Tektronix 494AP service manual Introduction, Sectfon6 494A/494ApServicc Vot.1

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Sectfon6 - 494A/494ApServicc Vot.1

MAINTENANCE

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INTRODUCTION

This sectiondescribesproceduresfol reducingand pr€venting instrum€nt. malfunction, tioubleshootint methods, correctavemalntenance,and proceduresfor recalibratingthose assembtiesthat normallydo not requireroutinecalibration.

Removing the Instrument trom its Cabinet

T-opreparethe standardinstrumentfor maintenance or adiustment,performthe followingsteps-

1.S€t the instrumenton lts facs or frontpanel.

2.Loosenthe four screwsin th€ feet.

3.Pullthe cover up and off.

4.Place the instrumenton the work bench and reconnectthe power cord.

Static-Sensitive Componentg

4.Nothingcapabl€of generatingor hotdinga static charge should be allowed on the work station sur- face.

5..Keep the cornponent leads shortEd together wheneverpossible.

9Pick up componentsby the body, never by the leads.

7.Do not slidethe componentsover anysurface.

8.Avoid handlingcomponentsin areasthat hav€a floor or work-surfacecoveringcapabfeof generating a staticcharge.

9.UsE a solderingiron that ls connectedto €arth ground.

10.Use only specialanti-staticsuctiontype or wick type desolderingtools.

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RELATIVESUSCEPTIBILITYTO

STATICDISCHARGEDAMAGE

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This instrumentcontainselectricalcomponentsthat 9an be damagedby static discharge. Seeiabte 6_1for the relativesusceptibitityof varioui classesof semicon- ductors. Static voltages of 1 kV to 30 kV can occur in unprotectedenvironments.

Staticdischargecan damageany semicon_ ductorcomponentin this instrumint.

Observethe followingprecautionsto avoiddamage:

1.Minimize handling of static-sensitivecom-ponents.

2.Transportand store static-sensitivecomponentsor assembli€sin their originalcontainers,on metal- ized or conductivefoam, Labelpackagesthat con- tainsstatic-sensitiveassEmblies or com,-ponents.

3.Dischargebody static voltage by wearing a groundedwrist strap while handlingthese com_ ponents. Statie-sensitive assemblies or com- ponents should be handtedand servicedonly at staticfreework stationsby qualifiedserviceperson_ nel.

MOS or CMOS microcircuits or discretes,or linearmicrocircuitswith

TTL(L€astSensitive)
VoltageEqulvalentfor Levels:
1 - 1 0 0 t o 5 0 0 V	a - 5 0 0 V	f a 4 0 0 t o
		1000V (estl
2 - 200to 500 v	5 - 400to 600 v	8 - 9 0 0 V
3 - 2 5 0 V	6 - 6 0 0 t o 8 0 0 V	9 - 1 2 0 0 V

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aVoltage discharged from a 100 pF capacitor through a resistance of 100{).

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