Like Channelmaniac said, probably a bad power supply. I have the power supply here so I will check it out later. All of the ram were good though, I would have thought they would have died but you will never know for sure.
One thing is sure, it's the worst one yet!
How do I find the bad chips? Again like CM said. For example, the X and Y channels are pretty much identical . If you have 4 missing inputs to a chip then either that chip is dragging them down or the one that is sending those signals has failed. A lot of the time you will see activity with a logic probe so you need a comparator to check the logic is correct (or the timing)
The state machine is the hard part because an area may look dead but really it's just waiting for a go signal. For that area I keep a section of good IC's on some anti static foam...I can quickly run through each chip with the comparator if something looks odd.
Omegaman, I replaced all the RAM myself, I got the thing to test and it told me they were bad so I changed them, hoping the game would spring to life for my trouble. After I did the test gave me the same results and I knew I was out of my league, so I sat on it hoping I could find someone a hell of a lot smarter than me that was willing to give it a go...
