Sharp No Heat – High-Voltage Circuit Failure

Microwave runs (light on, turntable spinning, fan noise) but food does not heat at all.

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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, Open high-voltage diode, Open high-voltage capacitor, Failed high-voltage transformer or inverter module

How to Fix / Troubleshooting

Critical safety warning: The high-voltage section inside a Sharp microwave can be lethal. Do not attempt to test or replace the magnetron, transformer, capacitor, or diode unless you are a trained technician with proper tools and procedures.

User-level checks:

  • 1. Confirm symptom: Heat a cup of water for 1–2 minutes. If the water remains cold and the unit appears to run normally, heating has failed.
  • 2. Check power supply: Ensure the microwave is on a dedicated outlet with correct voltage. Low voltage can reduce heating but usually not to zero.
  • 3. Listen and smell: Note any unusual buzzing, crackling, or burning smells. These can indicate a failing high-voltage component.

Recommendation: Discontinue use and contact a Sharp-authorized service center. High-voltage diagnosis (testing the magnetron, transformer, capacitor, and diode) and replacement must be done professionally.

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Repair Difficulty

Professional Required 5/5

Required Part

Magnetron
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