home, in most cases without removing the tuner or chassis from cabinet.

Use with any 40MHz receiver ... black and white or color ... tube or transistor.Completely self contained and battery operated; MI. II, all solid state, improved version of original"subber." Uses L.E.D. indicator, has higher gain with wide range control affording more than 40db ofgain reduction. Use on the bench or In the home ... anywhere.Substitutes the VHF tuner and tests the UHF tuner. Provides signal to simplify testing of tuner, i.f. systemand AGC system. Comes complete with extension cables and instructions.

TV TUNER SUBBER MK. II net 531.95 Contact your dist...boar.

Include SI 50 shipping and handling on peeled mail «dem we ship C.O.D.

CASTLE TV TUNER SERVICE. INC.5701 N. Western Ave. Chicago. Illinois 60645 .n.no. 13121 - 561.6334


42 ELECTRONIC SERVICING December. 1972For More Details Circle (17) on Reply Card

Can you name the 32 Personal ties and 16 United Way Services


Some answersfrom the june survey

A Profile Of Full -Time TechniciansShop Owners -total years in business18% have been in business less than 2 years15% have been in business 2 but less than 5 years8% have been in business 5 but less than 10 years59% have been in business 10 or more years

Technician Employees -years workedfor present employer47% have been employed for less than 2 years31% have been employed 2 but less than 5 years10% have been employed 6 but less than 9 years12% have been employed 10 or more years

Wages of Experienced Owner-Benchmen5% earned $2.00 or less per hour15% earned $2.01 to $3.00 per hour30% earned $3.01 to $4.00 per hour50% earned more than $4.00 per hour

Wages of Experienced Benchmen4% earned $2.00 or less per hour13% earned $2.01 to $3.00 per hour24% earned $3.01 to $4.00 per hour59% earned more than $4.00 per hour

Wages Of Experienced Owner-Outsidemen5% earned $2.00 or less per hour19% earned $2.01 to $3.00 per hour39% earned $3.01 to $4.00 per hour37% earned more than $4.00 per hour

Wages of Experienced Outsidemen3% earned $2.00 or less per hour18% earned $2.01 to $3.00 per hour31% earned $3.01 to $4.00 per hour48% earned more than $4.00 per hour

Wages of Trainees54% earned $2.00 or less per hour35% earned $2.01 to $3.00 per hour8% earned $3.01 to $4.00 per hour3% earned more than $4.00 per hour

A Profile Of Full -Time ShopsFull -Time Employees79% of the shops had 2 or less outside men78% of the shops had 2 or less bench men

Number Of Service Trucks77% operated 1 truck21% operated 2 to 5 trucks2% operated 5 to 10 trucks1% operated more than 10 trucks

Estimates and S-ervice Contracts37% of the shops offered free estimates21% of the shops offered contracts on TV's

Thousands of you sent back the surveycards which were included in the Juneissue of ELECTRONIC SERVICING.These survey results are presented inappreciation of your help.

Opinions Of Owners And Managers AboutRegulation and Service Associations26% wanted no regulation24% favored regulation by local government21% favored controls by national government29% favored certification controls by associations37% actually belonged to some service association

Sources of Gross Shop Income50% obtained from service labor (estimated)35% obtained from parts sales (estimated)15% obtained from retail sales (estimated)

Method Of Pricing Replacement Parts39% figured cost plus 50%29% figured cost plus 51% to 75%26% figured cost plus 76% to 100%6% figured cost plus over 100%

Percentage Of Shops Selling Merchandise52% sold TV receivers51% sold stereo machines11% sold communications equipment72% sold antennas

Gross Shop Income According To Products Repaired50% obtained from repairing color receivers (est)30% obtained from repairing b -w receivers (est)12% obtained from repairing stereo receivers (est)8% obtained from repairing car radios (est)

Charges For Bench Labor40% charged $9.00 or less per hour34% charged $9.01 to $12.00 per hour16% charged $12.01 to $14.00 per hour10% charged over $14.00 per hour

Charges For B -W TV Service Call (1st 30 minutes)52% charged $8.00 or less per call24% charged $8.01 to $10.00 per call14% charged $10.01 to $12.00 per call10% charged over $12.00 per call

Charges For Color TV Service Call (1st 30 minutes)22% charged $8.00 or less28% charged $8.01 to $10.0022% charged $10.01 to $12.0028% charged over $12.00

Charges for Setup Of Color TV (1st 30 minutes)20% charged $8.00 or less24% charged $8.01 to $10.0028% charged $10.01 to $12.0028% charged over $12.00

Charges For Stereo Service Call (1st 30 minutes)36% charged $8.00 or less30% charged $8.01 to $10.0016% charged $10.01 to $12.0018% charged over $12.00


Productmfor further informat on on anyof the following Items, circle theassociated number on thereader service card.

Power Line MonitorProduct: Model EP -110 voltagemonitor by Logitek, Inc.Features: When electric companiesreduce electricity due to powershortages, the Model EP -110 auto-matically prevents damage to

household appliances. When linevoltage drops below 100 volts, itautomatically disconnects equip-ment from the line. When powerreturns to normal, it automaticallyreconnects equipment. A built-intime delay prevents short durationline drops from disconnecting andrestarting equipment.Price: Model EP -110 sells for$19.95.


Auto Burglar AlarmProduct: "Auto Alarm" by MetraElectronics Corp.Features: The new alarm is con-tained in a small plastic case withan on/off switch integral with thecase, and can be easily concealedbehind the dashboard. The autoalarm senses any current change inthe car's electrical system such asthe dome light turning on when adoor is opened, opening lightedglove compartments, trunks, etc.

after a 6 -to -8 second delay, thealarm triggers, blowing the car'shorn in pulsating blasts. An option-al siren may be connected to thealarm system instead, along withan optional parking -light flasher. It

can be connected with a single wireconnection to the horn buttonswitch wire and a wire to ground.Price: The alarm has two modeldesignations, type MBA -335 forAMC, Chrysler and GM cars sellsfor $18.95 and MBA -335R forFord -made cars and foreign carsthat do not have a horn relay sellsfor $20.95.


