Black+Decker No heating / high-voltage system failure

Microwave runs but does not heat food; turntable rotates and light is on, but food remains cold.

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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 magnetron, Defective high-voltage diode, Faulty high-voltage capacitor, Failed high-voltage transformer

How to Fix / Troubleshooting

Critical safety warning: The high-voltage section contains lethal voltages even when unplugged. Do not attempt to service the magnetron, transformer, capacitor, or diode unless you are trained and can safely discharge capacitors.

  • Confirm symptom:
    • Place a microwave-safe cup of water inside.
    • Run on HIGH for 1–2 minutes.
    • If the water is still cold, heating has failed.
  • Check basics:
    • Ensure you are not using metal containers or foil.
    • Verify the power level is set to 100% (HIGH).
  • Visual inspection only:
    • Unplug the unit and remove the outer cabinet.
    • Look for obvious burn marks or melted components near the magnetron and HV transformer.

Actual testing and replacement of the magnetron, HV diode, capacitor, or transformer in Black+Decker microwaves should be performed by a qualified technician due to shock and radiation hazards.

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Repair Difficulty

Professional Required 5/5

Required Part

Magnetron
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