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

On Oct 15, 8:13*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.

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

It appears this might be a Sears Kenmore Microwave, but not positively
identified as such.

hr(bob) wrote:
On Oct 15, 8:13 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.

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

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.

"RF" wrote in message
...
Hi Experts,

This model 721.63252 301 has gone belly up for the 2nd time in
2 years.

[bla bla bla]

Didn't we just do this (Kenmore bellyup 2 times x 2 years) to
death on 9/27 and now it is back ?


Kenmore Microwave Oven goes belly up - twice in 2 years.

In article ,
"Jon Danniken" wrote:
"Jon Danniken" wrote:
RF wrote:

I mean damn.... alot of good people gave lots of great answers
and here it is re-posted anew ?
it is very insulting to those people who gave their time and help
to repost the whole damn lot with no new question and apparently
no work to look at the schemats and links given to the OP.

let me guess ... you didn't like the answers so you went and
found some appliance repair portal that just redirects the
questions back to usenet (s.e.r) ? oh no looks like you just
took it out of (alt.home.repair) and added it to (s.e.e)

next try alt.energy.high-voltage.magnetron

did you thank anybody the first time... for their time

sigh...

robb wrote:
"RF" wrote in message
...
Hi Experts,

This model 721.63252 301 has gone belly up for the 2nd time in
2 years.
[bla bla bla]

Didn't we just do this (Kenmore bellyup 2 times x 2 years) to
death on 9/27 and now it is back ?

That was just an examination for that newsgroup and the scores
were a bit low, so I had to try for the professionals :-)


Kenmore Microwave Oven goes belly up - twice in 2 years.

In article ,
"Jon Danniken" wrote:
"Jon Danniken" wrote:
RF wrote:

I mean damn.... alot of good people gave lots of great answers
and here it is re-posted anew ?
it is very insulting to those people who gave their time and help
to repost the whole damn lot with no new question and apparently
no work to look at the schemats and links given to the OP.

As I mentioned above, the professionals are the ones to go to.

let me guess ... you didn't like the answers so you went and
found some appliance repair portal that just redirects the
questions back to usenet (s.e.r) ? oh no looks like you just
took it out of (alt.home.repair) and added it to (s.e.e)

Wrong, wrong and wrong. I relied on that oven purely to boil
water and, because I have numerous other appliances, there
was no rush and I'm still in no rush.

next try alt.energy.high-voltage.magnetron

did you thank anybody the first time... for their time

Very near the end of the thread I wrote:

"Thanks to all for your efforts.

I have ordered Diode A ($16 incl shipping)and now
I am waiting for the sparks to fly :-) "

Use your glasses next time.


sigh...

hr(bob) wrote:
On Oct 15, 8:13 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.

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

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

On Sat, 17 Oct 2009 09:28:04 -0400, Meat Plow
wrote:

On Fri, 16 Oct 2009 19:22:01 -0700, Jeff Liebermann
wrote:
You might wanna look into a diode with better ratings. I see 15Kv
500ma diodes available in the same form factor.

Oh yeah that's it, **** with the safety issues dumbass.

Such "safety" issues are for people that don't understand how things
work. Increasing the voltage and current rations on the damping diode
25% might give a the OP a bit more voltage margin if he's doing
something that might cause arcing. However, it's not going to prevent
blowing the breaker or the diode with a very high VSWR situation
caused by an arc simulating a sorted waveguide, which reflects all the
forward power back to the maggot-tron. For infinite VSWR, the
maggot-tron is going to see about twice the normal operating voltage
(if the reflected signal is in phase) or twice the current draw (if
the reflected signal is otto phase). Both those situation will blow
the diode from either too much voltage or too much current.

My assumption (possibly incorrect) is that commodity consumer products
are usually designed with minimim component specs and margin to save
costs. Under normal operating conditions, it wouldn't matter if it
were a 12kV/350ma or 15kV/500ma diode but the lower rating is probably
a few pennies cheaper. If it's a bad fit between around the waveguide
causing internal arcing, then it won't matter which one is used.
Either both blow. If it's something else, it might offer slightly
more time before blowing to determine the cause.

