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HomeRepair HelpMicrowave RepairMicrowave is sparking or arcing Repair
Microwave is sparking or arcing
Microwave sparking or arcing should not be ignored. Stop using the microwave, unplug it, and inspect the waveguide cover first. A damaged, burned, loose, or missing waveguide cover can arc inside the oven cavity and should be replaced. If the sparks occur in the cabinet area rather than the cavity, a shorted door switch, such as the primary door switch, secondary door switch, or monitor switch, is a likely cause. Next, inspect the magnetron behind the waveguide cover for burn marks or damage, followed by the high-voltage diode, which may be visibly burned or fail a continuity test. Less common causes include burnt microwave shelf supports and chipped interior paint that exposes the metal cavity. Do not operate the microwave if you see smoke or notice a burning smell. Repairs involving the magnetron or high-voltage diode, and any repair requiring the outer cabinet to be removed, expose you to a high-voltage capacitor that can store a lethal charge even after the microwave is unplugged. The capacitor must be properly discharged before interior work, so use a qualified technician if you are not familiar with that procedure. Enter your model number to find the exact replacement part for your microwave.
01 - Microwave Diode
If the microwave is sparking or arcing in the cabinet area, and not in the oven cavity, you will likely see smoke or there will be a burning smell. The appliance's diode is one of the components that could be damaged and causing the sparking or arcing. When the diode fails, it is often visibly burned out. Inspect the diode and if the diode is burned out, replace it. If inspecting the diode proves inconclusive, test it with a multimeter that uses a 9-volt battery or put a 9-volt battery in series with the diode. When the leads are reversed, the diode should only have continuity in one direction..
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02 - Microwave Door Switch
If the microwave is sparking or arcing in the cabinet area, and not in the oven cavity, you will likely see smoke or there will be a burning smell. One of the appliance's door switches could have shorted and is causing the sparking or arcing. You should inspect each door switch for burn marks or damage and test the components with a multimeter to determine if any the door switches are malfunctioning.
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03 - Microwave Magnetron
If the microwave is sparking or arcing behind the waveguide cover in the oven cavity, you will likely see smoke or there will be a burning smell. The appliance's magnetron is one of the components that could be damaged and causing the sparking or arcing. Inspect the magnetron for burn marks or damage and replace if necessary.
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04 - Microwave Waveguide Cover
The waveguide cover might be damaged and arcing or burning. If this is the case or if the cover will not stay in place, replace it with a new one.
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05 - Microwave Paint
The paint on the interior of the microwave might be chipped. If the paint is chipped, the interior metal will be exposed, causing the microwave to spark or arc. Check the interior of the microwave for any spots where the paint has chipped away. If there are any damaged spots, gently sand the compromised area and touch them up with microwave oven interior paint.
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06 - Microwave Touch-Up Paint
The paint on the interior of the microwave might be chipped. If the paint is chipped, the interior metal will be exposed, causing the microwave to spark or arc. Check the interior of the microwave for any spots where the paint has chipped away. If there are any damaged spots, gently sand the compromised area and touch them up with microwave oven interior paint.
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07 - Microwave Shelf Support
Some microwave ovens will have cooking shelf supports on the interior walls. Inspect the shelf supports for any burnt spots or damage. If there are any burnt or damaged spots, replace with new supports as needed.
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Frequently Asked Questions
What should I do if my microwave is sparking inside?
Why is my microwave sparking near the door or in the cabinet area?
How do I test a microwave door switch or diode when the microwave is arcing?
Could the magnetron be causing my microwave to spark?
How do I find the correct waveguide cover or other microwave replacement part?