For industrial maintenance and consumer servicing ...- 7371 - beveled tip 2 imf 7579 - beveled tip 3 7592 beveled tip 5 7553 - eeveled tip 4-71411- micro soldering tip.7436 - regular

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Electronic Servicing.Editorial. advertising arid circulation curie:spondence should be addressed to P.0Box 12901, Overland Park, KS 66212 lasuburb of Kansas City, MO), (913) 888-4664.

EDITORIALBill Rhodes. Editorial DirectorCarl Babcoke, Consumer Servicing

ConsultantKevin Kious. Managing EditorMarjorie Riggin, Editorial Assistant

ARTDudley Rose. Art DirectorLinda M. Pocsik, Graphic Designer

CIRCULATION..iohn C. Arnst, DirectorEvelyn Rogers, ManagerDee Manies. Reader Correspondent

ADMINISTRATIONR J Hancock. PresidentGeorge Laughead, Publisher

ADVERTISINGGreg Garrison, National Sales ManagerMary Birnbaum, Production Manager

Regional advertising sales offices listednear Advertiser's Index.

Member,(...ABP American Business Press

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ELECTRONIC SERVICING (USPS 462-050) (withwhich is combined PF Reporter) is publishedmonthly by Intertec Publishing Corp., P.O. Box42901, 9221 Ouivira Road, Overland Park, KS66212. Second Class Postage paid at ShawneeMission, KS 66201. Send Form 3579 to P.O. Box'2901, Overland Park, KS 66212.

ELECTRONIC SERVICING is edited fortechnicians who repair home -entertainmentelectronic equipment (such as TV, radio,tape, stereo and record players) and forindustrial technicians who repair defectiveproduction -line merchandise, test equip-ment. or industrial controls in factories.

Subscription prices to qualified subscrib-ers: 1 year-S12, 2 years-$19, 3 years-S24, in the USA and its possessions.Foreign countries: 1 year-$17, 2 years -827. 3 years-$35. Subscription prices to allothers: 1 year-$25. 2 years-$50, in theUSA and its possessions. Foreign coun-tries: 1 year-$36. 2 years-S72. Singlecopy price $2.25, back copies $3.00.Adjustment necessitated by subscriptiontermination to single copy rate. Allow 6 to8 weeks delivery for change of addressAllow 6 to 8 weeks for new subscriptions

INTERTEC PUBLISHING CORP01981 All rights reserved

Next month in

Electronic Servicing

TV antenna source guide

MRO parts: how to buy them

A computerized service operation

Locating MRO parts and components

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May 1981 Electronic Servicing 1

For industrial maintenance and consumer servicing professionals

Electronic ServicingMay 1981 fl Volume 31, No. 5

INDUSTRIALMRO

8 Planning the industrial maintenance shopBy Elwood Gilliland, technical consultant,Electric Service Company, Casper, WYThe operations of several shops are described.

18 Applications of digital scopesBy Peter C. Dale, product manager,instruments division, Gould Inc., Cleveland, OH

CONSUMERSERVICING &INDUSTRIALMRO

22 Index of 1980 articlesCompiled by Warren G. Parker, Metairie, LA

CONSUMERSERVICING

25 Audio servicing with aswept -frequency generatorBy Kirk Vistain, West Chicago, ILInternal actions and typical applicationsof an audio sweeper.

30 The well-equipped audio test benchBy Kirk Vistain, West Chicago, IL

32 Typical auto audiocassette repairsBy Homer L. Davidson, Davidson Radio & TV,Fort Dodge, IATwelve case histories are discussed.

Departments 4 Scanner6 People

40 Test equipment

40 Reader's exchange41 Symcure42 Product Report

About the cover Ease of operation, safety and instrumentation accuracy are

featured in this electric motor test console designed and builtby the Electric Service Company, Casper, WY.

:_z)Copyright, 1981, by intertec Publishing Corporation. All rights reserved. Material may not

be reproduced or photocopied in any form without written permission of publisher.

2 Electronic Servicing May 1981

At A.W. Sperry we re contin-ually broadening and refiningour instrument line to matchyour job requirements. Some ofour best innovations have come from your sug-gestions. That's why A.W. Sperry's instrumentsare safety -engineered and designed with yourneeds in mind.When you look at our line-up, you're looking atwhat you've helped us to accomp:ish. Weappreciate the joint effort to make test

A.W. SPERRY GIVES YOUA MEASURABLE ADVANTAGE

IN MEASURINGINSTRUMENTS

measurements easier ant saferfor you. For quality testinginstruments, you'll find A.W.Sperry's job -matched "meter

reader's meters" the preferred choice.See the latest line-up in our Mini -Catalog.For a free copy call your distributor or A.W.Sperry Instruments Inc., 245 Marcus Blvd.,Hauppauge, New York 11787, 800-645-5398Toll -Free. (N.Y., Hawaii, Alaska call collect516-231-7050).

A.W. SPERRY INSTRUMENTS INC.The Measurable Advantage.

Circle IL) on Reply Card

electronic METTnews of the industry

1T

N ESDA/ISC ET'snew referral service

Three manufacturers of ,:lectronicdevices have received a list ofqualified servicers for their productsthrough a new referral service of theNational Electronic Service DealersAssociation (NESDA) and the Inter-national Society of Certified Elec-tronic Technicians (ISCET).

Because of occasional inquiriesfrom manufacturers, NESDA andISCET surveyed their members tofind out which products they werepresently servicing and which prod-ucts they or their technicians werequalified to service. The survey alsoquestioned if the members had thenecessary test equipment to service aparticular product, if they wouldlike to add the product to their ser-vice business and if they or theirtechnicians would be willing to at-tend training on the servicing of theproduct. Products surveyed includ-ed; color televisions, projection tele-visions, VCRs, videodiscs, stereos,short wave receivers, CBs, com-munication equipment, scanners,TV games, telephone equipment,computers and medical equipment.

The survey results have been com-puterized and a list of qualified ser-vicers for any category is availablefrom the NESDA office. Memberswishing to add their service facilityto the list may request copies of thesurvey form from NESDA, 2708West Berry St., Fort Worth, TX76109 (817) 921-9061.

CPD extendsregional marketing

Service dealers can now buy Sonyparts direct from Consumer Prod-ucts Distributing, Inc. (CPD).CPD has extended its regional directmarketing of Sony parts to includeservice dealers throughout theUnited States. National advertisingby the company began in March.

For specific Sony parts price in-formation and/or a CPD credit ap-plication contact: Dan Harp,General Manager, CPD, Inc., 3330Pagosa Court, Indianapolis, IN46226. Phone: (317) 897-4602.

Perma Power appointsSkor, Inc. to covernorth central states

Perma Power Electronics has ap-pointed Skor, Inc. as manufactur-er's representatives covering NorthDakota, South Dakota, Minnesota,and western Wisconsin (UTP 25).According to Michael Shatz, PermaPower's sales manager, Skor willhandle sales to all trade classes of allthree lines of Perma Power prod-ucts:

Headed by Gene Kurzweg, Skor,Inc. is located at 1821 UniversityAvenue, St. Paul, Minnesota 55104

First quarter salesabove 1980

Total U.S. market sales toretailers of television receivers andvideocassette recorders registeredsharp increases over last year in thefirst quarter of 1981, according tostatistics compiled by the MarketingServices Department, Electronic In-dustries Association's ConsumerElectronics Group.

Videocassette recorder sales toretailers in the first three months of1981 increased by 69.8 percent overthe same period last year while thecolor television set sales were up16.9 percent and monochrome TVset sales rose 16.5 percent over thefirst quarter of 1980.

First quarter sales to retailers ofvideocassette recorders amounted to268,514, up 69.8 percent over158,124 units sold in the comparableperiod last year. March 1981 salesof this product were 102,926, a gainof 64.1 percent over 62,704 unitssold in the same month of 1980.

Sales of color television sets in thefirst quarter were 2,684,802 units,an increase of 16.9 percent over2,297,056 units sold in the com-parable period a year ago. Color TVsales in March 1981 were 992,320,up 6.2 percent over 934,414 unitssold in the same month of 1980.

Monochrome television receiversales in the first quarter of 1981climbed to 1,483,036 units, a rise of16.5 percent above 1,272,703 unitssold in the same quarter a year ago.

Motorola's WeiszreceivesEIA Medal of Honor

The Electronic IndustriesAssociation announced William J.Weisz, vice chairman and chiefoperating officer of Motorola, Inc.,as recipient of the industry's highestaward, the 1981 EIA Medal ofHonor. Annually bestowed by theassociation, this award recognizesoutstanding contributions to the ad-vancement of the electronics in-dustry and high personal achieve-ment in the field of industrymanagement.

Weisz' contributions to the elec-tronics industry and efforts onbehalf of the private enterprisesystem have been recognizedthrough numerous past awards in-cluding the Freedoms Foundationof Valley Forge Award, the MITCorporate Leadership Award, theNational Electronics ConferenceAward of Merit and an honorarydoctorate of business administra-tion from St. Ambrose College.

ConsolidationPTS Electronics has consolidated

its Los Angeles -Paramount and SanDiego operations. Since March 27,1981, southern California servicefacilities have been- based at thesouthern California district officelocated at 5111 University Avenue,San Diego, CA 92105; (714)280-7070.

Distributorbookings and shipmentsshow strong gains

Industrial distribution's Marchshipments grew 4% from Februarywhile bookings gained 5%, accord-ing to the NEDA DistributionBusiness Index data, just released bythe National Electronic DistributorsAssociation.

The industry's book -to -bill ratiofor March was 1.10 to 1.

Compared to the report'sreference month of May 1980,shipments were 6% greater, whilebookings were up 12%.


00.1M11=

GE promotesVCR trainingin the South

General Electric has launched aVCR training program that coversthe 12 southeastern and westernstates. The two day sessions aredesigned to give the service dealer"hands on" experience not only inservicing the GE VCR machines,but to understand VCR service ingeneral. Sencore, manufacturer ofelectronic test instruments, isassisting in the GE program.Because of Sencore's belief thattraining is important to the servicedealer, Sencore has provided sixcomplete set-ups of their SC60oscilloscope, DVM56 digital voltmeter, PR57 variable isolationtransformer and leakage tester,CG25 color bar generator and VA48video analyzer for the technicians touse in the GE training sessions.

The cooperative GE-Sencoreeffort has been well received.

TRW namesdistributors

The fixed resistor distributoroperation of TRW/IRC Resistorshas named Resco/Raleigh adistributor. Effective immediately,Resco/Raleigh will distributeTRW/IRC's complete line of fixedresistors, including carbon composi-tion, metal film, and wire woundresistors, as well as resistive net-works.

Resco/ Raleigh's territory includesNorth Carolina, South Carolina,Georgia, and eastern Tennessee.

Resco/Raleigh's contact: BillBagliani, president, Highway 70West and Resco Court, Raleigh, NC27612. Telephone: (919) 781-5700.

Also in the news and effective im-mediately, Peak Electronics willdistribute TRW/IRC's complete linein the Philidelphia metropolitanarea: eastern Pennsylvania,southern New Jersey, andDelaware.

Peak's contact: Jay Peikin, presi-dent, 354-356 West LancasterAvenue, Wayne, PA 19087.Telephone: (215) 293-9000.

1980 exportsshow gain

U.S. consumer electronics exportsand imports experienced substantialchanges in 1980, according tostatistics released by the marketingservices department of the Elec-tronics Industries Association'sConsumer Electronics Group.

Exports of color televisionreceivers in 1980 increased to787,638 units, a gain of 110.2 per-cent over 374,653 units exported in1979. Customs value of color TV ex-ports increased to $276,982,380 in1980. Exports of monochrometelevision increased by 6.7 percentto 168,857 units in 1980 and exportsof TV combinations increased in1980 to 13,425 units, up 49.2 per-cent over 8,997 units exported in1979.

Audio and videotape equipmentexports increased in 1980 but ex-ports of entertainment band radiosdeclined while auto radio shipmentsout of the country held about evenwith 1979.

EIA supportslimited indemnificationfor government suppliers

Testifying on behalf of U.S.government suppliers, the Elec-tronic Industries Association of-fered its support to H.R. 1504, a billthat, if enacted, would provide for aproper and fair allocation, betweenuser and supplier, of product liabili-ty risks which are inevitablyassociated with certain governmentprocurement programs.

According to EIA's president,Peter F. McCloskey, H.R. 1504would withhold indemnification inthose cases where the accident wascaused by the supplier's "primaryand active or willful negligence," aprovision the association believes isa well -reasoned and fair criterionfor determining when and when notto shift such losses from the supplierto the government.

EIA's statement further indicatedthat the enactment of H.R. 1504would result in a reduction in thegovernment's total acquisition costs.

Price reductionsannounced by Kester

Because of a recent drop in theprice of tin, Kester Solder has re-duced prices by five percent onmany items in its distributor line, asannounced recently by the LittonIndustries division.

NESDA advocatesHall of Fame

An Electronics Hall of FameCenter may become a reality due tothe work of two NESDA regionalvice presidents, Gene Dillinghamand Bill Lawler, who are proposingthe project to electronics industryassociations throughout the nation.

NESDA is inviting EIA, ERA,NEDA, ITA, NARDA, NABER,NAVA, NAB, NATESA and allother national associations in theelectronics industry to join togetherin making this Hall of Fame Centerpossible, through formation of aHall of Fame foundation to ad-minister operation of Hall of Fameand the center. Some of the notedpersonalities now in the Hall ofFame include are: Thomas A.Edison, inventor of the electriclight, the phonograph, and the mo-tion picture; Dr. Lee de Forest, thefather of radio; Hugo Gernsback,publisher, inventor, and electronicprognosticator; and General DavidSarnoff, color TV pioneer.

The Hall of Fame Center will in-clude an electronics museumdisplaying electronic equipmentfrom the past, present and future;an industry technical library, elec-tronics archives for use by all of theindustry; and exhibits displayingphotos and personal histories of thefamous personalities in the world ofelectronics. The concept of a centerwas endorsed by the CaliforniaState Electronics Association and byparticipants in the Western StatesConference. Dillingham and Lawlerare asked for support from all alliedelectronics trade associations. In-quiries should be sent to NESDA,Attn.: J. W. Williams, 2708 WestBerry Street, Fort Worth, TX76109.


