Intermittent power faults, resets or dead circuits.

Cracked header pin joints on the power supply

Cause: Vibration and plugging cause fine cracks in the solder around the power supply header pins.

Checks

• Look closely at the header pin solder joints and for burnt or damaged pins.

Fix

• Remove the old solder fully, then resolder each header pin with fresh solder.
• Replace any burnt or damaged header pins.

Systems

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

Related tips

• Burnt 3J1 square power input connector
• Replace the 3J6 logic power connector
• Power circuits in a System 3-7 game
• First power-up check on a dead game
• What the power supply board takes in and puts out
• Test the power supply with its outputs unplugged
• Spare transistors for driver board and power supply
• Swapping power supply boards between generations

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