Circuit Breaker/FuseCombination Caddy

Product: Model 094076 "2 in 1"caddy by Littelfuse, Inc.Features: The fuses and circuitbreakers are designed to safeguardelectronic circuits in such applica-tions as black and white and colorTV, high fidelity stereo equipment,AM and FM radios, audio ampli-fiers, motor controls, electronicbusiness machines, digital and ana-

111 --1111110111MPOW

10\lt

log test instruments, vending ma-chines and others. The caddy ishoused in a sturdy plastic box withtransparent top. Amperages of thecircuit breakers in the caddy are: 2,2.75, 3, 3.5, 4, 4.5, 5 and 7 amps.There are five each of the followingfuses in the caddy: 3AG1, 2 amp;2AG Slo-Blo 2, 3 amp; 3AG PigtailI amp; and 3AG Slo-Blo Pigtail 2amp.Price: The Model 094076 caddysells for $23.00.


Tool KitProduct: JTK-90 tool kit by JensenTools and AlloysFeatures: The kit includes morethan 60 precision tools. The toolsare securely packaged in an attachecase which features hardwood con-struction, black Marvelon cover-

ing, and solid brass hardware.Most of the tools are mounted on aremovable tool pallet in the coverof the case. Remaining tools arelocated in the bottom of the case,and there is also room for spareparts and special tools. A pocketfor instruction manuals is locatedbehind the tool pallet.Price: The JTK-90 is furnishedwith a Triplett No. 310 VOM andis priced at less than $225.00. With-out the tester, the kit sells for$175.00.


Got A Troubleshooting Tip?

If you've recently run across anunusual trouble symptom, send athorough description of it and thesolution to:

Troubleshooting Tip,Electronic Servicing1014 Wyandotte St.

Kansas City, Mo. 64105


DIAL&CODERDelta's Instant

EmergencyTelephone

Warning System.

Dial & Coder guards you around -the -clock, signaling alarm for any emer-gency condition where a simple contactclosure activates the system. Completelysolid state, Dial & Coder utilizes thelatest in discrete and integrated circuittechnology to provide immediate remotesignaling between any two telephones.

CHECK THESE FEATURES! Dial any phone number up to eight

digits. Change numbers in ten seconds. Over 100 different code combinations

allow multi -phone connections. Works with any direct contact switch. Unlimited applications. Use with in-

trusion detectors, fire & smoke detec-tors or a simple button control. Allowschildren, clerks, or physically handi-capped to call for help.

Automatic redialer when busy signalreceived.

Microphone can be added for audiosurveillance.

Self-contained power supply. Oncetripped, unit cannot be stopped.

This one's really priced right!

Made in U.S.A.Write or Call today for free sales details'

DELTA PRODUCTS, INC.P.O. Box 1147, Grand Junction, Cob. 81501.

Dept. E S (303) 242-9000

Superior Products At Sensible PricesFor More Details Circle (19) on Reply Card

46 ELECTRONIC SERVICING December

Signal -Subbing(Continued from page 27)

load is in the retrace portion, be-cause that's where the DC poweris applied.

If the breaker holds with thejumper in place, it means the over-load happens only during thesweep operation. Remove thejumper. Unplug the yoke (but don'toperate very long this way to avoiddamage). If the breaker holds, theyoke is shorted. If the breakertrips, plug in the yoke and discon-nect the output transformer. Anabnormally -heavy load on the

transformer is indicated, if thebreaker holds now. Connect thetransformer, but in turn, discon-nect each load on it. Gassy high -voltage rectifier tubes are commonin the CTC40.

SummaryIt has been necessary to skim

lightly over many of these tests.Each one of us must practice untilwe get the "feel" of what results toexpect from injection of sweep -pulses into the many variations ofhorizontal circuits. After you getthe hang of it, you'll wonder howyou ever serviced without thesemethods. 0

entolone

111[111111

100. Alco Electronic Products, Inc.-A new 12 -page Condensed Ca-talog lists and illustrates the Alcofamily of front panel electroniccomponents. Six major categoriesof product lines are described inthis Catalog which include: Minia-ture toggles, push buttons, printedcircuits, slides, paddles, proximity,keyboards, etc: high quality alumi-num and plastic knobs with set-screws: unusual isolation relayscombining relay transformer andcontacts in one small package:neon and incandescent, seven -segment, single plane readouts,with logic and other accessories:lamps and indicator assemblies,both incandescent and neon: cer-amin terminal strips of various con-figurations.

101. Electronic Devices, Inc.-isoffering a new, 6 -page catalog onits line of standard and fast recov-ery silicon rectifiers for industrial,commercial and military applica-tions. The new catalog devotes in-dividual pages to ratings and elec-trical characteristics as well asdimensional drawings of casestyles for EDI bridges, high -vol-tage axial lead rectifier cartridges,

1972

high -voltage rectifier assembliesand miniature axial lead rectifiers.

102. Brookstone Co.-The firm'snew 1973 edition containshundreds of useful products rarelysold by industrial distributors orfound in stores. The collection in-cludes hard -to -find hand tools andsmall power tools used by wood-workers, metalworkers, machin-ists, technicians, designers, pro-duction, maintenance and servicepersonnel.

