Midway L board Space Invaders..
Power verified at board.. reset signal operating properly. Clock section seems fine. Watchdog fires when H ROM is pulled but does not fire when test ROM is running (as expected). Also following the 8080 test procedure without luck.
cap kit and RAM socketed. Same symptoms before and after. Daughter connector replaced, edge connectors cleaned up and verified. Swapped 8080...
First picture is the display of the v1.3 test ROM. 2nd picture is display of
@philmurr test ROM. 3rd is with ROM removed. Also the saucer sound plays continuously.
RAM replaced as indicated by Phil's test. However, no matter how many are replaced, it seems to keep reporting another 1 bad, often 1 I have already replaced.
Chasing my tail. Either the RAM is getting smoked or there is something else wrong.
I have checked the 7404s and there seems to be reliable activity (they have been socketed and swapped).
Grounding pin 7 on various RAM does change the display but does not fix it.
The 8216s are original and appear to have good activity.
This board has seen better days... it was dragged across something that tore up some traces, they were repaired previously. I have verified that there is continuity across all repairs and they match a working board.
I don't know what else I can do to save this board. I'm assuming it is an addressing issue but I don't know where to start