2012 27" iMac making a electrical buzzing voltage noise

Discussion in 'iMac' started by PavelT, Feb 12, 2013.

  1. macrumors member

    Joined:
    Nov 12, 2012
    #1
    ok, so i wanted to make a new thread about this topic because the last one was cluttered with confusion, so i am making this new one a bit more specific. ok. well my new late 2012 late 27' 1TB non-fusion iMac makes an electrical buzzing noise and NOT the fan and NOT the spinning hard drive (i know what a fan and hdd sounds like) when it is plugged in. it doesn't matter when it is On or Off, as long as it is plugged in. it also happens usually in the evening time, every day. only unplugging it, then noise will stop, of course. i have tried many things to try to get to the root of the problem.

    i have already tried: to no avail.

    - i have tried unplugging every thing plugged in one by one to see if something is interfering with my iMac cord.

    - have tried various outlets.

    - i have tried putting the iMac cord through a surge protector.

    - i have tried putting the iMac cord through a APC voltage Regulator.

    - my previous 2010 21.5 iMac never had this problem.

    - the noise is on the side where the power button is located, under the display by air fan vents. about 5 inches to the left of the apple decal. an electrical voltage type of noise.

    - i am already talking to apple care about this issue.


    HERE is a sample of what the noise sounds like: (sorry, there is a dog barking about halfway into the recording)

    https://soundcloud.com/pavl-1/2012-imac-electrical-noise


    any thoughts would be much appreciated. thanks.
     
  2. Moderator

    SandboxGeneral

    Staff Member

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    #2
    It's still new and under warranty, why not bring it into an Apple Store?
     
  3. thread starter macrumors member

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    Nov 12, 2012
    #3
    sorry i forgot to mention it is custom bto 27 -i7, 680mx, 1tb non-fusion.

    bringing it into an apple store would not replace it, instantly.

    i already had it looked at by the not so-genius bar. and they found nothing and it passed their diagnostic tests.

    i wish i was making this up, but this buzzing noise is loud and very much there. apple rep on the phone said the new 27s should not be making any noise other than occasional fan and hdd noise, which is understandable..and should absolutely not be making noise when it is turned off. i am currently working this out, trying to find a solution with an apple senior advisor. because i cannot afford to be without a computer right now.
     
  4. Moderator

    SandboxGeneral

    Staff Member

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    #4
    I would venture to say it's a power supply if you're confident that it's not the HDD or fans. You say an Apple Store looked at this, heard the noise and said there was nothing wrong? :confused:
     
  5. macrumors G5

    Macman45

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    #5
    As SBG has pointed out, it's new...Bite the bullet, phone your Apple rep and get it swapped out...That buzzing is probably PSU related, but it shouldn't be there...it's a hassle, but it makes sense in the end.
     
  6. thread starter macrumors member

    Joined:
    Nov 12, 2012
    #6
    yeah, they just passed the diagnostics at apple store and said they could not produce the problem. however, its so loud at the apple store with consumer hysteria to even hear a small shouting match. Not sure about the backrooms, but you would have to observe it to actually hear it, not just run a test and go back to the sales floor. which sounds like they would do because their geniuses and all.:apple:

    and yeah i am tryin to figure something out with an apple rep but i cant afford to be without a computer for weeks on end. so me sending this back, and waiting for a backordered bto 27 is not a very good option for me.
     
  7. WilliamG, Feb 13, 2013
    Last edited: Feb 13, 2013

    macrumors 603

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    #7
    I had the EXACT same system as you, with the non-fusion 1TB. I had a buzzing sound as well, and for me it was actually the graphics card. I assume yours sounds like mine, which sounds very similar to this... It's coil whine from the graphics card (at least in my case).

    http://www.youtube.com/watch?v=tDRDAXkH35Y

    I was able to pay the difference in the Apple Store to get the Fusion drive model, which was the only difference between my order and the one in the store, if you're interested in doing so. You may want to speak to AppleCare/the store, and see if you can do that if you want to. For me it was a better alternative than waiting over a month for a replacement.

