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Cybercowboy 09-23-2020 2:02pm

Magnetrons are pretty cool...
 
1 Attachment(s)
when they aren't burnt up. Our microwave (Thermadore) which matched our double ovens started arcing awhile back, then totally quit. I figured I'd at least take a swing at fixing it since I paid way more than I should have just to have a matching built-in microwave back in 2009 or whenever it was. Pulled it out, took the cover off, and the first thing I checked was the magnetron since it's pretty simple to do. Oh, it was fried all right. I don't think anything else is wrong with it, and a replacement was only $80 plus a few bucks in shipping. New magnetron will be here Friday hopefully.

mrvette 09-23-2020 3:40pm

How you know it didn't take out the power supply?? :issues:

Cybercowboy 09-23-2020 3:45pm

Quote:

Originally Posted by mrvette (Post 1808177)
How you know it didn't take out the power supply?? :issues:

It's possible, but everything else works (front panel, etc.) So main power supply is fine, fuse is fine. If the high voltage side was fubar I'd expect to see some scorching somewhere, but it all looks great. I may need to replace the high voltage diodes if it's still not working, or worse case the HV transformer, but the magnetron looks like it failed in a way that wasn't a dead short. It just doesn't make little waves.

I am a bit worried that there is some sort of fuse on the HV side because I don't have the schematics for this thing. If that's the case I may be screwed unless I can find it. I know the controller recognized the fault because it literally started scrolling "Send in for service" when it stopped working. I'm hoping it just sensed the load was wrong somehow. We'll see.

mrvette 09-23-2020 5:39pm

Prolly cheeper to buy anodder won........


:D:issues:

04 commemorative 09-23-2020 7:44pm

Are you from the future :confused5:

Rikki Z-06 09-23-2020 8:42pm

1 Attachment(s)
Attachment 47560

Cybercowboy 09-23-2020 8:42pm

Quote:

Originally Posted by mrvette (Post 1808214)
Prolly cheeper to buy anodder won........


:D:issues:

Sure, but this one matches the ovens and is worth fixing for a hundred or less. I actually have a new one that I can make fit in a pinch but this one is nicer.

Cybercowboy 09-23-2020 8:44pm

Keep in mind. That burned end of the magnetron is supposed to be in vacuum. Well, maybe not the very end but it is a vacuum tube. Easy part to replace.

ZipZap 09-23-2020 11:30pm

Don't mess up the fuzz button. If you end up scrapping, you'll find that the gold brillo pad looking piece is actually a single strand, likely beryllium of some sort. We played with those things constructing coupled cavity TWT's for some radars that would cook you along with the food.

Unless the fix is really straightforward, be careful as even the lowest power microwave ovens these days depend on devices like these, and excellent/effective shielding, to keep from shriveling your berries.:seasix:

Millenium Vette 09-24-2020 12:44am

Quote:

Originally Posted by mrvette (Post 1808214)
Prolly cheeper to buy anodder won........


:D:issues:

In all candor, I didn't come in here because I give a shit about your microwave, I just wanted to see what mrvette had to say.....

Quote:

Originally Posted by ZipZap (Post 1808257)
Don't mess up the fuzz button. If you end up scrapping, you'll find that the gold brillo pad looking piece is actually a single strand, likely beryllium of some sort. We played with those things constructing coupled cavity TWT's for some radars that would cook you along with the food.

Unless the fix is really straightforward, be careful as even the lowest power microwave ovens these days depend on devices like these, and excellent/effective shielding, to keep from shriveling your berries.:seasix:


I spoke too soon, looks like mrvette has some competition in this hizzy.

Shriveling your berries? So, by brewing up some microwave popcorn it will **** up fun night? Not doubting, just want a little clarification. This shit might be getting scary....

ZipZap 09-24-2020 1:21am

If I were going to undertake a repair on something that is putting out 1kw of RF energy, I'd sure as hell have a schematic and understand a safe repair. We take extra care on anything over a few milliwatts. Yes, it will make your nads go away, but you'll probably have other issues first.

I have no idea what the resources are that Cowboy has, but microwave ovens are something with which one needs to take extra care. I'm not an appliance repairman, but I do understand microwave leakage. I'm sure any replacement part comes with instructions on how to best keep the energy in the oven, as opposed to attacking your flesh.

