Here's what I'm looking at...
Starting condition:
- Working Pac-Man board with no sound.
- (Note: both 1A 12VAC fuses blew at least once at this point, so I'm thinking there was a pre-existing underlying issue that has possibly been exacerbated?)
- Sound amp seemed totally dead, so I replaced it with a new amp and heat sink.
Current condition:
- Both 1A 12VAC fuses blow shortly after powering on. They're good for a few seconds, then start visibly glowing like a toaster heating element, then blow.
- This also happens with a second known-working Pac-Man board.
- This happens even if everything else (monitor, coin door, control panel, marquee light) is disconnect and only the board edge connector is plugged in.
- During the brief period before both 1A 12VAC fuses blow, neither board produces sound, although there's a slight buzzing from the speaker.
- Both boards work WITH SOUND in another (Pac-Man mini/cabaret) cabinet, suggesting the issue is with the first cabinet, which is an upright with no coin door lights and two 60w light bulb sockets for the marquee light.
Any suggestions on what to check or look for? Should I be focusing my attention towards a possible wiring harness issue or perhaps a transformer issue?