I'm not sure why some people appear to be turning this into rocket science.

Here is a reply from John Gallawa of Microtech at
http://www.gallawa.com/microtech/, generally regarded as the most
comprehensive site for microwave ovens on the Web.

First my question (similar but not word-for-word what I posted here)
and then John's reply:

Someone emailed me in a huff about having used ordinary paint to touch
up a microwave and now everything "smells funky" and it "smokes". This
was done under where the turntable wheels move.

Have you ever heard of problems of this type? They say that it was
white gloss enamel, that they waited 24 hours for it to dry, and that
surfaces were cleaned thoroughly.

I've been trying to get them to do some tests to determine if it is a
continuing problem or just residual solvent odor that will go away.
I had them remove the turntable and just put a cup of water in to act
as a load. They then said there was no smoke but the water smelled so
bad they couldn't get near it.

Any info would be appreciated.

Thanks!

--- sam

From: John (via email):

First, though, it is probably not the paint. If they used standard
enamel, that should be fine. We used to use off-white enamel to repaint
cavities.

If the reason they cleaned and repainted the cavity surfaces was because
of discoloring due to arcing, then possibly there were some tiny (the
size of a needle point is all it takes) traces of carbon residue that
were not completely eliminated and were subsequently painted over. Or
perhaps the wheels of the roller ring/turntable assembly have developed
microscopic carbon tracks that are producing small amounts of arcing.

Of course, there is the possibility of another problem that is just
coincidental to the paint job. For example, there could be infinitesimal
amounts of arcing from the waveguide cover to an adjacent metal surface,
so small that it is goes noticed.

For removing residual odor, we have always had good success by
placing used coffee grounds in the cooking cavity overnight for several
nights. The grounds do a good job of absorbing lingering odors.

The only problem we ever had with re-painting cavities was the fact that
we weren't a paint shop. As long as the surfaces were properly prepared
(and that was always the crucial part), though, and the paint was
appropriately applied, the outcome was usually acceptable. While cavity
paint was available from some manufacturers, in many cases, we would
simply purchase a can of off-white enamel from the local hardware store,
and this served the purpose.

In fact, I have now been able to determine from testing done by the
person who originally was complaining that it is probably just residual
odor at this point. I had them run the oven with just a water load to
see if the area of the new paint heated up or behaved strangely. It
did not. They'll have to try the coffee grounds I guess.

Thanks to all who responded.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
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