-alw am.,

MU m in the news

W. J. (Judd) Clark, director -national sales, has been promoted todirector -marketing and businessdevelopment at ITT Cannon Elec-tric-North America. He is respon-sible for sales, marketing, distribu-tion, advertising, sales promotion,customer training and programmanagement.

Clark replaces L. Wayne Oliverwho was named president inSeptember.

Reliance Electric announced theappointment of Robert W. Richeyas general manager of FederalPacific Electric (F.P.E.), a sub-sidiary of Reliance.

In this new position, Richey willbe responsible for Federal PacificElectric operations in the UnitedStates and Mexico as well as for theinternational business of Cornell-Dubilier Electronics, a subsidiary ofF.P.E.

Blonder -Tongue LaboratoriesInc. has announced the appoint-ment of Charles J. Goetsch tomanager, service department.Goetsch joined the company in 1962and has held a number of positionsin the product design and engineer-ing departments, including systemsengineering manager.

William R. Cranford, director -market planning and development,has been named director -new prod-uct planning for ITT Cannon Elec-tric, North America. He will beresponsible for identifying newproduct opportunities and coord-inating priorities with availabletalent, capital and capacity. Aveteran of over 33 years with ITTCannon, he has held numerous posi-tions, including sales engineercustomer service manager, andmanager -consumer products.

RCA has elected James M. Alicvice president for electronic servicesand VideoDisc planning. In addi-tion to his new responsibilities, Alicwill continue to be responsible forbusiness management and controlsfor the RCA SelectaVisionVideoDisc project.

Simultaneously, the appoint-ments were announced of George D.Prestwich as president of the RCAService Company, replacing JamesJ. Badaracco, who has been ap-pointed division vice president ofspecial marketing programs; and ofJoseph W. Karoly, vice presidentfor special projects.

Named division vice president,distributor and special productsdivision: Edward A. Boschetti. Pro-gressing with RCA since 1951,Boschetti now has total responsibili-ty for sales, merchandising,marketing services, product plan-ning and engineering, all productsof this division.


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Gene Chaiken, president of AlmoElectronic Corporation, has beenelected president of the NationalElectronic Distributors Association(NEDA) for the fiscal year begin-ning April 1. He had previouslybeen first vice president.

Three new distributor executivesjoined the NEDA officers' roster forthe first time: Dan Robbin, vicepresident, marketing, Time Elec-tronics, is vice president, industrial;Phil L. Webb, vice president,specialty distributing, is vice presi-dent, MRO; and Paul F. Carroll,president, semiconductor spec-ialists, is treasurer.

Past president Marvin Perkel ofQAR Electronics moved to chair-man of the board. Officers re-elected for a second term include:first vice president, Richard Lind-holm, president, Melvin Elec-tronics; vice president, consumer,Eldon Schoedel, vice president,Klaus Radio; vice president,general, Jack Hinterschied, presi-dent, Whitehead Radio; secretary,Robert R. Daugherty, president,Swieco, Inc.

A new management team hasbeen announced by Klein Tools.Those promoted are: Richard T.Klein, formerly president, to vicechairman; Michael S. Klein, former-ly vice president, administration, topresident; Vincent Nugent, fromsenior vice president, manufactur-ing, to senior vice president, cor-porate planning; Joseph Reilly,from vice president, finance, tosenior vice president, finance;Mathias A. Klein, III from vicepresident to vice president,manufacturing; Richard T. KleinJr., to corporate quality controlmanager and elected corporatesecretary; Steven T. Klein, regionalsales manager, elected assistant cor-porate secretary; Dan Foshee, fromregional sales manager to nationalsales manager.

H. James McGill has been ap-pointed manager, national ter-ritorial sales, for WestinghouseElectric's Industry Productsmarketing, and Charles H. Hawkshas been named to assume the posi-tion of director of distribution.

Robert B. Lukingbeal has beetappointed senior vice president ofoperations including responsibilityfor a realigned engineeringorganization within the N.A.P.Consumer Electronics Corporation.

N.A P. Consumer Electronics, anew subsidiary formed when NorthAmerican Philips Corporation ac-quired GTE Entertainment Prod-ucts, manufactures and marketsunder the Magnavox, Philco andSylvania brands.

Reporting to Lukingbeal, former-ly vice president of operations,Magnavox Consumer Electronics,are new vice presidents John R.D'Aiuto and Eugene Lubchenko.

D'Aiuto, named vice president ofcolor TV engineering, previouslydirected engineering for GTE.Lubchenko, formerly vice presidentof engineering, Magnavox, is vicepresident of new products andsystems.

Also announced: the appointmentof William A. Enser as director ofplanning. Enser was formerlymanager of financial planning andadministration, GTE.


Planning the industrialmaintenance shop

By Elwood Gilliland, technical consultant, Electric Service Co., Casper, WY

Planning and equipping an industrial service and repair shopcan be simple or complex, depending on the market being served.

The author gives points on shop planning and reviews howseveral companies have built successful facilities.

A growing industrial repairmarket offers opportunity for theservice shop to expand and divers-ify. But don't expect an easy pathto success. There's no such thing asa tried and true method for develop-ing an industrial electronic repaircapability. Industrial controls arehighly sophisticated, must work insevere environments and are appliedwhere downtime is often computedin thousands of dollars an hour.

Servicing industrial electronicequipment can be the technician'sgreatest challenge. Successful serv-ice companies have learned that a"total systems approach" to trouble-shooting is necessary, requiring notonly a knowledge of the controlsand their operation but also anunderstanding of the equipment orprocess being controlled. The finaldiagnosis may very well pinpoint aproblem that is nonelectronic.

Many well established electricalrepair companies have created anelectronics department to providetheir customers with more com-plete service and to remain viable inthe marketplace as technology ad-vances. Jim Shumberg, owner andfounder of Eltron Electric inHouston, provides a good exampleof how a small, well -managed in-dustrial electrical repair companycan develop the capability for solid-state repair. In 1979, Shumberg at-tended a one -week training course inbasic solid-state controls sponsoredby the Electrical Apparatus ServiceAssociation.

"Until that time," he says, "I wastotally unaware that such a tremen-dous industrial repair market ex-

isted, or even how to approach therepair of this equipment." Eltron isconcentrating on the repair of smallsingle and three phase dc motordrives that can be brought into theshop, but the company is also work-ing toward establishing a separateelectronics department with fullfield service capability.

There are few guidelines for ex-panding into the industrial elec-tronic repair market, but an analysisof successful operations revealsseveral common traits. Most com-panies have moved into an area

closely related to their original fieldof expertise, and they have grownslowly and carefully, often relyingon other departments to support thefledgling operation.

Equipping the shopThe company planning to expand

into the industrial repair market canexpect to make a substantial invest-ment in test equipment. GeorgeMendell of Rainbow Electric,Franklin Park, IL, says, "The newdrives are becoming more and morecomplex. Today it may take a

'1111111. '*

Desi Halasz, Electric Service Company technician, troubleshoots a video recorderfor one of the company's many industrial customers. Mining companies are usingthis medium to make excavator time/motion studies.


$10,000 oscilloscope to meet theserequirements. Our portable unitsfor field work run between $1500and $3000."

Richard High of Sullivan Electric,Cincinnati, OH, makes a similarcomment: "We have a much higherdollar investment in equipment inthe electronics group for dollarreturn than in any of our otherdepartments."

To troubleshoot printed circuitboards (where sufficient volume ex-ists), companies such as Rainbowand Sullivan and Galco of HazelPark, MI, have a sizeable invest-ment in specially built test fixtures,enabling them to make repairswithout the entire system.

Many smaller companies, unableto justify an extensive investment intest equipment, have purchasedgeneral purpose gear and then meettheir special requirements withrented equipment. Bruno Peter ofB&B Dynamo & Armature in Win-nipeg, Manitoba, has obtainedequipment on occasion from CAEAircraft Ltd. in Canada. Continen-tal Resources and Electro Rent Cor-poration are two US companies of-fering test equipment on a rentalbasis and can provide fast deliveryeither by air freight or United ParcelService.

Test equipment requirements areas diverse as the industrial controlsbeing serviced, and it would be dif-ficult to make specific recommenda-tions. Marlin Engel of Electric Ser-vice Company, Casper, WY, says,"A lot of test equipment re-quirements are basic to any type ofelectronic servicing: equipment likehigh impedance meters, transistortesters and capacitance bridges.When analyzing new markets, youneed to see which of your otherequipment will make the crossover."For field work, however, batterypowered or line isolated oscillo-scopes are mandatory because mostindustrial controls cannot begrounded. Many technicians haveapplied a conventional line -poweredscope with disastrous results, com-pounding an otherwise simplerepair. A dual trace scope is a mustfor working on three phase SCRequipment to make phase com-parisons of the firing pulses.

Training for industrial repairOne of the major hurdles to clear

in developing an industrial elec-tronic repair capability is hiring

qualified technicians. The rule isthat such a person can't be found;one has to be trained. Most in-dustrial shops are hiring technicianswith a general electronicsbackground, such as graduates ofmilitary schools or two-year tradeschools, and then providing on-the-job training covering the specifics.

High of Sullivan Electric says, "Inour area there's no problemrecruiting technicians. Our ads forhelp in this field bring a largerresponse than the other crafts whichwe employ. But none of them havemuch SCR experience and that com-ponent is really the heart of the dcmotor drives which we service.

"For service work, we look for anindividual who is accustomed to amaintenance environment as op-posed to someone who has onlyassembly line experience."

Mendell of Rainbow describes asimilar approach: "We hiretechnical school graduates and feelthat a person's attitude and initiativeare equally important to theirtechnical training. The new man willwork in the shop for a while andthen accompany the senior techni-cians on service calls. The second

man is an expense you can't chargethe customer for, and you just haveto hope that they will developenough loyalty to stay with you."

But what about the service shopsituated away from the largemetropolitan areas? Peter of B&BDynamo & Armature describes asituation typical of the small shop ina remote region: "Trained techni-cians don't exist in our area." Hesays this continent could benefitfrom the European concept of pro-viding specific apprenticeship typetraining for craftsmen at a muchearlier age. The few American com-panies that have hired one of thesehighly trained individuals will readi-ly agree.

Harold Moore of Johnson Elec-tric in Pueblo, CO, has workeddiligently to help the smaller serviceshop acquire a solid-state capability.As chairman of the Electrical Ap-paratus Service Association's(EASA) Solid State Committee, hewas instrumental in the establish-ment of a one week traveling pro-gram in basic solid-state controls.

"This course has been highly suc-cessful in helping members to learnthe basics of test equipment opera -

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M RO shop

tion and provide componentfamiliarization, but we are stilllooking for an effective method ofteaching troubleshooting," he says.Moore said a lot of EASA shops aresending their employees to schoolsoffered by the various equipmentmanufacturers. Although the quali-ty of training is excellent, it is oftenexpensive and limited to a fewspecific types of equipment.

He has also worked with a local

junior college. A basic course wasdeveloped, but to date the advancedprogram has not materializedbecause an instructor has not beenfound. "It's hard to find an in-dividual of this caliber because theyare highly sought after by the in-dustry and can make a lot moremoney in that field," Moore said.

Rainbow ElectricRainbow Electric of Franklin

Park, IL, is recognized as one of thecountry's leaders in servicing and

Ron Borino, Electric Service Company technician, watches as a CCTV camera andlight assembly begins its 600 foot descent into a uranium mine ventilation shaft.

Ross Heller, mine engineer stands beside the interrogater of an automatic vehicleidentification system. Each truck carries a digitally coded transponder, which is ac-tivated as the vehicle crosses over a buried 600V antenna.

repairing of the sophisticated solid-state motor drives that keep in-dustry rolling. Owner GeorgeMendell has justifiable pride in histeam of six crack electronic techni-cians that specializes exclusively inthe servicing of variable speed dcand ac motor controls. It has takenMendell 15 years to develop the In-dustrial Controls Department thataugments Rainbow's 30 man electricmotor sales and repair business.

There are many reasons for thephenomenal success of the com-pany, but Mendell considers hislocation to be an important con-tributing factor. The ControlDepartment headquarters is only 10minutes from Chicago's O'Hare In-ternational Airport, which hasflights to major US cities every halfhour. Each of Rainbow's techni-cians, on call 24 hours a day, is fur-nished with a company car, a fullcomplement of all major creditcards and is equipped with a smallportable battery -powered oscillo-scope and other test equipment thatcan be transported as carry -on lug-gage to minimize the possibility ofequipment damage. A technician isnever dispatched on a service call,however, until the nature of the

andhe is armed with the appropriate testequipment and replacement spareparts.

The company is an authorizedfield service center for a dozen dif-ferent manufacturers includingERC, WER, Louis Allis and Fincor.The technicians are backed up byone of the country's largest inven-tories of motors and drives, andspare parts, including replacementPC boards, SCRs, and otherdiscrete components.

Mendell's motto is "Don't die onthe job." If the technician has a par-ticularly tough problem and hasn'tisolated the difficulty within a fewhours, he is encouraged to foregohis pride and consult with the drivemanufacturer or one of Rainbow'sother technicians for advice.Mendell insists that when his techni-cians are on the job there be nosecrets kept from the customer. Hesays his people will gladly answerquestions pertaining to the opera-tion of the equipment and thenature of the repair and will assistthe customer in finding ways toeliminate or minimize futuredowntime. Mendell's philosophy -"You may teach yourself out of an


occasional service call but you havegained a customer for life"-haspaid big dividends in terms ofsatisfied customers.

Mendell says good communica-tions is an essential ingredient inevery phase of Rainbow's opera-tions. Special work forms have beendeveloped to ensure that every jobstep, from the issuing of an initialpurchase order to the signature forthe completed repair, has beenproperly authorized anddocumented.

The company has been closelyallied with the plastics industry foryears; and Mendell stresses the im-portance of understandingmachinery and processes involved,and puts a strong emphasis oncustomer rapport.

Sullivan ElectricSullivan Electric, one of the coun-

try's oldest electrical repair com-panies, began as an electrical con-tractor in 1898. Sullivan's president,Richard High, credits the company'slongevity, in part, to its ability to"look toward the future." It waswith this in mind that the companyestablished an Electronics Depart-

ment to supplement its wiring, panelbuilding and motor repair opera-tions.

High says his company specializesprimarily in the repair of SCR dcmotor drives widely used by smallmanufacturers in his area. Sullivanparticularly tries to promote the ser-vice of small packaged drives thatrange from fractional to fivehorsepower. These drives aregenerally self-contained, incor-porating the regulator, SCR powerpackage and controls in a singleenclosure. The units are consideredby many, because of their low cost,to be throwaway items. But thecompany has made a profitablebusiness of this previously neglectedarea by developing rapidtroubleshooting techniques and pro-viding quick turn -around.

