Testing a bridge rectifier out of circuit

Steps

• A bench test only catches a shorted or open bridge; a bridge that passes can still cause resets. In-circuit readings, especially on BR2, are often misleading.
• Identify the leads: the case marks one AC lead and the "+" lead. The other AC lead is diagonal to the marked AC lead, and "-" is diagonal to "+". Mark them on the board; the DC leads go to the bridge's filter capacitor.
• Meter on diode test. Black lead on "+", red lead on each AC lead in turn: 0.4-0.6 each.
• Red lead on "-", black lead on each AC lead in turn: 0.4-0.6 each.
• Anything outside 0.4-0.6, typically a zero, means the bridge is bad.

Systems

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

Related tips

• Bridge rectifiers to use on WPC-S and earlier driver boards
• Replacement bridge rectifier and diode ratings
• WPC power driver bridge rectifiers and +5 V regulator
• Replacing a driver board bridge rectifier without tearing traces
• Mount replacement bridges raised off the board
• Shorted or open bridge rectifiers
• Bridge positions on WPC-S and earlier driver boards
• Coil 50 V test point and circuit (WPC-S and earlier)

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