Maintenance- 494A/4g4ApServtceVot.1

MICROCOMPUTERSYSTEMMAINTENANCE

a o a a

o

I

I

a

Severalmaintenanceaids are built into the micro- computer syst€m. Th€se operating tssts dEmonstrate correct performanceor indicate the locationof a prob_ lem,if any.

The switch settingsthat set up two of these tests are describedfirst. Theseare followedby descriptions of the threetests.

In the first test, the microcomputerexecutesa self_ test that verifies,as much as possible,correctopera- tion. RAM, ROM, and interfaceadaptersare checked. Any failure found is indicatedby LEDs on the GplB board.

The secondtest forces the microcornputerto cycle throughall of its addresses.This test requiresless of the systemto run than does the first test, so it may be usedto troubleshootproblemsthat disablethe first test mode.

The third test exercisesthe instrumentbus to iso_ late problemsin data transfer betweenthe microcom- puterandthe instrument.

Option Switches

S1050 on the Memoryboard selectsthe microcom- puter system test modes, as well as selectingsom€ instrumentoptions. S1010 on th€ Z-Axisboardselects rnost ot the instrumentoptionsexclusively.Table6_10 shows the selections controlled by the individual switchesof 51010andS1050.

The microcomputerr€ads these switchesonly at power-up.Any changein a switch positiontakes effect whenthe instrumentis next poweredup.

Power-up Sell Test

Switch

lesilist

1

2

3

4

5

6

'7

Table 6-1O

SETTINGS

s 1 0 1 0 Open

Open Closed€xcept in Option41 instruments

Open Closed except in non- programmableinstruments

Not used Open

Open When set open (program- mable instruments only) causesinstrumentto output tront-panel settings (no waveform)when RESETTO LOCALis pressed in TALK ONLY mode. When set closed, causes the instru- ment to output both the front-panelsettingsand the currentwaveform.

Closed

Open except in 7 & S c l o s e d - N o r m a l

Option 07 Operation

instruments 7 closed I open Not defined

7open8 closed: Longver- sion of the power-up self test which reports on the GPIBboard.

7 & 8 open- Instrumentbus

o e o

a

o o o o o o a

t

o o o o o

t a o o

,

t

a

Normalinstrumentoperationis selectedby closing switches #7 and #8 of Si050. At power-up,thepro_ cessor executessteps 1 and 2, the first part of step 3, and steps 4 and 5 of the MicrocomputerSystemTest (describednext). lf the first two steps in the test are successful,any problemsin the other three steps are reportedon the crt. Possibleerror messagesare:

"RAMXXTESTSBAD.PUSHA BUTTONTO CONT.'

'ROM

XXTESTSBAD.PUSHA BUTTONTO CONT."

"ROMXX MISPLACEDPUSH. A BUTTONTO CONT." TIMER TESTSBAD.PUSHA BUTTONTO CONT."

Cross-referencetables betweenthe ROM and BAM numbersgiven in error messages(XX)and the circuit numbersof the parts are givenin Table6-11and Table 6-12.

lf the entiretest is successfulthe. instrumentinitial- izesandbeginsnormaloperation.

a o o o o o

t o

O

6-50

I

o o

Page 174
Image 174
Tektronix 494AP service manual A a, O o o o a, Lesilist, Maintenance- 494A/4g4ApServtceVot.1, Settings