"This type of equipment is idealfor us because it can be brought intoour shop for service," High says."The only additional piece of equip-ment that we need is the motor, andwe have them readily available. Fur-thermore, no complicated applica-tion problems are generally en-countered with equipment of thissize." His two technicians will also

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answer field service calls within a 50mile radius and can generally pro-vide sane -day service.

High stresses that an importantaspect of the repair is final testing,and the group has built a load teststation with a dynamometer to en-sure every unit will perform satisfac-torily under operating conditions.

Sullivan finds a ready market forits services among small manufac-turers that do not have their ownelectrical staff; additional businesscomes as the result of referrals madeby the various equipment manufac-turers.

GalcoIn 1975, electrical engineer Don

Gallasco decided to form his owncompany, Galco, to specialize in therepair of solid-state adjustablespeed drives and controls. Now hehas a staff of 16 with an impressivebackground in servicing complexequipment such as numerical con-trols, axis and spindle drives, tapereaders, tachometers and resolvers.The volume of service and repairwork is divided about equally be-tween field service calls, made na-tionwide, and shop repairs con -

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ducted in Galco's facility. The com-pany is an authorized servicerepresentative for a number ofmanufacturers, including EatonDynamic, Cutler Hammer, Elec-trical Regulator, Sabina Electric andEngineering, and WER Industrial.

Gallaso originally worked almostexclusively with the auto industrybut he recognized early the existenceof an unlimited market supporting

other repair companies around thecountry by providing semiconduc-tors and replacement printed circuitboards. The diversification intocomponent sales has been so suc-cessful that it now represents ap-proximately 50% of the company'stotal dollar volume. A nationwideclientele has been developed that in-cludes many companies in the elec-trical apparatus repair and electricalcontracting business. Galco nowmaintains one of the largest inven-

A Galco engineer works on the computer interface for a custom motor control ap-plication. The company "marries" the computer to conventional motor drives wherecomplex sequencing is required.

A Rainbow Electric technician services components in a dc control.

tories of power semiconductors inthe country. The company has doneextensive research on componentsubstitution and has the capabilityof cross-referencing expensive orobsolete devices to cost-effectivegeneric replacements. Galco also in-ventories a large stock of new andrebuilt replacement printed circuitboards, and all rebuilt boards aretested and guaranteed.

"It's important not to get toobroad," Gallasco said. "It's impossi-ble to be proficient on the vast varie-ty of equipment that exists, and weoften have to turn down work thatlies beyond our area of expertise.We can't be all things to all people."

The problem of componentsubstitution has always plagued in-dustrial troubleshooters having tocontend with special house numbersor to buy an entire assembly when asingle component would suffice.Galco's entry into this market prom-ises to be a real help to the in-dependent service company.

Electric Service CompanyThe Wyoming energy boom has

touched off an unprecedented in-dustrial expansion, resulting innumerous electronic service oppor-tunities. Electric Service Company,a 35 -year -old electrical contractingand motor repair company, hasrecently created a Technical ServiceDepartment to meet these needs.

Two years ago, Marlin Engel wasbrought in to organize and managethe new department. Engel, who hasmore than 20 years of communica-tions, sound and CCTV experience,and a knack for organization, sayshe is glad he made the transitionfrom consumer to commercial andindustrial electronics.

"I made the change because I sawan inevitable growth in this field andwas challenged by the opportunityto service equipment which is anecessity rather than a luxury," hesays. He has a staff of eight thatsells, designs, installs, services andrepairs CCTV, sound and securitysystems, and industrial controls.The group also provides technicalsupport for the company's WiringDepartment personnel that performfull-time electrical and electronicmaintenance for several of thestate's largest refining, milling andmanufacturing operations. Addi-tionally, the company providesauthorized field service for theEMICC variable frequency submer-


sible pump drives.Engel, who had previously

established four consumer serviceorganizations, says that creating anentirely new industrial serviceoperation in the widely scatteredand sparsely populated Wyomingarea has its own unique set of prob-lems.

"We grew much faster than an-ticipated," he says, "and it was dif-ficult to train so many new people atonce. Later, as we add new in-dividuals one or two at a time, it willbe much easier."

He wants the technicians tospecialize, but not to the point thatthey can't cross over and assist withthe other disciplines in the event ofan emergency.

"I guess you could say we givethem a minor in General Electronicswith a major in Sound, Security,CCTV, or Industrial Controls," hesays. It's not uncommon for thecompany's technicians to travel 250miles on a service call. "We try togroup routine service calls to keepthe cost down," he says, "and tominimize emergency calls, we offerscheduled preventative mainte-nance." The company will also trainthe customers' maintenance person-nel to do minor repair and providesphone consultation when necessary.

The company's design philosophyis to approach every job individuallyand to find equipment that meetsthe application, not merely makethe application fit what they sell.Engel says that to be competitive inthe marketplace, franchises anddistributorships offering significantpricing advantages are essential.However, he stresses that to berealistic the minimum inventory re-quirements must be adjusted to fitthe smaller market area.

The group's expertise in com-munications has unlockednumerous jobs of a very specializedand unusual nature. For example,the company received a contract toinstall and maintain an AutomaticVehicle Identification system for alarge surface coal mine. This equip-ment uses a radio frequency link tointerrogate the massive 120 ton coalhaulers as they enter the dump hop-per. Each unit responds with its owndigitally coded identificationnumber, which is then automaticallylogged on a printer along with theincoming and outgoing vehicleweight.

The company prefers to design at

the system level using off -the -shelfequipment whenever possible, butits ability to do in-house circuitdesign has often enabled a system tobe tailored exactly to the customer'sneeds. One project that illustratesthe company's innovative capabilitywas the design and installation of asound system console for a local airservice. The unit incorporates asolid-state priority interrupt schemethat automatically routes thecustomer's Unicom frequency,tower scanner, public address an-nouncements or background musicto the sound system in accordancewith their importance. Chief techni-cian Desi Halasz, who built and in-stalled the system, said it has per-formed unfailingly since its installa-tion two years ago.

Another example of thecompany's design -and -buildcapability is the large motor testconsole developed for use in thecompany's own motor shop finaltest area. This state-of-the-artsystem uses IC logic to provide con-trol, instrumentation and alarmfunctions unobtainable in conven-tional commercially available units.

Electric Service Company hasfound that once a capability andreputation for industrial servicing isdeveloped, any project could comeup. The company recently con-tracted to provide manpower andvideo equipment for an inspectionof the 600 foot ventilation shaft in alarge underground uranium mine. Aspecial platform was fabricated tocarry the camera, an RCA TC2000in a Vicon housing with a 4mm lens,along with automotive batteries andheadlights to provide the necessaryillumination. Camera power andvideo signals were fed over a pig-gyback cable. A large air winch wasused to raise and lower the assemblywhile the technicians checked thecondition of the metal casing usingan RCA TC1210 monitor on thesurface.

The Electric Service Company ismaking an important contributionserving Wyoming's new industrialmarket. Engel is optimistic, and atthe same time cautious, as he ex-plains the tack he wants to take.

"We've been in a training phase,developing policies and methods,"he says. "Now, as these become amatter of routine, we will begin toanalyze new markets. Currently, wewant to work at improving our effi-ciency."

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Applications of digital scopesBy Peter C. Dale, product manager, instruments division, Gould Inc., Cleveland, OH

They look like traditional scopes,and some models even double as anordinary oscilloscope. Yet, func-tionally they are extensions ofmeters and recorders. They adaptanalog monitoring and recordingsystems to the capture and analysisof all sorts of one-shot physical

phenomena, yet also serve as a ver-satile portable troubleshooting in-strument.

It might seem that the addition ofmemory capabilities to a scopewould not be very significant. Thisview overlooks the fact that the newdigital scopes can not only freeze

time but can output it at reducedspeed to conventional recorders.Data can be made to evolve just as itdoes on a pen recorder, yet thescope can keep only the significantevents.

For example, digital scopes can beset to capture transient events occur -

INPUT

INPUTAMP

ADCONVERTER

TRIGGERAMP

DIGITALSTORE

CRT

1

NORMALD -A DOT lid V

CONVERTER JOINER OUTPUTAMP

REFRESHOR ROLL

CONTROLLOGIC

SWEEPGEN

L

X

OUTPUTAMP

Figure 1 -Typical digital -scope block diagram for one channel. Upper bypass loop provides real-time viewing as in a conven-

tional scope (normal mode).

Figure 2 Challenging the process: In A, an 80kHz sine wave is displayed in real time as it would appear on a conventional scope.In B, this signal has been transformed into dots by a digital scope, and in C, the dots are joined by straight-line constructions. Atthis high frequency, the scope's sampling rate of 1MHz means only 12 dots are available to plot each wave repetition(1,000,000/80,000 = 12). Because the instant of digital sampling does not occur at exactly the same point wave -to -wave, someslight variation appears between identical waveforms. Thus, some peak values may be minutely clipped as shown here, or if asuperimposed megahertz transient occurred between two adjacent dots, it might be missed entirely. If such sampling errors arecritical, a much higher sampling -rate instrument would be required.

Ideal forField workStorage channelsMemory sizeFrequency limitsPrice

General purposeOne-shot electromechanical phenomenaFully portable1 tooUp to 4000 dots2 Megahertz or less$3000 and up

ProcessinHigh-speed electronics analysisLimited to laboratory useUp to 40Up to 24,000 dotsBeyond 1 gigahertz (with repetitive -wave sampling)$10,000 and up

Figure 3- General purpose vs. processing scopes.


ring at anything from extremelyslow to speeds in excess of100,000Hz (less than 10o), storethis information indefinitely, ex-pand it for analysis, and show whathappened just before the key eventor trigger point occurred. Thedigital scope can be used alone formonitoring and troubleshooting, orsignals captured in memory can beoutput in analog or digital form toadvanced computerized testsystems.

Thus, the digital scope hasbecome a monitoring/computing"front end" for existing measuringsystems. For a modest investment, itextends system capabilities, par-ticularly the pen sensitivity or fre-quency response of 1Hz for a strip -chart recorder by a factor of 105 or100Hz for an oscillograph by a fac-tor of 103.

How digitizing worksTo understand what's going on in-

side a typical digital scope, look at atypical schematic (Figure 1). This isa simplified version of one channelof a scope that can also function asa conventional scope - displayingthe amplified input signal directlyon the CRT in real time by bypass-ing the digitizing section entirely.

To digitize, though, the analogsignal must be converted, and thespeed capabilities of the converterare the key to the frequencyresponse of the digital scope. Con-sider the converter a shuttering win-dow that opens typically for 'As(sampling rate). In that time period,the input signal value must be mat-ched with a digitally generated rampor successive logic approximationswith an accuracy of 1 part in 256,typically (28 or an 8 -bit word). Inother words, 256 decisions must bemade to arrive at a value for justone dot. Because it takes 5 to 10dots to accurately represent awaveform (for example a 100kHzsine wave), it becomes obvious whyit takes 256MHz ramp speed todigitize through the 1MHz windowa signal with a frequency of only100kHz, or a 2560:1 relationshipbetween digitizing speed and input

Editors note: This general article illustrates some ofthe applications in which the new generation of digitalscopes can be of special value in industrial servicing,R&D and manufacturing. The illustrations show ap-plications with the new Gould series 4000 digitalstorage oscilloscope, but the general applications arenot limited to this scope.

signal frequency. Thus, the state-of-the-art in digital circuitry mustmove well into the gigahertz regionto make possible digital storage ofmegahertz waveforms. This willalways be a key limiting factor.

The capacity of the digital storeor memory is another key scopecharacteristic. Usually, a singlememory serves all channels. On a2 -channel scope, for example, ifboth channels are storing, the finitenumber of memory dots is spreadover two signals; half the resolutionthe memory would have with alldots would be devoted to a singlesignal. Also, the number of memorybits used for each dot (word) willlimit the total dot capacity of agiven memory. For example, an8000 -bit (8k) memory, used 8

bits/dot (for 1 part in 256 accuracy)has a capacity of 1000 dots, but at10 bits/dot (1 part in 1000 accuracy)has only 800 dots to drawwaveforms.

Details of the trigger amplifier arebeyond the scope of this article, but,in general, it controls the input ofdata to the store and its release tothe display CRT or an outputprinter. The trigger can be from anexternal event (contact closure) orset to capture whenever anypredetermined combination ofsignal polarity, slope or level occurs.The scope can be armed to captureand hold the first occurrence ofthese trigger conditions or to con-tinually update the displayed signalwhen they re -occur (refresh mode).

The D/A converter does not fullyrecreate the original analog signal;some information between the dots,lost during the sampling process, isgone forever. The D/A merely plotsthe dots stored in memory. Somedigital scopes have an optionalfeature, dot joining (Figure 2),which constructs simple straightlines between consecutive dots thatmay or may not represent what ac-tually happened between samples.Similarly, when the stored dots areoutput to a pen recorder, the scan-ning rate must be optimized to theresponse of the pen so that pen iner-tia can be used to smooth out thesteps between dots. If the pen is toofast or the signal too siow, thewaveform will appear as a series ofsteps.

Other memory methodsStorage of oscilloscope traces did

not originate with the digital scope.Tube -type storage scopes that freezewaveforms by varying the retentionrate of the phosphors on the CRTscreen or by storing charge on amesh behind the screen have beenaround for a long time. Unlimitedby the speed of a digitizing process,they can store anything the scopecan write on the screen, but for alimited period depending on thedesign and screen phosphors.However, they cannot output thisinformation electronically, onlyphotographically. They are essen-tially cameras, and cannot showwhat happened before they weretriggered, or expand a waveformdetailed analysis. In some tube -storage designs, the previous signalmust be erased before a new signal

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Digital scopes

can be stored, which can mean miss-ing events during the erase period.Unlike the tube -storage display,which can flicker or glow at high orlow frequencies, the stored digitalscope trace is constantly refreshedfrom the digital store and thereforeuniform at all frequencies.

The field of currently availabledigital scopes can be divided intotwo primary categories: the general-purpose scope that this article is

Figure 4-Pre-trigger options: With thesame triggering criteria (signal level,slope and polarity), the upper traceshows only post -trigger data as wouldbe seen with a tube -storage scope, butthe lower trace (set for '/4 pre -trigger)captures additional information on im-

primarily concerned with, and theprocessing scopes that offer fullcomputer microprocessing. The twoare compared in Figure 3.

