MasterChef Stuck Relay or Shorted Control Circuit

Microwave interior light, fan, and turntable run when the door is closed, even without pressing START.

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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

Welded power relay contacts on control board, Shorted triac (if used), Miswired door switch circuit, Control board failure

How to Fix / Troubleshooting

Safety first: Immediately unplug the microwave. This is a serious safety issue.

Steps:

  • 1. Do not use the unit: Operating a microwave with uncontrolled power can be dangerous.
  • 2. Inspect door switches (experienced DIYers): Verify that the door interlock switches are correctly wired and actuated only when the door is closed.
  • 3. Check control board: If wiring and switches are correct, the main control board likely has a stuck relay or shorted output device.

Recommendation: Replace the control board and re-test. Due to the safety implications, professional service is strongly advised.

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Repair Difficulty

Professional Required 5/5

Required Part

Main Control Board
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