F9
Daewoo Internal Short Circuit Detected

Microwave shows F9 and may trip the household breaker

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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 line filter, Shorted power cord, Shorted high-voltage component, Damaged wiring harness contacting chassis

How to Fix / Troubleshooting

Critical safety warning: An internal short can cause fire or electric shock. If the breaker trips or you smell burning, disconnect power immediately and do not reuse the appliance until inspected.

User-level actions:

  • 1. Inspect cord and plug: With the unit unplugged, check the power cord and plug for visible damage or burn marks. Replace the cord if damaged.
  • 2. Try a different outlet: Plug into a known-good outlet on a different circuit to rule out house wiring issues. If F9 or breaker trips persist, internal faults are likely.

Technician-level actions:

  • Inspect line filter, wiring harness, and HV components for shorts or burn marks.
  • Test components individually for insulation breakdown.

Recommendation: Do not attempt to operate the microwave until a qualified technician has identified and repaired the short.

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Repair Difficulty

Professional Required 5/5

Required Part

Line Filter Board
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