Microwave oven flashed and groaned, staining cover of waveguide
While thawing a single frankfurter between pyroceramic plates on the moving carousel, the oven groaned loudly and flashed at the waveguide cover. Afterwards the waveguide cover was discolored over an area the size of a quarter but intact. Internal enamel was intact also. No fuse reacted. After wiping the cover with a damp cloth, I heated a pint of water in a tough glass measuring cup and then a cup+ of water in a ceramic mug, successfully and without incident. Was one frankfurter too small and flat to absorb the rated 1100 watts? Does the oven probably need repair?
Re: Microwave oven flashed and groaned, staining cover of...
I suspect the water content of the frankfurther was your issue. Operating a mwave at full capacity without adequate load to absorb energy would cause something like this to occur. Ultimately the energy had to go somewhere, it chose the weakest point to dissapate. You mention to glasses of water heated up fine? Then no worrie if theres no additional funny noises.
Suggest you lower the power level to around 25% to cook a furter. :o) Or put a mug of water in with it.
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It is possible the magnetron may have been destroyed. Arcing in the waveguide would likely cause a significant increase of cathode to plate current through it; possibly melting it internally. You could also have failure of the high voltage rectifier; caused also by high current. If that's the only problem, then it's possibly repairable for a reasonable cost. You would have to repair and repainted the waveguide. Some waveguides have a vertical bar in them to aid in dispersion of the microwaves. If this is loose and shorting, then you'd have to replace the entire frame/cavity. Not very practical.
Microwave Glass Trays, : Arcing Inside the Microwave - Microwave Glass Trays ...glass tray, microwave plate, glass trays, turntable, microwave oven, carousel, ...microwave energy, and will eventually it will start producing arcs and put out one heck... the damage is non-repairable and the unit should no longer be operated.
Microwave oven does not respond to START button. First ..... but with the leakage from the spot welded waveguide inside the unit. ... My clue in was a spark between the waveguide and the case, when I was messing with the Controller PCB.) ...
Waveguide coverSparking and
arcing in a microwave can be caused by a damaged waveguide cover. Try
removing the waveguide cover to see if the problem persists. Once
removed, the waveguide cover can be inspected for burns, which will
indicate if this is the issue. If the waveguide cover is burnt or will
not stay in the proper spot it will need to be replaced.
sparking or arcing in your microwave is near a rack support, any exposed
metallic area can be covered with a microwave cavity support. It is
also recommended to replace the rack supports in this situation to
ensure the issue is resolved.
Cavity paintIf sparking
or arcing in the microwave is visible on the side walls, the paint
covering the metallic areas could have worn off or chipped. This can
possibly cause pitting in the side walls or ceiling. If this is the
case, it can be repaired with microwave cavity pain
This sounds like carbon build up reacting to RF energy. You need to find where the burn spot is and correct it. It's probably behind or on the waveguide cover usually on the right side of the oven cavity. It looks like a brownish-tan plate about 2-3 inches by 4-5 inches. It's actually made out of mica or plastic. If you can't find the source of this problem, it may be inside the waveguide in which case the unit is not really repairable.
Oh dear, I hope the magnetron still works. That plate you describe is called the Waveguide Cover. This cover must be kept clean otherwise the food particles will carbonize and cause exactly what you have described. Contact the manufacturers web site for a supplier in your area or look on ebay, espares.co.uk depending on your location. When it has been changed, I hope the magnetron/aerial is OK.
You may have a shorted high voltage diode, but I would suspect that you also have a failed magnetron, and with the burns you mention, the waveguide of the oven is possibly damaged, which is unrepairable.
Details covering some previous
models are in
their bulletin here. Even if your model is not on
the list, the same problem can occur.
That bulletin has a picture of a burned waveguide.
happy to help you with free advice and we'd appreciate your thoughtful
rating of our answer.
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.