Dan_Musicant writes:

I found a MW oven in the street a few weeks ago and brought it home
thinking it either works or I'll tear it open and salvage the magnets.

It seemed dead, but yesterday I opened it up and the fuse tested dead
(250v, 15amp). I had a 125v 15 amp fuse and putting it in, the oven
appears to work.

Two questions:

1. Can I leave that fuse in there or should I get a 250v 15 amp instead?

2. A MW oven troubleshooting site says:

NOTE: Fuses do not usually blow on their own. A fuse may blow because of
problems with the interlock switches or with high voltage circuitry. It
is also possible, though rare, that a power surge will cause a fuse to
blow.

Actually, they do sometimes blow on their own after many years. So, it's
quite possible it will be fine. Since you're running it on 125 VAC, a
125 fuse should be acceptable electrically, though an exact replacement
type might be best from a liability point of view. All sorts of other
causes can result in a blown fuse but if you use the oven, it will
probably be obvious fairly quickly if there are still problems.

I have a MW oven I prefer, and figure to store this in my garage for
that day when my current one dies (they always seem to eventually). What
are the interlock switches and can I fix a bad one? Or is it possible I
could fix a high voltage circuitry problem? TIA for some help.

Read the safety warnings at:

http://www.repairfaq.org/sam/micfaq.htm

Then decide if you're experienced enough to try. But, yes, it's possible
to fix almost any problem in a microwave oven that hasn't resulted in
physical damage.

WARNING: Microwave ovens are probably the MOST dangerous consumer appliance or
electronic equipment to service, and not due to the microwaves.

PS This oven was FILTHY! I cleaned tons of crud off the inside, but
more interestingly, the ventilation holes were 70+% clogged with grease.
It's all clean now. Could that bad ventilation have anything to do with
that fuse being blown?

Quite possible..

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