Microwave makes a loud buzzing or humming noise during operation, louder than normal, sometimes with reduced heating.

Safety first: High-voltage components are dangerous. Limit DIY work to external checks.

• Step 1 – Compare with normal: If the noise is significantly louder than when the unit was new, suspect a failing high-voltage component.
• Step 2 – Check installation: Ensure the microwave is securely mounted and not vibrating against cabinetry.
• Step 3 – Stop use if burning smell or sparks: If you notice a burning smell or see sparks, stop using the microwave immediately and unplug it.
• Step 4 – Professional diagnosis: Have a technician inspect the magnetron, transformer, and internal wiring for arcing or mechanical looseness and replace as needed.