As Mr Meat Plow mumbled, check for arcing. The snapping noise you
heard may have been arcing in the waveguide or maggot-tron. You can
usually see some evidence of the burn like damage on the waveguide
walls. If you have it apart, it's easy to inspect (with a dental
mirror). I must be leading a charmed life, but I've only seen arcing
twice.

Yeah, in both of the microwave ovens you worked on.

Full disclosu I vaguely recall repairing (i.e. replaced parts
inside) about 5 assorted microwave ovens. It's not what I normally
do. I will concede that I'm not that experienced in mw oven repair.
One point for you.

Both were caused by a bad fit between the waveguide and the
maggot-tron causing high VSWR and thus high voltages. You might want
to check if everything is assembled correctly and fits tight.

No **** Sherlock.

Thanks. I perform an un-natural act by agreeing with your comment and
you still shovel the manure. What does it take to obtain your
approval?



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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.

On Sun, 18 Oct 2009 10:37:57 -0400, Meat Plow
wrote:

I did factory repair for cheap brands like but not limited to Goldstar
and Tatung (basically Korean) back when the Amana Radar Range models
started to be taken over by those who didn't have a grand to spend on
the cheapest Amana. Also have worked on a ton of commercial Amanas
(every Burger King seemed to have at least one back then.)

Ok, you're an experienced expert, assuming you didn't just juggle
sub-assemblies and modules. However, I still think that increasing
the diode rating 25% is a good idea and doesn't have an effect on
safety, unless the diode is somehow used as a crowbar to blow the
fuse.

On another note, stop with the cheap shot innuendoes. It's hard to
respect those even with the vast knowledge you have when they ****
with you in a non humorous manner.

I'm not sure I know how to do that without being abusive, abrasive,
irritating, obnoxious, humiliating, etc. I've been answering usenet
questions for so long, that it's become almost an institution. It's
also fun. Of course, when customers pay for my advice, I can be
diplomatic. On rare occasions, I even use a spelling chequer.

It might be helpful if I point out that few of my assorted usenet
rants are intended to be insulting. They're intended to inspire the
intended target to think. I never offer an opinion without
substantiation, usually in detail, and with plenty of examples, URL's,
analogies, and detail. I've experimented with various styles of
answering questions and engaging in discussions. Humor, mixed with
satire, and a dash of "you're not meeting my expectations" is what
seems to work best for me. Motivation through humiliation is not very
popular or politically correct, but it works well. For example,
getting people with questions to supply enough information to answer
their question is often a difficult process. If you are on the
receiving end of one of my detailed rants, you might ask yourself why
I would spend the time on you.

Re-reading my previous rants in this thread, I don't see where I have
"****(ed) with you in a non-humorous manner". If I did, it was not
intentional, so please accept my apologies. However, if you're
complaining about my style or method of argumentation, as I indicated,
I'm not sure I can change that even if I wanted to do so.

However, I'll offer you a deal. I'll try to control my verbal fencing
with you, if you will ease up on the profanity (even when I screwup).
I don't have a problem with profanity, except that it creates a
generally unprofessional impression. I just hate to see someone do
that to themselves.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote in
:

On Sun, 18 Oct 2009 10:37:57 -0400, Meat Plow
wrote:

I did factory repair for cheap brands like but not limited to Goldstar
and Tatung (basically Korean) back when the Amana Radar Range models
started to be taken over by those who didn't have a grand to spend on
the cheapest Amana. Also have worked on a ton of commercial Amanas
(every Burger King seemed to have at least one back then.)

Ok, you're an experienced expert, assuming you didn't just juggle
sub-assemblies and modules. However, I still think that increasing
the diode rating 25% is a good idea and doesn't have an effect on
safety, unless the diode is somehow used as a crowbar to blow the
fuse.

I note he didn't answer my question about HOW increasing the rating on the
HV diode would affect safety". Instead,he made an attack.
IOW,he doesn't know,thus not so "expert".

I don't believe the HV diode is "used as a crowbar" to blow the fuse,nor is
the diode intended to blow as a "safety" device.