103. Dremel Manufacturing Co.-has introduced a two -page datasheet featuring its new do-it-your-self burglarly prevention kit forhome and office consisting of a"Theft -Guard" electric engraverand burglar warning window stick-ers. Helpful instructions are givenon how to burglar-proof home andoffice valuables such as TV sets,radios, stereo sound equipment,sports gear, cameras, businessmachines, typewriters and anyitem attractive to burglars, by usingthe engraver. The user engraveshis driver's license number gn allitems of value be it metal, plastic,glass, leather or wood. 0

test enuipmeni

urnFeatures and/or specificationslisted are obtained from manufacturersreports For more information aboutany product listed, circle theassociated number on the readerservice card in this issue.

Dual -Trace Triggered SweepOscilloscope

Product: Model 1470 by B&K,Dynascan Corp.Features: Applications include:viewing simultaneously two wave-forms that are frequency or phase -

related, such as in digital circuitry:checking frequency dividers:checking differential amplifiers forbalance: relay testing and sequenc-ing: measuring amplifier phaseshift. The 1470 offers DC to 10MHz bandwidth, 10 mV/cm sensi-tivity, maximum sweep of .2microseconds/cm, and fully auto-matic and triggered sweep. It per-mits dual display of waveforms in 6

modes: Channel 1, Channel 2.Chopped (for low -frequency wave-forms), Alternate, Add and Chan-nel 2 Invert. In the first 2 modes.only one input signal will be dis-played. In the alternate mode,Channel 1 and 2 inputs are dis-played on alternate sweeps-thetwo traces appearing as simultane-ous waveforms. Operation is from105-125 VAC, 50-60 Hz, and isavailable for 117/234 VAC.Size: 9 inches x 10 inches x 17

inches.Price: The 1470 requires twoprobes, the PR -20, a combination10:1/DIRECT probe with spring -

loaded clip -on tip for $19.95 andthe PR -16, which is similar to thePR -20, but does not have the clip -

on feature, at $14.95. Model 1470sells for $499.95.


Audio Level MeterProduct: NI1N I -V U portable levelmeter by Edison Electronics.Features: The MINI -VU is de-signed for use as a utility levelmeter in checking audio distribu-tion systems, remote lines, and inother similar applications. A selec-tor switch provides for bridgingeither balanced or unbalanced au-dio circuits. With an 11 -positionselector switch that provides levelranges from -60VU to +40VU, theMINI -VU becomes an extremelyversatile test instrument. A self-contained mercury cell that mini-mizes battery deterioration whenthe unit is not in operation, pro-vides the power.Price: The MINI -VU sells for$145.00.



Send your own Photo -Tip to theeditor. Yes, we pay.

START THE NEW YEARWITH A GREAT BARGAIN!

GET THESE TWO TV TECH AID BOOKS ATREDUCED PRICES:

1971 B&W BOOK - NOW $4.951970 -BOOK FORM - NOW $4.95

TV TECH AID BOOKS ARE FILLED WITH THE LATEST QUICK -SERVICING INFO ON COLOR TV, B&W TV, AND STEREO ...

TV Tech Aid Takes you right to the source of the trouble without guesswork and wasted time. In each monthly issue you receive over 40actual causes and cures of color and B&W TV trouble symptoms. Youalso receive timely and complete information about circuit modifica-tions and other valuable service data.

USE THE COUPON BELOW TO PLACE YOUR 1973SUBSCRIPTION (12 ISSUES 57.95) OR VALUABLE BACK ISSUES

SEND YOUR CHECK

OR MONEY ORDER

TO:

TV TECH AIDP. 0. Box 603

Kings ParkN.Y. 11754

Li 1969 12 issues $4.95

17, 1971 B&W Book $4.95

H 1972 12 issues $7.95

Name

Address

City

State

1970 -Book Form $4.95

1971 12 issues $5.95

1973 All New 12 issues $7.95

Zip


December, 1972 ELECTRONIC SERVICING 47

SOLVE YOUR DRIVEBELT PROBLEMS IN

MINUTESwith ONEIDA'S all newDRIVE BELT KITS

Eliminates "Down Time" on special andforeign belts.

No need to stock replacement belts; makesany size in minutes.

No molds or complicated vulcanizing proc-esses to follow.

No special skill required, cutting guide, cut-ting tools and adhesive all included.

Special Insta-Welds adhesive makes re-placement belts as strong as or strongerthan originals for lasting repairs.

ORK-1 Round Rubber DriveBelt Kit $19.95

ORK-2 Flat and SquareRubber Drive Belt Kit $19.95

ORK-3 "0" Ring Kit . ..$19.95Get up to five times your investment back in beltsales. Each of these kits will make from 80-100dollars or more in rubber drive belts. Includedwith the kit is the special cutting guide, razorblade, Special Insta-Weld® adhesive, a large quan-tity of rubber stock and easy -to -follow directions.Nothing has been left out. Packed in an attractive.handy, plastic box that fits into the tube caddy oron the bench. Now, you can replace over 90% ofthe belts found on tape recorders, phonographsand cassette recorders, both foreign and domestic,right on the spot. Check with your distributor now.If he doesn't stock them, ask him to order themfor you today.

PERMABOND ADHESIVEPOWERWITH

ONEIDA'SI nsta-Weld®

Makes SpaceAge Bonds

Great for: Rubber Plastic Metal Ceramics Glass Etc.

Insta-Weld® is new, not epoxy, nothing you haveheard of before. There is no mixing, just applyand hold parts together. Just seconds are all thatis required for a bond stronger than anything youcould ever get before. One drop supports 2,000pounds per square inch.

Now make economical repairs that were never be-fore possible. Extremely economical, up to 132bonds per tube.

NEW INSTA-WELIronly $2.00 per 2 -gram tube

neidaELECTRONICp INFAG.

. 16335INC.

