I am working on a Shaq Attaq and the sound board(s) are not working. They do not work with the game ROMs nor with Marco's test ROMs. The LED on the main board just stays on. I have measured (literally) every IC pin with a scope and all have 'valid' TTL levels. The address and data busses are running. These tests were done on the bench. With the test ROMs both 'A8' LEDs and the on board one glow because they have a waveform rather than a fixed level. I socketed both RAM chips and, while the original ones were out, checked them and they were fine. I changed them anyway since I had new ones. Any suggestions on what else might be good to check?
Thanks, as always.