So picked up an NBA Jam recently and I had no video/audio. I tracked down issue to CPU board. Game boots up and plays, just no audio/video. Put in CPU board from my Totan and everything works perfectly.
Upon further examination on the 'bad' CPU board, the battery holder has been removed and u1, u2, u3, and u5 have been replaced. I also tested ASIC, CPU, Game ROM, Security chip, and RAM.
There was some minor battery damage (yes I know it can be misleading how bad it really is). I replaced and socketed u5 and there was some corrosion on the legs, and I repaired a trace next to the chip.
Overall the board looks great, just can't figure out what to look for now. u1, u2, and u3 were replaced as per the schematics it looked like those directly affected the I/o and audio connector.
I'm competent with testing, troubleshooting, soldering, etc. so if someone would like to assist me I am up to the challenge.
Thanks!