They are clearly two entirely dif-ferent classes of instruments. Just asa computer wouldn't be used when ahand-held calculator will do, a pro-cessing scope wouldn't be purchasedwhen fast Fourier transforms, signalaveraging or spectrum analysis areneeded.

Key digital functionsHere are some of the unique func-

tions of digital scopes:Pre -trigger information - At any

time, a 1000 -word memory containsa digitized dot indicating the instan-taneous signal value plus the 999dots that preceded it. When thescope display is triggered, 100% ofpre -trigger information is displayed,but no post -trigger data; or the trig-ger point can be moved to half pre -trigger, half post -trigger or someother desired combination (Figure4). In tube -type storage, only post -trigger viewing is available.

Roll mode-Equivalent to 100%pre -trigger in real time; in this mode

data rolls by from right to left

Figure 5-Trace expansion: The original trace as captured in A, is expanded in B toview transients that occurred immediately after triggering, left.

Figure 6- Function generation: Com-posite waveform was created by combin-ing elements of a square wave,sawtooth, and sine wave produced by asignal generator with a "hand -drawn"stairstep wave produced by varying thevertical deflection of a slow -movingsweep signal. This waveform can thenbe output as a test signal.

Figure 7 - Aliasing for amusement:Deliberately inputting a high frequencysignal beyond the scope's sampling ratecauses it to become confused and pro-duce random or alias dots that with dotjoining and X -Y plotting become line art.

just as it does in a strip -chartrecorder - fresh information entersright and exits left and can be stop-ped any time by either a predeter-mined trigger condition or bypushing a store button. This isuseful for monitoring a slowlychanging event.

Transient comparisons-With astored previous signal on display,any subsequent occurrences can bevisually compared and evensuperimposed for detailed analysisof trends. Through expansion, atrace can be magnified to examinetrace portions in detail (Figure 5).

Transient capture-The digitalscope is ideal for capturing transientphenomena even when the unit isunattended. The triggering condi-tions are preset - typically a trigger-ing window or acceptable band ofhigh and low signal values - and theunit will freeze the first occurrenceof an out -of -limit condition. With arecording output option, somescopes can automatically warm up astrip -chart recorder, output thetransient signal, record it, shut offthe recorder, and then rearm itselfto capture and record the next tran-sient condition, all without humanintervention.

X/Y plots-With X -with -timeand Y -with -time waveforms digitiz-ed in memory, it is a simple task tocompute an X -Y plot. Some digitalscopes can display the plot directly,others output X/T or Y/T data to aconventional X/Y recorder. Withdirect viewing, many plots can bescanned and only those that requirepermanent recording chosen forprinting.

Function generation-With anextremely slow sweep rate and no in-put signal, the basic scope beam -positioning controls can be used togenerate practically any desiredwaveform (Figure 6). Once "hand -drawn" and captured in memory,this signal can be output singularlyor repetitively for use as a signal forcontrol, triggering or transienttesting. In a lighter vein, Figure 7,the scope can be used as an "amuse-ment generator" by deliberatelyoverloading the scope's samplingrate with higher frequencies tocreate random dots that, when join-ed, form geometric line patterns.

Typical applicationsWith this wide range of available


ELEMENTAL SIGNALTRANSDUCERS CONDITIONERS

DIGITALSCOPE

RECORDING/ANALYSIS

FLOW

PRESSURE

STRAIN

LOAD

TEMPERATURE

DISPLACEMENT

POWER

VOLTAGE

CURRENT

AMPLIFICATION, ETC.

OUTPUT UNIT

.

.1!)3

INTERFACE

STRIP CHARTRECORDER

XY RECORDER

COMPUTERSYSTEM

Figure 8 - As the heart of an expansive monitoring, measuring and recording system, the digital scope offers many new in-strumentation capabilities.

functions, the new digital scopes arefinding many interesting applicationareas:

Field troubleshooting-The por-tability and flexibility of the digitalscope make it an idealtroubleshooting tool when coupledwith a suitable array of simpletransducers for temperature,

pressure, strain, acceleration,displacement or basic electricalvoltage and current measurement.Suitably calibrated, they enable thescope to make absolute and com-parative measurements in a full timespectrum from very fast events tothe very slow. Examples: checkingshock, vibration, noise, monitoring

power surges or electrical transients;analyzing thermal stress or fatigue;isolating piping faults; andestablishing safety limits.

Production and quality con-trol-The speed of digital scopesand their X -Y modes enable 100%performance checks at production -line speeds. Permanent straingauges on forging and punch pressescan be routinely monitored forstress overloads. Electrical motorsand SCR control circuits can be fine-tuned. OSHA and EPA criteria canbe continuously monitored.

R&D -Lab applications are near-ly infinite, and for detailed analysisa processing scope may be needed ora general-purpose digital scope can

courtesy of Fluid Regulators Corp.

Figure 10 - Valve test traces: uppertrace is valve pressure; lower trace iscoil current.

Figure 9 - (Left) Testing of high-pressuregas -venting solenoid valve.


Digital scopes

be tied into a computing system withsuitable interfacing. Examples: pro-totype evaluation and destructivetesting, IC and turbine engine effi-

ciency research, resonance -frequency checks, bearing vibrationstudies, establishing plastic/elasticmaterials criteria, telephone

Figure 11 - Technician uses digital scope to check out SCR control system on elec-trical lift truck converted from older resistive controls.

Figure 12 - Lab test of contactor was performed unattended to avoid any arcinghazards. The scope captured traces for voltage and current automatically, for thetransfer after viewing to the recorder.

switching transient checks, chemicalcorrosion studies and seismicresearch.

Medical -Some of the first usesfor digital scopes were in heartresearch, particularly the vectrocar-diography of heart patients understress. Other medical examples:heart sound monitoring, ECG,brain research, neuroscience,cybernetics, respiratory exams andresearch, enzymatic reaction studiesand speech analysis.

The impact of digitalThus, the immediate impact of

digital scopes will be as an impor-tant new tool that greatly extendsmeasurement and analysis ofphysical transients and otherphenomena. Basically a monitoringdevice, it can output for recordingonly those results that need re-cording or further signal processing(Figure 8).

As semiconductor technologyyields higher speed A/D convertersand improved memories, digitalscopes will replace more and moreconventional storage -tube scopes inthe analysis of high-speed electronicwaveforms. Using currentlyavailable digital bus interfaces(IEEE -488), digital scopes are readyto contribute to highly sophisticatedmeasurement systems, including theability to "handshake on the bus"with data "conversations," althoughthe digital scopes are mostly talkers(supply data), not listeners (respondto commands).

Applications: verifyingvalve performance

The high-pressure gas -ventingsolenoid valve in Figure 9 is used fora critical trimming operation in amilitary application. The ability ofeach valve to open under 2500 -psipressure within 10ms must be

courtesy of HE1 Electrical Mfg. Co.

Figure 13 -Closeup of the resultingtrace.


verified and recorded to qualify thelot. A test fixture holds the valveunder pressure and a pressuretransducer produces the upper scopetrace. A digital voltmeter monitorssolenoid voltage. Solenoid current,the lower trace, is used to show coilenergization. The scope is set to cap-ture 'A of the current pre -triggertrace to use as the demarcationpoint for pressure response.

When the coil is energized, Figure10, the current trace (set to break atthe first horizontal grid line) dropswith inrush and then levels off atsteady-state current. Meanwhile theupper pressure trace shows nochange for two subsequent grid lines(5ms/division) before pressurestarts to bleed off. Thus, responsetime is clearly 10ms, and as soon asthis data and solenoid serial numberare logged, the scope is reset and anew solenoid placed in the fixture torepeat the test.

The key digital features that makethis an efficient and reliable produc-tion test are the ability easily tocalibrate the zero current point, tocapture and hold the trace in-

definitely, and the speed andsimplicity of the whole operation;production people are easily trainedto get consistent results.

Applications: developingelectric -car controls

Modern electrical -vehicle controlsystems rely on SCRs for smoothperformance and fine-tuned controlat various operating speeds but stillrequire dc contactors for switchinghigh levels of power. This high -voltage contactor for mining equip-ment and electric cars, Figure 11, isused for initially arming the SCR,for bypassing it when full power isrequired and for interrupting theload in emergencies if the SCRshould fail under closed-circuit con-ditions.

In the development of the contac-tor, the design of the unit had to bethoroughly tested and documented.Besides measuring arc time, currentrise, arcking patterns and bridgetemperature, the designers were par-ticularly interested in the ability ofmagnetic blow-out horns to ex-tinguish the arc in less than 5ms.

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Though the contactor is rated for400A continuous current at 250V,overloading currents of many timesthis had to be demonstrated andevaluated to establish rating validi-ty.

In this test, Figure 12, a 250Vbank of industrial batteries wasswitched into a large motor/genera-tor load. Inrush current, Figure 13,builds to 2500A as battery voltage atthe contactor drops from 250V to50V. At this point (5ms after initialcontact closure), an automatic con-trol circuit opens the power circuitto test the contactor's interruptingability, but also to protect the motorfrom overload current. Instead of aclean break, the contactor chatteredseveral times before the arc wasfinally extinguished, as shown bythe jagged voltage curve and decay-ing current curve at the right of thetrace. Because of the digital scope'sability to capture and output this in-formation to the direct -writingoscillograph alongside, this data canbe permanently recorded for com-parison with later tests under relatedconditions. 0

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Index of 1980 articlesCompiled by Warren G. Parker, Metairie, LA

Titles of articles1981 Consumer electronic products Aug 21 Typical repairs of older Zenith TVs, solidA close look at digital signals, part 1 Jan 13 state Jan 20A close look at digital signals, part 2 Feb 20 Understanding CTC 99 horizontal sweep Feb 27AGC problems in tube TV, part 1 Jun 23 Unique features of DMMs Mar 8AGC problems in tube TV, part 2 Jul 18 Updated tube-AGC basics Jun 28Antenna roundup Jul 14 Verify tube defects and prevent callbacks May 27Basic design of logic probes Sep 13Calculating service labor rates Jan 34 ANTENNASComparison of VOMs, VTVMs, and DMMs Mar 6 Antenna roundup Jul 14Digital probe roundup Sep 14 Selecting TV antennas Apr 14Employer -employee contracts Mar 22 Tips for installing antennas Jul 8Features and circuits of Sony receivers Dec 24Franchising the electronic service industry Aug 8Index of 1979 articles Jan 31 COLOR TVIndustrial maintenance with portable scopes Oct 11 AGC problems in tube TVs, part 1 Jun 23Industrial product test reports May 14 AGC problems in tube TVs, part 2 Jul 18Locating ac leakage in industrial plants Feb 15 More Zenith TV repairs, solid-state Feb 38Locating MRO parts Jun 20 RCA chroma circuits and servicing Jul 23More Zenith TV repairs, solid-state Feb 38 RCA luminance circuits Jun 32Multimeter roundup Mar 12 RCA troubleshooting charts Apr 22New scope features Oct 20 Servicing RCA frequency -synthesis tuning May 18

workshop Dec Typical repairs of older Zenith TVs, solid-Practical scope tips, part 1 Oct 14 state Jan 20Practical scope tips, part 2 Nov 19 Updated tube-AGC basics Jun 20Practical transient protection Apr 8 Verify tube defects and prevent callbacks May 27Preventing damage from transients Feb 7Programmable controller applications Mar 18 DIGITALRCA chroma circuits and servicing Jul 23 A close look at digital signals, part 1 Jan 13RCA CTC 99 vertical sweep, part 1 Aug 28 A close look at digital signals, part 2 Feb 20RCA CTC 99 vertical sweep, part 2 Sep 22 Basic design of logic probes Sep 13RCA luminance circuits Jun 32 Digital probe roundup Sep 14RCA SCR regulator and horizontal oscillator Jan 24 Troubleshooting digital equipment Sep 18RCA troubleshooting charts Apr 22Selecting replacement capacitors Jun 14Selecting TV antennas Apr 14 HORIZONTAL & HV

Semiconductor source guideServicing audiocassette tape recorders,

Aug 12 Practical scope tips, part 1Practical scope tips, part 2

OctNov

1419

part 1 Nov 31 RCA troubleshooting charts Apr 22

Servicing audiocassette tape recorders,part 2

Servicing electrocardiographsServicing RCA frequency -synthesis tuning

DecJul

May

14

3318

Troubleshooting RCA hot supply andhorizontal

Understanding CTC 99 horizontal sweepVerify tube defects and prevent callbacks

MarFebMay

242727

Soldering and desoldering equipment Nov 4Solid-state switches keep artificial hearts INDUSTRIAL ELECTRONICS

beating May 11 Basic design of logic probes Sep 13Solving vertical problems in old TVs,

vacuum tube Apr 31

Digital probe roundupIndustrial maintenance with portable scopes

SepOct

14

11Special meter and calibration services Industrial product test reports May 14

for MRO Aug 18 Locating ac leakage in industrial plants Feb 15Techniques for fast, efficient soldering Nov 7 Locating MRO parts Jun 20Testing diodes by voltage drop Jul 30 Planning an industrial maintenance workshop Dec 5Testing wow and flutter Dec 22 Practical transient protection Apr 8Tips for installing TV antennas Jul 8 Programmable controller applications Mar 18Troubleshooting digital equipment Sep 18 Soldering and desoldering equipment Nov 4Troubleshooting RCA hot supply and Special meters and calibration services

horizontal Mar 24 for MRO Aug 18Typical CB radio repairs Nov 25 Testing diodes by voltage drop Jul 30


MEDICAL ELECTRONICSServicing electrocardiographs Jul 33Solid-state switches keep artificial hearts

beating May 11

MISCELLANEOUS1981 Consumer electronic products Aug 21

AGC problems in tube TVs, part 1 Jun 23AGC problems in tube TVs, part 2 Jul 18Basic design of logic probes Sep 13Calculating service labor rates Jan 34Employer -employee contracts Mar 22Features and circuits of Sony receivers Dec 24Franchising the electronic service industry Aug 8Index of 1979 articles Jan 31

