I hooked this PCB up to the test rig this afternoon, there was no output to the screen.
I checked the output from the crystal at A13 and all was okay there, I moved on to the 74LS04 next to it at A12 and the inputs and outputs were fine.
Next I moved onto the 9331-1J PROM at A11, there were stuck pins and no data where there should be.
I reseated the chip and the boards now displayed garbage on screen.
I was a bit sus on the socket so it was replaced and the PROM reinserted.
Powered it back up and the game now runs perfectly.
The control inputs were tested and it plays fine.
I thought this was going to be a challenging one with no schematics available for the bootleg board, I haven't looked to see if the original board schematics are similar but I have another one of these to look at next so I'll have a look and see what's available.
