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Imac 27 High pitch noise

C

civictyper10

macrumors newbie
Original poster
May 27, 2010
5
0
I received my Imac 27 I7 and after the initial setup, I notice that the computer was making an high pitch noise coming from the left corner, when I change the screen brightness to minimum or to maximum the noise disappears, if the screen brightness is between 40 to 90% the noise starts again, as I´m an electronic engineer, I decided to disassemble the imac to search the cause and I found it. The problem is caused by the coils from the led backlight board, see picture and youtube video for better understanding, if someone on this forum works as an electronic engineer at apple, please check it and address this issue to the development team of the circuit.

You should push the volume up to listen the high frequency noise coming from the coils in the video.
http://www.youtube.com/watch?v=_8MWUH9ZhL0
 

Attachments

  • Led backlight board imac 27.jpg
    Led backlight board imac 27.jpg
    98.8 KB · Views: 3,447
I couldn't hear any noise (too high a frequency for YouTube?), but a buzzing converter points to a stability problem of the screen LED power supply - a shame really.
Also, it would be nice to have better resolution picture.

Tom B.
 
I can hear the noise. You either need to turn the volume up or get better speakers ;)

And unfortunately, many type of LCD screens have this problem. Its nothing new and not only limited to the iMacs.
 
How can apple keep on selling products like this with a price tag of 2000 euros, that´s what I paid for and with such quality problems, I can´t understand, I have a macbook pro, a ipod classic and a ipod shuffle no problems whatsoever, and those products were way cheaper than the Imac.
 
Nope, nothing here. Some static-like white noise, board handling noises, but no high pitch noise on my side (my computer is past its' prime, though). I can hear a buzzing noise on this YouTube piece though.

Tom B.
 
you should listen carefully, it´s not a buzz, it´s like a dog whistle


Btom said:
Nope, nothing here. Some static-like white noise, board handling noises, but no high pitch noise on my side (my computer is past its' prime, though). I can hear a buzzing noise on this YouTube piece though.

Tom B.
Click to expand...
 
I have the same dog whistle type sound that I can only hear while 5 feet away in bed.
 
I have a white 24" C2D iMac (just over 3 years old now) and I have the same thing. If I have the brightness on anything but max then the noise is noticeable/increases.
 
I am on my 3rd iMac with this same problem, only mine have been accompanied with a sporadic buzzing noise which is also associated with the screen brightness, which is more prominent if the computer is running a little hotter. I recently attempted to get a refund altogether just because I am tired of the headache and lugging this monster around, but get this: after 3 faulty machines (as diagnosed by an Apple Care senior advisor), the engineering department placed a necessity on this computer to be physically inspected by an Apple-certified technician. The closest Apple Retail Store is almost 2 hours from my home. So if I take it, come back home, and then have to make an entire other round trip to pick the thing back up, that's 8 hours of driving, gas, wear and tear on my car, plus managing to get the time off work to take this thing in AT MY EXPENSE. Somehow, this doesn't seem right.

I must say, though, I've had a great experience with Apple's phone tech support through Apple Care. However, once the case was handed over to Customer Relations, my entire experience turned sour. All the while through the technical support, I kept being told that "there should be no noises associated with adjusting the screen brightness." My ultimatum is to either a. make the drive as described above, b. Fex Ex it to them (AT MY EXPENSE), or c. live with the noise, worry about long-term failure, and sell the thing once Apple Care is up. I am so completely disgusted with this multiple-month long situation that I am opting for the latter choice.

I wish anyone else trying to get their machine that have this issue repaired/replaced the best of luck. I certainly haven't had it. :mad:
 
Hi, i have simmilar problem on the imac 27 i7, but maybe lower frequency and all the time, independly of brigness.
noise seems to come from left lower corner.
attached you have a audio recording done with the imac internal microphone (just seeting a coin or simmilar on top of the microphone to amplify the noise on the computer case) and a plot of the audio spectrum. the freq of the noise is at 123Hz.

jl

civictyper10 said:
I received my Imac 27 I7 and after the initial setup, I notice that the computer was making an high pitch noise coming from the left corner, when I change the screen brightness to minimum or to maximum the noise disappears, if the screen brightness is between 40 to 90% the noise starts again, as I´m an electronic engineer, I decided to disassemble the imac to search the cause and I found it. The problem is caused by the coils from the led backlight board, see picture and youtube video for better understanding, if someone on this forum works as an electronic engineer at apple, please check it and address this issue to the development team of the circuit.

You should push the volume up to listen the high frequency noise coming from the coils in the video.
http://www.youtube.com/watch?v=_8MWUH9ZhL0
Click to expand...
 

