Making loud Hum when not on, but plugged in.

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Microwave Oven

Repair guides and troubleshooting information for microwave ovens.

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Jay @jay72983

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게시됨: 2014년 10월 20일

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Making loud Hum when not on, but plugged in.

Samsung SMH2117S Microwave started making a loud hum a few days ago, I unplugged it over night and left it, plugged it back in the next day and still a loud hum, the hum stops when you open the door. As soon as you close the door, without pressing any buttons or starting the microwave the hum comes back. I took the microwave down from above the range, removed the cover to try and pin point where the noise is coming from. the hum is coming from the Magnetron. The unit will still heat food, and everything else seems to be working as normal. I don't really feel like it is safe to leave plugged in or even use. I have found a price on a new magnetron for this product for $115.(i live in canada) i have no problem buying a new one and replacing it. But i want to make sure that is the real problem.

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I took mine apart to find that the power supply was poorly epoxyied . When I powered it up the wingdings were vibrating within the transformer. I ended up Zip-Tie ing them together to reduce the noise and so-far-so-good.

Eric Smith 의 2019년 4월 14일

I have the same problem with my Frigidaire FFMV164LSA. It makes a humming sound (sort of like a refrigerator running) when it’s plugged in. If I open the door the humming stops. It heats fine.

Ryan 의 2019년 11월 2일

I have the same exact issue Ryan with the same exact model. Tried cleaning all the switches but it still happens. Would be great to know how to fix

Dan 의 2019년 11월 27일

I’m here with the exact same problem. Model ME18H704SFS

Judy@AZJudy.com 의 2019년 8월 23일

Mine is exactly the same model as yours. Joe fix worked! :)

Juan Manuel Jimenez 의 2019년 8월 27일

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Joe @joe98735

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게시됨: 2015년 3월 16일

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I had a Maytag microwave doing this. The unit was only 4-5 years old. After testing transformers and magnetron and other interior components I traced the problem to the lower door switch. I tightened the screws just inside the door because one was slightly loose. You could not tell this by opening and closing the door only by applying a screw driver to the screw. I tightened it and everything worked the way it should.

Hope this helps.

Joe

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Thanks! Worked for me and took 2 seconds to do for my samsung microwave. I tightened both screws where the latches engage, and it no longer hums now.

Benjamin Gray 의 2017년 10월 7일

Wow. Thank You. Just, thank you.

Juan Manuel Jimenez 의 2019년 8월 27일

My microwave is now making the HUM sound (same sound when I am heating the food and the plate is turning). My microwave brand is Frigidaire and I don’t have screws on door to tighten, what can it be? Joe. It makes that sound the lights on and only stops when open door.

cxavi_007 의 2021년 5월 27일

Oh, my!! Three days before Thanksgiving, and the microwave is humming and overheating. First, I prayed, then I checked on the internet for possible answers, and find this response by Joe. The screws in the door didn't fit any screwdriver bit that I had, so I just pushed on the door frame, and voila! now everything is as it should be! JOE YOU SAVED THANKSGIVING!!

Shirley Schofield 의 2021년 11월 22일

I don’t understand how this worked, but it did. Thanks! Hardest part was finding the star screwdriver to fit the screws that are next to the latch receiving part of the unit. Samsung from 2018.

Joe Kaulbach 의 2022년 8월 4일

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I took mine apart to find that the power supply was poorly epoxyied . When I powered it up the wingdings were vibrating within the transformer. I ended up Zip-Tie ing them together to reduce the noise and so-far-so-good. — Eric Smith
I have the same problem with my Frigidaire FFMV164LSA. It makes a humming sound (sort of like a refrigerator running) when it’s plugged in. If I open the door the humming stops. It heats fine. — Ryan
I have the same exact issue Ryan with the same exact model. Tried cleaning all the switches but it still happens. Would be great to know how to fix — Dan
Thanks! Worked for me and took 2 seconds to do for my samsung microwave. I tightened both screws where the latches engage, and it no longer hums now. — Benjamin Gray
My microwave is now making the HUM sound (same sound when I am heating the food and the plate is turning). My microwave brand is Frigidaire and I don’t have screws on door to tighten, what can it be? Joe. It makes that sound the lights on and only stops when open door. — cxavi_007
Oh, my!! Three days before Thanksgiving, and the microwave is humming and overheating. First, I prayed, then I checked on the internet for possible answers, and find this response by Joe. The screws in the door didn't fit any screwdriver bit that I had, so I just pushed on the door frame, and voila! now everything is as it should be! JOE YOU SAVED THANKSGIVING!! — Shirley Schofield
I don’t understand how this worked, but it did. Thanks! Hardest part was finding the star screwdriver to fit the screws that are next to the latch receiving part of the unit. Samsung from 2018. — Joe Kaulbach