    I've yet to hear that buzzing on my replacement (and I've sadly had several replacements due to screen issues). In any case, the buzzing that I experienced is gone, which is key.
     
  8. thread starter macrumors member

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    Nov 12, 2012
    #8
    i see. so they had i7-chip, 680 gpu, 27 inch imacs on hand at the apple store? because that is what i have. im really skeptic on the fusion thing, i do not want it. i use an external ssd as my osx...my apple store does not have any custom options on the imac.. they would swap me for an regular, low end 27 inch, because that is all they carry at the apple store (Apple has confiremd with me this already) But i am not willing to downgrade. i need the i7 most importantly because of the raw video editing that i do, it would eat all of the i5 too easy. downgrading would just not be fair to me at all, considering i bought this machine....and i saw the youtube of your gpu, mine sounds similar, but mine sounds a bit more voltage electrical sounding..
     
  9. macrumors 65816

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    Lincoln, UK
    #9
    I had a similar problem with my white 24" iMac. I found that the buzzing went away if I turned the screen brightness up full (I usually had it at about 40%). I took it to the genius bar. They couldn't hear the problem in the store, but they replaced the screen and the buzzing was gone. I had a very complex and complete description of the problem and what I had tried to solve it. I put that into an image and made it my iMac wallpaper for when I took it in. Perhaps the lengths I went to made them believe me.
     
  10. thread starter macrumors member

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    Nov 12, 2012
    #10
    thanks. it has nothing to do with brightness though. i have turned it up and down, just in case. and i believe that issue was known and corrected in 2010 imac refreshes. could be wrong but yeah.
     
  11. macrumors 603

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    Seattle
    #11
    You don't have to be skeptical of the fusion drive. I separated the fusion on my replacement, so I have a 120GB SSD that I boot Windows 7 off of, and then the 1TB for photos etc. I also boot off an external SSD via Thunderbolt.

    That YouTube video is not my GPU. It's just a pretty close approximation of what the GPU in my 2012 iMac was doing. It was all electrical sounding, but that was the best I could do in terms of showing you roughly what it sounds like.

    If you don't mind paying the difference, I'd suggest just taking your system in and paying the difference to the fusion model, separating the fusion disks in Terminal, and forgetting this ever happened.
     
  12. macrumors 6502a

    Joined:
    Feb 16, 2010
    #12
    When the iMac is switched off the only thing running is the +5 volt standby power supply. If the buzz is that loud, there's a problem with the +5v STBY, possibly due to loosely wound, insufficiently secured coils, or defective filtering capacitors on the AC line side.

    A slight buzz when you put your ear to the case is one thing, but a loud buzz, audible away from the iMac indicates a problem that needs to be corrected.
     
  13. macrumors 603

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    #13
    Good call. I failed to notice the sound is present when the system is OFF, too. That's definitely power-related, and not GPU-related, then. Whether it's the computer or outside factors is a mystery to me.
     
  14. macrumors regular

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    New York
    #14
    I'm not sure if this is related to the buzzing that you guys are noticing, but I notice that once my Mac is on for an hour or more I get what seems to be an electrical buzzing noise when the screen brightness is set high. When I lower the brightness the buzzing noise goes away.

    I also get a clicking noise, which sounds similar to the release of static electricity, around the perimeter of the display when my iMac has been on for an hour or so and I change the brightness on the display from high to low or low to high.

    I'm on my 2nd replacement. My last replacement had the same issues. This time around these issue weren't apparent at first but seemed to develop after a week or so. I spoke to Apple and they said that this was not normal behavior so my 3rd replacement is on it's way.

    I'm also having\had some major image retention\persistence with my last two units but that's another issue...

    Can you guys check to see if the screen's brightness also effects your buzzing noise? I'm by no means an electrical expert but I'm curious to see if more 2012 iMac owners with buzzing noises are finding that the two are correlated.
     
