SilverCrest
Excessive High-Voltage Transformer or Magnetron Noise
Microwave makes loud buzzing or humming noise while heating, louder than normal
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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 high-voltage transformer, Magnetron internal arcing, Loose mounting bolts on transformer, Metal object or foil inside cavity causing arcing
How to Fix / Troubleshooting
SAFETY: Loud buzzing can indicate arcing or high-voltage stress. Stop the microwave immediately if you see sparks.
- Step 1 – Cavity inspection:
- Remove any metal utensils, foil, or dishes with metallic trim.
- Inspect the waveguide cover (mica plate on the side wall) for burns or holes.
- Step 2 – Test with water only:
- Place a cup of water inside and run for 30–60 seconds.
- If the loud buzz persists with no visible arcing, the transformer or magnetron may be failing.
- Step 3 – Professional service:
- Internal high-voltage components should be checked and replaced only by a technician.
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Repair Difficulty
Professional Required
5/5
Required Part
High-Voltage Transformer
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