Attachments

  • noise imac 27 i7.zip
    248.3 KB · Views: 257
Total iMac 27'' fail

Hi to all!
I am new here, so hello to everybody!!
Well, I can totally hear the sound described above. It just hits my nerves.
My story about iMac 27'' goes like this:
I bought one a few weeks ago. But sometimes it turned on (you had to roll the dice or play lottery whether it was going to turn on or not - basically the screen didn't turn on, not the machine itself). It turned out to be a backlit (don't know if the spelling is right, but anyway..) problem +it had somekind of dead pixel, which could be seen even when the computer was turned off (!) - it looked like some sort of crystal thingy - misconstruction of the screen(??) don't reall know...(any ideas from you are totally welcome!) :)
Anyways, the seller (by the way I live in Greece) was kind enough to give me a new iMac. So I waited for 2 weeks and the new machine arrived, but...has these issues: 1. It makes a buzz noise from the upper left corner of the back of the machine when the brightness falls to minimum, 2. I CAN hear this high pitch noise when the brightness is between 30-90% or something (I want to puke in 15 minutes because of it, really), 3. 4 dead pixels (black) and the crystal thingy is back in te center and a bit downwards of the screen. And the most unlike event: I took it to the store (which is the also the official service center) the buzz noise stopped (what the hell..?), they couldn't hear the high pitch sound, and for the pixels I asked them how many is needed to get a replaement (and they didn't know!!).
The conclusion: I am the Anti-Christ(!) or a werewolf(!) or something and I can hear sounds with high frequency... :))
No serisoulsy, would it be my fault if I smash the computer or not??
Please, any suggestions?? One thing is for sure: I won't ever, ever going to buy a product by Apple - the most irresponsible company in our days.

Thanks for reading, hope to get some advice from you...
Looking forward,

Yours Antony
 
Hi Tony,

Sorry for the late reply, If you go to the store with the computer, it´s very difficult to hear the noise because there is so much sound frequencies around your ears, therefore you and the technician have to listen to it, in a quite room, to completely trace the noise coming from the iMac, otherwise the technician would think that you are crazy and won´t believe you.

I made some tests and I can say with 100% confidence that:

Buzz noise = to power supply
High frequency noise = Led backlight board

Best regards.

tonysan said:
Hi to all!
I am new here, so hello to everybody!!
Well, I can totally hear the sound described above. It just hits my nerves.
My story about iMac 27'' goes like this:
I bought one a few weeks ago. But sometimes it turned on (you had to roll the dice or play lottery whether it was going to turn on or not - basically the screen didn't turn on, not the machine itself). It turned out to be a backlit (don't know if the spelling is right, but anyway..) problem +it had somekind of dead pixel, which could be seen even when the computer was turned off (!) - it looked like some sort of crystal thingy - misconstruction of the screen(??) don't reall know...(any ideas from you are totally welcome!) :)
Anyways, the seller (by the way I live in Greece) was kind enough to give me a new iMac. So I waited for 2 weeks and the new machine arrived, but...has these issues: 1. It makes a buzz noise from the upper left corner of the back of the machine when the brightness falls to minimum, 2. I CAN hear this high pitch noise when the brightness is between 30-90% or something (I want to puke in 15 minutes because of it, really), 3. 4 dead pixels (black) and the crystal thingy is back in te center and a bit downwards of the screen. And the most unlike event: I took it to the store (which is the also the official service center) the buzz noise stopped (what the hell..?), they couldn't hear the high pitch sound, and for the pixels I asked them how many is needed to get a replaement (and they didn't know!!).
The conclusion: I am the Anti-Christ(!) or a werewolf(!) or something and I can hear sounds with high frequency... :))
No serisoulsy, would it be my fault if I smash the computer or not??
Please, any suggestions?? One thing is for sure: I won't ever, ever going to buy a product by Apple - the most irresponsible company in our days.

Thanks for reading, hope to get some advice from you...
Looking forward,

Yours Antony
Click to expand...
 
civictyper10 said:
Hi Tony,

Sorry for the late reply, If you go to the store with the computer, it´s very difficult to hear the noise because there is so much sound frequencies around your ears, therefore you and the technician have to listen to it, in a quite room, to completely trace the noise coming from the iMac, otherwise the technician would think that you are crazy and won´t believe you.

I made some tests and I can say with 100% confidence that:

Buzz noise = to power supply
High frequency noise = Led backlight board

Best regards.
Click to expand...

Hi again!!
Thanks a lot for your reply. I appreciate it more than you can imagine.
The funny thing is this:
The technician told me that he fixed - changed both the power supply chip(?) (from inside) and the backlight supply, and guess what: 1. the buzz noise remains exactly the same, 2. the high pitch noise remains the same. It is as if he didn't repair anything..
Any ideas? For example is he lying?? Or the machine is so f***ed up (trully sorry for the language, but the whole situation is really annoying) that I need to return my money or give me a replacement?
Thank you for once more,

Yours

Antony

P.S. Here are 2 videos that I recorded with the buzzing noise:

http://rapidshare.com/files/398851435/iMAcBuzzNoise.rar.html

Feel free to check it out

Thank you again
 
I just got a 27" i7 iMac today and mine is exhibiting this issue. The machine is running VERY hot, and it's emitting a very high frequency squeal sound (like an electronic squeal but loud). When I turn the screen brightness to 50% then the sound goes away. It is the loudest when the screen brightness is between 80% - 90%. I can still hear the noise at full brightness but it's not as loud, still unbearable...but with the screen that bright I get a severe headache. I can't run the machine at anything but 50% to 60% brightness or this loud squeal is too annoying to deal with. I think maybe this has to do with the LCD overheating or something, I mean the machine is really, really hot.
 