john.lorne.andrews @johnlornea15848 평판: 25 1 · Answer 1 · 2017-07-06T13:14:58-07:00

john.lorne.andrews @johnlornea15848

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게시됨: 2017년 7월 6일

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There is a safety switch (thermostat) that is often located just behind the user interface. If there is an issue with the thermostat or connection it can cause a hum in the motor of the fan motor. Give the safety switches a test for continuity. This was the issue with a humming Samsung microwave I just repaired.

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This is happening with my Samsung microwave it's just started happening an it only a few years old it's in a house I rent. Should I call the landlord? Yes now that You mentioned it the door seems a little loose

Michael Crawford 의 2018년 11월 1일

This sounds like my problem. When door is closed it sounds like a fan is running near top right of microwave. I will try to figure out how to disassemble the front control panel and locate that thermostat.

Jack Burton 의 2020년 6월 24일

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avxnj1 @avxnj1 평판: 13 2 · Answer 2 · 2017-04-13T19:00:34-07:00

avxnj1 @avxnj1

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게시됨: 2017년 4월 13일

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There are three micro-switches on the latch board. When the door is shut, two of them should be closed and one should be open. If the third one fails and remains closed, it creates an unintended circuit loop that causes hum, although not necessarily operation at full power. I replaced all three switches (since the unit had to be opened up anyway) and the problem appears to have been solved. It may be intermittent however, as it did occur once in the past and went away on its own. The current assumption is that it the switch was still the culprit and replacing it should make a lasting repair.

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andrea Zalazar @andreazalazar 평판: 1 · Answer 3 · 2019-02-03T14:36:08-07:00

andrea Zalazar @andreazalazar

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게시됨: 2019년 2월 3일

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mine sounds like that and blow the fuss, i buy another and blow it again, dont know what to do.

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If your microwave is blowing your fuse you want to look at your door switches or inspect if something is grounding out in your high voltage circuit. (HV transformer, HV capacitor, or magnetron) . Remember that a fuse gets blown because too much amperage is pulled through the unit. If nothing is grounding out and your door switches test okay, try opening up the microswitches to see if there is any damage inside them. It's possible for a micro switch to allow continuity but still be damaged and cause the unit to fail.

nfld_batman 의 2019년 2월 3일

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Eric Smith @ericsmith81441 평판: 1 · Answer 4 · 2019-12-10T16:34:06-07:00

Eric Smith @ericsmith81441

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게시됨: 2019년 12월 10일

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I figured out my samsung's power transformer was coming unglued in terms of the steel laminations. I wrapped zip ties around the laminations to keep them from vibrating. Now it is all fixed.

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I have a Hamilton Beach microwave and my son left the door open all night and now it hums like it is on when it isn't and the top gets hot.

deanna77758 의 2022년 2월 4일

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M. Yaghi @myaghi 평판: 1 · Answer 5 · 2020-11-15T12:13:25-07:00

M. Yaghi @myaghi

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게시됨: 2020년 11월 15일

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I had the same problem, I tested all door switches. They were all fine. I tested the power relay on the main board and found it stuck on closed shorting the power to the transformer. Relay is available for $6. But I rewired a car relay and problem solved.

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Thanks for the tip, turns out mine was a stuck relay switch I give it a tap and seems ok for now but will probably need replacing soon

Richard 의 2023년 4월 8일

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BMoon @bmoon85657 평판: 1 · Answer 6 · 2023-10-04T07:28:11-07:00

I had the same problem with my Whirlpool Microwave. It has done this off and on for several years. Usually unplugging it for a little while resolved the problem but not this time. I found that the R2 relay on the control board was stuck on. I removed it and soldered in wires to a 12vdc /30A automotive relay and the problem was solved. The relay I removed had a two-pin metal bridge that appeared to be just for mounting support but since it looked like it soldered into runs on the board, I added the yellow jumper wire. I also removed the diode from the board because the relay assembly I installed already had a diode.