Tristar
No Power – Main Fuse / Power Input Failure
Microwave does not power on at all; display is blank and no lights or sounds when door is opened or buttons are pressed.
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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
Blown main ceramic fuse, Faulty power cord, Failed line filter board, Open thermal fuse on cavity or magnetron
How to Fix / Troubleshooting
Safety: Unplug the microwave before opening the cabinet. Even with no power, internal components can be hazardous.
Steps to troubleshoot no power:
- 1. Check outlet: Test the wall outlet with another appliance. Reset any tripped breakers or replace blown house fuses.
- 2. Inspect power cord: Look for cuts, burns, or crushed sections. Replace the cord if damaged.
- 3. Access main fuse: Remove the outer cabinet and locate the main ceramic fuse near the power entry or line filter board. Remove and test for continuity. Replace only with the same rating if blown.
- 4. Check thermal fuses: Locate thermal fuses on the cavity top and magnetron. Test for continuity. Replace any open thermal fuse with the correct Tristar part.
- 5. If fuse blows again: If the new main fuse blows immediately, there is a short in the high-voltage or control circuit. Stop and contact a technician for further diagnosis.
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Repair Difficulty
Medium
3/5
Required Part
Main Ceramic Fuse
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