Hardware Diagnostics Tests on a Star Wars board, how does it work?

I'm repairing a Star Wars board set that has Matrix Errors in the
normal self test (amongst other now repaired faults), and I can't
seem to get the 'Hardware Diagnostics Tests' via DIP switches working
properly via the option switches and grounding of the DIAGN test point.

I am setting the option switches (SW2 at 10D) correctly to the requested
tests 15-20 by the normal self test error screen, and all I get is the
3 LED's flashing continuously (manual says this is 'unimplemented position')
and no test number shown on the display either (which is a CRO in XY at the moment)

I have tried this on a good working board also, and it does the same thing so I
figure I must be doing something wrong or unexpected to get these test working properly.
I've tried the switch positions reversed, and even the other switches SW3 at 10E just in case.

The manual says(and I am doing):
1. Set the Self-Test switch to the on (up) position. (I assume this means Self Test input to GND?)
2. Ground the DIAGN test point on the Main PCB.
3. Set the option switches as indicated in the test procedure and momentarily ground the RESET test point on the Main PCB.
   If an unimplemented switch position is selected, LED 1, 2, and 3 on the Main PCB will all flash on and off about
   once per second.
   Also, the display will show the number of the test for Hardware Diagnostic Tests 10 through 26 (if
   the AVG PCB and display are working).

BTW, the problem on the faulty board is no stars or ships in gameplay, picture & music hangs
once death star is shown, but can still fire and see shots (I assume matrix errors are hanging it up)
When in normal self test, matrix errors listed correspond with tests 15 to 20 in the
Troubleshooting manual.
Problem is on the Main PCB (Rev A), RAM's are OK, Vector PROM's are ok, asst. other IC's so far
tested in the Matrix section are ok, but not done them all yet.

Arrrgghh, what am I doing wrong? ;-)

Thanks very much,

Marc

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Received on Wed Apr 3 16:58:17 2002