Locating MRO parts Jun 20RCA CTC 99 vertical sweep, part 1 Aug 28RCA CTC 99 vertical sweep, part 2 Sep 22RCA luminance circuits Jun 32Selecting replacement capacitors Jun 14Semiconductor source guide Aug 12Servicing audiocassette tape recorders,

part 1 Nov 31

Servicing audiocassette tape recorders,part 2 Dec 14

Soldering and desoldering equipment Nov 4Solving vertical problems of old TVs, vacuum

tube Apr 31Techniques for fast, efficient soldering Nov 7

Testing diodes by voltage drop Jul 30Testing wow and flutter Dec 22Typical CB repairs Nov 25Updated tube-AGC basics Jun 28

REPORTS FROM THE TEST LABB&K-Precision 1535 oscilloscope Nov 15Data Precision 936 DMM Jun 12Hickok 240 video genreator Oct 6Keithley Instruments 130 digital

multimeter Aug 16Sencore DVM-56 digital multimeter Apr 18Sencore PR -57 ac powerite Sep 8Sencore SC -60 oscilloscope Dec 11

Viz WR-549A pulse generator Jan 11

SERVICING METHODSIndustrial maintenance with portable scopes Oct 11

More Zenith TV repairs, solid state Feb 38Practical scope tips, part 1 Oct 14Practical scope tips, part 2 Nov 19RCA troubleshooting charts Apr 22Servicing audiocassette tape recorders,

part 1 Nov 31

Servicing audiocassette tape recorders,part 2 Dec 14

Servicing RCA frequency -synthesis tuning May 18Testing diodes by voltage drop Jul 30

Testing wow and flutter Dec 22Typical repairs of older Zenith TVs,

solid-state Jan 20Verify tube defects and prevent callbacks May 27

SOLID-STATE SERVICINGMore Zenith TV repairs, solid-state Feb 38Practical transient protection Apr 8Preventing damage from transients Feb 7

RCA CTC 99 vertical sweep, part 1 Aug 28RCA CTC 99 vertical sweep, part 2 Sep 22RCA luminance circuits Jun 32RCA SCR regulator and horizontal oscillator Jan 24RCA troubleshooting charts Apr 22Semiconductor source guide Aug 12Servicing RCA frequency -synthesis tuning May 18Testing diodes by voltage drop Jul 30Typical CB repairs Nov 25Typical repairs of older Zenith TVs,

solid-state Jan 20Understanding CTC 99 horizontal sweep Feb 27

TEST EQUIPMENTComparison of VOMs, VTVMs, and DMMs Mar 6Industrial maintenance with portable scopes Oct 11

Multimeter roundup Mar 12New scope features Oct 20Practical scope tips, part 1 Oct 14Practical scope tips, part 2 Nov 19Special meters and calibration services for MRO Aug 18Unique features of DMMs Mar 8

Symcure

ADMIRALM55, vertical lock is erratic Mar 21M55, AGC overload, might improve when warm Mar 21M55, no raster, sound and H V ok Mar 21M55, intermittent loss of red, blue, or green Mar 21M55, excessive brightness Mar 21

M55, vertical instability on cable signals Mar 21

MAGNAVOXT985/86, no raster, no picture, H V normal Aug 271985/86, horizontal cannot be locked,

vertical normal Aug 271985/86, no high voltage or horizontal sweep Aug 27T985/86, no sound, R203 overheats when sound

module is plugged in Aug 27T985/86, no sound, R203 overheats whether or not the

sound module is plugged in Aug

RCACTC53, distorted video, similar to bad AGC Apr 30CTC85, no height Sep 6


Index

CTC87, short period of audio followed by 25EC58, no picture, no sound, breaker trips Jul 6

shutdown Jun 31 25EC58, tripped breaker, when reset, loud, hum,

CTC87, no height Nov 14 retrips Oct 8

CTC87/101, no sound and no picture, shutdown 25EC58, no luminance signal, no brightness Oct 8

condition Nov 14 25EC58, height varies at bottom of raster Oct 8

CTC87, erratic startup Apr 30 25EC58, weak color is missing, but strongCTC88, sound distorted Jun 31 color normal Oct 8

CTC88, short blast, sound, then shutdown. Jun 31 SGw/remote, no remote operation, manualCTC91, no high voltage Apr 30 normal Dec 26

CTC92, no picture or sound, fusible resistoropen Sep 6

CTC92, no sound and no picture, shutdown Troubleshooting tipscondition Nov 14

CTC92, erratic tuner or station selection Jun 31 ADMIRALCTC93, wrong horizontal frequency Jun 31 2M1OCA,C, shrinking picture Jun 11

CTC93, picture dark Sep 6

CTC97, lack of regulation causes shutdown Apr 30 CHANNEL MASTERCTC97, little control of brightness Apr 30 6128/29, no HV, breaker trips May 31

CTC97, no height Nov 14

CTC97HC, no height Apr 30 GENERAL ELECTRICCTC97, height collapses erratically Sep 6 UA, lack of raster height at bottom Jun 8

CTC99, shutdown giving no soundor picture Jun 31 HITACHI

CTC99, compression and retrace at top of CA568, black corner Aug 38

picture Sep 6

CTC99/101, no color, but IF and oscillator signals MAGNAVOXenter IC U800 Sep 6 T950, no vertical sweep, raster non linear Mar 37

T936, low Bplus, without picture Jun 8

SYLVANIAD16, beat pattern in color, and interference is MOTOROLA

radiated Feb 6 19TS929, vertical roll and no color Jun 11

E20, no height Feb 6 LC19TS-929, no picture, reset breaker, ok untilE21, no vertical or horizontal locking Feb 6 receiver is turned off Feb 40

E21, circuit breaker trips instantly Feb 6

E21, excessive brightness with blooming Feb 6 PACKARD BELLE21, dim picture and color smearing Feb 6 98C18, intermittent video and black marks in

picture Sep 39

ZENITH 98C21, AGC overload Sep 39

4B25C19, intermittent low sound volume Oct 8

9JB1, excessive brightness with retrace lines Jan 4 PANASONIC12FB12, width varies intermittently, center CT26, no HV or picture Aug 38

foldover Jul 6 CT98, picture pulling Jun 8

12HB1X, 1" lack of scan at all sides CT329, buzz in sound Dec 37

of raster May 30

12HB1X, picture flashes bright and dark May 30 RCA12 JB2X, weak or intermittent audio volume Jan 4 CTC62A, no picture and no sound Dec 37

13HC10, right and left edges bowed, Jul 6 CTC72, receiver dead, only dial lamp19GB1, intermittent loss of height Jul 6 comes on Apr 21

19GB1, vertical foldover with retrace lines Jul 6 CTC72B, no sound, raster, or HV Feb 40

19GB1, bottom foldover with erratic rolling Jul 6 CTC81A, chattering relay Aug 37

19GB1Z, audio intermittent and/or CRT heaterlights Oct 8 SANYO

19GC38Z, low brightness May 30 CT711, drifting vertical frequency May 31

19HC20, insufficient contrast Dec 36

19HC45, excessive snow all channels Jan 4 SYLVANIA19HC50, no raster or rapid flashing in picture Jan 4 E10, AGC overload causes loss of HV Mar 37

23HC50, drive line during zoom function Dec 36

25CC50, height about 1" Dec 36 ZENITH25DC56, no color at left edge of screen Dec 36 14A10C29, no color when TV is cold Sep 40

25DC56, green skin hues May 30 14B36, fading contrast Dec 37

25DC56, excessive brightness without control Dec 36 19GC45Z1, vertical blanking bar locked in25EC58, no UHF reception, VHF normal May 30 center Jun 11


Audio

servicing

with a

swept -

frequency

generatorBy Kirk Vistain, West Chicago, IL

Swept function generators are most valuable for saving large amounts oftechnicians' time. Described briefly are the internal actions of ar, audiosweeper; the typical applications are explained thoroughly.

Swept -frequency functiongenerators (often called audiosweepers) are becoming indispen-sable instruments on many audiotest benches. Although some of thetests normally made by audiosweepers can be done with fargreater precision by other in-struments, the audio sweepers canshorten most tests to a fraction ofthe time necessary with slower andmore accurate generators.

A modern function generatorusually has a switch that selects sine,square or triangle waveshape of theoutput signal over the 20Hz to20kHz audio range plus higher fre-quencies up to 3MHz (depending onthe model). Sine waves are made bymulti -stage soft clipping oftriangular waveshapes. The distor-tion seldom is lower than about 1%.This is satisfactory for all quick testsexcept measurements of total har-monic distortion (THD).

Frequency -response graphsIt is possible to plot the frequency

response of an amplifier or tone -control circuit by applying sinewaves of important frequencies oneat a time and comparing the inputvs. the output signal voltages of thetested device. If the generator has

flat response (within 0.1dB, for ex-ample), the input voltage level canbe neglected and the graph made ofoutput voltages at key frequencies.A line is drawn between the dotsrepresenting the test frequencies.Frequency response of a stereoamplifier might be plotted at each10Hz point between 20Hz and100Hz, each 20Hz point between100Hz and 200Hz, each 200Hz to1 kHz, and perhaps every 1 kHz upto 20kHz. Of course, time can besaved and the accuracy improved bymaking the test frequencies furtherapart where the response has littlevariation, and adding more test fre-quencies in areas showing a largervariation of response.

Clearly, these frequency -responsegraphs can be very helpful (and asaccurate as the test meter), but thepreparation of each graph is timeconsuming. Audio technicians andengineers long ago found methodsof speeding up routine and non-critical response tests.

Automated graphsRotation of a sine wave -generator

dial in synchronism with lateralmovement of an ink -pen recordingchart can produce a continuous andfairly accurate frequency -response

curve. Early systems had cumber-some mechanical linkages betweengeneratcr and chart; more advancedsystems incorporated selsyns. Thismechanical method obviously re-quires excessive trouble, wastedtime and greater expense.

When a hard copy of the responsecurve is not needed, it is more prac-tical to view the curve on a scope,but the older systems could notsweep fast enough for effectivescope viewing. An electronic -sweepsystem was needed.

LSI integrated circuitAbout 1970, the old ink -graph

method was made obsolete bydevelopment of a large-scale in-tegration (LSI) integrated circuitthat provided dial -variable or elec-tronic audio sweep, the usual threeoutput waveforms of functiongenerators, and required only a fewcomponents in addition to the IC(Figure 1). Central to all functiongenerators and audio sweepers is avoltage -controlled oscillator (VCO)that varies frequency according tothe applied dc voltage. This dcvoltage can be varied in severalways: by dc voltage from a variablecontrol with a calibrated dial; an ex-ternal dc voltage, either fixed or


RAMP

GENERATOR

8038FUNCTION GENERATOR

0

VARIABLE

LINEAR

LOG

CONVERTER

FREQUENCY

VERNIER

o-LOG

Figure 1 Several types or auaio-sweep function generators have beenbuilt around Intersil 8038 ICs, asshown in this block diagram. Func-tion generators usually provide achoice of sine, square or trianglewaveshapes. The dcV ramp signalsweeps the repetition frequencywithin the prescribed limits.

Sweep

variable; or a repeated ramp dcvoltage. A switch determines thehighest sweep frequency. Addedversatility is made possible by achoice of linear or log ramps.

Sweep linearityExpansions of low or high fre-

quency portions of the sweep spec-trum are allowed by different rampwaveshapes (see Figure 2).

A linear ramp provides satisfac-tory separation of high frequencies,but it compresses the low frequen-cies below about 1000Hz, whichmight obscure narrow peaks orvalleys that fall between the cycles.

When additional low -frequencycycles are needed, the ramp outputcan be switched through a

logarithmic converter. This logsweep waveform expands the lowfrequencies and compresses the highfrequencies (Figure 2B) to simulatehand -drawn curves on log graphpaper.

q-0

FREQUENCY

RANGE

o-i

IL

SQUARE

(.)

TRIANGLE o. o

SINE

WAVESHAPE

SELECTOR

POWER

SUPPLY

HI 11H I

AUDIO SWEEP GENERATOR

I PI

Figure 2 Linear and logarithmic ramps provide different frequency spreads. (A) Withlinear sweep, the low frequencies (left end of top trace) are compressed while thehigh frequencies (right end of each sweep) are expanded. Lower trace shows thelinear ramp waveform. (B) A log ramp waveform (lower trace) expands the low fre-quencies (left) and compresses the high frequencies (right part of the upper trace).Linear or log is chosen according to need.

Remember that the responsecurve of audio sweep follows thepcsitive tips of the sine waves asthough a line had been added be-tween these tips.

Applications of audio sweepersMeasuring amplifier frequency

response is the most common ap-plication of audio sweepers, asshown in Figure 3. A single stage,several stages or a complete channelof a stereo amplifier, including toneor loudness control, can beevaluated. The sweeper signal isconnected to the desired input; thescope monitors the output. If theoutput stage is designed to drivespeakers, the speaker should bedisconnected and a noninductivehigh -wattage precision resistor (of

the same value as the speaker -impedance rating) should be con-nected as the amplifier's load. Thereare several reasons for using a dum-my load (rather than a speaker) dur-ing response tests. If the test is con-ducted at high volume, the audiblesound would be excessive. Also, theimpedance of any speaker varieswith frequency, so a load resistorprovides the constant load requiredfor accurate tests. Other stagesusually do not require any externalload, so long as the scope does notload the stage excessively. Measuring frequency response.Sine waves must be used for allfrequency -response graphs, whetherproduced by a sweeper or drawnmanually.

Frequency response of swept sine


SWEEP

GENERATOR

---"---1011TPUTRAMP

INPUT

AMP

0 0 0BASS MID TREBLE

VERT HURI/0 00

CHECKING FREQUENCY RESPONSE

Ill

,I,1'

Figure 3 Amplifier stages or complete stereo amplifiers can be checked for frequency response (including tone -control actions)by connecting the audio sweep generator signal to the amplifier input and the amplifier output toa scope (A). A power amplifiermust have a high -wattage noninductive resistor connected to the output as a speaker substitute. (B) Bass boost increases theamplitude of low -frequency sinewaves at the sweep's left side. This audio sweep covered from 50Hz to about 2500Hz; the scopesweep time was 100ms/div. (C) Mid -frequency boost increases the amplitude near the 5kHz center section of the 500Hz to 25kHzgenerator sweep. Markers are at 10kHz and 15kHz. Scope sweep was 10ms/div. (D) Treble boost increased the amplitude of thehigh -frequency sinewaves above about 3kHz at the right end of the sweep. Markers and scope -sweep time are identical with theprevious example. Imagine the response curve as touching the positive -peak tips of each sine wave. Ignore the negative peaks;however, they can be examined for nonsymmetrical waveshapes.

waves is measured from the ac zero -voltage point of each sine wave tothe positive tip of that sine wave.With a waveform sufficiently pureto be called a sine wave, the zero -voltage point is exactly in the ver-tical center of the waveform.Operate the scope in the ac mode toeliminate any supply voltages orother dcV from the waveform.