AC Leakage Current TesterProduct: Model 301 by SotcherMeasurement.Features: The Model 301 allowsanyone to quickly identify an elec-trical defect in 120V equipmentbefore it can become a safety orfire hazard. Meets OSHA require-ments by detecting any leakagefrom 0.5 milliamp up to a deadshort and displaying the GO/NOGO condition on dependable neonlamps. Other features: accuratesimulation of normal body imped-ance, built-in calibration standard.ground wire continuity check. in-

dependent high and low currentsolid-state circuits, and no batter-ies to change. The tester comescomplete with detailed instructionsand a shock proof test pad.Price: Model 301 sells for $150.00.


FET TesterProduct: IT -121 by Heath Co.Features: The IT -121 checks tran-sistors, diodes, FET's, SCR's,triacs, and unijunction transistorsin or out of circuit. Five currentranges measure leakage as low asItLA and collector currents as highas I A. Gain (DC Beta), transcon-ductance (GM), and leakage valuesare read directly on large meterface, has color -coded pushbuttonrange selection, battery tested cir-cuit, and handy 3 -foot leads.Price: The IT -121 sells for $49.95. For More Details Circle (38) on Reply Card

25 -MHz BandwidthOscilloscope

Product: Model D66 by Tektronix,Inc.Features: Sweep rates are from 2s/div to 100 ns/div (20 ns/div with5X magnifier), X -Y measurementcapability, 5 percent accuracy andI4-ns risetime. Deflection factorsextend to 10 mV/cm at full band-width, to 1 mV/cm at 15 MHz.Size and Weight: 9 1/2 inches x 8 1/4inches x 14 1/2 inches and weighs25 1/2 pounds.Price: The D66 sells for $795.00.


FM Multiplex Stereo GeneratorProduct: Model LSG-231 by Lead-er Instruments Corp.Features: The LSG-23I has a pilotsignal frequency of 19 KHz with±2 Hz accuracy. The 1 KHz audio

signal is accurate to ± 1 percent.Signal separation is rated at 50 dBwith output voltage at 0 to 3V rmscontinuously variable. It is easy tooperate, compact and completewith a handy tilt stand.

Size and Weight: 8 inches x 12inches x 3 1/2 inches; 5.5 lbs.Price: Model LSG-231 sells for$229.95.



audio systemsil

Features and/or specificationslisted are obtained from manufacturersreports For more information aboutany product listed. circle theassociated number on the readerservice card in this issue

Tape Speed CheckerProduct: LFM-30 by Leader In-struments Corp.

Features: This new instrument willcheck tape recorder speeds at 1, 2,3, 4, 5, 6, 7, 8, and 9 KHz frequen-cies with one stipulation: recorderoutput frequency must be a multi-ple of 1 KHz. The unit has a testrange of -3 percent to 43 percentwith an input level of 100MV rms.Input impedance is 150 K ohms. Itis offered with a standard test tapeat 4 KHz and a leather -like carry-ing case.Size and Weight: 11 inches x 1

inches x 1 1/2 inches: 2 pounds.Price: The LFM-30 sells for$129.95.


Cassette Recorder/PlayerMaintenance Kit

Product: QM -1 Cassette Mainte-nance Kit by Nortronics Co., Inc.Features: The kit is used for thecleaning, maintenance and demag-netization of cassette recorders andplayers through an effectivepersonal -preventive maintenanceprogram any machine owner canperform. The new kit contains sixQM -Series accessories which aresuited for routine cleaning andmaintenance of heads, capstan,

pressure rollers and tape guides. Acassette head demagnetizer is in-cluded for degaussing heads. Aprofessional splicer and supply ofbleed -free Mylar Splicing Tape areincluded to facilitate editing andrepair of .150 inch tapes.

Specifications: The kit includes: 3oz. can of QM -103 Spray Cleaner;QM -141 Cassette Life Extenderwith 1 1/4 oz. bottle of Tape HeadCleaner; QM -240 Cassette HeadDemagnetizer; QM -340 Splicer for1/8 inch tape; QM -501 inch roll,Mylar Splicing Tape and QM -5026 -inch soft cotton M -Tips.Price: The maintenance kit sells for$26.90.


Speaker ProtectorProduct: Model R47001 by RobinsIndustries Corp.

PlimeMIINJE

STEREO

SPEAKER

PROTECTOR-twiny!

ELECTRONIC FUSE"

ELECTRONICALLY LIMITS SPEAKER LOAD

SOLID STATE SELF -POWERED

PROTECT YOUR COSTLY HI-FI SYSTEM

Features: It has soid-state circuitryand is self contained, requiring nei-ther batteries nor line current. Theprotector automatically limits out -


THE NAMEANDTEPRODUCT

s is the standardTHAT

or PA. eameolWhatever your PA needs, from a small office to large auditorium,with amplifiers in every power range, including mobile,Precision Electronics delivers the product and value . . .

including an entire line of accessories. Get all the facts,without obligation, on the "right sound" for your needs.Complete and mail this coupon today.

NAME

COMPANY

ADDRESS

CITY STATE

Mail to: PRECISION ELECTRONICS, INC.9101 King St., Franklin Park, Illinois 60131

ZIP

For More Details Circle (22) on Reply CardDecember. 1972. ELECTRONIC SERVICING 49

A#C7111 rih:5 0SHIPEI F

IWO

TOMORROW.

II...

_- L ......_.- TAPE

PLAYERS

fil

PARTS & ACCESSORIES DC MOTORS & BELTS

COMPLETE CATA OG AVAILABLE.

