Hoover Noisy High-Voltage Transformer or Magnetron

Microwave heats but makes a loud buzzing or humming noise that is much louder than normal during operation.

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.

Possible Causes

Failing high-voltage transformer, Magnetron internal arcing, Loose transformer mounting bolts, High-voltage diode under load stress

How to Fix / Troubleshooting

Safety first: Unplug the microwave immediately if the noise is accompanied by burning smell or smoke.

User-level checks:

Confirm that the noise only occurs when heating (not in standby).
Remove any metallic or reflective items from the cavity that could cause arcing.
If the noise persists on every cook cycle, discontinue use.

Next steps:

Loud buzzing often indicates a failing transformer or magnetron. These are high-voltage parts and must be replaced by a qualified technician.
Do not attempt to tighten internal components yourself unless you are trained; high-voltage capacitors can retain charge.

Repair Difficulty

Professional Required 5/5

Required Part

High-Voltage Transformer

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