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Microwave sparking or arcing inside

Rule out metal in the cavity first (foil, twist ties, metal-trimmed dishes, a rack on a model not meant for it). The most common part failure is a grease-soaked, carbonized waveguide cover. Chipped cavity paint and a damaged magnetron antenna cap are next. Stop using the unit until fixed, since continued arcing can damage the magnetron.

Single source ~30 min easyBrands: All

Before you start

  • Stop using the microwave while it arcs
  • Waveguide cover replacement is done from inside the cavity with the unit unplugged
  • Anything behind the cavity walls (magnetron, waveguide) is high-voltage territory: the HV capacitor can hold a lethal charge even when unplugged; trained techs only, with the capacitor discharged

Diagnostic steps

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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