An excellent procedure, when ac-curacy is needed, is to adjust thescope for a total waveform height ofeight divisions. Move thewaveform's zero -voltage point tothe graticule's center horizontal line.When the scope is in the preferredac mode, this point can be foundeasily by selecting the ground posi-tion of the mode switch. Theresulting line represents zerovoltage. Move the line to cover thecenter graticule line, return to accoupling and carefully adjust thewaveform height for four divisionsabove the line. Each of the fourdivisions then represents 25% of theamplitude. Of course, a response

curve with strong variations shouldhave the highest amplitude pointcover the four divisions.

With precise scope adjustments,the sweep response curve can bemeasured to about 5%, which is ap-proximately 0.5dB. However, mostmeasurements are not that demand-ing and a brief look at the display issufficient.

Remember that scopes arecalibrated in peak -to -peak, whileaudio readings usually are made indecibels. The voltage readings canbe changed mathematically todecibels when necessary. For almostall quick response checks, it is suffi-cient to know only these few ap-proximations: a reduction of about10% is -1dB, a reduction of about30% is -3dB and a reduction ofabout 50% is -6dB. Also, an in-crease of about 10% is + 1dB, an in-crease of about 30% is + 3dB anddouble amplitude (100% increase) is+ 6dB. Scope adjustments. One potentialproblem is obtaining a stable display

on the scope. Triggered scopesusually provide better stability thanis possible from recurrent types. Notall audio -sweep generators have thesame output signal or provide accessto the ramp for locking.

The best display method for real-time applications (not tape or discsignals previously recorded) is to usethe X -Y mode. Single -trace scopesusually provide a way for thesweeper -ramp signal to be amplifiedby the horizontal -sweep amplifierwhile the vertical channel suppliesthe height. Minor adjustments oframp frequency and scope widthshould provide a rock -solid displayof one sweep.

Dual -trace scopes often have X -Ycapability using one channel for ver-tical height and the other forhorizontal sweep (and width).Where available, this is preferredbecause of the extra calibrations.

Scopes without provision for X -Yvector displays must be locked byapplication of the sweeper ramp (orsync) signal to the external -sync in -


SWEEP

GENERATOR

OUTPUT

ki0

RAMP

LEFT IN

RIGHT IN

LEFT OUT°

RIGHT OUTO

TAPE RECORDER

0 O

HORIZ

CHECKING RECORDING BIAS

i

11t VIII nil 11"IPA

111111111 p !II! till

1'Figure 4 Stereo tape recordings can be tested for frequency responseand the effects of recording supersonic bias by connecting

as shown in the (A) block diagram. Recording the ramp signal on one channel provides stable locking of the scope. The

amplitude of supersonic bias affects the audio distortion and high -frequency response of the recorded signal on the tape. (B)

This is the swept -audio signal from the generator, which covers the 500Hz to 25kHz range. (C) Excessive supersonic bias

reduces the amplitude of the high frequencies. (D) Insufficient supersonic bias produces excessive high -frequency response

while increasing the distortion.

Audiocassetteput of the scope. Careful ad-justments of scope sync level,polarity and sweep rate usually pro-vide a stable display.

When testing tape recorders (orother non -real-time applications),the sweeper sync output cannot beused unless the recorder is a stereotype in which the sweep waveformcan be recorded on one channel andthe sync ramp signal on the other(see Figure 4). This works well afterthe optimum recording level is

determined.With monaural tape recorders,

the scope locking must be done bythe scope's internal sync. Thestability might not be steady, but thecurve can be seen well enough formost purposes.

Usually, scope locking stability isnot a problem, because it is easierthan with video waveforms. Mostsweeper and scope combinationsprovide excellent stability.

Keep in mind that the lowestsweeper frequency showing onecomplete cycle on the scope screen is

variable, depending on sweep rate,range and the sweep -rampwaveshape (linear or log). It will notbe less than about five times thereciprocal of the sweeper ramprepetition rate. For a sweeper logramp of 10ms, the lowest complete -cycle frequency is about 500Hz. A100ms log ramp would show alowest signal frequency of about50Hz. To display a complete 20Hz-20kHz audio spectrum, a ramp fre-quency of 4Hz (250ms) is required.Unfortunately, a storage scope isnecessary to prevent flickering.

Practical experience indicates thatoptimum coverage is produced by aramp rep frequency of 60Hz (16ms)which gives adequate results downto about 300Hz of sweeper -outputsignal. This is sufficient for tape -recorder adjustments and other ap-plications.

It is instructive to connect thesweeper and scope to an amplifierhaving tone controls and watch thescreen while the controls are ad-justed (Figure 3). Notice that thecurve (tips of sine waves) is different

from an RF or IF sweep -alignmentcurve demodulated to remove thecarrier and thus display only theamplitude variations. Audio sweepshows the carrier sine waves, in-cluding both positive and negativepeaks.

The ability to examine both sinewave peaks often is an advantage,because various kinds of distortionappear as symmetry unbalance(positive and negative peaks notidentical).

Adjusting recorder biasPerhaps the most valuable ap-

plication of an audio sweeper is ad-justing recording bias and head tiltin audiotape recorders, particularlywith two -head models that preventreal-time monitoring during re-cording.

Before swept -audio generatorswere available, it was necessary toperform a tedious and expensiveseries of spot frequency recordingsand playbacks before finding theoptimum amplitude of supersonicrecording bias (Figure 4). For exam -


SWEEP

GENERATOR

OUTPUT

GND

SPEAKER

VERT0

RAMP

H OR IL

0-

CHECKING SPEAKER IMPEDANCE

OR

SYNC

Figure 5 Variations of speaker im-pedance and identification of any reso-nant points can be viewed by connectinga resistor (perhaps 100ft) betweensweeper and speaker. Most speakershave a large impedance increase at thecone -resonant point, a minimum im-pedance at perhaps 400Hz and rising im-pedance to the audio limits. (Allowancesmust be made for horns and tweeters.)Crossovers can also be tested. If theseries resistor is made equal to thespeaker's rated impedance, the sweptcurve will trace the approximate fre-quency response of the speaker.

ple, it was necessary to record at1kHz and 10kHz, rewind and checkthe relative levels. If they were notthe same, the bias amplitude was ad-justed and the recording andplayback steps repeated until the op-timum point was reached. Withcassette machines, tape dropoutsoften gave false results that com-pounded the problem and requiredrepeated tests.

With an audio -sweep generator, itstill is necessary to record, rewindand evaluate, but the information ismore complete. A low 20kHz levelbecause of a dropout becomes visi-ble, eliminating confusing results.Also, it can be seen if optimum bias-ing for 10kHz has placed a peak at5kHz or some other frequency.

This information can be obtainedby plotting many frequencies forseveral recordings, but the sweeperinformation is obtained inmilliseconds vs. several minutes byseparate frequency tests.

Another helpful procedure is toproduce a working test tape. Fewcommercial test tapes have swepttones, but usually have discrete fre-quencies in sequence, and perhapsfive minutes is required to check

playback alignment.A sweep tape can be made using a

high quality tape machine that hasbeen calibrated carefully from astandard non -sweep test tape so it isflat over the required range. Thenthe sweep generator is used torecord a swept -audio test tape. Ifcare is used in calibration and re-cording, the tape is a good workingstandard test tape that permits rapidadjustments of playback equaliza-tion and azimuth.

Checking VU metersSpecifications of professional

volume -unit (VU) level meters callfor identical readings of a con-tinuous 1000Hz tone and the sametone in 300Hz bursts. A 1000Hztone that regularly is keyed on for0.3s and off for 0.7s should producethe same VU -meter reading as acontinuous 1000Hz tone of the sameamplitude produces.

If the audio -sweep generator hasa tone -burst function, it can be usedto determine whether the VU metermeets this standard. Adjust a fre-quency counter for sampling at a1Hz or longer rate and vary thenumber of cycles in the burst untilthe counter reads 300. If the audiosignal has been previously adjustedfor a 1000Hz tone burst at 1 secondintervals, the burst should contain300Hz of the 1000Hz signal.

VU meters in professional -qualitytape recorders probably will meetthe specification, but most cassettemachines will not, because thelimited headroom does not permitthat much damping.

Speaker and crossover checksFigure 5 shows how to test

speaker resonant points and im-pedance across the audio band. Theresistor between speaker andsweeper should have a value about10 times the speaker impedance sothe change of impedance will pro-duce a large, easily interpreted in-dication.

Woofer speakers have a largeresonance somewhere in the 20Hz to100Hz range that shows as a peak inthe sweep waveform. Others mighthave resonance near their cutoff fre-quency, and a possibility of minorimpedance peaks at higher fre-quencies.

Individual speakers connected bycrossovers can be tested for the ef-fects of the crossover sections andthe resonances by feeding the sweepthrough a resistor to the crossoverinput and placing the scope acrosseach woofer, midrange and tweeterin turn.

Other applicationsBecause many swept function

generators have repetition rates upto one or more megaHertzes, theycan be used to sweep -align the RFand IF stages of AM radios, tomeasure the locking range and cap-ture range of PLLs, determinepower -supply resonance or to testand calibrate speedometers andtachometers under dynamic condi-tions.

Other uses are possible in researchand development work, com-munications and related fields.Swept -frequency function genera-tors are versatile instruments ofgreat usefulness in many applica-tions. For stereo and audiotaperecording servicing, these audiosweepers are indispensable.


Audio performance and audioproducts have matured. No longeran afterthought, these new audioproducts have specifications equalto the complex and sophisticatedcircuit designs. And the repair ofthese complicated machinesdemands technicians well -trainedand highly qualified.

In the same way, the test -benchinstruments must match or exceedthe exacting specifications of themachines tested. Test equipment isrequired for troubleshooting ob-vious defects as well as performanceverification (proof of distortion,frequency response and noisespecifications). General suggestionsabout suitable types of equipmentwill be given.

Audio equipment often is com-bined with eight -track, cassette oropen -reel tape machines,phonograph turntables andchangers, and combinations of AM,FM or AM/FM-multiplex radiotuners. A competent audio techni-cian must be capable of repairingand calibrating RF, IF andmultiplex radio circuits, andmechanical systems in addition toaudio stages. Also, many of thecassette decks, FM digital -tuningsystems and function selectors havemicroprocessor or other controllogic.

Test -equipment requirementsThe following list shows the most

essential audio test equipment:

The well-equipped

audio test benchBy Kirk Vistain, West Chicago, IL

Test equipment for an audio -repair bench is determinedby the product specifications and the types of measurements.

oscilloscope. For waveform infor-mation, a good scope is imperative.A high quality dual -trace triggeredscope with a top response of around30MHz is recommended. The dual -trace feature allows comparisons ofamplitude and waveform betweentwo stereo channels. Wide band-width is needed for accuratereproduction of fast -rise -timewaveshapes and for analyzing IFwaveforms in FM receivers. ac millivoltmeter. A dual -channel meter calibrated in dBmW,dBV and RMS acV is preferred. Itshould have frequency responsefrom 20Hz to 1MHz and measuredown to lmV. Millivoltmeters areused for testing stereo separation,power output, signal-to-noise ratioand tape -recorder calibrations. FM signal generator. One essen-tial is a precision and calibrated at-tenuator capable of providing FM -carrier frequencies at levels between0.51.1.V and 10,000µV across 300u .The built-in multiplex generatorshould have a channel separation of50dB or more. Composite and IFoutputs are helpful. And the audiototal harmonic distortion (THD)should be lower than 0.1%. distortion analyzer. This instru-ment should have a low -distortionvariable -frequency audio sine wavesignal and a harmonic -distortionmeter that doubles as an acmillivoltmeter. Combining thesethree functions in one instrumentreduces the cabling and interfacing

problems while saving bench spaceand cost. Because the THD meteroften is called on to measure lessthan 0.01% distortion, the distor-tion analyzer should read to 0.001%or better over the 10Hz to 100kHzrange. swept function generator. A func-tion generator provides a choice ofsine, triangle or square waveforms.Purity of the sine waves can bearound 1010, because lower distor-tion is needed for performanceverification and not for servicing.Linear and log sweeping of frequen-cy allows quick and approximatemeasurements of frequencyresponse, tone -control action andthe optimum level of tape recordingac bias. Square waves help revealdamped oscillation and slow slewrate. A frequency repetition be-

tween 3Hz and 3MHz is recom-mended with sine -wave THD lessthan 107o, output flatness better than0.5dB across the range, and risetime of faster than 6Ons. Otheruseful features are an output offsetdcV, burst adjustments and sym-metry adjustments. wow -and -flutter meter. Thesemeters are essential for evaluatingthe drive -system performance ofdisc turntables and tape machines.A test signal of 3kHz is measuredfor any undesired frequencymodulation by the dive system. Afull-scale sensitivity of 0.1% and achoice of several weighting modesare desirable. Also, most wow -and -


A Swept -function generatorB Wow and flutter meterC Dual -channel millivoltmeter

flutter meters can measure drift (along-term speed variation). Moredetails were given on pages 22 and23 in the December 1980 issue ofElectronic Servicing. conventional test instruments.Additionally, a well-equipped audiobench should have basic in-struments, such as a digitalmultitester, variable acVtransformer, VOM, transistor testerand an adjustable power supply.

Specialized devices include these:test speakers, non -inductive 8 thigh -wattage load resistors, an FM -stereo radio receiver, many testtapes and records, and gauges formeasuring tension, torque andmechanical clearance. Another

D MillivoltmeterE Distortion analyzerF Dual -trace oscilloscope

necessity is a test panel that permitsswitch selection of the most com-monly used interconnections.

Of course, soldering irons,vacuum -type solder removers,greases and chemicals, hand tools,and a stock of transistors andreplacement parts are required.

Future needsProbably, an AM -stereo

generator will be needed in the nearfuture, after a single standard isadopted. Few AM -radio sections arecomplex enough to require anysophisticated test equipment.

As microprocessors and digital -logic circuits become more popular,a digital test probe will be essential.

