Bomann
Abnormal Noise – High-Voltage Component or Magnetron Arcing
Microwave runs but makes loud buzzing or humming noises, louder than usual, sometimes accompanied by a burning smell.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failing magnetron, Shorted high-voltage diode, Saturated high-voltage transformer, Arcing at waveguide or stirrer cover
How to Fix / Troubleshooting
Safety: Stop using the microwave immediately if you hear loud buzzing or smell burning. Unplug the unit.
- Step 1 – Inspect inside cavity: Look for burn marks, melted plastic, or arcing around the waveguide cover (usually a mica or plastic panel on the side or top wall). Replace a damaged waveguide cover.
- Step 2 – Check for metal objects: Ensure no metal utensils, foil, or twist ties were used. These can cause arcing and noise.
- Step 3 – Listen to transformer area: With a technician present, the source of the noise can be localized to the transformer or magnetron. A failing magnetron often causes loud buzzing and no or poor heating.
- Step 4 – Professional repair: Replacement of magnetron, diode, or transformer must be done by a qualified technician due to high-voltage hazards.
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Repair Difficulty
Professional Required
5/5
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