If your microwave oven doesn’t heat, you may have a problem with the high voltage diode or rectifier. This component helps provide the high voltage that powers the magnetron. The high voltage diode is located near the magnetron and the high voltage capacitor, so that access will require removing the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then test the diode for continuity with a multi-meter. Diodes are polarity specific, and you should see low resistance with the meter leads in one direction and higher resistance when the meter leads are reversed. Most multi-meters will have a particular setting for diodes or rectifiers. If the high voltage diode shows low resistance in both directions or shows no continuity at all, then it will need to be replaced. If you find the high voltage diode tests okay, then you will need to determine whether power is being supplied to the circuit. This is a high voltage circuit, and a qualified technician can only perform a further test.

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