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Buzzing LED Cinema Display (non-Thunderbolt). Why is this happening?

Hi,


I've been noticing a buzzing sound coming from the bottom left of my LED Cinema Display. I've only started to hear it in the last month, previously there was no buzzing sound. Sometimes it gets really loud when I boot the Mac, and then it disappears. Sometimes it buzzes for about 2-3 hours. It's been happening everyday now. Can someone explain why, because I haven't experienced this before a month back. I've been using this Mac since January this year.


Sophie

Mac Pro, Mac OS X (10.6.8)

Posted on Sep 10, 2013 6:47 PM

Reply
7 replies

Sep 11, 2013 3:31 PM in response to galr0cker

The following is from the Technician's Guide for the 24" LED Cinema Display and appears to apply to the 27" also; for a buzzing noise check:


  1. Verify display’s USB and Mini DisplayPort connectors are plugged into known-good supported system.
  2. Tilt display to hinge limits to determine if mechanical noise is generated by the hinge mechanism. Repair/replace mechanism if needed.
  3. Play sound sample at loud and soft volume levels to determine if noise is caused by the left/right/ subwoofer speakers or the amplifier circuit.
  4. Verify that the air intake/outflow vents are not obstructed.


I have the 27" display also and just learned myself from researching your problem that it's got a fan inside which keeps it cool. If none of the checks identify the source of the problem and you've had it less than a year, it should be covered by the warranty. Box it up and see what an Apple Genius says.

Dec 2, 2013 2:10 PM in response to galr0cker

I too have this problem and I too think it is the fan cooling the screen that is making the noise because when I increase the brightness on the cinema display the noise gets louder and more intense.


It sounds like the fan blades are going against something. When I plug the mag safe into my MBP things get really out of hand and the noise gets really loud and irritating.


Does anyone have any thoughts on how to make sure what is the problem and how to fix it without having to send it to an apple service center?


Thank you.

Dec 3, 2013 6:30 AM in response to FCPXLL

Well, some development. I thought it was the fan making the sound but I have started to suspect that maybe the case is that the fans "intensity" somehow affects the speakers which amplifies the fan noise. (??) Could that happen? Or maybe it is not the fan at all and the electronics are affecting the speakers. Intresting indeed.


Today I put my ear to the vent on the back of the screen (behind the stand) to listnen to the noise and it came out very loud, even louder than under the screen. So I thought, well it has to be the fan then because that is where it is located. But as I read another post here on the forums from Bleengrass (https://discussions.apple.com/thread/5597577?answerId=23999708022#23999708022) it struck me that it is also where the subwoofer is located. And thus it led me to belive in the theory that it is the speakers I am hearing.


So now I am wondering what could cause this and how to fix it. I will go to the mac service store nearby this afternoon and hear what they have to say. I will report back!


Stay tuned.

Dec 4, 2013 4:03 PM in response to FCPXLL

Ok, the visit to apple service center helped me not very much as anticipated. Of course they wanted me to carry the display to the store so they could fix it and that would probably cost me around 2000 swedish kronor (about 300USD) so that is out of the question.


BUT!!


I have stumpled upon a very intruiging thread where a guy has uploaded a video of the noise his display is making and it is identical to the noise I am hearing from my display! I was very happy to find this. The solution though seems a bit complicated to me as a novice in electronics but it involves swapping some parts on the power supply board in the display and I am tempted to give it a try.


Check out the thread here:


http://www.badcaps.net/forum/showthread.php?t=23699


Intresting is it not?

Dec 4, 2013 4:34 PM in response to FCPXLL

Electrolytic capacitors are so named because they have their capacitive material bathed in an ion-rich electrolyte inside a sealed can. If the capacitor gets too hot, the seal is broken, or it gets too old, the electrolyte gets too hot, the hot liquid expands and the stamped X on the top of the capacitor gets pushed upward and becomes domed instead the original flat.


Electrolytic capacitors have a polarity. You need to look closely at the exisiting ones to be sure you understand what side is + and what side is - before removing, and if the board in not marked, to mark the polarity so that you can figure it out when the old device is removed and the markings on it are gone.


When replacing, it is always OK to go same or higher Voltage range, same or higher heat range, and same or somewhat higher capacitance. Shapes are not standard -- the new ones you buy may not be exactly the same shape. Try to keep the leads as short as practical.

Dec 5, 2013 9:13 AM in response to Grant Bennet-Alder

Thank you for your help Grant!


This answers alot of questons for me and probably for others too. It seems like ALOT of people have this problem with the buzzing. There are even multiple videos on youtube with lots of different iMac machines and displays with this buzz. Doesnt have to be the capacitors in those cases but I feel pretty sure that that is my problem. I will open my screen up, photograph the components and the procedure and post my findings/results here when I am done. I just have to get the right parts first. Hope this solves it!


Thank you again.

Buzzing LED Cinema Display (non-Thunderbolt). Why is this happening?

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