CALL YOUR WELTRON DISTRIBUTOR TODAY!

or write or call direct:

eltron®COMPANY

514 East Peabody Street. Durham. N.C. 27702919-682-0333


AUTT1ESQUIRTstopsoll thenoise.A squirt of Quietrolefrom the handy Spray Packsilences any moving T.V.part. Cleans as itlubricates, too. Guaranteesquiet, trouble -freeoperation. Absolutely safefor any black and white orcolor set. Try it and seewhy it's preferred by topservicemen everywhere.

Also available in bottles,and the new silicone-"Silitron."

LUIRI-CLEANER6.1.« Cent..i.

o.d *the. r

ow

Product of

QUIETROLECOMPANY

Audio Systems(Continued from page 49)

put of the stereo hi-fi amplifierwithout impairing tone quality.Limiting is achieved by a com-pressing action, which can be pre-set to defy excessive levels. Con-trolling the levels and equalizing

them can even produce a back-ground music effect.Price: The R47001 speaker protec-tor sells for $29.50.


Transparent StereophonesProduct: PRO -B VI by SuperexElectronics Corp.Features: The heart of the unit is itswoofer with controlled acousticsuspension and carefully matchednew ceramic tweeter that takes theresponse past the limit of hearing.The PRO -B VI features a new"Clip -Cord" consisting of a fifteenfoot coil cord and a three footstraight section at the headphones.Attached to the straight section is aclothing clip that permits the pull ofthe coil cord to be absorbed at thebelt or shirt pocket, while insuringeasy movement with minimalweight or head pull.Price: Model PRO -B VI sells for For More Details Circle (44) on Reply Card

Four -Channel Tape PlayerProduct: Model I2R800 by RCAParts and Accessories.Features: The Q-8 sound is createdby the simultaneous playback offour separate sound tracks throughfour separate speakers. Designedto play both Q-8 and stereo 8 tapes,the 12R800 features eight solid-state integrated circuits and deliv-ers over 32 watts of peak powerstereo sound.


Tired ofhand-me-downcopies ofELECTRONIC

SERVICING?

Fourth page of a five -page articlemissing by the time you get to readELECTRONIC SERVICING? Sche-matic diagram missing? Then youneed a subscription of your own!Priced right and packed with profit-able information each month! Use theconvenient order form inside theback cover of this issue! P.S. If

that's missing, too, send us a notewith your name and address-we'llcontact you with full details!

Spartanburg. South Carolina


Features and/or specificationslisted are obtained from manufacturers'reports. For more information aboutany product listed, circle theassociated number on tne readerservice card in this issue.

All -Channel Four -Set CouplerProduct: Model M F-84 TV/FMcoupler by Jerrold ElectronicsCorp.Features: The MF-84 coupler isrecommended for splitting signalsso that four TV sets can be at-tached to a single outdoor antenna.Low loss and high isolation be-tween sets make it good for colorTV. The MF-84 passes all frequen-cies between 54 MHz (Channel 2)and 890 MHz (Channel 83). Inser-tion loss is only 7 dB and isolation

The No.1 Antenna forMetropolitan Areas...

RMS `STAR -TRACK'#SK- 716 VHF/UHF/FMCOLOR ANTENNA...Similar design to Space TrackingAntennas- 5 UHF Disc Directors,VHF Cut -to -Channel Elements, I DrivenElement, and 10 Corner ReflectorElements. 23 Elements for maximumreception--- Up to 50 miles on VHFand up to 50 miles on UHF. Singledown -lead- includes VHF/UHF Splitter.Suggested Retail. $ 39.95

Breaking Sales Recordssince their introduction- 6 performanceproven models for all areas- See YourDistributor.

RMS ELECTRONICS, INC.50 Antin Place, Bronx, N.Y. 10462

Tel. (212) 892-6700

between sets is at least 15 dB. Itcan be mounted along a baseboard,to the back of a TV set, in thebasement or the attic. Weather re-sistant, it can even be mountedoutdoors on the mast or outside awindow.Price: The MF-84 sells for $5.90.For More Details Circle (50) on Reply Card

Broadband AmplifierProduct: PAM -300 series amplifierby American Electronic Laborato-ries, Inc.Features: The amplifier is solidstate with a high -dynamic range

covering the entire 30 to 300 MHzVHF band. The PAM -300 is usefulfor telemetry, ECM, monopulse,communications receiver applica-tions, as well as in mulitcouplersand other frequency -distortion sys-tems, including critical surveillancesystems.

NF 11.1

inMPO, IMO

MOOEL PAWDOO

J.9

PF OU1

Specifications: The noise figure is5.5 dB with an output of up to +10dBm at I dB compression. Gain is24 dB while gain variation is only±0.5 dB. For two -20 dBm inputsignals. the second -order intermo-dulation products are -40 dB andthe third -order intermodulationproducts are -65 dB.


DESIGNED FORSTRIP TYPE TUNERS

B/W AND COLOR

ADHESIVE HOLDSTUNER TAB TOSHIELD COVER

NON -EVAPORATING CLEANER

GREATER PROFITS FOR TUNER MAINTENANCE

CONTINUOUSLY CLEANS.POLISHES AND LUBRICATESCONTACTS

WILL NOT DETUNE OR CAUSEFREQUENCY DRIFT

HARMLESS TO PLASTICS ANDTUNER COMPONENTS

FAST AND SIMPLE TO INSTALL

THE ONLY REPLACEABLETUNER TAB TUNER

SEE YOUR LOCAL PARTS DISTRIBUTOROR CONTACT

UNIVERSAL TUNER TABS MFG., INC.Hopkins. Minnesota 55343

For More Details Circle (28) on Reply Card For More Details Circle (25) on Reply Card


MOLDED PLASTIC

COLOR CODED

AMP FUSES20 Different

Models

Reliable protective fusing devicefor replacement of original man-ufacturer's part numbers.

Listed in Howard Sams' Photo -facts and Counterfacts.

