Toshiba No Heat – Magnetron / High Voltage Failure

Microwave runs (light on, turntable rotating, fan running) 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,Defective high-voltage transformer or inverter,Open high-voltage diode,Blown high-voltage capacitor

How to Fix / Troubleshooting

Critical safety warning: No-heat conditions are almost always related to the high-voltage system. These components can store lethal charge even when unplugged.

User-level checks only:

  • 1. Confirm symptom: Heat a cup of water for 1–2 minutes. If it remains cold while the oven appears to run normally, heating has failed.
  • 2. Check power level settings: Ensure the power level is set to 100% (HIGH) and not to a low level or defrost mode.
  • 3. Try different modes: On grill/convection models, test grill-only or convection-only. If those work, the issue is specific to the microwave HV system.
  • 4. Power reset: Unplug for 5–10 minutes, then test again. If still no heat, internal components require professional diagnosis.

Do not open the cabinet: Contact a Toshiba-authorized technician to test and replace the magnetron, transformer/inverter, diode, or capacitor as needed.

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Repair Difficulty

Professional Required 5/5

Required Part

Magnetron
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