I have a Exidy 440 board set with Chiller roms that currently has no sound and no video after boot. Upon boot, no scream, it will pass all the tests then go to a blank screen. I can enter the test mode and run all the tests. The only test it fails is in the collision interrupt test (Y-coord). I can not find on the schematics where the collision circuits are. Does anyone know what chips are associated with that section or where to start? I think the sound is a separate issue. I have checked the voltages and getting 4.95 - 4.98v at the chips (both sound and cpu boards).
