Fitting a remote battery holder

Steps

• Mount an AA holder away from the CPU board and wire it to the board battery points.
• Optionally put a 1N4004 in series in the first cell position, band toward the red (positive) lead side.
• The diode adds protection and drops the voltage slightly, so the game warns with "Adjustment Failure" before the cells are low enough to leak.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• Fitting a remote battery holder to a WPC CPU board
• Replacing the CPU battery with a remote AA pack
• Fit a remote AA battery pack to a System 80 CPU board
• Checking the battery holder voltages on the CPU board
• Fitting a new switch diode the right way round
• Coil diode and wire orientation when replacing a coil
• Replace SE9302 drivers with TIP102, and renew the parts around them
• No score displays light at all

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell