Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor

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Screen backlight goes out randomly.

I bought a 2011 iMac used knowing that there was a problem with it "shutting off at random times" and I thought I could simply replace the power supply. After receiving the computer I noticed that the only thing that's shutting off was the backlight because I could shine a flashlight at the screen and the computer was working fine. I then replaced the led backlight control board, but the problem persists. Now all i can think to do is replace the lcd itself, but I can't figure out what part would be compatible. Would a screen listed from a 2009 or 2010 iMac of the same size also work? In addition I don't know if there is a better place to buy the parts than eBay. Thanks for any help you can give:)

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What does an external monitor do?

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External monitor always worked fine, as did the iMac screen itself (if you aimed a bright light at it at the right angle you could see the screen was on and working, it just wasn't lit).

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Update: nothing I tried fixed the problem, and then the graphics card went out completely. After putting it in storage for months I finally decided to try a new graphics card (or rather a used one from eBay, but new to me) and it worked... perfectly... and four months later still haven't had any issues. For many this may have other causes but in my case it appears to have been a faulty graphics card. By now I have a closet full of iMac parts I tried to fix it with, but at least it works now.

Hope this helps, and good luck :)

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For others with this issue: it may be worth trying to replace the LED backlight board first, as it appears to solve the issue for some and is much easier and less expensive to replace. If that doesn't work, its probably the graphics card. I was able to buy a parts computer on eBay for less than the selling price of a replacement graphics card. Also, you can list the faulty one online (as faulty) and someone will pay a lot more than you'd expect for it, they have ways of fixing them. I literally paid less for the parts computer than what some guy paid for my broken graphics card, so I've made money, which seems crazy.

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Most Helpful Answer

I've resolved my issue by replacing the LED BackLight board (cost me about 45 EUR via AliExpress).

Got it fixed within hour by following iFixIt tutorial. Was quite easy to do, just take your time. If i need to do it again i could do it within 15 minutes... :-)

Display hasn't failed once since i replaced it!

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I've the same problem and just ordered a replacement backlight board. I'll let you know if it fixs the problem on my iMac!

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Hi Melissa,

Did you got it fixed? Or still waiting for package from China?

Gr,

Dennis

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Hi,

Yes I changed the backlight board and it fixed the problem !! Yeaaah ;)

30$ + 30min of work... totally worth it !

Mathias (took the wrong account last time)

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Hi Mathias,

Great to hear :)

Dennis

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Hi Dennis,

I have the same issue and am sitting here with my iMac pulled apart and my new and old LED board side by side - guess what - the sync connector is different?!?!

You mentioned AliExpress - do you recall what you searched for to find yours? did it have any similar issues?

Thanks

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See if Apple will replace the board, do not mention that you changed the back light board. I know the LEDs do not show this but experience says this is the problem: https://support.apple.com/en-us/HT203787

Due to high demand Apple has extended this period of time in a lot of cases, mention the term, "Warranty Exception".

The last four characters of the serial number must contain one of the following groups (for example, xxxxxxxxDHJQ):

DHJQ, DHJW, DL8Q, DNGH, DNJ9, or DMW8

DPM1, DPM2, DPNV, DNY0, DRVP, DY6F, F610

If the iMac falls within one of the above the serial number categories and is confirmed to have the graphics card issues, Apple will replace the AMD card free of charge up to three years from the computer’s purchase date. Additionally, if an affected iMac user had their graphics card already replaced at cost, the customer is said to be eligible for a refund.

http://9to5mac.com/2013/08/16/apple-open...

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My iMac had already had the graphics card replaced a few years ago by apple under warranty and by now is far outside the three year period. The graphics card did end up being the issue though, and I was able to find one fairly inexpensively online and replace it myself.

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I bought an used iMac with this problem for a good price to solve the problem, just like you. I got it temporary worked around, maybe you can try it.

Unplugging the power for a while and putting display brightness to lowest seem to have worked around the problem for a while.

I think the built in power adapter or backlight board is the issue. These are both always powered when plugged in.

This week this workaround didn't work anymore and I'll replace both. I'll let you know what the culprit was.

If you have it resolved before me please let me know what you did.

Dennis van der Pool

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I have been continuing to use mine with the problem. It only goes out on rare occasions, and usually comes back on when I restart the computer. Sometimes it won't, and then usually when I come back to it later in the day it starts working again. I have replaced both the backlight board and the power adapter. Neither seemed to make any difference. From the research I have done, it sounds like this is most likely a problem with the display itself. I haven't wanted to purchase a new display so i've been using it as-is. I hope this helps and if you have any luck with replacing either part or fix it some other way please update me.

Good luck:)

Michael

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i have a same problem - iMac 27" (Mid 2011) 8Gb RAM - HD Seagate Barracuda 3TB (upgrade).

· Some persons make sure that it owes to itself bad RAM or RAM bad SLOTS.

· Others make sure that it is the videocard AMD Radeon HD 6970M, (Apple replaces them still in teams out of guarantee).

· Others suspect in the HardDrives (SMART Issues), also the substitutions of HD`s originals and the matter of the sensors and noisy fans and overheath.

· You were suspecting in the LCD's and the Backlights.

·Others also have accused the PowerSources.

It had never had so many suspects for only one problem and apparently nobody has found a probable answer.

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I have the same issue, took it to the genius bar and they told my mac didn't qualify for the replacing program cuz it has 5 years from the purchase date and theprogram only covers 4 years, this is bulsh! Gonna try with the backlight board.

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I've the same problem... like many, many others on the Apple Support Communities.

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Michael Ginther will be eternally grateful.
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