A game with three or four flippers resets when both cabinet flipper buttons are held.

Game resets when both flipper buttons are pressed

Cause: The +5/+12 V filter capacitor is too small (or worn) for the flipper load.

Checks

• Check the value of C15 (C10 on System 7).

Fix

• Fit a new filter capacitor of at least 15,000 mfd.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A
• Williams System 7

Related tips

• Game reboots when the flipper buttons are pressed
• Pressing both flippers resets the game: replace big filter cap C15
• Random lockups from the 12 V logic pin
• Overnight test to separate connector faults from power faults
• Flippers dead: fuse and coil voltage
• Where flipper power comes from
• +5 V logic low or noisy
• Cracked header pin joints on the power supply

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)