There's a reason for the size of the holes that are in the front of your mw oven behind the glass. There are a bunch of other protections in place to make sure the RF stays where it is wanted.

It will be interesting to me whether the warning message goes away with a replacement, or is some sort of thing that needs "manufacturer intervention".

mrvette 09-24-2020 5:08am

I wooden be concerned about Micro wave leakage, that's contained in the overall design of the unit, metal box and mesh behind/in door glass....and the function of the door latch/etc.....

:dance:

Norm 09-24-2020 6:16am

Just replaced my 30 yo Kenmore last week. Honey tried to warm up her coffee, it started to look like a mini-fireworks display, then poof.....nothing. Went right down to BJ's, bought a new one, took the old one to the transfer station (dump) with the last load.

Cybercowboy 09-24-2020 7:36am

Quote:

Originally Posted by ZipZap (Post 1808265)
If I were going to undertake a repair on something that is putting out 1kw of RF energy, I'd sure as hell have a schematic and understand a safe repair. We take extra care on anything over a few milliwatts. Yes, it will make your nads go away, but you'll probably have other issues first.

I have no idea what the resources are that Cowboy has, but microwave ovens are something with which one needs to take extra care. I'm not an appliance repairman, but I do understand microwave leakage. I'm sure any replacement part comes with instructions on how to best keep the energy in the oven, as opposed to attacking your flesh.

There's a reason for the size of the holes that are in the front of your mw oven behind the glass. There are a bunch of other protections in place to make sure the RF stays where it is wanted.

It will be interesting to me whether the warning message goes away with a replacement, or is some sort of thing that needs "manufacturer intervention".

LOL I have a degree in electrical engineering and have worked on many high voltage circuits in the past. Hell, I had a job at Motorola for awhile doing nothing but repairing oscilloscopes and other test devices, most of which had high voltage circuits. I know how to work on them. There's nothing difficult about replacing a magnetron. You simply need a 20k ohm ceramic resistor with leads on each end to discharge the high voltage capacitor. Then you can safely work on any part you want. You put it back together before plugging it in, and you can test each high voltage component un-powered. I even replaced the mica plate that covers the end of the wave guide by cutting out one from some mica material I had laying around that's better than what came with this microwave. I'm more comfortable working on a high voltage circuit than I am a modern car engine actually.

In this case this microwave's high voltage circuit is much more sophisticated than the typical $150 microwave. It doesn't use a resonant high-Q circuit with a big old capacitor. Instead it uses a switching circuit, so big transistors and diodes with smaller caps.

Cybercowboy 09-24-2020 8:15am

Quote:

Originally Posted by Norm (Post 1808270)
Just replaced my 30 yo Kenmore last week. Honey tried to warm up her coffee, it started to look like a mini-fireworks display, then poof.....nothing. Went right down to BJ's, bought a new one, took the old one to the transfer station (dump) with the last load.

If this one was just sitting on a counter I would have done the same thing. But no, it's a built-in with a nice trim piece that matches the double ovens and looks nice so attempting a repair first. I'd say that most microwaves that stop working could be repaired easily, it's almost always one of about six things. Is it worth it? Eh, depends. People get a new washer or dryer when they stop working, but usually they can be repaired fairly easily too. Again, it's usually one of about six things.

MadInNc 09-24-2020 8:29am

3 Attachment(s)
Mmmmm microwaved Bacon 🥓🥓🥓🥓

Cybercowboy 09-24-2020 8:47am

The middle gif looks like a toaster oven. :lol:

ZipZap 09-24-2020 10:05am

Quote:

Originally Posted by Cybercowboy (Post 1808281)
LOL I have a degree in electrical engineering and have worked on many high voltage circuits in the past.

FWIW, so do I. Don't forget the seal on the new part to keep the RF in the box. I still am interested in the idiot-proof measures, and whether the warning/interlock needs a "secret code" to unlock. Let us know:seasix:

JetMechZ16 09-24-2020 10:21am

1 Attachment(s)
I use em to light up bulbs.

Attachment 47573

z06psi 09-24-2020 10:34am

Quote:

Originally Posted by Cybercowboy (Post 1808307)
The middle gif looks like a toaster oven. :lol:

That is a Radar Range. First commercial microwave. We actually had one give to us by the wife's grandparents after we were married.

Damn thing worked until 2011 when we moved to Hawaii. Thing weighed 60-70 pounds.


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