Cylindrical motor start capacitor with two terminals, the kind used on compressors and motors

Microwave HV capacitor and bleeder resistor

The HV capacitor has a built-in bleeder resistor meant to drain its charge, but bleeders fail, so always discharge by hand. A shorted capacitor blows the HV fuse immediately. Resistance tests catch shorts; a capacitance reading is better.

Cross-checked ~20 min advancedBrands: All

Before you start

DANGER: the microwave high-voltage capacitor can hold a lethal charge after the cord is unplugged
Trained technicians only. Unplug, wait, discharge the HV capacitor with an insulated discharge tool and confirm 0 V with a meter before touching anything inside
Never operate the oven with the outer cabinet off or with door interlocks bypassed
Inexperienced users and handymen without HV training should refer the job
Never rely on the internal bleeder resistor; it can be open

Diagnostic steps

Unlock all 4 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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