FREE vest pocket cross refer-ence booklet indicating correctWorkman part numbers to manu-facturer's part numbers. No. X58

MANUFACTURED BY

WORKMAN5,5 .1,.,, nt trw TECMOLOG V /

sox 3828 SARASOTA FU 33570

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r\JEW ENDECO

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MODEL

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Kit 300K includes the famous Endecopencil desoldering iron Model 300, sixdifferent size tips (.038 to .090) for anyjob, tip cleaning tool, and metal standfor iron ... all in a handy lifetime steelstorage box. $19.90 net. Model 300K-3with a 3 -wire cord $20.90. Also a similarkit for military users. Kit 100K with largeEndeco iron (Model 100A) is $27.40, and3 -wire Kit 100AD-3 $28.40.

SEE YOUR DISTRIBUTOR OR WRITE

ENTERPRISEDEVELOPMENTCORPORATION

5127 E. 65th St., Indianapolis, Ind. 46220


52 ELECTRONIC SERVICING/December,

Antenna Systems(Continued from page 51)

Size: 13 inches x 13/4 inches x 6inches, including connectors andmounting flange.Price: The PAM -300 series sells for$350.00.


Color TV AntennaProduct: "Quantum" high -gainantenna by Channel Master.Features: The "Quantum" im-proves reception by blocking outelectrical interference. In caseswhere interference comes from thefront or side, the "Quantum" willdeliver a 10 dB improvement insignal-to-noise ratio. This is equiv-alent to a 10 dB increase in antennagain, and will bring about the samepicture improvement as 10 dB addi-tional forward gain. The "Quan-tum" reaches 35 dB. Transmissionline noise pickup is eliminated bythe use of coaxial line. There are 15"Quantum" models, designed forall reception areas and conditions,from metropolitan to the deepestfringe areas. Seven models coverVHF and FM; eight models alsoreceive UHF, using a tunable an-tenna that can be adjusted for peakperformance on any selected rangeof channels.


Yagi AntennaProduct: Model ASP -760 by TheAntenna Specialists Co.Features: Forward gain is 10 dBand the front -to -back ratio is inexcess of 15 dB across the entirehand. A weatherproof gammamatch delivers a VSWR of lessthan 1.5:1. All radiating and parasi-tic elements are welded to theboom, and all elements are goldirridite-treated for exceptional re-sistance to corrosion. The unit isfurnished with a solid cast alumi-num mounting clamp for installa-tion in either horizontal or verticalpolarization, plus 2 feet ofRG8A/U cable with male -type"N" connectors.Price: The ASP -760 sells for$71.50.


1972

Ntatement of Ownership, Management andCirculation, Act of August 1R, 1970; Sec-tion 3685, Title 39, United States Code).

1. Title of Publication: Electronic Servicing2. Date of Filling: October 12. 1972.

3. Frequency of issue: Monthly4. Location of known office of publica-

tion (Street, city, county, state, zip code) :1014 Wyandotte St., Kansas City, JacksonCounty. Missouri 64105.

5. Location of the headquarters or gen-

eral business offices of the publishers (notprinters): 1014 'Wyandotte St., Kansas City.Jackson County, Missouri 64105.

6. Names and addresses of publisher. editor.and managing editor: Publisher. Robert F. Hertel.1014 Wyandotte St.. Kansas City. Missouri 64105:Managing editor. Carl Babcoke. 1(114 WyandoteSt.. Kansas City. Missouri 64105.

7. Owner fif owned by a corporation. itsname and address must be stated and alsoimmediately thereunder the names and ad-dresses of stockholders owning or holding I

percent or more of total amount of stock.If not owned by a corporation, the namesand addresses of the individual owners mustbe given. If owned by a partnership or otherunincorporated firm. Its name and address,as well as that of each Individual must begiven.) Howard W. Sams & Co., Inc.-awholly owned subsidiary of International Tele-phone and Telegraph Corporation, 320 ParkAve.. New York, New York 100'22.

Known bondholders. mortgages, andother security holders owning or holding 1

percent or more of total amount of bonds,mortgages or other securities (If there are'lone, so state): None.

9. Paragraphs 7 and 8 Include. in caseswhere the stockholders or security holderappears upon the hooks of the company astrustee or in any other fiduciary relation,the name of the person or corporation forNV Onl such trustee Is acting, also the state-ments in the two uaragraphs show the af-fiant's full knowledge and belief as to thecircumstances and conditions under whichstockholders and security holders who do notappear upon the books of the company astrustees, hold stock and securities in a ca-pacity other than that of a bona fide owner.Names and addresses of Individuals who arestockholders of a corporation which itself Is

a stockholder or holder of bonds, mortgages&r other securities of the publishing corpora-tion have been included in paragraphs 7 and8 when the interests of such individuals areequivalent to 1 percent or more of the totalamount of the stock or securities of the pub-lishing corporation.

10. This item must be completed for all pub-lications except those which do not carry ad-vertising other than the publisher's own andwhich are named in sections 132.231. 132.2.32.

and 132,21.3, postal manual (Sections 4355a,435b, and 43.16 of Title 39, United StatesCode).

A ee No.Copies EachIssue During

Preceding12 Months

A. Total No. Copies Printed(Net Press Run) 62,928

B. Paid Circulation1. Sales through dealers and

carriers, street vendorsand counter sales 4.825 4.738

2. Mail Subscriptions 52.170 60.037C. Total Paid Circulation 56,995D. Free Distribution (including

64.775

samples) by Mail, Carrier orOther Means . .. 2,156 646

E. Total Distribution (sum ofandD) 69,151 65.421

F. Office Use, Left -Over,Unaccounted, Spoiledafter Printing 2,327

G. Total (sum of E F-3,777

should equal net press runshown in A) 62,928

I certify that the statements made 6434m8eabove are correct. (Signature of editor, pub-lisher, business manager, or owner).

