Swan High-Voltage Component Overload or Short

Microwave makes loud buzzing or humming noise during operation, louder than normal, sometimes with 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

Shorted magnetron, Failing high-voltage transformer, Shorted high-voltage diode, Arcing inside waveguide or cavity

How to Fix / Troubleshooting

Safety warning: Unplug the microwave immediately if you hear abnormal loud buzzing or smell burning. High-voltage components may be failing.

  • Step 1 – Inspect interior: Look inside the cavity for burn marks, especially near the waveguide cover (mica plate on the side wall). Replace a burnt or damaged waveguide cover.
  • Step 2 – Check for metal objects: Ensure no metal utensils, foil, or twist ties are inside causing arcing.
  • Step 3 – Do not continue use: If noise persists with correct loading and a clean cavity, internal HV components are likely failing. Further use can cause more damage or fire risk.
  • Step 4 – Professional repair: Have a qualified technician test and replace the magnetron, transformer, diode, or capacitor as needed.
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Repair Difficulty

Professional Required 5/5

Required Part

Magnetron
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