Microwave runs (light on, fan and turntable operating, normal humming sound) but food does not heat or heats very poorly.
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.
Possible Causes
How to Fix / Troubleshooting
Safety warning: Magnetron and high-voltage components operate at lethal voltages. Do not touch or test these parts unless you are a qualified technician with proper tools and procedures.
User-level checks:
- 1. Confirm load and container: Test with 250 ml of room-temperature water in a microwave-safe glass. Run at full power for 1–2 minutes. If the water barely warms, heating is inadequate.
- 2. Check power level and mode: Ensure the unit is not in a low-power or defrost mode. Set to 100% power and standard microwave mode.
- 3. Inspect cavity and waveguide cover: Look at the mica waveguide cover (usually on the side wall). If it is burnt, charred, or has holes, arcing may have damaged the magnetron or diode. Do not use the microwave until inspected.
Technician-level actions:
- 4. Test high-voltage diode and capacitor: With the unit unplugged and capacitor discharged, remove and test the HV diode and capacitor with appropriate methods. Replace any component that tests out of spec.
- 5. Inspect magnetron: Check for burn marks, cracks, or loose terminals. Measure filament continuity. Replace the magnetron with a Sage-compatible unit if defective.
- 6. Verify all connections: Ensure all high-voltage wiring and spade terminals are tight and correctly routed.
Because of the risks, magnetron and HV component replacement should be left to professionals. If your Sage microwave runs but does not heat, discontinue use and arrange service.