Power to microwave oven goes off and on

Gurus:
My 1999 Kenmore over the stove microwave/hood combination has a power supply issue.
I first noticed that food wasn't heating in the usual amount of time. I did not then notice that the unit was turning off and then back on, all by itself.
The same thing happens with the exhaust fan and light. If they are turned on, they go off and then back on within a couple of seconds. This is also true of the clock, though the power is never out long enough for it to reset to a blank ":".
Any ideas? Tom Milwaukee, WI
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A loose connection somewhere
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My opinion based on experience is the Microwave is shot, or getting there and is wreeking havoc with the power. My microwave did the same thing, complete power out and I had to wait several minutes before it would seem to reset itself, the beeper would go off and the LCD panel would light up again. Set the clock and ready to go until it happens again. I replaced the microwave (it was an Ewave model from Lowes) and the problem seems to have gone away. I would suggest before you start ripping out wires that you try another microwave.
I really find it fascinating how many people have the same or similar problems on this board. What are the odds?

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the odds are really good.
do a little searching on how the fuses in these things work. then replace yours. if it fails again shortly, you need to toss your microwave leaking microwave.
randy

to
you
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I agree with m Ransley that a loose connection is a good possibility. There shouldn't be too much in common with both the microwave and exhaust fan portion of the unit except the main (house) power supply and the connection around the microwave's internal fuse. BTW. A bad fuse itself would not usually cause such a symptom, maybe a bad fuse *holder*.
In the end someone is going to have to actually trace the power supply to see where it stops. I doubt anyone here in the newsgroups is going to be able to tell you where that is.
Unfortunately, intermittent problems are often the hardest to isolate and it may need to be used until it fails completely so the fault can be found. I wouldn't recommend that until the unit has at least been given the 'once over' with an eye for problem signs (arcing, discoloration, melting, etc.).
JMO
Dan O. - Appliance411.com http://ng.Appliance411.com/?ref411=Kenmore+microwave
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Dan O. wrote:

If the "fuse" was a self resetting thermo breaker, then it would do exactly as described. I do believe they are common in microwaves.

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Joseph E. Meehan

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While they are common on microwaves they are usually only found on the magnetron tube (the microwave 'generator') which if cut out would only stop operation of that tube and would not effect the exhaust fan or any lights.
JFYI
Dan O. - Appliance411.com http://ng.Appliance411.com/?ref411=microwave+oven
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Hi Tom,
If I may chime in w/my $.02,
The most common intermittent of this type that I see is caused by solder cracks on the controller pcboards. It's somewhat of a testimonial to the reliability of the electronics that the solder connections fail more often than the components themselves.
I see this a lot, on both microwaves and electronic control ranges. 'Have been resoldering them for many years, with good results. Sometimes you have to look at the conn's with a magnifying glass, but in cases like you're describing the faulty ones will be obvious once you get down to the conn. side of the board.
The old GE MHC's were well known for this - they'd burn a 1/4 inch hole right *through* the power/relay boards at the harness plug pins! But even they could be repaired, so don't be too hasty to scrap this one. Hold out for a technician who's not afraid to pull the board and take a look at it before condemning the whole unit.
'Shouldn't have to be pulled off the wall to do this. Access is usually pretty easy from the front.
PS - check your serial number. If it begins with 'XC', visit the Whirlpool website I've listed in the resource below. Yours may be covered under the recall (made between 1/98-10/01). You'll find more details in the 5-02 backissue of my newsletter, including the Whirlpool website where you can determine if your unit's affected, here: http://www.davesrepair.com/DRSNbackissues/drsn0502.htm
Hope that's of some help.
God bless,
Dave Harnish Dave's Repair Service New Albany, PA www.DavesRepair.com snipped-for-privacy@sosbbs.com 570-363-2404
I'm a 32-year pro appliance technician, and love sharing what I've learned - in a FREE Monthly Appliance Tips Newsletter. (Back issues now posted here too!) www.DavesRepair.com
John 3:3

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Gurus: Thanks for your thoughful responses. Based upon what you've told me, there MAY be hope for this machine and consequently I've called for in-home service that will cost $58 to give me an estimate. Though it is somewhat a roll of the dice, I feel its worth the risk that the estimate will come in too high to warrant actual repair. Based upon what I've read, it seems that this diagnosis/repair is not something I want to tackle myself.
I paid $450 for the unit new. What would you spend for a repair before throwing in the towel and buying a new one? I'm told that the newer microwave ovens are more cheaply made and last an average of only 6-9 years. Is that also your opinion?
Tom Milwaukee, WI

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it doesnt matter what you paid for it, what could you get a new comprable model for? have you replaced the fuse? you need to be careful when you open it up to replace it, but its not rocket science. there are also plenty of web pages describing how to discharge the capacitor for extra safety, but usually the fuse is somewhere it can be replaced relatively safely. use a plastic tool to pull and replace it.
as for 6-9 years, sounds about right based on the ones ive seen. although often they can be repaired (triacs seem to blow quite often) and last that long or longer.
randy

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