Bomann
Partial Power Delivery / Relay or HV Fault
Microwave fan runs but there is no turntable movement and 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
Failed main power relay, Open high-voltage transformer primary, Faulty control PCB output, Blown high-voltage fuse
How to Fix / Troubleshooting
Safety: Unplug the microwave before servicing. High-voltage components are dangerous.
- Step 1 – Confirm symptom: Verify that the fan runs and the interior light is on, but there is no heating and no turntable movement.
- Step 2 – Check turntable motor: Test the turntable motor as described in the turntable failure section. If both heating and turntable are out, suspect a common power issue.
- Step 3 – Inspect relays: On the control PCB, inspect the main power and HV relays for signs of burning or mechanical failure.
- Step 4 – Professional testing: A technician should test the transformer primary, HV fuse, and relay outputs to identify the failed component.
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Repair Difficulty
Hard
4/5
Required Part
Main Power Relay (on Control PCB)
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