Can anybody tell me why this microwave makes sound like it is going to transform into Optimus Prime?

Can someone diagnose the problem only by the sound in this YouTube Video, or maybe I have to do some more measurements?

Not sure if it is heating, worried to leave it ON for too long

[edit] Burnt mica plate burnt mica plate


That's a plasma arc sound. Clean the interior of the oven thoroughly Remove the cardboard, paper or mica cover over the hole that the microwaves pass into the oven, and clean in there too. Clean that little cover itself. Turn the over on and look for light sources inside, other than the lightbulb. Those are likely balls of glowing plasma. Clean around them til the sound and light goes away. If you can't find the source, it's best to buy a new oven. You're not getting the wattage the oven is rated for anymore, and balls of microwave plasma are capable of melting steel.

A good, thorough cleaning can often fix this problem.

| improve this answer | |
  • You were right, burned fat left a hole in a mica paper. I placed it upside-down, and it worked without that plasma noise. Not sure if it is safe on not. Should I replace it? – Kolos Aug 28 '15 at 14:58
  • I kept mine after that happened. It didn't burn the house down. I replaced it a few years later when it failed for other reasons. Yours should be OK to continue using – Wayfaring Stranger Aug 28 '15 at 15:15

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