Hands holding multimeter probes on motor wiring terminals

Generic photo: Bulat843 · Pexels License

Testing diodes and bridge rectifiers with a meter's diode mode

Many appliance parts run on DC made from AC by a diode or a four-diode bridge. Diode mode on a digital meter checks each junction: a small forward reading one way and open the other. Resistance mode is unreliable for this; use diode mode.

Cross-checked ~15 min easyBrands: All

Before you start

Unplug and verify dead; discharge any filter capacitor after the rectifier before testing
Microwave high-voltage diodes have their own procedure and hazards; do not use this guide on the HV circuit

Diagnostic steps

Unlock all 6 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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