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Other Hardware and Peripherals Other Apple systems and peripherals discussion.

27" LED Cinema Display - Power Supply Issue?


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parasbuy

 
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hey guys... I have a 2010 Mac Pro w/ 27" LED Cinema Display where it seems the power is going out intermittently. The display was making a white noise "shhhhh" sound for the last couple of days; including after I shut down the CPU, the display was continuing to make this noise. So I pulled out the plug and reinstalled it after some time, and nothing... no display, no sound, no shhhhh, and my iphone connected to the USB port was not being charged. Leaning over the CPU, I hit something (maybe the desk, maybe the cables?) but the display came on.

Having only one display, switching out is not really an option here. I'm ready to open the display up and the question is if you guys agree that it's probably the power supply board that needs to be replaced, or if it's something else that I don't know about. It seems clear that it is not the Logic Board, and I don't think it's the Mini-Display card on the CPU. It could be a cable, of course, but I'll switch out the cables just in case. Anything else I should think about? Anybody know of an IC or a cap on the supply board that has been particularly problematic?

Thanks.
Paras.
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Mine was the cable with a lot of the same symptoms. I had mine replaced by Apple and it was around $100. The power supply and logic board are fairly inexpensive as well. I had too much invested to scrap the monitor so I chose to go to Apple.

From what I could gather from the Genius, the cable failure is pretty high. He told me that he saw many more cable issues vs. Logic board and power supply issues.

All of the parts can be purchased on various online sites if you choose self service over Apple. You can also get instruction from the iFixIt website.

Good Luck!

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parasbuy

 
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Great... thanks, JohnCL!

Do you remember which cable it was... was it the DC Power Supply Cable (922-9354)? See attached.

Thanks a lot.
Paras.
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File Type: pdf led_cinema_display_27-exploded.pdf (459.2 KB, 4 views)
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My issue was the all in one cable (922-9362)

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Are we discussing the Mac Pro as stated or a MacBook Pro by chance? First up suggest removing gfx card and cable/s and re-seating if indeed a Mac Pro and a flashed PC or Mac card?

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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parasbuy

 
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Thanks... yes, it's a Mac Pro, not MBP.
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Happy New Year All.... I ended up replacing the all-in-one cable on the Cinema Display and this definitely helped. The display does not go out blank intermittently anymore and works as expected.

However, I still have an incessant white noise problem emanating from the display. The white noise gets louder with increased brightness and doesn't completely go away even if the brightness is reduced to the lowest setting.

Unless I'm wrong, it looks like this display does not have a separate backlight inverter board. So I'm thinking it could be an LED cable, Logic Board, or Power Supply Board. Any other suggestions? Is there a way I can triangulate down further?

Thank you.
Paras.
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Try removing the Mac Pro's graphics card, cleaning and reseating firmly. Bit of a nuisance those double connectors to the logic board.

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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parasbuy

 
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done. re-sat the graphics card... no change.

I also noticed that when the computer and display are off, and a peripheral like an iPhone is connected to the USB port on the back of the display, I also get the static white noise emanating from the display. If the iPhone is not connected, everything is silent.

Thanks.
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I would lean toward a failing power supply, or some kind of grounding issue. These kinds of things are tough to diagnose and throwing money at them for parts is not always the best answer. Do you have an Apple store nearby that you can go to for diagnosis? Maybe they have seen this before.

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Yes... but I don't have AppleCare, so I"m trying to do this myself.

I think so too, but the power supply board and logic board were replace a couple of years ago; I suppose they could be bad again.
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Quote:
Originally Posted by parasbuy View Post
Yes... but I don't have AppleCare, so I"m trying to do this myself.

I think so too, but the power supply board and logic board were replace a couple of years ago; I suppose they could be bad again.
I understand. Even without AppleCare a true Apple store will diagnose for free. They can hopefully tell you what is wrong with it to steer you in the right direction for repair.

Remember, it has to be an Apple store, not an authorized repair center. I have seen a lot of people go to authorized centers expecting free diagnosis and then getting a bill

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parasbuy

 
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OK, will do. Thanks.
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OK... the Genius Bar guys were able to reproduce the problem that the volume of the white noise increases with increased brightness. This would mean that the LCD Panel Part #661-5542 would need to be replaced at a cost of $800. The Genius did say that in his opinion it was very probably the LED Driver or the LED Driver Cable inside the LCD Panel; however, Apple would only be able to replace the entire LCD Panel, not just the LED Driver and/or cable. He also said that he did not think it was the Power Supply board because the way that the LCD Panel is connected to the Power Supply board would cause the display to go on/off completely, but not give the white noise problem that we are seeing... he would not elaborate further. He also pretty confident that the Logic Board was fine, as well.

Any thoughts one how I could find the manufacturer of the LCD Panel or obtain just the LED Driver/Cable and replace it? Any insights on the Power Supply Board connection to the LCD Panel?

Thanks!
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OK.. I think I was able to figure out that the LCD Panel is made by LG Semicon LM270WQ1(SD)(B1):

The Apple model # for this item is : 661-5542, LM270WQ1(SD)(B1)
Compatible Apple Model #'s for this item are : A1316, MC007LL/A

and that the LCD Controller Board for LM270WQ1-SDB1 is available on EBay for $89.99:

LCD Controller Board for LM270WQ1-SDB1

This board works with the FI-X30SSL-HL 30-pin cable that is used on the LM270WQ1-SDB1

Can anyone confirm or deny any of these? Should I be able to drop in this LCD Controller Board and be good to go?

Thanks.
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