G Stereo receiverH Test panelI Variable AC supply

N ideo equipment needsMany audio and auto -sound

shops now are servicing videodiscplayers and videocassette tapemachines. This requires other testdevices such as an NTSC (or phase-

locked) generator, video monitor,test tapes and discs, mechanicalgauges and various test jigs.

The homes of the future willprobably have integrated audio/video reproduction systems orhome -entertainment centers undermicroprocessor control. Othertechnicans with a broad experienceand basic knowledge of solid-state,audio, video, mechanical and digitalproducts will find servicing thesenew products profitable.


Typical autoaudiocassette

repairsService problems in auto versions of cassette tape machines

are similar to those in portable or deck types,although unusual symptoms are encountered occasionally.

Twelve typical case histories are described.

By Homer L. Davidson, Davidson Radio & TV, Fort Dodge, IA

About 60% of all problems withcassette players in autos originate inthe mechanical system; the other40% are electronic problems. Andabout 85% of the mechanicalfailures involve complaints of slowtape speed or tape dragging.

Most people do not notice a tape -speed error up to 10% if the incor-rect speed is constant. However, theslightest variation can be noticed as

a pitch change. A slow change oftape speed produces wow; rapidvariations cause flutter. Manycassette machines have AM/FMradios included (Figure 1).

Details of 12 problems with autoaudiocassette machines arepresented.

Wow problemsThe first step in all cases of wow

Figure 1 Many auto cassette players (or player/recorders) arecombined with AM/FM/stereo radios. One audio channel wasrepaired by replacement of the power -output integrated cir-cuit.

is to clean all moving parts withalcohol and a cleaning stick.Remove any oil from rubber -tiredrive pulleys or spindles. Use tape -head cleaner on the capstan,pressure roller and head to removeoxide. Clean the cassette -loadingarea using alcohol on a cloth. Checkthe motor drive belt for worn areasor cracks (Figure 1). Remove par-ticles of rubber or other residuefrom the motor pulley. Check for aloose drive belt. It can cause wow.Hold the flywheel while the motor

Figure 2 Check for a motor drive belt that is broken or off thepulley. Next, examine the belt for oil or cracks. Hold theflywheel while the motor is rotating. If the motor pulley con-tinues to tuf.-, in3ido the belt. replace the belt.


rotates. If the motor shaft spinseasily inside the belt, a new drivebelt should be installed.

Sanyo FF453MEven after cleaning and lubrica-

tion are completed, some speedvariations were noticed. Some autocassette players have a variable con-trol to adjust the proper tape -travelspeed. The control varies the power -

supply voltage and thus the motorspeed. In this case, adjustment ofthe control (following a thoroughcleanup) solved the problem.

Speed differences betweenmachines

Customer complaints sometimesare caused by playing a certain tapeon an auto cassette having slightlyslow speed, after the tape had beenrecorded on a home deck which wasrunning a bit fast. Such an extremedifference in music pitch from thetwo speeds can be noticed easily.

The solution is to use a test tapeto measure the speed. Or, check themachines with a tape recorded on aprofessional -quality machine.

Craig XA93Intermittent mechanical opera -

Figure 3 Before removing a belt, make asketch, as shown at B, showing the patharound pulleys and flywheels. Use thedrawing to prevent mistakes during in-stallation of a new belt.

tion was the complaint about theCraig. After the metal bottom coverwas removed, several puddles of oilcould be seen, and oil continued todrip from the mechanism. This wasa clear case of the owner's using ex-cessive oil in a futile attempt to solvea slow -speed or wow problem.

When over -oiling is found, it isbest to remove most rotating com-ponents. Each rubber -tire wheel ordriving surface must be cleanedthoroughly with alcohol and abrush. In extreme cases, these partsshould be allowed to soak in a panof alcohol for a time. A solution ofcleaning detergent also can be used.

Although the flywheels are metal,any oil remaining on them can dripor run onto other components.Flywheels should also be cleaned ofoil.

A motor -drive belt that has beensaturated with oil should be re-placed because it might have stretch-ed or softened from the oil. Beforethe belt is removed, draw a sketch ofthe belt's path around the variousrotating surfaces (Figure 3). Thediagram eliminates much trial -and -

error experimenting. Replace a drivebelt with one of the original lengthor about 1/4 -inch shorter.

Fast tape travelA model JS600 Met Sound

machine having automatic reversinghad normal tape speed in one direc-tion but fast speed in the other.After the metal covers were re-moved, two separate capstans andflywheels were revealed. However,the flywheel and belt -drives ap-peared to be normal. The belt wasremoved and all surfaces werecleaned with alcohol and a cloth.

During an attempt to clean theseparate pressure rollers andcapstans, several turns of tape werefound wrapped around one capstanshaft. This gives the effect of alarger shaft diameter, thus movingthe tape faster.

The tape was cut away, revealinga large buildup of oxide residue. Toprevent damage to the capstanshaft, a plastic -blade screwdriverwas used to scrape away the oxide,then alcohol on a cleaning tipremoved the remainder. Nextchecked were bearings of thepressure roller and the area betweenthe support bracket and thepressure -roller bearing.

After these repairs, the forwardand reverse tape speeds were iden-tical.

Figure 4 When tape -travel is too fast, check for tape scraps wrapped around thecapstan shaft and for a motor drive belt that rides too high on the motor pulley. Adefective motor also can run fast. But check for a speed control before replacing amotor. The control might be defective or misadjusted


Audiocassette

Defects causing fast tape travelare rare. Other possible causes (inaddition to tape wrapped aroundthe capstan shaft) are a defectivemotor or a defective or misadjustedspeed control (Figure 4).

In another repair, the 2400 -RPMmotor in a Pioneer model KP4000cassette player was found to be pro-ducing excessively fast tape speed.

Craig model 3510 withconstant reversing

Some auto cassette players have areverse button for manual trackchange plus an automatic -reversesystem that at the end of a tape willmove the head contacts and reversethe tape movement to play the tape'sother track. Such models usuallyhave two capstan/flywheelassemblies and two heads.

In the Craig model 3510, thedirection of tape travel was reversedquickly before the tape could play inthe forward direction. This causedswitching sounds without audio in

the speakers.The usual cause of track -

switching at the incorrect timeis a problem of corroded com-mutator slip -ring contacts. Thiscommutator assembly is below thecapstan -pulley system.

In the Craig model 3510, the com-mutator is driven by a small rubberbelt, which was missing. After asearch, the belt was discovered inthe bottom of the player. Without abelt, the commutator will notrotate, thus applying power con-stantly to the reverse solenoid andkeeping the tape movement re-versed. This rapid reversing actionwill force the end -of -play light toflash on and off.

Directly driven commutatorsusually can be repaired quickly bycleaning the commutator rings withalcohol and a cleaning stick. Also,make sure the small metal switchtongs are clean. In belt -drivenmodels, the commutator belt mustbe in place and not dragging or slip -

Figure 5 Tape wound around the capstan shaft and erratic fastforward can be caused by insufficient torque of the take-upreel. Examine the take-up reel to determine whether it has atension adjustment. The one shown has spider -type flatsprings that can be lifted up and moved to the next high step inthe plastic hub.

ping. Clean it in the same way as thecapstan belts. Make certain themetal screws holding the com-mutator contact tongs are tight andin line with the corresponding ringson the commutator shaft.

Tape jammingwithout fast forward

Suspect problems with the take-up spindle assembly when symp-toms of no fast forward combinedwith tape jamming are found. Whenthe take-up reel is not rotating, thetape is pulled out of the cassette bythe capstan and pressure roller, butit does not reel onto the take-uphub. Instead, the tape wraps aroundthe capstan or pressure roller, caus-ing a jam. The jamming can be erra-tic, of course.

A Panasonic model RS -246S hadthese two symptoms: When the bot-tom cover was removed, a smallpulley was found rolling aroundloose inside the machine. A visualinspection proved the small drive

Figure 6 Failure to load or improper loading of the cassettecan be caused by missing or broken tension springs or a bentloading platform. Models with end loading (shown here) shouldbe checked for correct clearance and set -down of the cassette.If a reel spider or shaft is bent, the cassette hubs might beprevented from sliding over the loading reels.


cam and rubber pulley had fallenfrom the bottom of the take-up reelassembly. Securing the same pulleywith a new "C" washer cured thetape jamming and the lack of fastforward.

Tape jammingTape jamming when it incorrectly

winds around the capstan can becaused also by insufficient tensionof the take-up reel slip clutch. Alltake-up reels must slip at the correcttape tension to accommodate thedifference between capstan and reelrotations as the diameter of thewound tape changes. This is acritical balance between too much

FLYWHEEL DROPPED CAPSTAN FLYWHEEL FLYWHEEL DRAGGING

SUPPORT BRACKET

FLYWHEEL PROBLEMSBENT BRACKET

Figure 7 A continuous scraping noise can result from a loose flywheel that ridesagainst the bracket. A bent bracket also allows contact with the flywheel.

Figure 8 Broken wires at the playback head might cause intermittent volume in oneor both channels or a buzzing, rushing sound. Usually these joints can be resolcered.

tension (perhaps breaking the tapeor causing tape slippage past thecapstan) and too little tension thatstops proper reeling of the tape andallows the tape to build up andbecome caught by the capstan.

Some cassette machines alloweasy adjustment of the take-up ten-sion by moving the spider -typepressure springs on the plastic take-up spindle (Figure 5) to a higherplateau.

Other machines provide a smallset screw. Rotation of the set screwchanges the slip -clutch tension.

An Audio Flair model 501 had aloose "C" washer at the top of thetake-up spindle which allowed thespindle to rise too high, thus lessen-ing the tension and allowing take-upslippage. A loose plastic cap on topof the spindle also can cause theproblem.

Improper tape movement in othermachines can be produced by dirtyor sticky capstan shafts or pressure -roller assemblies. Clean themthoroughly with alcohol. Check thecapstan shaft for score marks orgrooves. If the problem repeatsfollowing cleaning, install a newcapstan/flywheel assembly.

Defective cassettes can also pre-vent smooth movement of the tape.When other individual cassettesoperate normally, the one thatdoesn't is to blame. These cassettesshould be discarded, althoughtransfer of the tape to a repair bodysometimes cures the problem.

Gibbs model 1807 ejectscassette

Suspect a defective loadingmechanism or a corroded revolvingcommutator if a cassette plays just afew seconds and then is ejected.This happened with a Gibbs model1807, and a thorough cleaning ofthe commutator contacts solved theproblem.

Other machines should have thelocking levers of the mechanical -loading assembly checked. They cancause mechanical ejection. Clean alllevers and lubricated bearings of theloading assembly. Improper springtension can result in poor seating ofthe loading platform.

With models having a pressure -type -tension ejection system, check


Audiocassette

for dry or hard -to -rotate take-upspindles. Any increased tension canactivate the end -of -tape mode, caus-ing the ejection of the cassette (asthough it is at the end of the tape).A defective cassette with its tapewound too tightly can force erraticejection of the cassette.

Failure to loadSome cassettes are loaded into the

tape machine lengthwise (endloading). Others have front loadingwith the cassette's rear edge insertedfirst. When a cassette will not seatproperly, suspect foreign objects inthe loading area. Or the loadingplatform might be stuck in a wrongposition. In mechanical -loadingplatforms, check for worn or bentlevers and sliding areas withoutlubrication. Also, stretched or weakloading springs (see Figure 6) cancause incorrect tension.

Clean off all dirt and grease fromthe sliding areas, using a light oil.This often cures failure to load.

In a Craig model 59, the cassette

would not seat. Lubrication of bear-ings and sliding -cam areas using oilsolved the loading problem. Tensionof a weak loading spring can be in-creased sometimes by cutting offone or two turns and re -attachingthat end.

If the machine has end loading,check for a bent spindle. Aftermany hours of operation, the rear-most spindle can be bent enoughthat the cassette hub cannot be slidover the mechanism's spindle. Thespindle bearing might be bent to oneside. If the shaft cannot be alignedproperly, a new one should be in-stalled.

Grinding noise inSanyo FT642

A continuous grinding noise dur-ing operation of a Sanyo machinewas caused by a bent bracket underthe flywheel (Figure 7), allowing theflywheel to ride on the bracket.Usually, a bent bracket can bestraightened.

The same noise can be produced

VR2-D

VOLUME

C54 47pF

R51 68t! ON OFF

ieb--4- + 12V

14 13 12 11 10 9

IC102AUDIO

2 3

C53 "i.gti.100/tF

50K

C52'- R54

10022

8

6 7

560(.1C62

470pF

TO RIGHT

CHANNEL

470pF SPEAKER

C56

TROUBLESOME COMPONENTS

Figure 9 After dc -voltage and ohmmeter tests around an IC have failed to prove an in-tegrated circuit is defective, remove the IC and use an ohmmeter to test all resistorsand capacitors in the circuit. These power -output ICs sometimes produce loisysound. C53 gave trouble in one machine.

when a metal flywheel becomesloose and moves down the capstanshaft. If the flywheel is loose on theshaft, a new assembly must be in-stalled.

Loud continuous noiseA Pioneer model KP4000 had a

loud continuous buzzing noise whena tape was played and the volumecontrol was at maximum. Reducingthe volume -control setting reducedthe noise, indicating the audiostages were not the cause. One com-mon problem (with models thatmove the tape heads during loading)is broken wires at the heads. Yearsof operation often break thesedelicate, shielded wires.

Locate the broken joints visuallyand then solder them carefully(Figure 8).

One channel deadA defective output transistor is

the most likely suspect when novolume is obtained in one stereospeaker. Many newer models haveone or two ICs for output poweramplifiers of both channels.

There is no practical method oftesting these ICs, but dc -voltagesand signal -tracing tests should bemade before a suspected IC isreplaced. An audio -output IC wasreplaced in a Sanyo model FLT418,but unfortuntely the machine stillfailed to operate.

While a suspected IC is removedand before a new one is installed, itis best to check all resistors andcapacitors of the stage with an ohm-meter. These tests can find out -of -tolerance resistors and shorted orleaky capacitors.

In the Sanyo, the C53 100pFbypass capacitor was leaking(Figure 9), and this eliminated allsound from the right -channelspeakers.

SummaryThe majority of problems in auto

audiocassette tape player/recordersoriginate in the mechanism. Often,a thorough clean-up and minimumlubrication will solve most speedproblems. Remember, excessiveamounts of lubricant sometimes willproduce other defects in the future.Do not over -oil or over -lubricate. 0


For the man that would rather fix it himself

Technical Publications hasservice manuals designed for you!SES-13 Small (Air Cooled) Engines Service Manual. $9.95(336 pages). You can service your own engines onlawnmowers, tractor sprayers and other power equip-ment. Special section on fundamentals, troubleshooting,preventive maintenance. Step-by-step instructions.

