I just inherited a sight-unseen 1993 Bally ProSlots 5500 machine. When I received it, the jumper pins for the battery-enable were broken off and there was no battery.
I believe I fixed that problem (maybe?) and of course received 83F error on first bootup. Cleared RAM and machine boots up - but I still cannot do a full power off without losing settings. I checked voltage to the battery leads/connections on the MPU and they're showing + 3V.
I'm also getting random MPU restarts, without pressing the reset button. When this happens all of the lights on the tree, reel light, marquee light, etc., those do not go off, so I don't think it's a power supply issue but rather an MPU issue.
Can any advise me on where to go from here. I have a multimeter and can check voltages, but I'm not super comfy doing that unless I know exactly what and where I'm doing it.
Does anyone have any ideas for me? Any and all help would be appreciated.
BTW, I can tell the MPU is resetting, because the "WINNER PAID" and other LCDs will be lit up - for example, showing 0 credits with DOOR OPEN (S.O) error - then those will go blank for about 5-10 seconds, then they'll come back.