Sharp Noisy High-Voltage Transformer or Magnetron

Microwave makes loud buzzing or humming noise while running, with reduced or no heating.

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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 high-voltage diode, Failing magnetron, Loose transformer mounting bolts, Saturated or failing high-voltage transformer

How to Fix / Troubleshooting

Safety: Unplug the microwave immediately if the noise is very loud or accompanied by a burning smell.

User checks:

  • 1. Confirm source: Listen carefully; a loud metallic buzz from the side or rear often points to the transformer or magnetron area.
  • 2. Check load: Never run the microwave empty. Place a cup of water inside and test again; running empty can damage the magnetron.

Advanced (technician only): Inspect transformer mounting, test the high-voltage diode and capacitor, and evaluate the magnetron. Replace any noisy or shorted components with Sharp-approved parts.

Recommendation: Due to high-voltage risk, have a professional diagnose and repair loud buzzing issues.

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Repair Difficulty

Professional Required 5/5

Required Part

High-Voltage Transformer
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