Things to try:
*) Substitute ROMs, RAMs and the microprocessor if you can.
I have seen _Asteroids_ boards with the "Self-test works, but won't work in game play" caused by a bad vector PROM. This is on the other side of the motherboard from the ROMs and RAMs. IIRC, I think the vector PROM on _Lunar Lander_ is identical to that used on _Asteroids_ and _Asteroids Deluxe_, but I can't say for sure at the moment because I do not have my notes in front of me. Anybody else, feel free to confirm or refute this.
As for the other board problem, can you verify that the on-board voltage regulators are working OK? The 7815 and 7915 must work, because they feed the op-amps in the output video circuitry. If you've got a 'scope (or even a logic probe), check the inputs of the DACs for activity.
HTH,
Matt J. McCullar
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Received on Thu Aug 22 21:19:49 2002
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