Trying to fix a Sega CD model 1. System plays audio CDs but doesn’t boot games. It is definitely the motherboard, I have tested the drive and mixer/power boards in another unit and they both work fine. I have recapped the board but no change. All the traces seem to be good and the solder joints on the main asic seem to be fine. The bios loads normally and there are saves on the system so most of the functionality works. Any ideas?