--
Jim Yanik
jyanik
at
localnet
dot com

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

Jim Yanik wrote:

Jeff Liebermann wrote in
:


On Sun, 18 Oct 2009 10:37:57 -0400, Meat Plow
wrote:


I did factory repair for cheap brands like but not limited to Goldstar
and Tatung (basically Korean) back when the Amana Radar Range models
started to be taken over by those who didn't have a grand to spend on
the cheapest Amana. Also have worked on a ton of commercial Amanas
(every Burger King seemed to have at least one back then.)

Ok, you're an experienced expert, assuming you didn't just juggle
sub-assemblies and modules. However, I still think that increasing
the diode rating 25% is a good idea and doesn't have an effect on
safety, unless the diode is somehow used as a crowbar to blow the
fuse.


I note he didn't answer my question about HOW increasing the rating on the
HV diode would affect safety". Instead,he made an attack.
IOW,he doesn't know,thus not so "expert".

I don't believe the HV diode is "used as a crowbar" to blow the fuse,nor is
the diode intended to blow as a "safety" device.

You can put in a higher rated Diode/rectifier, it just cost more..

Most likely the original one is border line.

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.

"RF" wrote in message
...
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

On Mon, 19 Oct 2009 03:21:08 -0400, "Michael A. Terrell"
wrote:

Harbor Freight has several different sets of security bits:
http://search.harborfreight.com/cpisearch/web/search.do?keyword=security+bit&Submit=Go

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.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

On Mon, 19 Oct 2009 03:21:08 -0400, "Michael A. Terrell"
wrote:

Harbor Freight has several different sets of security bits:
http://search.harborfreight.com/cpisearch/web/search.do?keyword=security+bit&Submit=Go

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.

--
Best Regards:
Baron.

"bw" wrote in
:


"RF" wrote in message
...
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




Harbor Freight sells those bits.

On my Nissan sentra,I encountered two 5-lobed security screws,at first I
thought it was the usual 6-lobed Torx.Fortunately,the screws had an
integral washer that was thick enough for my mini-channellock pliers.
the screws were on the Mass airflow sensor/housing.

--
Jim Yanik
jyanik
at
localnet
dot com

Meat Plow wrote:

On Sun, 18 Oct 2009 10:41:29 -0700, Jeff Liebermann
wrote:

On Sun, 18 Oct 2009 10:37:57 -0400, Meat Plow
wrote:

I did factory repair for cheap brands like but not limited to Goldstar
and Tatung (basically Korean) back when the Amana Radar Range models
started to be taken over by those who didn't have a grand to spend on
the cheapest Amana. Also have worked on a ton of commercial Amanas
(every Burger King seemed to have at least one back then.)

Ok, you're an experienced expert, assuming you didn't just juggle
sub-assemblies and modules. However, I still think that increasing
the diode rating 25% is a good idea and doesn't have an effect on
safety, unless the diode is somehow used as a crowbar to blow the
fuse.

Well what would you rather have, a magnetron gone wild, stuff being
heated to the point of fire or a shorted diode blowing a fuse? I was
taught in seminars by factory representatives never to exceed the
ratings of parts if we had to use subs. And to always use factory
supplied parts first. Do I feel this practical every time? No. But I
tend to trust those that designed the equipment first. Does that
mean your microwave is going to blow sky high or melt down if you
replace the diode with one that has a 25% increased rating? I doubt
it. Would I suggest you exceed the factory ratings on any part? Not
where public safety including children are concerned.


Do you really think that the OEM for the HV rectifer only ships units
that break down exactly at the rated voltage? It is the minimum rating,
and often the rectifier will handle the 25% you're complaining about.
The original rectifier may have been able to stand 100% more PIV than
the guarantteed voltage

The transformer will saturate if the line voltage is too high.
Anything that increases the load current will blow the line fuse.

What 'I' would rather have is a technician that actually understands
the circuit they are working on instead of one who makes mindless rants.


--
The movie 'Deliverance' isn't a documentary!

