Following on the repair with the stuck switch repair. (IC23) I play tested the board
only to find a new problem.
This MPU3 board continues to give me the run-around.
After replacing IC23 (which sorted the stuck switch) the board seemed to run OK,
although it did reset once.
Continued use throws up another problem. After 5-10 minutes of operation the machines
Powering off and back on and the machine does not boot. If the machine is left for
15-20 minutes, the machine will boot again and play for 5 minutes before it normal
operation halts and the machine crashes.
The fault is heat related. So after a some consultation, begin with D44 and D45 the
large power diodes.
Re-flow solder on to pads. Although the old solder is grim and the joints look cold,
there is no change in operation after the machine is reassembled. The original fault
The RAM is socketed so it makes sense to quickly eliminate it. I have new RAM in
stock, so I replace both RAM chips.
Play it for 5 minutes and see what happens, so far so good. I left it on for 4-5
hours, playing it off and on during that time and it seems happy enough.