Repair and disassembly guides for GE Microwave ovens.

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Can I repair my - noisy but cold - microwave oven?

I have a GE JES738 700 Watt microwave oven that now makes a loud(er) sound when I try to heat something. The problem is that it no longer heats anything.

If it is something that I can fix, where would I find the parts?

Is it a complicated or dangerous process to mess with the inside of a microwave? Should I pay a local repair service to fix it?

Should I recycle the - just over a year old - appliance and purchase a new one?

Answered! View the answer I have this problem too

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Maybe something burst from the microwave like a light bulb or a circuit popped? If you feel like it is working fine otherwise you should concerned with local repair person except to mess with it.

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Microwave ovens generate high voltages (thousands of volts) and dangerous amounts of radio-frequency radiation. Attempting to repair one is NOT for the amateur tinkerer. I advise recycling or trashing it and getting a new one (they don't cost much these days.)

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I object to the first sentence, which is pure fear mongering. The next two sentences are sufficient and to the point. There's already enough misinformation and fear mongering about microwave ovens on the internet to go around without adding to it!

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Will oven cleaner hurt the inside of micro oven,why does paint not stick to most microwave oven s?

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Je crois que justement, Il n'est pas indiqué de vouloir réparer un micro ondes. Autant en acheter un neuf, l'appareil étant dangereux à cause de son voltage trop élevée et de différence hertzienne.

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je ne suis pas d'accord. J'ai réparé en toute sécurité et avec succès de nombreux fours à micro-ondes. Vous devez posséder la compréhension du circuit électrique de base et suivre quelques précautions élémentaires

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Most Helpful Answer

If you hear a very loud buzzing, it is probably a shorted high-voltge diode. This may be a small black stick wired to the high-voltage capacitor (metal can with two terminals), or could be inside the can.

You would have to replace it.

I doubt if the magnetron is bad, they are very reliable and last a long time.

I designed microwave ovens for 30 years.

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I agree with Tom. Magnetrons are quite reliable. And, if it's true that Tom designed microwaves for 30 years (or even a year), he's the guy I'd listen to.

I've been a EE for almost 40 years, and I'd take his word over mine.

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I'm wondering how reliable Magnetrons are today. I actually stumbled on this web site looking for answers as to why each successive microwave oven that I've owned has had a shorter life. The first lasted from about 1971 to 2001. The next died in 2010. And the last one died just three days ago (7/23/2015). In each case the magnetron failed. I know that one person's experience doesn't necessarily extrapolate to the general population, but the salesman at the appliance store indicated that my experience is typical. He suggested that they are all made in one factory in China and either intentionally or unintentionally aren't made to last 30 years any longer.

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That's true China doesn't make products last like in the good ole days. I avoid buying their products when I can. You should watch the video "Death by China" it will open your eyes to a lot.

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Over the years I have repaired several microwave ovens. All of them had the same symptom - more noise than usual and no heat. The high voltage circuit of these units is extremely simple comprising a large transformer, capacitor, diode and magnetron. Personally I have never seen a capacitor or a transformer fail so the diagnosis usually comes down to the diode or magnetron - about $10.00 or $50-$80 respectively. You do need to be extremely wary of the killer voltages when checking these units. As already mentioned disconnect the power cord and using a well-insulated screwdriver short out the terminals of the capacitor just in case. A magnetron can be checked with a standard test meter on the ohms range. First check the resistance between the two magnetron terminals (remove the wires first). The resistance should be very low - in the range of a few ohms. Next check the resistance between each terminal and the metal fins of the magnetron. The resistance here should be too high to measure (in essence an open circuit). If the magnetron passes both these tests then it is quite likely fine. A microwave diode can be open or short circuited. A short circuited diode creates noise and no heat and an open circuited diode creates no additional noise but also no heat. Testing the diode using a regular test meter is not usually successful because the testing voltage has to be quite high. I always have a spare good diode to substitute as they are quite cheap. I also concur with other readers that if a magnetron is suspected as the failure cause then it may be more cost-effective and safer to just buy a new one. However I repaired my own over the stove model by replacing a faulty magnetron for a quarter the cost of replacing the unit. Above all stay safe.

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I have an LG under cabinet 1000+W MW that has these symptoms. My question after some reading is: Does the unit have to be taken down from under the cabinet? Will I be able to replace diode and/or capacitor from behind the control panel?

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Just be sure to bleed the HV charges across the two capacitor terminals, then you are good to go. See this http://www.microtechfactoryservice.com/c...

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Wow, the ignorance expressed here is astounding. I can see why "people" are warned away from repairing their microwave.