WLMS-1 Walking Lawnmower Service Manual $7.95 (128pages). The complete guide to the care and repair of yourwalk -behind, push -type lawnmower. Exploded views anddiagrams.

CSS-6 Chain Saw Service Manual. $8.95 (over 300 pages).Here's everything you need to know to tear down, repair,reassemble and adjust most popular chain saws. A trulycomplete chain saw manual.

GSM -1 Small AC Generator Service Manual $7.95. A brandnew manual that contains maintenance, service andtroubleshcoting procedures, as well as wiring schematicsfor most generator models. Covers electrical powerplantsunder 8kW that generate alternating current and aredriven by air cooled engines.

OS1-8 Outboard Motor Service Manual Volume 1 $8.95(236 pages). Covers motors below 30 hp.

0S2.8 Outboard Motor Service Manual Volume 2 $8.95(232 pages). Covers motors with 30 hp and above. BothVolumes 1 and 2 provide detailed fundamentals onperiodic servicing.

Put these books to work on your own equipment...(Or service outside equipment for profit!)

C Small (Air Cooled) Engines Service Manual1 . Walking Lawnmower Service Manual

Chain Saw Service Manual Small AC Generator Service Manual Outboard Motor Service Manual (Vol. 1) Outboard Motor Service Manual (Vol. 2)

Remittance must accompany orders of less than $25.00.Postage paid when payment accompanies order. Allow lourweeks for delivery.

How to send money: The best way to send money is yourown personal check, post office money order, expressmoney order or by bank draft or check. DO NOT SEND CUR-RENCY OR STAMPS.

Check Money Order Enclosed Ship C.O.D. (No C.O.D.s outside of U.S.)

Missouri and Kansas Residents add 4% sales tax.Tennessee Residents add 6% sales tax.

Write for a free catalog covering our entire line of servicemanuals and wheel -type tractor service manuals. VISA MASTERCHARGECredit Card NumberExpiration Date

L

Please Print.

Name

Street

City

State Zip

Signature

124 TechnicalW Publications

DivisionIntertee Publishing Corp.P.O. Box 12901, Dept. ESOverland Park, KS 66212(913) 666.466

test mimeo! YET111

Inexpensive scopeBritish -made, dual trace and solid

state model 14D-10, from ScopexInstruments, is expected to sell forabout $700. The unit provides a

aaimmx

switched -mode power supply, 2mVsensitivity over its full bandwidth of10 MHz, an add and invert facilityand X -Y operation. Additionalfeatures are a display area of 3.9 x3.1 inches (100mm x 80mm) and fullprobe compensation. The add andinvert facility enables computer ser-vice engineers to align floppy diskdrives and other peripherals.


reader's /of

DMM, true RMSSimpson Electric has announced

availability of model 461-2R, a new,compact, hand -portable digitalmultimeter that reads true RMS onac voltage and ac current ranges. It

t::

-.0n.1: ait

has frequency response up to 50kHz and will respond to the RMSvalue of any wave shape, thus pro-viding more accurate measurementsof noisy or complex ac voltagewaveforms.


TV sync measurementTelevision sync capabilities have

been added to Hewlett-Packard's100 MHz models 1740A, 1741A,and 1742A oscilloscopes. This newoption (005) adds the circuits andcontrols necessary for triggering ona composite video signal whilemaintaining measurement capabili-ties for design and troubleshooting.Scope inputs are modified to pro-vide matching to video signals.Channel A incorporates a built-in 75ohm input for impedance matchingmost video sources. Channel B has aTV clamp that stabilizes the displayof video signals. This TV sync cir-cuit locks on to one complete frameof video, with switching betweenfields accomplished with a pushbut-ton. TV line scan capability allowsindividual lines to be singled out forinspection and measurement. Seg-ments of individual lines may alsobe examined in the triggered mode.


Needed: Hickok models 539A or 539B tube tester ingood condition. Paul Capito, 637 W. 21st St., Erie,PA 16502.

Needed: TV service manuals that include flowtroubleshooting charts like those in RCA TechnicalReference Library, Tab books, GE, Motorola, Zenithand other manufacturers. Will buy used. Also needed:Variac power supply. P. {later, 428 W. RooseveltBlvd., Philadelphia, PA 19120.

Needed: Any schematics manuals for radio, TV tester.Will buy or copy and return. Monami, Box 194,Ridgefield, NJ 07657.

Needed: Manual and schematic for Watermanpocketscope model S1OA. Will buy or trade test equip-ment for Sencore YF33 ringer, or Heathkit yoke -flyback tester, Ken Miller, 10027 Calvin St., Pitts-burgh, PA 15235.

Needed: Schematic for GEC Consolidated Elec-trodynamics Corporation test oscillator model 20A.

Alectra division. C. Jorgensen, 41778 Fremont Blvd.,Fremont, CA 94538.

Needed: Old radio tube of the 01 (or similar) type thatcontains an evaporated magnesium "getter," for use inX-ray generation experiments. Pat Kelly, 2211-C S.Atlantic Blvd., Commerce, CA 90040.

Needed: Will buy or borrow manuals for RCAWR64B (bar/dot generator), W969A (TV sweepgenerator), WA44C (audio generator), WR5OB (RFgenerator), Hickok 615 (sweep/mark generator),Telohmike Sprague TO -6. Ed Howell, Box 73, FollyBeach, SC 29439.

Needed: B and K CB signal generator model 2040 orequivalent. The T. V. Shop, 1461 Senter, Burlington,CO 80807.

Needed: Good used or new 520KB22 and 320AWB22picture tubes. Send cost detail to H. Geller, 12622N.E. 3rd St., Bellevue, WA 98005.


TV turn on now owner's optionTo prevent unauthorized use of

TV sets and other electrical equip-ment and to forestall "walk away"thefts of small electrical items: NewIdeas' Electric Plug Pad-lok. NewIdeas, Inc., responding to a publicneed recognized by Cable TV,modified the shackles of suitablepadlocks so that almost any electricplug may be locked effectively.

Cost of the Electric Plug Pad-lokis $4.95 for a package of two brasslocks ant' six keys.


RFI filterClifford Industries has an-

nounced an RFI filter to preventradio RFI from causing power sup-plies to shut down. Circuits in theVista power supplies have over -voltage protection (OVP) current -limit and fold -back circuits. Thesecircuits were being affected byvoltage spikes caused by RFItransmission in close proximity tothe power supply.

Vista's line of power suppliesfrom 10 amps through 55 amps hasan adjustable output voltage of 13.2to 14.4 volts. Meteredunits -2ORM, 3ORM and5ORM -can be adjusted from 3 to15 volts


Soldering aid tools in new shapesDesco Industries Inc. is producing

a line of soldering aids that featuresnew designs, made from stainlesssteel for its non wetting and nonmagnetic properties. Plastic handlesare designed to fit the hand for re-duced fatigue and surgical control.


Pocket phoneAn addition to their line of

Freedom Phone cordless telephoneshas been announced by ElectraCompany, a division of Masco Cor-poration of Indiana. The pocket-size unit offers full capabilities of aregular phone, yet can be operatedup to 600 ft. away from its connec-

tion to the phone line. With its baseunit centrally located, completemobility, without a cord, isavailable over approximately aquarter -mile square area. The phonecan be used to make outgoing callsas well as take calls, indoors or out.

The new Pocket Freedom Phoneis an inch in depth, 2 3/4 -inches wide,and 5 3/41 -inches long, finished inblack and grey. Although designedto be pocketable, the phone has anoptional carrying case and belt loop.Suggested retail price: $329.95.


Solder cream Vapor phaseA solder cream formulated for

use with vapor phase reflow solder-ing systems has been developed byMulticore Solders.

Conventional solder creams cause"solder balling." This occursbecause of the solvation or washingeffect created by the vapors whichpreferentially remove the flux fromthe soldering area before it reachesits activation temperature. Thesesolder balls are generally indicativeof poor wetting or dewetting andcan create potential electrical shorts.

Multicore's vapor phase soldercream provides oxide -free solderparticles homogeneously dispersedin a highly efficient non -corrosiveRA, RMA or non -cleaning Xersinflux medium. The flux has been for-mulated to overcome the vaporwashing effect problem. The systemhas been proved in extensive testingusing commonly used vapor phaseprocess liquids.

Vapor phase solder cream can beapplied by screen or syringe and isavailable in 25g syringes or 500gjars.


Temp check displayMicro Electronic Systems an-

nounces the Hot Spot, a hand-heldunit that displays the temperaturefor control in iron tip soldering. Aconnector permits use with standardMCr-NiAl thermocouples.



ramarketalace

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Each initial or abbreviation counts a full word.

Minimum classified charge $3.00.

For ads on which replies are sent to us forforwarding (blind ads), there is an additionalcharge of 53.00 per insertion to cover departmentnumber, processing of replies, and mailing costs.

Classified columns are not open to advertising ofany products regularly produced by manufactur-ers unless used and no longer owned by themanufacturer or distributor.

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FOR SALE: SAMS PHOTOFACTS-090 thru 598 Com-plete. S400.00 or best offer plus shipping. Also manyservice and text manuals, list sent with SASE. TECHSURPLUS, 2615 Harwood Road, Baltimore, Maryland,21234

5-81-1t

FOR SALE: Well established RCA Sales and Serviceshop near beautiful Minnesota River, attached tocountry store and spacious 3 bedroom home. Fordetails call owner, 507-925-4448. 5-81-21

T.V. AND 2 -WAY RADIO TECHNICIANS WANTED forimmediate employment. Excellent salary, fringebenefits, good working conditions with progressiveElectronic Retail -Service Corporation. Miller's Elec-tronics, Inc. -Hwy 24 - Goodland, Kansas 67735.913-899-2386. Equal Opportunity Employer 5-81-1t

"SUPREME Television -Radio Diagram manuals dis-counted 60%. Free information. SASE. Beitman, 1760Balsam, Highland Park, IL 60035." 5-81-1t

1 - 88K 415 Swoopmarkin Generator -S250,1- Tektronix 524AD Scope - $250; 2 - PrecisionUTUM EV-10 both - S100.00; 1 - RCA WO -91BScope -$200.00. TELE-Sonic, 164 Halstead Ave., Har-rison NY 10528,914-835-0111 5.81-21

WANTED: SENCORE YF33 RINGER - Mitchell Elec.tronics, 4 Golf Ave.. Maywood, NJ. 07607. 5-811 t

SAMS PHOTOFACTS 33-796 30% complete. Sell all orpart. List available. R. L. Wollam, 1 Woods Ct., Hun-tington, NY 11743. 5-81-11

PRINTED CIRCUIT boards from your sketch or art-work. Affordable prices. Also fun kit projects. Freedetails DANOCINTHS INC Dept. ES, Box 261,Westland, M148185. 5.81 -tin

30 CHANNELCABLE TV

CONVERTER

ORDER No. 196AE047

E "I`CO ROUTE 9N.PLATTSBURGH, N.Y. 12901Tel.: 15181 561-8700.


TUBES FOR TV AND RADIO -3.5s ea. Washington TVService, 1330 E. Florence Ave., Los Angeles, CA 90001.

3-81-9t

SAMS PHOTOFACTS, 1 thru 1899 complete withcabinets $1100.00. No delivery. Oaklandon Elec-tronics, 7145 HAWKS HILL RD., Oaklandon, IN 46236317/823-6338. 5-81-1t

WantedNEED GOOD USED 520KB22 and 320AWBZZ CRT's. H.Geller, 12622 NE Third, Bellevue, Washington, 98005.

5-81-1t

MIRROR IN THE LID, and other PRE -1946 Televisionsets wanted for substantial cash. Also interested in12AP4, MW -31-3 Pre -War picture tubes, parts,literature on Pre -War Television, Arnold Chase, 9Rushleigh Road. West Hartford, Conn. 06117 (203)521.5280 241-71

DESPERATELY NEED: Information on "Telicon" pro-jection TVs from 1947, RCA "Test Lamp" for 1940'sprojection TVs. Arnold Chase, 9 Rushleigh Road. WestHartford, Conn. 06117 (203) 521-5280. 2-81-7t

Business OpportunityTV TECHNICIAN! Increase your income up to$60,000 yearly. Rent -lease -sell TVs new -used,even from comfort of your home. Basic Prelimi-naries S4 00. Perrys TV Systems, Hwy. 181 Box142, R1, Bremen, KY 42325 12-80-tf

FIX IT FAST WITH PHOTOFACP. Photofacto 1981 In-dex lists available service data for over 110,000 TV's,Radios, CB's, Auto Radios, Scanner -Monitors, andVCR's produced since 1946. Send $2.50 plus 50 centsshipping to Howard W. Sams Co., Dept. X 0115, 4300W. 62nd St., Indpls., IN 46268. 3.81-31

To get moreInformation...on items advertised ordescribed in this publica-tion, use the Reader Ser-vice Card.As a free service for ourreaders, we forward yourinquiry to the product'smanufacturer. Reader Ser-vice Card is pre -ad-dressed.

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Electronic ServicingAthertlaIng Sales offices

NATIONAL SALES MANAGERGreg Garrison,P.O. Box 12901,Overland Park, KS 66212Phone: (913) 888-4664

LONDON, ENGLANDJohn Ashcroft & Co . John Ashcraft,12 Bear St.Leicester Square, London, WC2H 7ASEnglandPhone: 930-0525Telex: 895-2387

AMSTERDAM, HOLLANDJohn Ashcraft 6 Co.. John J. Lucassen,Akerdijk 150A, 1171 PV-BadhoevedorpHollandPhone: 0-2968-6226

TOKYO, JAPANInternational Media Representatives, Ltd.2-29, Toranomon 1-chome, Minato-kuTokyo 105, JapanPhone: 502-0656

NORWOOD, AUSTRALIAWilliamson & Associates, John Williamson,No. 2 Edmund St., Norwood, S.A. 5067AustraliaPhone: 42-7074


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Documents

For industrial maintenance and consumer servicing ...- 7371 - beveled tip 2 imf 7579 - beveled tip 3 7592 beveled tip 5 7553 - eeveled tip 4-71411- micro soldering tip.7436 - regular