WardC said:
I just got a 27" i7 iMac today and mine is exhibiting this issue. The machine is running VERY hot, and it's emitting a very high frequency squeal sound (like an electronic squeal but loud). When I turn the screen brightness to 50% then the sound goes away. It is the loudest when the screen brightness is between 80% - 90%. I can still hear the noise at full brightness but it's not as loud, still unbearable...but with the screen that bright I get a severe headache. I can't run the machine at anything but 50% to 60% brightness or this loud squeal is too annoying to deal with. I think maybe this has to do with the LCD overheating or something, I mean the machine is really, really hot.
Click to expand...

Back to the shop, get refund, buy yourself another one a few days later...

Tom B.
 
Btom said:
Back to the shop, get refund, buy yourself another one a few days later...

Tom B.
Click to expand...

I am taking it back to the Apple Store tomorrow. I just hope they will give me a full refund and not charge me a $219.90 restocking fee (my receipt says that I will have this exact restocking fee on returns).

Does anybody know Apple's policy on this? If I can prove that it's defective can I get a full refund? I've now decided I don't want to put up with this and I'd rather not exchange for another iMac, I've decided I'd rather keep my old monitor and probably get a Mac Pro. So will I have to pay the steep restocking fee on return?
 
WardC said:
I am taking it back to the Apple Store tomorrow. I just hope they will give me a full refund and not charge me a $219.90 restocking fee (my receipt says that I will have this exact restocking fee on returns).

Does anybody know Apple's policy on this? If I can prove that it's defective can I get a full refund? I've now decided I don't want to put up with this and I'd rather not exchange for another iMac, I've decided I'd rather keep my old monitor and probably get a Mac Pro. So will I have to pay the steep restocking fee on return?
Click to expand...

I took my flickering yellow i5 back within 10 days and I got every cent back. IIRC, if it is defective, they won't charge a restocking fee.
 
WardC said:
I am taking it back to the Apple Store tomorrow. I just hope they will give me a full refund and not charge me a $219.90 restocking fee (my receipt says that I will have this exact restocking fee on returns).

Does anybody know Apple's policy on this? If I can prove that it's defective can I get a full refund? I've now decided I don't want to put up with this and I'd rather not exchange for another iMac, I've decided I'd rather keep my old monitor and probably get a Mac Pro. So will I have to pay the steep restocking fee on return?
Click to expand...

If they charge restocking fee on a FAULTY unit, I'd call it a new (crooked) business model and call Apple directly.

Tom B.
 
I took the 27" iMac back to the Apple Store this morning. They gave me a full refund ($2,340.40 - including tax)...I opted for the Apple Gift Card refund which I am going to use on the purchase of a Mac Pro from the Apple Store website. At least they gave me a full refund!! I don't have to put up with this noisy machine anymore. It was the "dog whistle" sound, very loud extremely high pitched whine coming from the LED screen.
 
Intermittent High Pitch Noise Imac

I pulled out the plug at the rear once shut down, apparently this resets the fan and power setting or something. Any way this worked for me!

No more high pitch noise, I think mine was associated with the fans.

Regards
 
Has anyone had any success

Has anyone had any success getting a technician to acknowledge this or any other sound-related backlight issue? I'm on my 3rd iMac. The first had the buzz when the display was dimmed, so I swapped it for one with the same problem. I packed that one up and exchanged it for a 3rd machine with this dog whistle that is infinitely more annoying than the buzz.

The "geniuses" at the Apple store have not been very helpful. They insisted they've never heard of this problem, and refused to offer me another replacement. After taking notes that were suspiciously different than the problem I described, the "genius" checked the computer in overnight to try and recreate the sound. Sure enough, three of their "geniuses" couldn't duplicate the sound in 24 hours...I was able to do so 15 minutes after bringing the machine back home.

The last technician I spoke to kept trying to tell me that since I've been through three machines, that the problem was environmental, or the sound was normal and I just had really acute hearing. I then had to explain for maybe the fourth or fifth time that the other two did not whistle like this, and if I would have known I'd be stuck with this whistling computer, I would have never brought the first one back. I don't think I should have to be longing for a less-annoying, yet still defective computer just to avoid this customer-service-hell they've put me through. And if it's just the natural hiss of the bulbs I'm hearing, why don't I hear them at 100% brightness...genius!? Finally, the technician said that all he could do at this point was refund my money...which I would gladly accept, only I'd be out $300 in rebates.

If anyone got one of these inept, converse-wearing hipsters to hear the whistle...please, let me know how you did so. Your help would be greatly appreciated.
 
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