What this usually is
Establishing whether the noise happens with the turntable removed halves the diagnosis. Two of the likely causes are cleared by hand in minutes. On this kind of cabinet the platform is shared across a large maker range, so the service part you need is usually still catalogued.
What you actually observe
- NEAR MISS — buzzing with sparking inside — Stop now; that is arcing and it belongs on the electrical page.
- A loud hum that starts only when cooking begins — The high-voltage transformer, which is normal at a moderate level and a finding if it has changed.
- The turntable judders rather than turning smoothly — Debris under the roller ring or a worn coupler.
- Vibration transmitted through the worktop — Often the oven feet or the surface rather than the oven itself.
The ranking that matters
- Turntable coupler or roller ring worn or dirty — Ranked first: Both parts lift out, wash and refit by hand, which makes this the cheapest fault in the entire subject. It sits at the top here since the platform is shared across a large maker range, so the service part you need is usually still catalogued.
- Foreign object in the cavity or under the plate — Second: It is found by lifting the plate out, which takes a moment.
- Cooling fan obstructed or its bearing dry — Third: A failing fan matters beyond the noise: the magnetron depends on that airflow.
Order of investigation
- Check whether the fan runs whenever the oven does — A silent fan with the oven running is a stop-now finding, since cooling is not optional.
- Listen at the vents for the cooling fan — A fan that whines or rattles is a finding, and a silent fan while cooking is a stop-now one.
- Note whether the noise only starts when cooking begins — Cooking-only noise is the transformer and the fan; running noise is mechanical.
Safe checks, step by step
- Clean the recess and the coupler — Wipe out dried spills from the well under the plate, which is where most grinding begins.
Tools: clothAbout 10 min
- Check the oven sits flat — Make sure all four feet are present and in contact, and that nothing is trapped underneath.
About 10 min
- Remove and wash the turntable and roller ring — Unplug the oven, lift both out, wash in warm soapy water, dry and refit them seated properly.
Tools: cloth, detergentAbout 15 min
- STOP before any electrical testing — Hand over here: the remaining checks need an instrument and an isolated appliance.
The hazard in this appliance class
Safety
This is the one kitchen appliance where opening the case is really dangerous: its capacitor can retain a charge that does not fade with time, and it sits inches from the panel screws. The high-voltage section retains a charge after the power is gone, so the cover is a technician boundary and not an homeowner one. The door, its latch and its switches are the containment system: if any of the three is damaged, stop using the oven and have it assessed rather than running it as it is.
When to call a technician
The turntable, the vents and the feet are homeowner work; everything inside is not. When the appliance is doing something it has never done before and nothing about the installation has changed, book it rather than watching it.
Related pages of the same kind
Scope of this page
A generalized page has generalized limits. It covers Comfee microwaves in aggregate, and a family- or model-level page — where one exists, linked from this page — will be more exact about clearances, fasteners and part identification than a generalized page can be. What is deliberately absent: wiring colours, fastener torques and part numbers, all of which change between families and belong on the page for that family. It says nothing about accessory kits or aftermarket conversions, which change the behaviour described above.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
