OBH Nordica
Output Relay / Control Drive Failure
Microwave timer counts down but the turntable, light, and fan do not run; no heating occurs.
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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 relay on control PCB, Broken relay coil drive, Open thermal fuse in primary circuit, Loose wiring to motors and transformer
How to Fix / Troubleshooting
Safety first: Disconnect power before accessing internal components.
- Step 1 – Confirm symptom: Start a cycle and observe that only the display counts down; no internal activity occurs.
- Step 2 – Check door switches: A faulty door switch can prevent activation of all loads. Test and replace any defective switches.
- Step 3 – Inspect wiring: Verify that the main harness from the control board to the transformer, fan, and turntable is securely connected.
- Step 4 – Check thermal fuse: Locate and test the primary thermal fuse or cut-out in the line to the transformer. Replace if open, but investigate overheating causes.
- Step 5 – Replace control PCB: If wiring and safety devices are intact, the main relay or its drive circuit on the PCB is likely faulty and the board should be replaced.
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Repair Difficulty
Hard
4/5
Required Part
Main Control PCB / Primary Thermal Fuse
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