Kenmore microwave 99921

[Wayne Tiffany]

This one's for the archives.

My microwave is a Kenmore, model #99921 (564.9998210) with a Sanyo 11355
controller board. Symptoms were that the light would come on with the door
open, but the only activity out of the display was to show a 0.

Solution - electrolytic filter cap on the downstream side of the bridge
rectifier coming in from the power supply transformer. I think it was 4700
uf @ 35v. It had failed to the point that one of the leads was no longer
attached inside. Replaced it and all appears to work just fine.

What's interesting is that when the uP got a voltage supply that apparently
had a bit too much ripple on it, rather than totally shutting down or
frying, it displayed a call for help by still showing something, rather than
a blank screen.

WT

 

[Mistress]

My microwave is a Kenmore, model #99921 (564.9998210) with a Sanyo 11355
controller board. Symptoms were that the light would come on with the door
open, but the only activity out of the display was to show a 0.

Gosh! Someone else still has one of these Sears microwaves. Mine is still
going strong after all these years. I have been through three magnetrons
and two HV caps and countless temp probes though.

 

[Wayne Tiffany]

That is quite interesting. I bought this one about 1984, and after probably
4-5 years I had to replace the magnetron. The only other issue (other than
the current one) has been with the piezo beeper on the circuit board. It
started sounding raspy, like it had a cold, you know, and then gradually got
worse until it quit. Personally, I prefer it without the beep as I find it
annoying, but the family complains. I have looked for a 3 wire piezo, but
haven't found one. I also can't see $100+ to replace the circuit board just
to make noise. My temp probe has never been a problem, but I also
don't think it's ever been used.

WT

 

[Sam Goldwasser]

That is quite interesting. I bought this one about 1984, and after probably
4-5 years I had to replace the magnetron. The only other issue (other than
the current one) has been with the piezo beeper on the circuit board. It
started sounding raspy, like it had a cold, you know, and then gradually got
worse until it quit. Personally, I prefer it without the beep as I find it
annoying, but the family complains. I have looked for a 3 wire piezo, but
haven't found one. I also can't see $100+ to replace the circuit board just
to make noise. My temp probe has never been a problem, but I also
don't think it's ever been used.

Digikey or Mouser or Jameco (forget which, maybe all) have 3 wire
piezos for a buck or two.

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[Isildur's Bane]

Considering it's 20 years old, maybe it's time to upgrade?

-Isildur's Bane

 

[Mistress]

The only other issue . . . has been with the piezo beeper on the circuit board. It
started sounding raspy, like it had a cold, you know, and then gradually got
worse until it quit. Personally, I prefer it without the beep

<Laugh>
My piezo buzzer is covered with a paper label to tone it down a bit.

 

[Wayne Tiffany]

Upgrade??? Surely you jest. True, there's a point, but as long as I can
fix it for pennies, that's my plan. It's a good, solid microwave with
enough features to be worth saving. Now, if the magnetron fails again, then
I'll probably call it quits. Then I'll send it to "Mistress" for parts for
hers!

WT

 

[Franc Zabkar]

Considering it's 20 years old, maybe it's time to upgrade?

Upgrade to a new microwave for want of a $2 piezo? I should hope not.

-Isildur's Bane

- Franc Zabkar

 

[Mistress]

Upgrade??? Surely you jest. True, there's a point, but as long as I can
fix it for pennies, that's my plan. It's a good, solid microwave with
enough features to be worth saving. Now, if the magnetron fails again, then
I'll probably call it quits. Then I'll send it to "Mistress" for parts for
hers!

Thank you. That's very considerate.

I should tell my story of how I came to have a "Sears Best" microwave. Back
then microwaves were the next, best thing and I was determined to have one.
But I could barely afford a "Sears War-On-Poverty" model. Which is what I
got.

A few months later my partner called me at work to say the microwave went
"pop" and died. A fuse, I figured, and promised to fix it when I got home.

Upon removing the cover from our "new" microwave I discovered what appeared
to be a perfectly amateur repair job. All the control wiring had been
stripped and twist-spliced together. None of these splices had any
insulation! Bits of the colored wire coating lay about the bottom of the
cabinet!

I called Sears. They sent a tech who could not offer any explanation. He
took it back to the shop to show his boss.

A few days later I called to find out where my replacement was. It didn't
sound like anyone had a plan. Nor could anyone yet explain how my sealed-
in-the-box new microwave could have been in such a state.

So I wrote a le its to the local store manager, and CC'd his boss in
Boston, saying that if Sears were to merely replace my microwave they would
be out nothing for trying to sell me damaged goods. I suggested a free
upgrade to the "Sears Best" model.

I wasn't expecting much of a response. But I got a nice letter saying "We
apologize. Come and get it."

So, for a while in those younger times, our finest piece of furniture was a
99921 Sears microwave.