Move the CPU batteries off the board
Steps
- Get a cheap four-AA battery holder and a 1N4004 diode.
- Wire the diode in series as a backup blocking diode, and use three AA cells.
- Mount the holder on the inside wall of the backbox and wire it to the CPU battery pads.
- Remove the original holder so leaks can no longer reach the CPU, driver board or interboard connector.
Systems
Related tips
- Replacing the CPU battery with a remote AA pack
- Switch row (return) circuit on the CPU board
- Fit a remote AA battery pack to a System 80 CPU board
- Fitting a remote battery holder to a WPC CPU board
- New batteries but still a memory error: check D25
- Testing CPU switch rows and columns with a diode and clip lead
- Early driver boards lack isolation diodes
- Move the batteries off the board
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)