Black+Decker Start circuit or door interlock not engaging

Microwave display works but pressing START does nothing; timer does not count down.

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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

Faulty START button on keypad, Defective membrane keypad, Door not detected as closed due to bad switch, Control board input failure

How to Fix / Troubleshooting

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

  • Check door status:
    • Ensure the door is fully closed and latched.
    • Verify that the interior light turns off when the door is closed (on models where this applies).
  • Test other buttons:
    • Try multiple keys (numbers, power level, clock).
    • If only START is unresponsive, the keypad may be partially failed.
  • Inspect keypad ribbon:
    • Remove the control panel.
    • Disconnect and reconnect the keypad ribbon cable to the control board.
  • Replace keypad/control panel: If START and other keys remain unresponsive, replace the membrane keypad or full control panel assembly.
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Repair Difficulty

Medium 3/5

Required Part

Membrane Keypad / Control Panel Assembly
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