Quick visual inspection highlighted a couple of missing caps and the rest of electrolytic's looking a bit tired. So after the board was cleaned up the capacitors were replaced, still no audio so time to poke about further.
Once I read or heard somewhere that you should use all your senses when debugging electronics, so with that in mind I set off.
Touching the audio amp produces an audible hiss, good sign the amp is working then and the problem is upstream. Further poking about and noticed the 68A09 was running pretty hot, check on the schematics showed this as the audio CPU so good chance this is the culprit. Verified the CPU as knackered with a scope.
Desoldered the old part and fitted a new CPU along with a DIP socket. Result. We've got audio again :)
Played through the game again just to verify, but still not near the 1CC level yet !!
 |
| New 68A09 installed |
No comments:
Post a Comment