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494A/494APServiceVot. 1

TABLEOF CONTENTS(Conr.)

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Section6 MAINTENANCE

 

 

 

 

 

(Conr)

 

 

 

 

 

FirmwareVersionand

 

 

 

 

Enor Message

 

 

 

 

 

Readout

6-15

SelectedComponents

 

 

 

 

 

 

 

..................

ReplacingEPROM

 

 

 

6-15

or ROMDevices

 

........

6-15

Surface-Mounted

 

 

 

 

 

Components

 

 

Replacing

 

 

.....6_16

Surface-Mount€d

 

 

 

Components

 

..............

6_17

Transistor

 

 

 

 

 

and Integrated

 

 

 

CircuitConfigurations

 

,..

DiodeCotorCode

 

 

6_17

 

 

6

g

MultipleTerminal

 

 

 

1

 

 

 

 

 

(Harmonica)

 

 

 

 

g

Connectors

 

 

ResistorValues

...............

 

6_1

 

.........

6-1g

CapacitorMarking

 

 

.....6_1g

Soldering

...................

 

 

g

Techniques

 

 

 

Replacing

pin

 

6-1

the Square

for

 

 

 

the Multi-pin

 

 

 

 

 

Connectors

6_1g

Servicing

 

 

 

 

 

 

 

 

the VR Module

6-1g

REPLACING

 

 

 

ASSEMELIES

 

 

 

ANDSUBASSEMBLTES

 

 

 

 

 

....................

Removing

 

 

 

6

19

and Installing

 

 

 

 

theGPIBBoard

 

.........

 

6-22

Removing

 

 

 

 

 

or Replacing

 

 

 

 

Semi-rigid

 

 

 

 

 

CoaxialCables

6_22

Replacing

 

 

 

 

 

 

 

 

the DualDiode

 

 

 

Assembty

 

............

6_22

in the 1st Mixer

 

Replaeing

 

......

6_23

the Crt

 

 

 

Repairing

 

 

 

 

 

the Crt

 

 

 

 

 

TraceRotationCoil

 

 

 

... 6-29

FrontPanelAssembly

 

 

 

 

Front-Panel

Removal...6-29

 

 

 

 

 

BoardRemoval

6_24

ReplacingFrontpanel

 

 

Pushbutton

 

 

 

 

 

Switches

 

6

24

MainPowerSuppty

 

 

 

 

 

 

 

 

ModuleRemoval

 

........

6_24

HighVottagepowerSupply

6_25

Removingand Replacingthe

 

 

 

lst LO

 

 

 

.. 6 _ 25

Replacing

 

 

 

 

 

the l st LO

 

 

 

 

 

InterfaceBoard

 

.........

6_25

FanAssembtyRernovaf

 

6-25

MAINTENANCE

 

 

 

 

 

 

 

 

ADJUSTMENTS

6.26

110MHztF Assembty

 

 

ReturnLossCalibration

 

6-26

.............2072MHz2ndConverter

6_26

FourCavityFilter

...........

6_27

Mixer

 

...........

 

,9 - 27

110MHzThreeCavityFitter

6_29

829MHz Converter

 

 

 

 

 

Maintenance

..............

 

6_29

Troubleshooting

 

 

 

 

 

and Calibrating

 

the2ndLO

 

 

..6-32

 

Page

Preparingthe 2nd LO

 

 

Assemblyfor Adjustment

6

-35

Reassemblingthe

 

 

2ndLO Assembty

.....6

-9g

Troubleshooting

 

and Calibrating

the 16-20 MHz PhaseLock

 

Section

6-40

Troubleshooting

 

Aidsfor the

 

2182MHzPhaseLocked

 

2ndLO Assembty

.....6-42

100MHzOsciltatorin the

 

3rdConverter

649

l st ConverterBias

6-,44.

AuxiliarySynthesizer

 

VCOAdjustment

6-44

BaselineLeveling

 

(VideoProcessor)

.....6-46

10 MHzReference

 

OscillatorAccuracy

.. 6-49

MICROCOMPUTERSYSTEM

MATNTENANCE............. ....6-50

OptionSwitches.......6-50

Power-upSelfTest... 6-50

MicrocomputerSystemTest ........6-51

AddressBusTest.....6-52

MicrocomputerBus .................6-52

MernoryAddressDecoders.....6-52

ProcessorAddressDecoder....6-59

GPIBBoard

AddressDecoders6-s3

ClocksahdControlLines.........6-54

InstrumentBusTest6-54

TROUBLESHOOTINGONTHE

INSTRUMENTBUS6-54

InstrumentBus DataTransfers....6-54

InstrumentBusRegisters,............6-56

Front-PanelRegisters6-62

TAPEOATATRANSFERPROGRAM.... 6-63

Section 7 THEORYOF OPERATION

 

 

 

FUNCTTONALDESCRpTtON

.... 7- 1

Whatlt Does

-

...........7 - 1

How lt Works

.......

7 - 1

First,Second,and

...........

7- 1

ThirdGonverters

lF Section

.. -

7 - 2

DisplaySection

 

.... 7 - 2

FrequencyControl Section .,....7

-2

Counterand

 

 

 

PhaseLock Section

, ...7 - 2

DigitalControl Section

7

-3

PowerSupplySection

7

- 3

OtherSections

7

- 3

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