Microwave makes loud buzzing or humming noise when heating, louder than usual.

Safety warning: Loud buzzing from the high-voltage area can indicate dangerous faults. Unplug the unit immediately if you smell burning or see smoke.

• Step 1 – Compare with normal: Some hum is normal, but a sudden increase in volume or a harsh buzzing suggests a problem.
• Step 2 – Check for loose panels: With power disconnected, gently press on the side and top panels. Tighten any loose screws that may allow vibration.
• Step 3 – Inspect transformer mounting: Remove the cover and visually check that the high-voltage transformer is firmly bolted to the chassis. Tighten mounting bolts if loose (avoid touching electrical terminals).
• Step 4 – Stop if noise persists: If the loud buzzing continues, the magnetron or transformer may be failing. Continued use can cause further damage or fire.
• Step 5 – Professional diagnosis: Have an OBH Nordica service technician test the high-voltage components and replace the transformer or magnetron as needed.