RF wrote:

whit3rd wrote:
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.


My thanks to everyone for their interest and efforts and my
condolences for the strains.

To answer a question from just above, there is no doubt that the hum
that appeared just before I shut the oven off was FAR louder than the
normal operating level.

The situation now is that the replacement diode I ordered has arrived
and is now
installed. Question now is, should I start up the oven or getter a
stronger diode?
Thanks Jeff for the suggestion.

I looked through the Sears website (Thanks Jeff) and found the model
but the transformer,
magnetron and diode are missing. Even a search for the word diode
gives nothing.

BTW, has anyone seen the wierd screws that are used to keep the cover
on the oven? They are Torx but with a difference. There is a tiny but
very strong spike right in the middle of the hole in the screw where
the key fits. SO in essence, to remove the screws the right way, a
Torx key with a hole in it is the way to go.

They are security Torx screws. There are also some that have one less
notch than standard Torx screw heads.

That should keep
most users away but not engineers, mechanics and other knowledgeable
folks :-)

--
Best Regards:
Baron.