Bally Midway
These are some tips for repairing bally midway games...
Ok let me do my disclaimer...This is not necessarily whats wrong with your game so dont blame me if you mess things up, these are just things that fixed some common problems with my games and I urge you to read the whole thing. This is for people with some electronics skills, if you dont know how to solder and read a voltmeter then send your board for repairs.... Ok that being said here we go
Rampage
Ok, I had a strange problem with this one. If you turned game on it would make a constant thumping sound (sounded like a chopper). The 2 boards in question were the mcr/2 dual power amp pc (A082-90910-F000) and the sounds good board (A084-91863-B000).
The leds on the sound board indicated that everything was fine. If you unplugged one of the speakers before powering on the game the thumping sound would sometimes stop. If you left the speakers unplugged and then plugged them in after powering up game the thumping sound was gone. The game had a switching power supply but I measured my voltages just to be safe. I had perfect voltages all around. So I started probing the board and noticed that sometimes the thumping would stop if I probed the vcc (5 volts) on some of the chips.
I adjusted +5 volts down to 4.7 and the thumping sound went away. :)
After all that work I found a replacement mcr/2 audio board and plugged it in.The sounds good board started failing. Turned the +5 volts back up and the sound came back.
So if your having this problem, you can adjust your +5 volts on your switching power supply. I would not go to low with the voltage but you should be safe between 3 and 5.
I didnt fry anything LOL