Fitting a remote battery holder to a WPC CPU board

Steps

• Use a four-cell AA holder but fit only three batteries. Use the fourth cell space for a 1N4004 or 1N5817 diode with its band toward the red wire (a plain wire link works too).
• Solder the holder's red lead to the main positive battery trace on the CPU board and the black lead to the main negative trace.
• Main battery terminals: WPC-89 and WPC-95 have positive top right and negative bottom left of the old holder; WPC-S is the mirror, positive bottom right and negative top left.
• Mount the pack away from the board so a leak can't reach it.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Fitting a remote battery holder
• Testing CPU switch rows and columns with a diode and clip lead
• "Check Fuse F114/F115" (F106/F101 on WPC-95): step-by-step
• Optos test good but still don't work: the opto board
• Replacing the CPU battery with a remote AA pack
• Fit a remote AA battery pack to a System 80 CPU board
• Move the CPU batteries off the board
• Why WPC coil diodes are on the driver board

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)