ROBERT E. HERTEL

SingleIssue

NearestTo Filing

Date

67.748

book ,]Thvi

Solid -State Electronic ProjectsAuthor: Charles D. RakesPublisher: Howard W. Sams & Co., Inc., Indi-anapolis, IndianaSize: 5 1/2 inches x 8 1/2 inches, 128 pagesPrice: Softcover, $3.95.

This book has been written to encourage hobby-ists, students, and technicians to take advantageof the new and surplus solid-state componentsbeing sold and build some solid-state electronicprojects. The book's projects are useful, educa-tional, and serve to demonstrate the operation ofa number of semiconductor devices. The book iseasy to understand and is supported by numer-ous schematic and pictorial diagrams. In addi-tion, all of the projects discussed have been pre-viously built, tested, and debugged.Contents: Basic Burglar Alarm Systems -Solid -

State Alarm Circuits -Solid -State AlarmSounders -Metal Locators -Electronic Music,Noise, And Sound Effect Circuits

Questions & Answers About Color TVAuthor: Leo G. SandsPublisher: Howard W. Sams & Co., Inc., Indi-anapolis, IndianaSize: 5 1/2 inches x 8 1/2 inches, 96 pagesPrice: Softcover, $3.95.The information contained in this book is pre-sented as answers to the most often asked ques-tions about color television. This book does notattempt to cover color television receivers fromA to Z. This would involve a much more techni-cal discussion than this book was intended for. Itis intended, however, to enlighten anyone withsome background in electronics about the mostimportant aspects of color television. The firstpart of the book concerns theory and operation.Part two covers installation procedures andproblems. The third part discusses color -televi-sion servicing. The concluding part tells how tomake simple modifications of and additions toreceivers to improve and extend their capabili-ties.

T & T VALUE SALERAYTHEON NEW JOBBER -BOXED TUBES

80% off LIST6588 5 for $3.45 6DW4 5 for $4.0561E6 5 for $8.80 383 5 for S4.4068K4 5 for $8.15 61S6 5 for $8.056006 5 for $5.85 6AX4 5 for $4.058FQ7 5 for $3.25 8F07 5 for $3.256826 5 for $3.40 6826 5 for $3.40113 S for $4.355U4 NEW JOBBER -BOXED !EC 10 for $4.9012DT8 NEW STANDARD -BOXED. 90% offlist 10 for $3.90

TRANSISTORS XACT. REPLACEMENT (BOXED)SK3018 -14E1'709 (list $2.25 ea.) 5 for $2.25SK3020 -HEP50 (list $2.20 ea.) 5 for $2.20SK3021 - HEP240 (list $3.15 ea.) 5 for $3.15SK3026 -HEP241 (list $3.00 ea.) 5 for $3.00SK3041 - HEP245 (list $4.20 ea.) 5 for $4.20SK3082 - HEP643 (list $3.90 ea.) 5 for $3.9011460 DIODES 50 for $1.002 AMP. 1000 PIV RECT 10 for $1.00401 40 MFD at 450 VOLTS, DC 2 for $1.0060 at 350. 100 at 350, 160 at 350 2 for $1.00100 MFD at 400 VOLTS. DC 2 for $1.003.58 COLOR CRYSTALS 2 for $1.50PHILCO TUNER, incl. 39051 51.17 $2.95PHILCO COLOR FLYBACK TRANS. 32-10093-1

$2HIGH VOLT ANODE LEAD El W 10 for 51:9005

1H) BACK of SET DIPOLE ANT 4 for $5.00

COLOR YOKE SPECIALSSYLVANIA 51-29986-2 $5.95ZENITH 589633 $5.95RAYTHEON. IEC. RCA. G.E..SYLVANIA. etc.. TUBES up to 80% off list

FREE GIFT WITH EVERY ORDER!

Minimum Order $30 F 0 B BrooklynCatalogs $1 - Refundable upon your order

CT & T SALES CO)4802 AVENUE K

BROOKLYN, N. Y. 11234Phone: (212) 241-5940

For

Better

Results

Use

Reader

Service

Card

on

Page

37

Clamp down on service time with

RCA Clamp TesterWV -526A

$54 (Optional DistributorResale Price)

- including tester, test leads, bat-tery, line splitter, shorting plug,splitter extension leads, carryingcase, and spare fuse.

It brings new efficiency to electri-cal servicing. Here's how: Measures AC current to 300 am-

peres, AC voltage to 600 voltsand resistance from 1 ohm to1,000 ohms on three easy -to -read color -coded scales.

-Stop-lock" switch freezes me-ter pointer - simplifies handlingin dark or hard -to -get -at areas.

High -impact plastic case for rug-ged usability.

See your RCA Distributor formore information. Or write: RCATest Equipment Headquarters,Harrison, N.J. 07029.

R ElectronicComponents

For More Details Circle (32) on Reply L-ard For More Details Circle (29) on Reply Card

YEATS dollies

1.1011 VW.

OST.._111RSATILE

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TRUCK

ONIELOPEO'

Vaats Appliance Dolly Sales Inc1302W. Fond du Lac Ave.

Mdwar kee, Wisconsin 53205 TEATS Maki No 5 566.50


FREE CATALOGHARD -TO -FIND PRECISION TOOLS

Lists more than 1 700 iterts-plierstweezers, wire strippers, vacuum systems,relay tools, optical equipment, tool kitsand cases. Also includes four pages ofuseful "Tool Tips" to aid in tool selection.

Ea JENSEN TOOLS4117 N. 44th S Phoenix. A,.. 85018

Tpoi.


