I'm trying to diagnose a dead Contra PCB that does this screen on boot with no sound:
I retraced a suspicious not pulsing signal from a couple of TTLs (which seem ok) to a Fujitsu MB8464A RAM.
Pins #7, 8 and 9 on this RAM are not pulsing (signal stuck at 1,7 V). Looking at the datasheet says these pins are Address Buffers.
I'm a little confused here. Do you know if this RAM chip is suspicious or should I definitely need to look anywhere else from these pins ?
Is this 6264 chip the WORK RAM?Pins 7-8-9 are address lines so,( assuming it's one of the work RAM), if they are stuck LOW or HIGH main program code cannot be executed properly and game doesn't boot.Trace back these address lines and see if the go straight to main CPU (or to buffers).Be patient and don't give up in any repair you do, this is the secret for the success!
