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Kenmore Microwave Oven - 2 failures in 2 years

R

RF

Jan 1, 1970
0
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.

The area near this diode has a magnetron coupled with 2 wires to a trafo and
one to a capacitor which continues through the diode to ground. A third
wire on
the trafo goes to the second terminal of the capacitor.

If I could have this diode identified , I'd greatly appreciate it.

TIA
 
R

RF

Jan 1, 1970
0
hr(bob) [email protected] said:
It appears this might be a Sears Kenmore Microwave, but not positively
identified as such.

Mr Bob, I personally bought it originally from Sears. It was probably
made in China
or at least many of the parts were.
 
R

RF

Jan 1, 1970
0
Jeff said:
Go unto:
<http://www3.sears.com>
and inscribe 721.63252301 into the search box. It should point to
exploded view diagrams with part numbers.
<http://www.searspartsdirect.com/partsdirect/getModel!retrieve.pd?modelNumber=721.63252301>

The diode is rather generic and commonly available:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=380157469830>
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260436360616>
12Kv 350ma

Thanks Jeff for the links.

That looks like a very good solution. Will check it out :)
 
R

RF

Jan 1, 1970
0
hr(bob) [email protected] said:
It appears this might be a Sears Kenmore Microwave, but not positively
identified as such.

I forgot to ask if you looked at the subject line:

Kenmore Microwave Oven - 2 failures in 2 years
 
R

RF

Jan 1, 1970
0
whit3rd said:
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.
That should keep
most users away but not engineers, mechanics and other knowledgeable
folks :)
 
B

Baron

Jan 1, 1970
0
RF said:
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.
 
B

bw

Jan 1, 1970
0
RF said:
whit3rd wrote:

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.

Security Torx
 
B

Bob Larter

Jan 1, 1970
0
Jeff said:
If I'm in a rush, I grab the Dremel tool, insert an abrasive disk, and
cut a slot across the head. Then, I just use an ordinary flat blade
screwdriver to extract the screw. I recently had a situation where I
couldn't do that, so I just used a die grinder and destroyed most of
the screw head. I consider tamper proof screws an attractive
nuisance.

Agreed. But I have a (Chinese, of course) set of Torx security
screwdriver bits, so I use them. I save the Dremel + cutting disk
technique for the /seriously weird/ screws.
 
B

Baron

Jan 1, 1970
0
Jeff said:
Thanks.

I have the 100 piece set, which I bought at the local hardware store
for about 3 times the price. It does NOT have 5 point Torx style
bits, but does include some other weird bits. About 2/3 of the set
are NOT security bits, but just common Torx, Allen, Phillips, straight
blade, etc bits. There are also some duplicate bits that seem to have
been added so that they total 100 bits. The quality of the supplied
bits are kinda marginal.

I also have several of the 33 piece sets, which are all security bits.
This is a good selection, but also do not include 5 point Torx style.
The quality of the bits are much better than the 100 piece set.

The five point ones are often found in automotive applications and
domestic electrical goods where there is an electrocution hazard.
Though I have seen some with a triangular recess with a centre pin.
 
J

JD

Jan 1, 1970
0
Jeff said:
Feh. My first repeater:
<http://802.11junk.com/jeffl/pics/Old Repeaters/slides/wb6eep-01.html>
was like that. 6m Pre-Prog receiver near the bottom. Unichannel
receiver hanging in back. Two 80D xmitters, with mobile power
supplied modified for AC operation, near the top. DC wire line remote
in the middle along with home made control and audio panels. Note how
cleverly I put all the heavy stuff on top so that it would topple when
moved. Driving around town with a 2500 and later a Princess (Schmoo)
phone on the floorboards was the ultimate in cool in the late 1960's.

Also, initially no touch tone. It was controlled by a rotary stepper
switch and a single tone decoder. Also, no PL. A later machine used
a Strowger switch when 10 functions were deemed insufficient. However,
it was way too big and and made far too much noise, so a WE 247B
materialized and I switched to Touch Tone. The first PC I used in a
repeater was for IRLP, not the controller. I keep wanting to build
and write code for my own PC based controller, but can't find the
time, excuse, or market to justify the effort.

One of the repeaters I listed (W6JWS-2m) is an Icom RP-1510 commercial
repeater owned by the local ARES group. I inherited the unpaid
lifetime maintenance contract on it when the previous tech died. I
had to remove a tangle of modifications, fix a few things, retune, and
deal with a nasty case of intermod at a new location. The quality of
the radio and controller are marginal, but it will probably remain in
service forever.

How we got from microwave ovens to this will remain a mystery.

Back to shoveling mud and muck. Yech.


Interesting discussions :)

If we may return to the original topic for a moment, I reassembled
everything
and now there is a loud hum. so I guess another component was busted
when the
diode went.

Any suggestions? I know there is some info above and I'll look for it
later today.

Thanks to all for your patience.
 
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