  15. macrumors 603

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    Seattle
    #15
    I've had several replacements for various reasons, and screen brightness has never had any affect on buzzing etc from my iMacs. And I've checked for it, too.
     
  16. thread starter macrumors member

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    Nov 12, 2012
    #16
    yeah but i need an i7 cpu, thats a must. so getting a fusion replacement from apple store would not work out though.:(

    ----------

    the electrical sound is present when it is on and when it is off, at the same exact loudness. and it usually happens in the evening, everyday.
     
  17. macrumors 603

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    Seattle
    #17
    The fusion model at the Apple Store is the i7 model.

    If it happens most often in the evening, the issue sounds like it's more with your house/residence than the computer, but it's tough to say for sure...
     
  18. macrumors 6502a

    Joined:
    Feb 16, 2010
    #18
    This is significant information. If it's happening mostly in the evening, usually the time of highest power consumption, it could be due to low voltage, so the iMac's PSU is working harder, or due to dirty power, such noise on the lines or distorted sine waveform.

    It sounds like you could be in the market for a good UPS. One you will find recommended in other threads, and the one I bought recently, is the CyberPower CP1350PFCLCD. They are available at Bestbuy US for $170. Make sure you get a PSU with pure sinewave output on battery, otherwise you'll get a stepped squarewave unit that could damage the iMac's PSU.

    APC has sinewave UPSs, but they are the SmartUPS series, and fairly expensive, and physically heavy.
     
  19. RHD
    macrumors 6502

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    #19
    Nice!
    I have made a note....
     
  20. WilliamG, Feb 15, 2013
    Last edited: Feb 15, 2013

    macrumors 603

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    #20
    While I agree a UPS might help the issue, I always have to reply to the pure sinewave stuff and say... BLAH. Nowhere does it say you need one of those. If it were an issue, Apple would specify so. I've been using non-pure sine wave UPSs for years with iMacs with no issues.

    And once again, I'll say pure sine wave is a solution looking for a problem (at least with regards Apple products). Honestly, if it were "proven," I'd have one of those UPSs. But until then... :)

    It sounds like, from what I gather, that extended outages might hurt the iMac. I just did a test, and on the UPS-only, I do get a buzzing from my iMac's PSU, indicating (again, from what I gather), that a pure sine wave would be better.

    But again, I haven't read any proof either way...
     
  21. Guest

    Joined:
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    Currently in Switzerland
    #21
    Had this problem before and can assure you, based on live testing: screen inverter or PSU. Nothing else.
     
  22. macrumors 603

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    Seattle
    #22
    Well if it's doing it with the system OFF as he says it is, it's definitely PSU/power related (not the screen).
     
  23. macrumors 6502a

    Joined:
    Feb 16, 2010
    #23
    I agree it's PSU related, but he also says it basically only happens in the evenings, which indicates the PSU could be reacting to anomalies with the AC power at those high load times.

    When I first got my 2012 iMac I was using an APC BackUPS, and a couple of days after I had the iMac I turned it on at the tail end of the UPSs startup self test. Talk about a loud noise. I still had my hand on the area of the iMac power button and felt the vibration. The iMac was immediately connected to a separate power bar until I got the CyberPower. I still use the APC with my desktop PC which draws about three times the power of the iMac, and doesn't protest the stepped square wave.
     
  24. thread starter macrumors member

    Joined:
    Nov 12, 2012
    #24
    interesting notes. yeah it happens everyday in the evenings. a electrical buzzing voltage sound that is loud (i can hear it about 5 feet away) i did purchase voltage regulator. this one to be exact:

    http://www.amazon.com/gp/product/B00009RA60/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

    And still the buzzing occured.

    Also i recorded another sample of the buzzing noise here:


    https://soundcloud.com/pavl-1/imac-noise3
     
  25. macrumors 603

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    Seattle
    #25
    Well it's clearly PSU-related. I can't imagine replacing the iMac would solve the issue, but you never know...

    Where are you located?
     

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