Does my microwave diode look good to you?

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It would be difficult for most people to measure the voltage while the microwave is running. Not counting on any stray radiation,but at the voltages in the microwave, it would burn out most meters. Also the high voltage would most likely go through the insulation and into the person doing the measuring. Very few meters that are found are rated for much over 1000 volts, less than half of what is used in many microwaves.
The ohmmeter in the common meters will not check the diode either. The voltage drop across the diode in the microwave is more than the meter is set up to measure in the ohms range. It is not around .7 volts as one would find in the lower voltage diodes. Internally the diode is made up of several diodes so the voltage drop is much more.
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The ohmmeter in the common meters will not check the diode either. The volt age drop across the diode in the microwave is more than the meter is set up to measure in the ohms range. It is not around .7 volts as one would find in the lower voltage diodes. Internally the diode is made up of several dio des so the voltage drop is much more.
correct
if the diode is good, with your symptoms i would next check the continuity of the filament in the magnetron or look for a blown fuse someplace
DO THIS WITH THE POWER DISCONNECTED Mark
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Actually, I have worked on microwaves that had a blown fuse. I put in a new fuse, and powered up, and the new fuse blew. Turns out the high voltage capacitor was shorted, and had to buy another one. My parts house showed them as no longer available. Ebay to the rescue. Got one that was fairly close, and it worked.
. Christopher A. Young Learn about Jesus www.lds.org .
On 8/26/2013 10:21 AM, snipped-for-privacy@yahoo.com wrote:

next check the continuity of the filament in the
magnetron or look for a blown fuse someplace

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What do you mean by a "microwave diode"?
To me, it's a point-contact diode used in microwave measurements. My experience has been that sample-to-sample variation is high.
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On 8/26/2013 5:30 AM, William Sommerwerck wrote:

"microwave diode" can mean many things to me since I've experience in electronics. The context in which it's being used in this thread is a discussion of the high voltage diode used in the power supply for the magnetron in a homeowner's microwave oven. ^_^
TDD
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On Mon, 26 Aug 2013 03:30:38 -0700, William Sommerwerck wrote:

I meant the high-voltage diode in the microwave oven.
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Sort of. A 9 volt battery isn't really a good test for a high voltage recifier. The forward drop will exceed that of that battery, at least a rated current of 0.3 to 0.5A, depending on the diode and oven.
The results of your test though, show the diode isn't open and isn't shorted, so that's good. I'd not bother to replace the diode at this point of the oven was in front of me.
I'd test the heater coil of the magnetron. It should measure close to dead short ohms if it's good. If it's open, well, that explains why there's no heat. You'd also want to make sure the transformer is even being turned on, you can usually tell this from just listening to the oven or watching lights flicker when the oven turns on.
Be sure you discarge the cap before you mess around in a microwave oven.
As mentioned in this thread by others, a normal volt meter cannot be safely used to test the HV section of a microwave. You really don't even need to for the most part either.
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On Mon, 26 Aug 2013 04:18:18 +0000 (UTC), "Danny D."

Since apparently there is no current in that direction, how about taking out the resistor and seeing what it says then?

Normally I'd say you should measure the voltages while it's in the circuit. That's a little different here since you'd have to have the cover off and that would expose you to a lot of microwaves. OTOH, it's not working so maybe there are no microwaves. I hate to rely on maybe. Do you have a microwave detector. I got one at Radio Shack about 30 years ago and it works well. I was able to test it because at that time I had Amana Model 2, and it didn't have door latches on it. So I could open the door a little before the safety switches turned the machine off, and I could see the detector reading rise from zero to at least half way across the scale (but I only allowed that for a second.) After that, I could check door leakage. RS doesn't still sell them iirc but you might find one used, or you might find a new one sold through another channel.
Here's exactly the same one I have, no bids yet, 18 hours left from my post time. If it doesnt' sell he'll probably relist it so click anyhow. http://www.ebay.com/itm/Micronta-Microwave-Leakage-Detector-/290963447557
and a new one for only 15 including shipping http://www.ebay.com/itm/General-MLD100-Microwave-Leak-Detectors-/200952444879
Here's one for more, $35 http://www.lessemf.com/mw-oven.html
And http://www.ebay.com/bhp/microwave-leak-detector

I'm self-taught for the most part, but I would have just measured the resistance directly with an ohmmeter, using the meter's internal battery, in both directions. If one direction is many times higher than the other, it's good. Even if I did it your way, I would do it my way too, to see if the results confirmed each other.
For more info, ask on sci.electronics.repair
***I used to have an Amana Radarrange model 2. I never saw a model 1, but this one looked just like the image of a microwave everyone used for years (except compeititors).
I got it used, fixed the door spring and had it for about 10 years. When it stopped working I called Amana and asked, figuring she might know which part failed most frequently. She suspected the magnetron. The next time I called, someone suspected the diode. I opened the high voltage cage**** and saw that there were cracks on the wires to the diode (one 20 or 30 times bigger than yours, counting heat radiation fins). I used silicione sealant by GE (available in black at auto parts stores, if color matters to the repairer) and put on large blobs of it, thicker than the thick wires. And it worked for another 10 years.
****The woman at Amana was very much afraid I wouldn't put the woven metal gasket back the way it had been and that it would leak. She also wouldn't send me a schematic. I had to promise her up and down that I had 20 years experience with electronics, and I would put the gasket just where it was, and she finally sent me a schematic, for free. I had to take apart another one^^ and I think they are designed differently now, but I would be very careful reassembling so as to not leak microwaves.
The next time it failed it did nothing, so it was the transformer. I think Amana wanted 380 dollars I said, "That's the price from 1970. They are worth less now (since you can buy a whole microwave for under 100.) After writing a letter -- I said, Save a few for your museum and the inventor's grandchildren and sell the rest at a price at which you will actually sell them -- and being referred to a place near Harrisburg, they lowered the price to the wholesale price, 250 or so. Much as I hated to part with model 2, I scrapped it.
^^This latest one has a bad relay, and I'll probably never get around to fixining it.
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