Samuel M. Goldwasser wrote:
"ManhattanMan" writes:

4 year old sharp microwave that overnight decided it'd do everything
but heat.

All functions normal, except heat. There is 120V applied to the HV
transformer primary, secondary measures 150 ohm, filament on both
transformer and magnetron shows negligible ohms, diode tests good on
back voltage, HV cap appears OK, magnatron does get very hot after a
couple of ten second tests...... ?????

I've had several with bad micro switches, HV cap, etc., but this one
does everything but heat for no reason.....

My guess would be magnetron. Since it's getting hot quickly, it
means it's getting more than filament power, but not putting anything
out.

But check he HV diode properly as described in another post or
at the S.E.R FAQ site below, or replace it. It will have a 6-10
V forward drop, so a VOM or DMM can't test it.

And the SAFETY issues are extremely critical!

Diode checked ok using the technique described w/15V applied, and the tests
were made with a saucer of water in the oven that didn't even lose it's
chill.
Oh well, we wanted a bigger model anyway....

Thanks for the replies........