A magnetron is not "radioactive", it emits nothing when not powered and it emits radio waves when powered, it is basically a form of "radio tube" and most emit the same freq. as your old cordless phone and wifi router, just a lot more energy, thus why a microwave can interfere with your old cordless phone or wifi. There is no "nasty radiation".

The only danger in a microwave is the HV capacitor which can kill you so learn how to safely discharge one, it is not hard if you have half a clue. All the ones I have ever dealt with self-discharged as designed but don't bet your life on it. When replacing any component inside make sure to route all wires as you found them. When replacing the magnetron (most can be purchased new for $30-$50) be sure the gasket (usually inc. with a new mag.) is in perfect shape and in place and that the mounting tabs/area is undamaged. If the mag. mount/area and the microwave in general is not bent/damaged then it won't be leaking any "radiation". If there is heavy arcing/burn damage around the mag. mount area this may be a cause for concern re leakage, on some models it is an easy repair, on other it is not and the amateur may want to stop at that point. Do not crush or break the old magnetron, some of the older ones can produce a dust from the ceramic insulator that is very harmful to breathe in.

As to quality, I have seen magnetron failures in one year old machines and the brand doesn't matter much, recent microwaves use magnetrons manufactured in one of two factories that supply most of the world and the standard/QC is not what it was 20 years ago. There are other factors leading to some machines failing more often like waveguide design issues (GE/Kenmore over the range models were infamous re this) but nothing the consumer or salesman will be able to know.

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No one on this page said that a magnetron is radioactive. In fact the word "radioactive" appears only in your post.

To say that the only danger is a charged capacitor ignores the fact that the magnetron (essentially a microwave vacuum tube) does generate VERY HIGH electromagnetic energy output through waveguide to the oven chamber.

If the shielding is defeated or compromised, you are in danger of severe bures due to the electromagnetic radiation if you put your hand in the path of the magnetron output.

This IS high energy radiation. Ot has nothing to do with radioactivity. And it IS very dangerous.

I have a very strong understanding of magnetrons, wave guide and radioactivity because I was a Nuclear Reactor Operator and an Electronic Technician in the US Navy.

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Steven Stewart very well put and thank you for clarifying .

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The hysterical posts re radioactivity were edited/removed years ago.

If you read my post completely you will see that I fully understand the issues you raise, ( warnings re damaged or burned areas etc.) I even addressed a generation of GE manufactured OTR units that had faulty waveguide design. Maybe you are assuming that people reading here will be working / powering on their units while they are apart? Other than that I can't see how a hand is going to get burned. I give readers here way more credit than that, maybe I shouldn't. Your qualifications don't impress me, how many microwaves have you repaired in the navy? I could care less about radar systems etc. that you worked on, totally different animals. I have volunteered in repair clinics for years and continue to to this day, 100s of microwaves repaired, all tested afterwards, none ever leaked. There have been a few over the years that were deemed lost causes, the damage was obvious even to the novice.

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You are awesome. I just replaced the HV capacitor. It's 1.0uF 2100V. The cap is shorted. Measured across the two terminals, isolated from magnetron and diodes. Here is how I bleed the capacitor http://www.microtechfactoryservice.com/c...

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the biggest thing in the microwave is the magnetron tube. They do wear out over time making it less and less powerful. There are other things that can go wrong inside, basic troubleshooting of powersupplies etc can give you success.

It seems from your question that is suddenly died. have a look if there is a short inside, maybe an insect or similar has shorted some high voltage part = accounting for the extra noise and lack of performance.

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If the unit is no longer heating food, then the cavity magnetron has gone bad. Probably not worth trying to get it fixed, as you should be able to get a 1000w or better oven for less the a repair shop would charge to fix this one. 700w is really pretty low power anymore. Fixing it yourself would be somewhat dangerous, due to the voltages required to generate the microwave energy - failing to make a connection and energizing the unit could cause a short or fire.

Were there any lightning storms around the time the microwave failed?

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Some time ago mine (unbranded) stopped working too. I opened it and, to avoid the nasty radiation, I disconnected the cables that powered the transformer and magnetron. When I tested those cables for power (to see if they where delivering it when it was supposed to) it was intermittent, depending on the contacts position. Diagnostic: faulty contact leads. It could have been anywhere upstream the HV transformer and, therefore, fixable without messing the dangerous stuff (assuming you already have the proper respect for the 220V), but it was just a bad contact :)

If nothing found there I would not have gone for the magnetron either... too risky.

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It can be possible that your microwave is defective, so it does not heat anything and makes noise. I suggest you to replace it by another one because you have said that your microwave is just 1 year old and it might be having its pending warranty. Like your problem, I have also faced problem in my single wall microwave oven but I got a replacement on it. So you can try out this solution.

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Curious. If I vote yes, it accepts my vote unconditionly. But if I vote no, then I need reputation points to be accepted. Huh?

