Microwave oven repair?

I have a Microwave oven that seems to make a strange noise at times when the magnetron might be turned on. For instance, if I just start a normal cook cycle, the noise happens at the beginning. If I start a low power cook cycle, I hear the noise several times during the cycle. The best way I could describe the noise would be a ringing or something vibrating at a high frequency.
I would guess the magnetron might be going bad, but it does still seem to cook normally. Anyone have another guess?
Thanks, Clark
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I DO know that it is not recommended for the common Joe to repair his own microwave - lest you fry your own brains with it. Sorry to rain on your parade.
--
Kate
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Not necessarily. And the intermittent noise that you hear during non continuous cooking is probably due to the circuit cutting the magnetron in and out. Most microwave ovens do not have different power 'levels'. Instead they cut the cooking in and out intermittently to get the same effect. So, if for example, you put the oven on 'defrost' it may only be on for less than 20% of the time to avoid cooking the item! Very firm warning: Do not; repeat NOT; attempt to repair a microwave oven yourself. Unless you are an experienced transmitter or microwave technician with the proper tools etc. This is serious; stuff. Microwaves are a 500 to 1000 watt transmitter inside a metal box, employing voltages up to 5000 volts. Not only that they can radiate RF (Radio frequency) energy; enough to cook your eyeballs or human flesh. Also they are, these days, so cheap that it is not worth the labour cost (unfortunately) to repair them at North American labour rates. I've fixed a few, sometimes paying up to $50 for a used magnetron! Not worth it nowadays. I've got one right now somebody gave me that I'm throwing out, because the top of the metal case is bent where somebody, locked out of their house, knelt on it getting in through a window. With the RF edge seal broken microwaves may be leaking out! Right at a child's eye level! It's also missing it's knobs! Please be extremely, extremely careful.
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Kate and Terry have a point. When I wanted a schmeatic for mine, 20 years ago, the Amana girl didn't want to send me one. I had to convince her I had 25 years experience and I knew how to put things together. Then I had to beg. They may well have changed things by now, but then the dangerous part, she reminded me, was the cage in which the microwave tube was located. It was a metal cage with small holes iirc in the sides, and a very condensed brillo pad formed into a rectangular gasket where the cage attached to the rest of it, and she made me promise to put that back exactly the way it was. Frankly that iddn't seem hard to do, but I didn't have to open it. IIRC, mine made sparking sounds, the microwave tube was far too expensive to buy, but she suggested the diodes might be bad. After I opened it, I found the cap on the tube was losing its insulation**, so I put a layer of GE silicon cement around the wire, and fixed it for under 10 cents.
**I don't reemmber how I fixed that without opening the cage.
Terry's right about leaks heating and boiling the inside of your eyeballs. You really don't want that.
I also had/have a microwave tester that Radio Shack used to sell, maybe still does, but my Amana model 2 had a door that sprang closed but didn't actually latch. I was able to verify the tester by cracking the door just a little, before the interlock turned off the power, and watching the meter move up.
Finally the main tranformer broke and they wanted 250 dollars for a replacement, when ovens were less than a 100. They were offering me the wholesale price! I tried to convince them that they should lower their price and maybe actually sell some. I wrote to Amana Iowa, and they wrote back as if the parts place in Pa. would give me the discount. But when I called them, it was back to the same old thing.
I wanted it because it was an antique, and bigger than 90% of what was sold then. It had no carousel and only full power, but I still liked it. But it is no more.
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If it is cooking normally, that's what really counts.

Probably banshees trapped in the case. They really hate induced voltages.
To know for sure when the magnetron is running, run it at 100%.
OR, run it any old way, with a table radio playing next to it, tuned to not the most powerful station. In my case, I'm usually listening to FM, WAMU and WCSP, both DC stations and I'm in Baltimore. And to get the best reception whenever the oven is NOT running, I have the cord stretched out and running right by the microwave. I don't know if radios have gotten better -- I doubt it -- but the ones I've used have been an expensive Panasonic stereo radio with a wood cabinet from the 60's or 70's, and a pretty cheap Sylvania? clock radio from the same period (it doesn't even have a sleep switch! which they've had since the 50's.). Interestingly, the "good" radio did less well on WAMU, and far less well when the microwave is running. Then, I couldn't make out what the radio was saying when listening to the nice one, but although there is static when the microwave is running with the clock radio, I can still follow the radio show, news or talk.
It might make static on AM too, but AM radio is pretty much the pits these days. So I don't know.
One thing I learned is that when the timer runs out, the magnetron stops immediately, even though the carousel and the light stay on until the thing stops beeping. 5 beeps.

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Unless this is one of the high end built-in units that is part of a matchig oven setup, etc, I would just use it till it quits and then buy a new one. They are so reasonably priced, that it's not worth screwing around with.
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I tend to disagree with the general tenor of some of these posts. You can definitely work safely - and tinker with - a microwave and its components. You simply have to make sure IT IS UNPLUGGED when you open it up and remove or replace anything (magnetron, etc.) Once you get past the capacitor (discharge it with a screwdriver) that may still be storing dangerous voltages (like CRTs do), you're fine. Just make sure the thing is unplugged.
This whole notion that you can't tinker with unless you have "the proper tools" and are a "trained technician" is patently false. If you enjoy amateur science, check out these links for great home experiments to try using a microwave:
"High Voltage in Your Kitchen: Unwise Microwave Oven Experiments,Part 1"
http://amasci.com/weird/microwave/voltage1.html
(btw, "unwise" in the title above is used tongue-in-cheek)
For general safety when taking apart microwaves, see the following:
http://www.repairfaq.org/sam/micfaq.htm#micmot
Chris
On Aug 9, 10:41 am, snipped-for-privacy@optonline.net wrote:

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Some folks would not even RECOGNIZE a capacitor. And having a multimeter to make tests is important. Some fuses cannot be visually checked for continuity.
also,it's best for the HV cap to discharge it with a 1KR/2W resistor,you can damage a cap by shorting it to discharge it.They aren't made to source high currents in a short time.And they carry around 2000 volts.

I'd venture that if you have to ask,then you don't know what you're doing,and should not mess with them. You need to do some research and learning first.
--
Jim Yanik
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Jim, of course your right. I didn't mean to imply the servicing of it wouldn't require the necessary getting up to speed in the required areas. But the advent of the web has really helped people chop down the learning curve somewhat in a lot of areas where previously folks wouldn't have dared to venture or had access to the pertinent info. I see a lot of DIYers doing subpanels and such, so people are definitely game. I was just responding to the ridiculousness of the idea that this is something that a DIY can't or shouldn't do. Anyone with enough initiative and energy to do some research and ask questions can certainly work on a microwave just as they do with subpanels or other such equipment. It's amazing how you can educate yourself with the help of good visuals on the net.
For a good description of how to do a capacitor discharge click:
http://www.physics.brown.edu/physics/demopages/Demo/em/demo/5c3020.htm
C
in

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You would be surprised at the number of people who,knowing nothing,ask for "quick fixes",and then jump right in.
--
Jim Yanik
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Jim Yanik wrote in message ...

Yes, I've paid a few of them to do repairs at my house more than once. ;-)
Cheri
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