Microwave necropsy

I have a Whirlpool Microwave RM280PXABO on top of a Whirlpool oven. As you know, I wrote recently asking advice about the fuse.
Well, I got a fuse, put it in, and the panel came alive with the clock and controls working.
I put a glass of water in it, and turned it on. The wires that come out of the capacitor in the power supply bundle caught on fire. The fuse did not engage, or the wire size was too small, and it didn't reach 20 amps.
Upon looking at the power supply bundle, I noticed that several wires had been cobbled together with wing nuts and electrician's tape, definitely not a factory fresh application. The transformer had been either moved, or replaced, and the holes in the frame were not into the original base of the transformer, hence I think it is not the original transformer. The wires are combinations of two wires of different colors.
SIL says that "It just quit working one day." From what I see, it was worked on, things were altered, and things were altered badly. I shall try to get an honest answer, but you know how that goes.
The control panel controls the microwave and oven. We may have to just take off the microwave, and leave the control panel, and just settle for using the oven, and put a different microwave in the available space, using the keypad on the new MW.
I need to find a capable electronics guy in our small burg who can come and find out just what's wrong. Good luck. I have put it on craigslist, and the local repair services want $100 to show up. I may bite the bullet, and do that if I can't find anyone for less.
Will keep you posted.
Steve
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That capacitor is for the magnetron function, and rated for over a thousand volts. It has been inexpertly modified, possibly including a different magnetron transformer. The schematic diagram for a microwave is actually very simple, and so are some of the technicians that purport to repair them.
Walk away from it. There are replacements that do the job. And a standalone unit could be a better choice. Funeral services can easily run over 5 thousand dollars.

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Oh, if you decide to throw it away, the two magnetron magnets are excellent for so many things.

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Michael B wrote:

Heck yeah, I've got about 80 of them from the ovens I dismantled a number of years ago. I keep one on the drill press to hold the chuck key, among other uses.
Jon
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That capacitor is for the magnetron function, and rated for over a thousand volts. It has been inexpertly modified, possibly including a different magnetron transformer. The schematic diagram for a microwave is actually very simple, and so are some of the technicians that purport to repair them.
Walk away from it. There are replacements that do the job. And a standalone unit could be a better choice. Funeral services can easily run over 5 thousand dollars.
reply:
My wife brings me home projects and involves me in things like one of those people who cannot turn down a stray cat or dog that becomes a money hole.
This oven MW combo has the proprietary one piece control panel that controls both the oven and MW. To take it off will be a hassle, or to try to use just the oven and control panel. We'll see. Maybe I can find someone smart enough to pull this one out, and get the MW working.
Steve
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On 1/9/2011 4:53 PM, Steve B wrote:

found it. It could be rebuilt, but the parts would probably cost more than a new(er) one. (Unless you could find one where the conventional oven was fried, and make a frankenstein out of the two of them, like with an old car.) I'd be inclined to yank the micro AND the oven and junk them, and install a new/used stacked unit (if I could find one cheap enough), or just a wall oven, and make a cubbyhole above it for a cheap micro. Which one gets used more? Not a fan of combo devices, because one part always dies before the others. Stacked ovens, printer/scanner/fax combos, TVs with built in DVD/VCR, all-in-one stereos, etc.
--
aem sends...

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My sediments, exactly. Only, I'm not a fan at all in the least in any way, form, shape, or fashion of putting a microwave above any hot device, and above countertop height.
Unless someone can pull off a miracle, I see this going to the junk yard, and a new large oven being put in the new cabinet, and the MW staying on the countertop, where it is now, and where I like it a lot, TYVM.
And no more puppies and kittens, neither.
Steve
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Funny how women like to assign these projects to husbands or other male victims. Next time she brings you a "puppy", tell her to go change your friggin' oil and coolant. Make sure she doesn't spill a drop on the driveway, but if she does, she has to git down with a scrub brush and some detergent.
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Don't know about your house, but at mine, SWMBO has many more subtle ways of getting even. And just as damaging. And even more painful................
Steve ;-)
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On 1/9/2011 11:33 AM, Steve B wrote:

fetch it, but craigs or freecycle or area ad papers or ma'n'pa appliance stores will have something that fits. Count yourself lucky it failed dead instead of failing flaming, and junk it before it kills somebody. Standard rule of thumb- if expected repair cost exceeds 50% of a replacement with same expected remaining lifespan, replace it. A couple of hundred bucks should pay for a used one.
I'm still a little fuzzy on exactly what this beast is- an over-stove micro with a shared control panel, or one of those stacked oven things?
(Googles) found it on appliance pro web site Xformer shows as over 200 bucks by itself: http://www.appliancepartspros.com/partsearch/model.aspx?model_id%9950
--
aem sends...

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Yeah, but a simple screw costs three and a half bucks from that same site. Easy enough to anticipate the genuine screwing to be gotten from Whirlpool. Let function win out over fashion. Trash it, save the magnets.
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It is a microwave over an oven. The face of the microwave has a control panel for the MW, and a stacked one for the oven. The two pieces are joined by sheetmetal enclosures. There are two motherboards, one for the MW, and one for the oven. It is one BIG honking unit. I hate microwaves over ovens or stoves, but sometimes you must use them for the space available.
I foresee a new very large oven on the event horizon, and present Panasonic inverter MW on the countertop.
My book will be coming out soon, and maybe with the promotion of that, I can get a decent large oven. The local ReStore, (Habitat for Humanity) has some killer deals once in a while on good stuff. My DIL spent $2600 for a replacement MW and oven for this unit, but she likes to get the biggest and best, and inherent bragging rights.
Steve
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On Sun, 9 Jan 2011 13:58:18 -0800, "Steve B"

What book is that? What's it about?
--
Work is the curse of the drinking class.

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On Sun, 09 Jan 2011 08:33:11 -0800, Steve B wrote:

Well if you didn't toast everything inside you could try replacing the high voltage diode and fuse it lighter. If it blows immediately you'll need to shotgun it. Replace the magnetron and capacitor also. I don't recommend the average Joe does this because of potentially lethal voltages present and the risk of radiation.
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1) Waterboard the SIL to get to the truth. Just for the entertainment, ya know? Find out what else the electrical shexpert in home has gotten his hands on.
2) Remove microwave and dispose of properly.
3) Go to a tile store, find some nice ones. Epoxy them to a piece of wood and mount the decorative panel where the microwave used to be.
4) Get a freestanding microwave.
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Truth is that just about any hi voltage transformer can be made to work in these things. They are pretty much universal, transformer, capacitor voltage doubler, and a rectifier with the resulting pulsating dc connected to the magnetron. A different transformer with similar specs will work. The control panel simply turns it on and off. Lower power is accomplished by varying the off and on time. There is a lot out on the web about troubleshooting. Biggest problem is that most people don't have a hi voltage meter and can't measure the voltage. But you can do passive checks of the components if you know what you are doing.
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