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
I would guess the magnetron might be going bad, but it does still seem to
cook normally. Anyone have another guess?
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
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.
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.
If it is cooking normally, that's what really counts.
Probably banshees trapped in the case. They really hate induced
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.
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.
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
and are a "trained technician" is patently false. If you enjoy amateur
check out these links for great home experiments to try using a
"High Voltage in Your Kitchen: Unwise Microwave Oven Experiments,Part
(btw, "unwise" in the title above is used tongue-in-cheek)
For general safety when taking apart microwaves, see the following:
On Aug 9, 10:41 am, firstname.lastname@example.org wrote:
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, 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
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
on a microwave just as they do with subpanels or other such equipment.
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:
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