Rejumpering the transformer for low line voltage (105 V tap)

Steps

• Only do this if the outlet measures 112 V AC or less on a 120 V supply and the game resets; above that it overstresses the regulators and possibly the transformer. A wrong jumper can damage the game.
• Unplug the game. You need a .093" round Molex pin extractor.
• At the transformer plug, move the jumper from pins 8 and 9 to pins 5 and 6 (pre-DCS games).
• On WPC-S and later the low-line arrangement is pins 1-11, 2-3, 4-10 and pin 5 to 6.

Line voltage is present in the cabinet and backbox with the game on; keep hands clear of the transformer and power wiring.

Systems

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

Related tips

• Using LED2 and LED3 to set the transformer tap
• 12 V and 50 V supplies read far too high: transformer line-voltage jumpers set wrong
• WPC transformer part numbers
• Voltages made by the WPC power driver board
• WPC transformers look alike but are not interchangeable
• Live voltage checks for the F114/F115 message

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