Recommended repair or magnetron replacement of broken microwave (Jenn-Air M170B)

This Jenn-Air (model M170B) 1,350 Watt microwave just stopped heating:

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I called Jenn-Air customer support who said there's no troubleshooting for when it doesn't heat. They said the magnetron may need to be replaced: Jenn-Air 800-536-6247 Customer Care

A replacement microwave oven has to fit over the electric oven:

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Interestingly, (since it was above the oven) the back sticker says: "May be built into a cabinet structure, but not for use adjacent to (with 2 feet of) any gas or electric range, cooktop or oven."
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But, that sticker also says: This microwave is approved for mounting directly over Jenn-Air wall ovens as follows: W2700 Series Using MK271 Trim Kit, W3000 Series Using MK301 Trim Kit

Having never worked on a microwave, I ask what the conventional wisdom is. Q: Is it generally feasible to replace just the magnetron? Q: Will similarly sized microwave ovens fit (22" widex13"tallx15" deep)? Q: Is it generally best to stick within the same brand? (e.g., JMC1116AB)?

Reply to
Danny D.
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Probably just needs a new thermal cutoff. This random page has a picture.

You should find a schematic inside the unit after you take off the cover. With some basic electronic troubleshooting skills you can identify which of the 2-3 thermal cutoffs has gone bad. They're cheap and generic, but come in different temp ranges.

(Now, have fun turning this thread into a 500 post thread, while all the helpful people teach you how to read a schematic and use your multimeter, and arm you with enough info to write the internet's most definitive treatise on microwave oven repair.)

Reply to
Smitty Two

Looks like less than 2 feet to me. For something other than a fuse I'd just replace it.

FWIW: Panasonic makes a really good microwave. "Invertor" 1300W. But I think you need one that's insulated to protect it from the heat of the oven.

Reply to
gonjah

Technically, probably yes. But, there are some obvious problems. One is, there are a lot of things that could cause it to stop heating, only one of which is the magnetron. Figuring out which it is, unless you have the suitable skills, schematics, etc will require a tech, service fee, etc.

The second is that if it is the magnetron, what does a new one cost? Could very likely be buckoo bucks. Generally, given the cost of a new regular microwave, it's not worth screwing around with. But since this is part of a built-in JennAire, I feel your pain.

I think that's unlikely. If it were that simple, could mix and match other companies products into that JennAir frame. For some odd reason, JennAir doesn't want you to be able to do that.....

I had an even older JennAir oven/microwave combo. I did a mini makeover of the kitchen and got rid of it. It was still working, but was outdated. So, I found a Kitchenaid double oven on Ebay. It was a floor model, but in perfect condition except for some sale stickers. That unit retailed for $3000. I got it for $1200. It was also a 30", which is a good thing, where the existing was 27". I had to carefully scope out the cabinet situation where it was going. And I had to cut apart the cabinet to make it fit. Including taking the cabinet from above to a cabinet shop and having them cut several inches off the bottom. But it came out great. Looks 1000% better.

I also like the idea of double ovens a lot more than the built-in microwaves. The look much nicer, are a selling point for kitchens today. And from what I have seen, the microwaves from the major kitchen appliance/oven manufacturers cost $1000 and suck compared to the $100 countertop model. They tend to be no larger, more confusing controls, don't heat as well. If the $100 one goes, you just buy another.

Just some things to consider. Maybe you should buy a countertop one and look for a great deal on a new double oven.....

Reply to
trader4

If you do replace it, I'm pretty sure you can find a replacement trim for your opening. That way you don't have to worry about the exact size.

I know Sears and Lowes sells them. HD probably does too.

Reply to
gonjah

Check fuses and electrical connections. I had one where corrosion eventually overheated the connection on the door switch and disabled it. I've fixed a few microwaves, and almost all had bad diodes. Certainly possible, but I've never seen a bad magnetron.

Be aware that the big cap can hold enough charge to kill you after days and days being off. Even if you don't get electrocuted, you can be seriously injured when you fly across the room and bang your head on the counter. And you'll be scraping pieces of skin off the sharp edges of the case.

I don't know of a good DIY way to discharge the cap. I once made the mistake of shorting it with a wire. Scared the crap outa me when the wire exploded.

Reply to
mike

Reply to
John Keiser

Could be. I'm not sure what the inverter does. I've been using mine daily for over 7 years now. It does have quite a few options.

Reply to
gonjah

Inverter should let you have continuous power control.

I cheaped out when I replaced mine and didn't get an inverter. I regret that decision.

It has 3X the power of the old one. And the 15-second on-time is way too long for power regulation on small loads.

Reply to
mike

I found only one so far - and it checked out at 0.5 ohms:

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Found it. Thanks!

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I seriously doubt I'll be writing a lot on this as all I'm trying to do is make a good decision as to how to proceed.

Reply to
Danny D.

I don't see any diodes yet; but I do see the big cap you speak of:

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Reply to
Danny D.

I'm wiggling everything on that control panel as we speak:

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Reply to
Danny D.

I had never thought of that; thanks for the good idea.

Looks like the bottom oven is a 27 inch variety.

Reply to
Danny D.

I'm confused why an inverter is needed for an AC appliance.

I do see three voltage transformers though.

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Reply to
Danny D.

Good to know! I'll bring the trim with me when I buy the replacement.

BTW, here's a full-size schematic where I'm looking for the thermal switch and fuses.

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Reply to
Danny D.

I have repaired a number of microwaves that I have owned. First is check the fuse, I have had a number go for no reason. Replace it and you are good again until it blows again in a few years. Second check the micro switches on the door latches, they interlock for safety, if one fails the oven will not work. There sometimes are three of them, some normally open and some normally closed, check them with a meter. Beyond that I have had one that burnt out a thin wire that carried about 13 amps, and then needed another part, it was cheaper to replace it than repair it.

Reply to
EXT

I've found microwaves tend to have a high voltage diode, and a high voltage capacitor. Both are known to go bad. I've repaired several microwave ovens, and it's been these two parts.

Christopher A. Young Learn more about Jesus

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A replacement microwave oven has to fit over the electric oven:

formatting link
Interestingly, (since it was above the oven) the back sticker says: "May be built into a cabinet structure, but not for use adjacent to (with 2 feet of) any gas or electric range, cooktop or oven."
formatting link
But, that sticker also says: This microwave is approved for mounting directly over Jenn-Air wall ovens as follows: W2700 Series Using MK271 Trim Kit, W3000 Series Using MK301 Trim Kit

Having never worked on a microwave, I ask what the conventional wisdom is. Q: Is it generally feasible to replace just the magnetron? Q: Will similarly sized microwave ovens fit (22" widex13"tallx15" deep)? Q: Is it generally best to stick within the same brand? (e.g., JMC1116AB)?

Reply to
Stormin Mormon

The ones I've worked on, the diode is connected to the cap. Your diode might be going from cap to the case of the unit.

Christopher A. Young Learn more about diodes

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I don't see any diodes yet; but I do see the big cap you speak of:

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Reply to
Stormin Mormon

Part labelled "H.V. Diode". Next to the magnetron, about 7 o'clock from the magnatron. Goes to case ground, like my last post suggested.

Christopher A. Young Learn more about Jesus

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BTW, here's a full-size schematic where I'm looking for the thermal switch and fuses.

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Reply to
Stormin Mormon

In this case I believe the "inverter" is basically a switch mode power supply to do away with the heavy transformer traditionaly used in microwaves. Think of the PSU in your computer. As another poster mentions, this does allow for finer power control but I never need that degree of control in our cooking. And I've read complaints of invert failures. For me, simple is better.

Reply to
John Keiser

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