Microwave runs but makes a loud buzzing or humming noise, louder than normal, sometimes accompanied by a burning smell.

Immediate safety warning: Unplug the microwave immediately if you hear loud buzzing with a burning smell or see smoke. Do not continue to operate.

• Inspect interior: Look inside the cavity for burn marks, especially near the waveguide cover (a small plastic or mica panel on the side or top). Replace a burnt or damaged waveguide cover.
• Check for metal objects: Ensure no metal utensils, foil, or twist ties were inside during operation.
• Technician-level HV inspection:
  • Remove the outer cover and inspect the HV transformer, capacitor, diode, and magnetron for burn marks or melted insulation.
  • Discharge the capacitor safely before testing.
  • Replace any visibly damaged HV components with Ambiano-compatible parts.

Note: Persistent loud buzzing usually indicates a serious HV fault; professional service or replacement of the microwave is recommended.