Buzzing spark / flashing - Thermador MBBS Microwave Oven

save your sanity and get another one at a resale shop..that one may catch fire..

Microwaves use a magnetron to generate microwave energy and direct it a rotating blade wheel to spread them around the inside of the oven. If there is any metal in the area to be heated, or any of the blades are bent, even a bit, the microwave energy can be reflected back up to the magnetron area. In this area there is now too much power and it sparks away, so it does not heat the item in the oven.
Because it is sparking it is now a safety hazard the sparks may melt and set fire to plastic parts in it. This is serious it could burn your house down. Bin this microwave and cut the cable off it to make sure no one else ever uses it.

This is a indicator the magnetron is going, take warm soapy water and wash until spotless, sometimes food particals will cause this, if no change! check interior for paint peeling and exposed metal, again a potential issue. If no change! the price of new one is worth considering due to attractive pricing.

Hi,

Here is a tip that will help you to figure out what is wrong with your Microwave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101

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Make sure the inside is clean of all grease and the paper like screen needs to be removed and cleaned also. If the screen is burned it needs to be replaced. You can find one at an appliance parts store.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

I think I would find another microwave. You do not need a fire hazard in your house.

Some units have a silica plate covering the waveguide opening. If it get burn spots on it, it'll do that. Remove the plate and try the unit. If it's OK, go to your MW repair shop and order a new plate.

Remember... always cover your food...

Geno

The noise is probably from the high-voltage transformer. When it is overloaded, the excess magnetic field it produces vibrates its wire coils. Odd that it only happens for a brief time. It is either defective itself (in which case it may go a long time) or it is getting overloaded by the magnatron/capacitor/diode on its output (in which case it will get worse shortly)
Hope Ya Fix it

This problem normaly happens when the door is not closed properly for a long time and flashing and buzzing starts to give user a indication for same. Allthough it is not risky as microwave oven has safty door switches wich does not allow oven to operate while door is open. Take care and close the door properly before you leave kitchen..