Nov 212010
 

The game was dead on startup but had SYNC.
I checked the primary Z80 on the second board and found the RESET line was totally dead. Traced it back to pin 4 of a 74LS02 @ location 7B. This is a NOR gate and even though both the inputs (pins 5 and 6) were at logic low, the output (pin 4) was dead. Replaced this IC and the game booted

 Posted by at 6:07 pm