Toshiba Short Circuit / Overcurrent on Startup

Microwave trips the household circuit breaker or blows a fuse when starting.

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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

Shorted high-voltage capacitor or diode,Shorted magnetron,Faulty line filter board,Short in power cord

How to Fix / Troubleshooting

Safety warning: Repeatedly resetting a tripping breaker can be dangerous. Do not continue to use the microwave until the cause is found.

User-level checks:

  • 1. Try another outlet: Plug the microwave into a different properly rated circuit to rule out a weak breaker (do not use extension cords).
  • 2. Observe timing: Note if the breaker trips immediately when START is pressed or after a few seconds of operation. Immediate trips often indicate a serious internal short.

Do not open the cabinet: Internal shorts in the HV system or line filter must be diagnosed by a technician using proper safety procedures.

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Repair Difficulty

Professional Required 5/5

Required Part

High-Voltage Capacitor
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