A Whirlpool VT256/SL microwave oven came in for recycling this week that looked like a good candidate for refurbishment. It was dead. It had a blown fuse and a shorted high voltage capacitor in the voltage doubler circuit. So I replaced the blown bits and it ran up sweet.
And then I checked out the waveguide covers because they sometimes get a bit carbonised and start arcing. We sell a lot of them through our online shop (sorry about the advert but hey you are getting a free blog post!)
This microwave has two mica waveguide covers – one at the top and one at the bottom. Most microwaves only have one.
So take a look at this photo.
The carbonisation happened around a bead of glue that goes across the waveguide cover, probably due to food residues getting trapped on it. Now take a look at the wall of the cavity above the waveguide cover. For some reason there is an extra level of indentation between the waveguide cover and the cavity wall. Why? And what does the glue do? Is the bead of glue in the wrong place? Should it have been acting as a sealant in the wide gap between the waveguide cover and the cavity wall?
I don’t think it is a deliberate ploy to create inbuilt obsolescence. The Whirlpool microwave ovens are generally built quite well.
I have come up with a decent fix for it so if you need one buy one here!