Tristar
No Heat – Magnetron / High-Voltage Circuit Failure
Microwave runs but does not heat food; turntable and interior light operate normally, no error code displayed.
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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, Open high-voltage diode, Faulty high-voltage transformer, Blown high-voltage fuse or thermal cutout on magnetron
How to Fix / Troubleshooting
Critical safety warning: The high-voltage section of a microwave is extremely dangerous. Do not attempt to test or replace the magnetron, transformer, capacitor, or diode unless you are a trained technician.
User-level checks:
- 1. Confirm no heat: Heat a cup of water for 1–2 minutes. If the water remains cold while the timer counts down and the turntable rotates, heating has failed.
- 2. Avoid repeated attempts: Do not keep running the microwave in this condition; it can damage internal components further.
- 3. Basic inspection: With the cabinet removed by a qualified person, visually inspect for burnt wiring or components near the magnetron and high-voltage area. Do not touch the capacitor or high-voltage wiring.
- 4. Professional repair: A technician will test the magnetron, high-voltage diode, transformer, and thermal cutouts, replacing the defective part(s). In many cases, replacing the magnetron and diode together is recommended on Tristar models.
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Repair Difficulty
Professional Required
5/5
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