Jeff Liebermann wrote:

On Mon, 19 Oct 2009 03:21:08 -0400, "Michael A. Terrell"
wrote:

Harbor Freight has several different sets of security bits:
http://search.harborfreight.com/cpisearch/web/search.do?keyword=security+bit&Submit=Go

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.

That is a nice set. It is on sale for $5.99 right now.


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 haven't found any low grade bits in the HF set I bought a couple
years ago. At one time Torx was considered a security bit, but they
became mainsteam and ruined that. I like that there are duplicates.
That way if you lose on on a jobsite you should have a spare.


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.


http://www.harborfreight.com/cpi/cta...emnumber=91796
is another nice set. Especially when it's on sale for half price.

Also, HF calls Torx either tourqe or star.

Did you know that HF had an assortment of 1/2W 5% carbon film
resistors at one time? It was a nice starter kit for newbies.


--
The movie 'Deliverance' isn't a documentary!

On Mon, 19 Oct 2009 11:01:39 -0400, Meat Plow
wrote:

We're now digging up my septic tank, so I'm in the correct frame of
mind to discuss such issues. Both my arms ache from shoveling (I'm
otto shape). Typing hurts, so I'll be brief.

Well what would you rather have, a magnetron gone wild, stuff being
heated to the point of fire or a shorted diode blowing a fuse?

That's a rather limited selection of options. I don't think any of
those apply to a change of diode rating. What might apply is if a
diode failure is used as a crowbar to blow the breaker or fuse. It
might also be used to protect the maggot-tron by sacrificing itself
before something else blows up. I doubt either of these are true.

Please note my previous comment that "such safety is for those that
don't understand how things work". If the OP were a clueless idiot,
with no electronics experience, no test equipment, and no
understanding of the hazards involved, my advice would be to replace
everything with manufacturer approved stock components. If the OP had
some idea of what he was doing, has some electronics repair
experience, and maybe owns a DVM, I would suggest that some
substitution might be tolerated, but to check with the experts first.
If the OP were able to design a microwave oven, understands exactly
how it works, knows what a damper diode does, and is safety conscious,
then I would suggest making all manner of radical circuit
modifications. After reading how he extracted the Torx security
screws, I consider the OP in the first category and somewhat regret
suggesting a substitute part.

I was
taught in seminars by factory representatives never to exceed the
ratings of parts if we had to use subs. And to always use factory
supplied parts first.

I got the same lecture when I was fixing consumer audio/radio/tv from
the various manufacturers. However, it wasn't a safety issue. It was
to avoid litigation based upon "unsafe" substitutions. The company
will honor the warranty after repairs only if the repairs were done
with approved parts. Substitute or modify, and the warranty is lost.
It's bad enough when customers attempt to fix their own equipment, and
then return it under warranty. It would be really bad if that were
done by a factory authorized warranty station. More simply, customers
can substitutes, while factory repair stations cannot.

Do I feel this practical every time? No. But I
tend to trust those that designed the equipment first.

I've never designed a microwave oven, but I can tell you how it works
in consumer electronics and marine radio. At some point, early along
the design cycle, the design is frozen. A major modification to one
radio turned into a 12 week design cycle, but my initial design was
frozen after only 2 weeks from start. I was finding errors all along
the way, but was not allowed to make any changes for fear of
introducing delays. Near the end, production required some changes,
which was where I snuck in some changes. There were also some changes
inspired by the dealers, as inspired by customers, and delivered
through marketing. On occasion, there have been cost cutting
exercises, which is another opportunity to fix things. Something like
"We can cut $0.0001 off the cost if we switch to a diode rating that
closer to the failure point. The savings, over millions of units,
will offset any increase in dealing with failures".

Today, things are done quite differently. There's usually no
breadboarding and the design cycle is MUCH shorter. The design is
simulated on a computah, there's no breadboard, and it goes directly
into production. If there are any problems, the standard answer is
that the replacement model is already in the pipe and to wait for the
replacement, and not fix the defect.

About the only thing that prevents total disaster is that most new
products are evolutionary, not revolutionary. Changes tend to be
small and earlier mistakes tend to eventually get fixed. However, my
adage of "features and functions get added faster than bugs get fixed"
also applies, thus keeping quality just above adequate.