The MARKETPLACEThis classified section is avail-

able to electronic technicians andowners or managers of serviceshops who have for sale surplussupplies and equipment or whoare seeking employment or re-cruiting employees.

Advertising Ratesin the ClassifiedSection are:

25 cents per word(minimum $3.00)

"Blind" ads $2.00additional

All letters capitalized --35 cents per word

Each ad insertion must be accom-panied by a check for the fullcost of the ad.

Deadline for acceptance is 30days prior to the date of theissue in which the ad is to bepublished.

This classified section is notopen to the regular paid productadvertising of manufacturers.

EDUCATION INSTRUCTION

Digital Computer Electronics self studylab. Audio and visual response. Careeroriented. Write: STELCOMP Scientific,4600 Duke St., Alexandria, Va. 22304.

12-72-1t

FOR SALE

TV & RADIO Tt. IfF.l irk EA " Free colorcatalog Cornell. 4221 University. San Diego.California 92105 9.72-6t

FOR SALE: 17TP4 17BP4 17BWP4 NewGECRT $15.00 FOB. Ross's, 112 South1st. West, Preston, Idaho. 83263. 12-72-1t

FOR SALE: TV business in Central Wis-consin, includes three bedroom apartmentabove store, apartment and store rental.Contact Wm. Rolloff, 2016 Wis. Ave., NewHalstein, Wis. 53061 (414) 898-5403.

12- 72-1t

WANTED

ELECTRONIC TECHNICIAN Benchman formodern service department. Must be A-1 andexperienced in all phases of shop work. Perma-nent position. 40 hour week, top pay and fringebenefits. Send resume and references Irequiredt.Small town. N.E. Florida. great place to live.Reid's TV Inc., 2510 Crill Avenue. Palatka.Florida 32077. 11-72-2t

WANTED- Hickok CA -99 adapter anddata for 799 tube tester. Ron Tommasini,2530-D Eastshore Place, Reno, Nevada89502. 12-72-1t.

POSITION WANTED: Audio and taperecorder specialist desires position as Elec-tronic technician to service home enter-tainment products in the area of Las Ve-gas or Reno, Nevada. Owner of authorizedfactory service station for 12 years. Miro,Box 581, Lake Mohegan, N.Y. 10547.

12- 72 -It

POSITION sought by young man (22)experienced in stereo/audio service (verylittle experience in TV). Would prefer Ari-zona but all offers considered. Write: TomHocker, 43 Hilltop Park, State College,Pa. 16801. 12-72-1t

advertisers'

I FCAdvance Applied ElectronicsB & K Mfg. Co. Div. of Dynascan

Corp 7

Bussmann Mfg. Div. McGrawEdison Co 23

Castle Tuner Service 42

Delta Products, Inc 46Eico Electronic Instrument Co..

Inc. 42

Enterprise Development Corp. 52

GC Electronics 30

Heath Company 12

Jensen Tools and Alloys 54

Leader Instruments Corp. 1

Lectrotech, Inc 13

Littlefuse, Inc. BCOneida Electronic Mfg., Inc. 48

Precision Tuner Service I I

Precision Electronics 49

Quietrole Company 50

RCA Electronic Components 17,53

RMS Electronic Components 51

Howard W. Sams & Co.. Inc. IBCSprague Products Co. 3

GTE Sylvania ElectronicComponents 9

T & T Sales Co. 53TV Tech Aid 47Tuner Service Corp. 5

Universal Tuner Tabs Mfg. 51

Weltron Co.. Inc. 50Workman Electronic Products, Inc. ... 52

Xcelite, Inc. 34

Yeats Appliance Dolly SIs. Co. 54

It involves giving them jobs. By hiringthe handicapped you do yourself a favor.You'll get skilled people who will be de-pendable and hard working. Some of thebest attendance records, in many busi-nesses, belong to handicapped employees.Next time you have a job opening, fill itwith a handicapped worker. You'll helpyourself by helping someone else.

Hire the handicappedPAO

PUBLIC ADVERTISING SYSTEMA DIVISION OF THE SCHOOL OF VISUAL ARTS


This guide identifies30,000 replacement parts

and does it fast.It's Sams new 13th Edition of the popularReplacement Control Guide.

It covers over 30,000 parts numbers of con-trols, shafts, switches and related hardwareitems made by Centralab, CTS-IRC and Mal-lory for over 70,000 models of :elevision,home radio, auto radio, CB radio, tape re-corders, and tape players.

In it you'll quickly find the mant. facturer'sand industry parts numbers for all those parts,with everything cross-referenced. Here is anessential, easy -to -use business tool for all

electronic parts distributors, dealers andservice technicians. And the price is only$1.50. Order as many copies as you'll seedfrom your Electronic Parts Distributor, or mailthis coupon today.

ES 122HOWARD W. SAMS AND COMPANY, INC.li 4300 West 62nd Street, Indianapolis. Indiana 45266

Please send copies of Replacement Control CuileNo. 06473 at $1.50. I enclose check for S(Include sales tax where applicable. Canadian Drizeslightly higher.)

Name

Address

City State Zip

For Wore Details Circle (2) on Reply Card

24hourwatch

Everyday. All over the world. On millions of 24 hour watch. All over the world. It's a bigtelevision sets, our sentry stands. The new assignment. But the Littelfuse Sentry is one ofLittelfuse Circuit Breaker. Meeting industry's television's brightest stars.new safety requirements of SE -O insulatingmaterials, our breaker is demanded by virtuallyall set manufacturers. It's the perfect replace-ment part too!

Contact your nearest Littelfuse source. He'llshow you the 19 available models with a varietyof packaging choices.

LITTELFUSELittelfuse, Inc. Subsidiary of Tracor, Inc.800 E. Northwest Highway, Des Plaines, III. 60016


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