Grundig Start Circuit / Relay Drive Fault

Microwave display is on but START button does nothing; no relay click, no fan, no light change.

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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

Defective START button on keypad, Faulty membrane keypad, Failed control board relay, Door switches not signaling closed

How to Fix / Troubleshooting

Safety first: Unplug the microwave before accessing the control panel.

Step-by-step checks:

  • 1. Check door status: Ensure the door is fully closed and that the door icon (if present) is not flashing.
  • 2. Try other functions: See if timer or clock settings respond. If only START is unresponsive, the keypad may be faulty.
  • 3. Inspect keypad: Remove the control panel and check the membrane keypad ribbon cable for damage or corrosion. Reseat the connector.
  • 4. Test door switches: Verify that all door interlock switches operate correctly with a multimeter.

If the keypad and door switches are good but the unit still does not start, the control PCB relay or logic may be defective and should be replaced.

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Repair Difficulty

Medium 3/5

Required Part

Membrane Keypad Panel
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