Test a bridge rectifier with a meter

Steps

• Turn the game off and set the meter to diode test.
• Black lead on the + terminal, red lead on each AC terminal in turn: expect 0.4 to 0.6 V each.
• Red lead on the - terminal, black lead on each AC terminal in turn: expect 0.4 to 0.6 V each.
• An open (no reading) or near-zero reading means the bridge is bad.

Systems

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

Related tips

• Backbox bridge rectifiers and their wires
• Upgrade logic rectifier diodes D7 and D8
• Loose wires on the backbox bridge rectifiers
• The backbox bridges and can capacitor are not logic power
• Flippers too weak for the top lock: loose, arcing bridge rectifier connections

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