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Dessy, we had the same problem...loud fan like noise, and not heating. I got on a few internet microwave problem forums and the answers were actually very helpful. After awhile of diagnosing the symptoms the problem, we finally reached the probability that the problem was a faulty magnetron. Then I called some local appliance repair guys, and they, without even coming out told me it was probably the magnetron and would cost about $150 to repair it. We decided to replace the unit for $50 bucks more, with an extended warranty. But I still want to say thanks to the posters here because I went from knowing nothing about a microwave to being able to almost diagnose problem, and knowing that a microwave has a magnetron, and that a magnetron is not a bad guy in an Avengers comic.

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(P.S. Lest I offend anyone, when I said "almost diagnose a problem" I say it with sarcasm.)

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I answered this question May 5, 2010, by agreeing with who I felt to be a "true professional," (Tom Lamb - who said he designed them) based on my 40 years experience as a degreed electrical engineer and electronics technician. I didn't call myself a "true professional" because anyone can claim it, even if they're an idiot. And, I certainly didn't want to sound like Brian Manuel or red.

Brian Manuel, you say you have a degree? Were you unskilled at the time you took your engineering courses? Aren't you glad your instructors didn't have the attitude you display, in that they shouldn't be giving advice to unskilled persons? I was one of those instructors, and of the thousands of unskilled I taught, I've never regretted the advice I gave.

The purpose of this site is to give the unskilled access to professional information from people like me and Tom. And, Brian, if you don't agree with its purpose, I agree that you should stop posting to this site, since your attitude shows you NOT to be a "true professional," .

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A person unskilled in the diagnosis of electrical circuits and components would be guessing at what is wrong with a micro. not heating. Silly to do (beyond checking the internal fuse perhaps) and they could harm themselves. I was speaking to the total hysteria and misinformation in some of the posts. I agree the clueless should call a repairman, buy a new micro. or seek out a repair clinic (I volunteer at one for a part of the year, done so for the past 7 years, see shot mags all the time, second only to bad door safety switches). To those who have successfully diagnosed and repaired other electronic or electromechanical items (beyond say, oh the internal fuse blew) diagnosing and repairing a microwave can be done. Respect the HV capacitor (read up if you have not dealt with them), check for arching/burning anywhere around the oven cavity, mag. / mag. mount, HV wiring, don't crush or break up the ceramic insulator on the old mag.

Maybe I am not in sync. with the purpose of this site Fred. I wanted to encourage those with some skills to not be afraid and led astray by some of the ignorant hysteria posted in this thread.

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Thanks, Red. It wasn't you that I was primarily addressing, but I appreciate your answer. My reaction was triggered by someone crowing about his being a "true" professional, as if the rest of us are just hacks.

Also of note is that Tom's answer received the highest score of all who posted to this question, as opposed to the "0" Brian Manuel received, which tells me the non-professional readers of this site are able to separate the professionals from the roosters (those who crow).

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We have a Magic Chef, two years old, that still heats OK, but makes a lot of extra noise. It is easy enough to open up, and I did discharge the high voltage capacitor, and remove the high voltage diode, so I could test it. The diode is good, the wiring looks good, and I can't find anything wrong with the fan or the turntable drive. I am reasonably sure that the magnetron is the source of the problem, but the economics of repair don't work out in this situation. A new, similar microwave oven sells for about 100 dollars. There is a nearby appliance service company, that does not have a fixed base, they only want to send out a service tech to our house, and the minimum service charge is 45 dollars. Add in the cost for parts and labor, and it makes no sense to repair this unit. I am wondering how anybody can make any money selling a new microwave oven for 100 dollars.

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The economics really don't work out for the average standard everyday $100 consumer counter top models. The only way it does is DIY. Salvaged magnetrons from scratch and dents or working machines that failed in another manner or units that were removed/replaced during remodel are available from some small appliance dealers for $10-$30.

For commercial units or over the range models that cost a lot more to purchase the economics can work out. New magnetrons can be purchased for most consumer models for $40 - $50. A lot of the postings here are people inquiring about OTR microwaves.

Other situations where people repair is if they have an odd size / built in or top of the line (maybe + convection oven) models.

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Maybe something burst from the microwave like a light bulb or a circuit popped? If you feel like it is working fine otherwise you should concerned with local repair person except to mess with it.

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People get hurt if they don't know a thing about stuff like this. Just because it's easy for you doesn't mean it is for them. I've taught people before and there are some I wouldn't even give a screwdriver. So before you start judging realize what's going on out there the general population in general are not able to work on things. So I can prove my sincerity and will not judge ( I let God do that) but you better realize what you are saying and to who.

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Mitra Cline will be eternally grateful.
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