So, you may trust the designer, but I wouldn't exactly trust the
design.

Does that
mean your microwave is going to blow sky high or melt down if you
replace the diode with one that has a 25% increased rating? I doubt
it.

Could that mean you agree with me?

Would I suggest you exceed the factory ratings on any part? Not
where public safety including children are concerned.

Not public safety or children. Think certifications, litigation,
liability, and tort law. For example, it's not UL or FCC certified if
ANY component changes were made (without applying for minor change
recertification).

Agreed. Sorry about the profanity, worked on too many CB radios back
when the boom was on and truckers would drive hundreds of miles to our
shop. We liked to make them feel at home if you know what I mean.

I got my start in RF doing CB radios. I designed two CB radios, a CB
pager, a mess of accessories, and worked for radio shops that did
mostly commercial, but also some CB. Yeah, profanity is part of the
culture. I managed to pickup a few choice words and phrases in high
skool that have been difficult to eradicate. At least I've purged
them from my writing. If I want to be abusive, there are other and
better ways.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 21 Oct 2009 09:04:11 -0400, Meat Plow
wrote:

Some times the best way to blow off some steam is with words.

Yep. I've learned more about effuent terminology and profanity while
working on the septic system than all the CB lingo in my chequered
past.

I've helped
design one of the best amateur radio repeaters in the Cleveland/Akron
area now being used for the backbone of NOAA - W8CLE and SKYWARN.

Well, working backwards, I either built or helped build:
W6JWS-2m Bonny Doon. (no photos)
K6BJ Santa Cruz. http://www.LearnByDestroying.com/k6bj/
KI6EH Watsonville. (no photos)
A bunch of junk in Smog Angeles I would like to forget.
WB6EEP West L.A.
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/wb6eep-01.html
and a bunch of commercial stuff.
http://802.11junk.com/jeffl/pics/Old%20Repeaters/index.html
My favorite was a repeater built into a hollowed out 4x4 fence post
and installed in a prominent location. Sorry, but no photos.

The problem with ham repeaters is that they seem to run forever,
usually with zero maintenance. When something finally breaks, I get
to fix it. When someone builds it wrong, I get to fix it. When
something blows, I get to repair it.

Design is usually done on the back of an envelope. Documentation? We
don't do no stinkin documentation:
http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html

One of the few smart things I've done is to NOT build my own repeater.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Meat Plow wrote:

On Wed, 21 Oct 2009 16:48:19 -0700, Jeff Liebermann
wrote:

On Wed, 21 Oct 2009 09:04:11 -0400, Meat Plow
wrote:

Some times the best way to blow off some steam is with words.

Yep. I've learned more about effuent terminology and profanity while
working on the septic system than all the CB lingo in my chequered
past.

Heh...septic systems suck. I've lived in two homes with them in my
youth and 5 kids in the house. #1 back in the mid 60's used to fill up
and leak through the ground. Made the grass around it nice and green
though #2 was in a home newly built for us in 1968. A brick ranch
out in then rural surroundings, no water/sewer. Never had a lick of
problems with that thing. It was a huge tank and cleverly made leech
bed from house block in sand and rock. I guess in that location the
tank could be made from house block and act partly as a leech bed of
its own. 20 years later they ran water and sewer and caved in the tank
and leech bed so I know what it looked like.

I've helped
design one of the best amateur radio repeaters in the Cleveland/Akron
area now being used for the backbone of NOAA - W8CLE and SKYWARN.

Well, working backwards, I either built or helped build:
W6JWS-2m Bonny Doon. (no photos)
K6BJ Santa Cruz. http://www.LearnByDestroying.com/k6bj/
KI6EH Watsonville. (no photos)
A bunch of junk in Smog Angeles I would like to forget.
WB6EEP West L.A.
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/wb6eep-01.html
and a bunch of commercial stuff.
http://802.11junk.com/jeffl/pics/Old%20Repeaters/index.html
My favorite was a repeater built into a hollowed out 4x4 fence post
and installed in a prominent location. Sorry, but no photos.

