OK Cavity Arcing / Waveguide Contamination or Damage

Microwave sparks inside the cavity during cooking; arcing sounds or bright flashes

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Possible Causes

Damaged or burnt waveguide cover (mica plate), Exposed metal in cavity (chips in paint), Use of metal containers or foil, Food splatter carbonized on cavity walls

How to Fix / Troubleshooting

Safety: Stop the microwave immediately if you see sparks. Unplug before inspection.

  • 1. Remove metal objects: Ensure no metal utensils, foil, or twist ties are inside.
  • 2. Inspect waveguide cover: Locate the small rectangular cover (usually on the side wall). If it is burnt, cracked, or has holes, it must be replaced.
  • 3. Clean the cavity: Thoroughly clean all walls and ceiling with mild detergent and water to remove grease and burnt food. Dry completely.
  • 4. Touch-up paint: If enamel is chipped exposing bare metal, use microwave-safe cavity touch-up paint to cover the area.
  • 5. Replace waveguide cover: Install a new mica waveguide cover designed for your OK model.
  • 6. Test with a cup of water: Run a short cycle and observe. If arcing persists, further inspection of the waveguide and magnetron is required by a technician.
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Repair Difficulty

Easy 2/5

Required Part

Waveguide Cover (Mica Plate)
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