On Oct 15, 6:13*pm, RF wrote:
Hi Experts,

This model 721.63252 301 has gone belly up for the 2nd time in 2 years.
Both times it blew there was a pop, then a smell of overheated plastic
and then a loud hum. I took it to Sears the first time and they replaced
the
diode. It then worked fine though it had *very small usage.

Now is the second time and it is off the warranty. I opened up the oven
case and
quickly found the diode. It has the marker T3512 and H6N below it. One
end of the
diode has two silver bands around it. It doesn't look overheated.

Do a test on the diode, then; it's unlikely that it is dead, but
possible.
A 'pop' can mean any kind of spark, a smell can be left over from
the first failure, and 'loud hum' might mean you hear the
fan motor loudly when you listen (but would ignore it in normal
circumstances).

Most microwave oven failures are traced to the interlock switches
and fuses, so check those too.

All tests will be with the power disconnected, and the capacitor
discharged
(i.e. crowbar it with an insulated handle tool), of course.