Microwave Oven Repair Guide - Microwave is not heating, but I hear buzzing

My microwave isn't heating and I can hear a loud buzzing noise.

Investigate these three areas if your microwave won't heat but you hear a loud buzzing or humming noise:

Power Diode

A diode is an electronic component that readily passes current in one direction only and blocks the flow of current in the opposing direction. If your microwave's diode has become defective, your microwave will not heat and you will hear a buzzing noise. Test the diode to determine if this is the cause of your problem. Replace it if it is defective.

How to test a microwave diode.
How to replace a microwave diode.

Find a diode for your microwave oven.

Picture of capacitor not currently available

High Voltage Capacitor

A capacitor is an electrical device which stores electricity. A defective capacitor may be why your microwave is not heating but you are hearing a buzzing or humming noise. The capacitor will have to be tested to determine if this is the cause of your problem. A defective capacitor will have to be replaced before your microwave will work again. Make sure you discharge the capacitor before you test it, though.

How to test a microwave capacitor.
How to replace a microwave capacitor.

Find a capacitor for your microwave oven.

Magnetron

A defective magnetron is the third possible cause of why your microwave is not heating, but you can hear a buzzing noise. Test your microwave's magnetron. Replace it if it is defective.

How to test a microwave magnetron.
How to replace a microwave magnetron.

Find a magnetron for your microwave oven.

CAUTION Your microwave oven is capable of giving you a serious electrical shock, even when it is unplugged. We strongly suggest you seek the assistance of an appliance repair technician when conducting any microwave oven repair.

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