Tristar
Line Short / Overcurrent on Startup
Microwave trips the household circuit breaker or blows the house fuse when starting a cook cycle.
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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, Shorted high-voltage diode, Shorted magnetron, Damaged power cord or line filter board
How to Fix / Troubleshooting
Critical safety warning: Repeated breaker tripping indicates a serious electrical fault. Do not continue to reset the breaker and retry; this can cause fire or further damage.
User-level steps:
- 1. Try a different outlet: Plug the microwave into a dedicated circuit (no other heavy loads) to rule out an overloaded circuit. If it still trips, the microwave is at fault.
- 2. Visual inspection: With the cabinet removed by a qualified person, inspect the power cord, line filter board, and wiring for obvious shorts or burn marks.
- 3. Professional diagnosis: Testing the high-voltage capacitor, diode, and magnetron for shorts requires specialized procedures. Contact a technician to identify and replace the shorted component.
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Repair Difficulty
Professional Required
5/5
Required Part
High-Voltage Capacitor
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