Bucky O'Hare Repair Logs
Symptom: Missing color
The blue output was missing. The custom hybrid, number 054573 at location U73 had inputs but no outputs. Replaced the hybrid and tested.
Forum Thread: Bucky O'Hare PCB Repair
Symptom: On boot up everything passes the tests except for the sound section, which gives the error: ‘Sound System Bad’
Diagnosis: Carried out all the usual checks in the sound section of RAM, ROM, sockets, address and data lines, Z80 CPU, YM2151 sound chip, tracks, inter-connections, etc, etc, etc – all looked fine.
All that was left was the 120-pin surface mounted custom CPU (054539) at location C4, so removed one from a spares board, replaced the suspect one, and the fault was still there! Argh! Put it to one side, dabbling at it for a while now and again, then decided to replace the YM2151 sound chip at location F2 – didn’t think it would make any difference but what the heck! And ……… that fixed the fault!
Now that’s the FIRST time that I’ve seen a self test actually check the function of a YM2151. Note: removing the (now socketed) YM2151 causes the error to return, so it wasn’t as if the sound chip was causing problems ‘upstream’ (ie pulling some lines high or low, etc). Very annoying but a lesson learned!
Cure: Replaced faulty YM2151 at location F2
Symptom: No green video output
Cure: Faulty custom SIL 054573 at location U72. Note: just removing ONE of these SILs (there are three, one for Red, one for Green, one for Blue) will stop ALL video output (except sync of course).
Repair Logs converted to wiki format by Brad from Aussie Arcade.