The problem with ham repeaters is that they seem to run forever,
usually with zero maintenance. When something finally breaks, I get
to fix it. When someone builds it wrong, I get to fix it. When
something blows, I get to repair it.

Design is usually done on the back of an envelope. Documentation? We
don't do no stinkin documentation:
http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html

One of the few smart things I've done is to NOT build my own repeater.

Well now adays using a prebuilt from a company like Icom, a cavity
duplexer and adding a Mirage repeater amp and a couple Diamond Super
Stationmasters, some 9913 or hard line is the way to go. Back in the
early 90s it was piece together a controller, mobile or bass rig, an
AT computer to handle the phone patch etc.... I know of one such beast
still in existence that I had a part in its equipping and that I had
modified a couple Motorola 160mhz "Pageboy" pagers for use on the
repeater. It's used every day all day long and part of the SKYWARN 2
meter network. I can hit it with a 5 watt HT 50+ miles away albeit
strategically located.


'90s? you should have tried building one in the late '60s. Motorola
Twin-V transmitter strip, a GE Pre-prog reciever strip, home brew power
supplies, Unijunction transistor timers and a surplus W.E. Touch tone
decoder and a homebrew phone patch. The diplexer was home brew out of
scrap copper pipe. All of this mounted in a surplus 3' shallow relay
rack.

There were no computers. It was on 146.01/146/61 and installed in the
pressbox at Lemon Monroe high School in Monroe Ohio. You could hit it
from the Dayton hamfest with a 1 W handheld.


--
The movie 'Deliverance' isn't a documentary!

On Thu, 22 Oct 2009 10:09:09 -0400, "Michael A. Terrell"
wrote:

'90s? you should have tried building one in the late '60s. Motorola
Twin-V transmitter strip, a GE Pre-prog reciever strip, home brew power
supplies, Unijunction transistor timers and a surplus W.E. Touch tone
decoder and a homebrew phone patch. The diplexer was home brew out of
scrap copper pipe. All of this mounted in a surplus 3' shallow relay
rack.

There were no computers. It was on 146.01/146/61 and installed in the
pressbox at Lemon Monroe high School in Monroe Ohio. You could hit it
from the Dayton hamfest with a 1 W handheld.

Feh. My first repeater:
http://802.11junk.com/jeffl/pics/Old%20Repeaters/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.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
On Thu, 22 Oct 2009 10:09:09 -0400, "Michael A. Terrell"
wrote:

'90s? you should have tried building one in the late '60s. Motorola
Twin-V transmitter strip, a GE Pre-prog reciever strip, home brew power
supplies, Unijunction transistor timers and a surplus W.E. Touch tone
decoder and a homebrew phone patch. The diplexer was home brew out of
scrap copper pipe. All of this mounted in a surplus 3' shallow relay
rack.

There were no computers. It was on 146.01/146/61 and installed in the
pressbox at Lemon Monroe high School in Monroe Ohio. You could hit it
from the Dayton hamfest with a 1 W handheld.

Feh. My first repeater:
http://802.11junk.com/jeffl/pics/Old%20Repeaters/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.

Meat Plow wrote:
On Thu, 22 Oct 2009 12:02:28 -0700, JD wrote:

snip

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.

Did you read my post advising you how to go about the repair?

Thanks for them.

"Replace the cap, diode and mag. Tear the cover off and inspect the
waveguide, stirrer and outlet covering for arcing. Check the interior
for arcing. Watch the cap it can bite you. Have a micro detector and
check for leaking door and overall leaks.

Or just buy a new oven.

Best for the buck in my opinion is the GE 1100 watt or Sharp."

I believe it's not worth the bother. The oven cost about $118
and the magnetron alone costs $69 + shipping.

Do these ovens have any scrap value?

Consumer Reports (Feb 2009) rated 3 Kenmore midsized countertop
models as the best. I'm beginning to lose confidence in them (C.R.).

Thanks for your support.

There is an excellent article in the following link on repairing
microwave ovens:

http://www.gallawa.com/microtech/safety.html#dischg

Good luck guys!