Figured I'd make a new thread - been trying to learn how to troubleshoot these things and I have Ray (Mundoman's) Asteroids board here. I went away last week and before I left, it would produce the test screen (with watchdog disabled) but in both normal and self-test modes the processor is watchdogging. In game mode, it would start to draw something and watchdog...no actual game or anything beyond what looks like maybe a 'P'.
Now that I tried it again, self test doesn't seem to work either (not sure what happened??), however if I push the dmago signal by writing to 0x3000 on the Fluke, it draws the self test screen with a brighter line going top-right to bottom-left behind it and flickering.
Connected the Fluke 9010a and all ram tests pass, as well as all the roms and proms. I also used the fluke to verify all the switch and dip switch inputs and they read perfectly.
I originally suspected the program counter at J4, and tried to piggyback one but that didn't seem to do anything.
Where to go from here??
Now that I tried it again, self test doesn't seem to work either (not sure what happened??), however if I push the dmago signal by writing to 0x3000 on the Fluke, it draws the self test screen with a brighter line going top-right to bottom-left behind it and flickering.
Connected the Fluke 9010a and all ram tests pass, as well as all the roms and proms. I also used the fluke to verify all the switch and dip switch inputs and they read perfectly.
I originally suspected the program counter at J4, and tried to piggyback one but that didn't seem to do anything.
Where to go from here??
