Currently Being ModeratedApr 15, 2013 8:29 AM (in response to mebyard)
I also have the exact same problem. It's going to be a 3rd visit to the repair shop in 2 weeks. Mid-2010 27" Imac, still on Apple care till 2014, fortunately.
At first, a year ago, half of the screen went dark (still visible). The shop changed the LCD screen and everything was fine for 11 months.
This year, the screen started going dark every two minutes, while the hard drive is still running. Came in a first time, they could not reproduce the problem. Finally, the screen just did not turn on anymore. In fact, video was visible, but no backlight. At which point they changed the LED Backlight Board. They test stressed it for 4 hours (involving I don't know what) and said it was fine.
We brought the computer home and now, we're back with the same problem: the screen turning off every few minutes or so...
So far then, we have an almost new LCD display and a new LED Backlight Board. What else is there that we could change, I'm asking? And at which point is Apple going to do something about this?
Bringing this massive computer every 3 days to the repair store has me asking a lot of questions about Apple products too...
Anyway, hope this info can also be of some help for others. I'll call Apple now and keep you posted.
Currently Being ModeratedMay 4, 2013 1:06 AM (in response to Ashadur)
I have the same problem with my mid-2011 27" Imac.
Resetting the SMC and PRAM worked only once. But I think it was more luck than anything...
I had to work this week with an external screen.
It also take ages before the gray screen is visible on my external screen, but my harddisk seems working fine. The screen is totally black, it is not just the backlight.
However this morning the 27inch screen popped up again. But I have a carepack, so I definitely make use of the warranty.
Currently Being ModeratedMay 13, 2013 5:28 PM (in response to mebyard)
I never had this problem until I installed 10.8. When I start the computer with the shift key down the computer boots up and works fine. In the old days that was a way to not load all the extentions and I am guessing it works the same now as I can not do everything I need , but the monitor stays on fine. Some part of the software in 10.8 is causing this. Apple needs to figure out what.
Currently Being ModeratedMay 16, 2013 4:33 AM (in response to rbtech)
I have a 27' iMac (2011) that is 18 months old (so not covered by the warranty) and my troubles started with some light flickering on the screen (left side). Then the left side of the screen became much darker than the right side, with flickering still present.
Since yesterday, the screen is turning itself off in an apparently random fashion. All these issues appear to be related to the same screen problem.
I would have ZERO qualms about paying this, except for the fact that this is not an isolated case, but a KNOWN ISSUE for the 27-inch iMac. In fact, when I google "27 iMac known issue", the very first item to show up is this:
Like I said, any product can turn out to be a lemon and I would have assumed my responsibility for not purchasing an Applecare extended warranty. But the fact is that this has been identified conclusively as a defective connection to the LG screen, which a lot of people are simply "re-soldering" themselves with perfect results.
All the information is contained in the following thread:
There is a LARGE number of people complaining of the same exact issue.
Apple has built its well-deserved reputation on doing right by its customers and admitting its mistakes in the past. I don't understand how this known issue is not treated with the same standard as its Hard Drive Replacement Program.
I hope Apple will reconsider. I am lifelong Apple fan and user, and this is the first time I am truly disappointed with the quality of one of their products...
Currently Being ModeratedMay 17, 2013 6:56 PM (in response to Ashadur)
Right, same issue on my iMac 27". I have Apple Care on it, will look into it this week.
I also run a second screen, so I have moved the screen prefs pane there so I can set brightness if I do get black-out. Finally, switched of the Automatic brightness adjust, testing that now. Adjusted manually to what I find comfortable under current office lighting. Office controlled temperatire at 20˚C.
System Version: OS X 10.8.3 (12D78)
Kernel Version: Darwin 12.3.0
Model Name: iMac
Model Identifier: iMac12,2
Processor Name: Intel Core i5
Processor Speed: 3.1 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 8 GB
Boot ROM Version: IM121.0047.B1F
SMC Version (system): 1.72f1
iStatMenus report all temperatures in range, GPU running rather hot at just over 71˚C
After 28 minutes running screen suddenly dimmed visibly.
Will report on that as a solution soon.
Currently Being ModeratedMay 21, 2013 7:19 AM (in response to Ashadur)
Hello All on this late-2011 iMac "Video Blackout" thread: I've got news that should be of interest to all affected.
I haven't posted in a while, but I've been watching. As we ALL know—those of us WITHOUT AppleCare and those WITH AppleCare—this issue is not a random component failure issue. It is either 1) an engineering or 2) a combined engineering & software issue. Unfortunately, for those of us WITHOUT AppleCare there isn't a good way to approach the company with the problem. The only way to broach the issue with Apple is to take the affected iMac into an Apple Store and let them start talking MONEY for repair (usually replacing the LCD backlight system to the tune of about $800-900 US).
My solution to the problem was equally expensive. Because I use my iMac professionally and semi-professionally, I had no recourse but to purchase the newest Late-2012 iMac. I am happy to report IT is working fine. But this expensive move freed me to experiment more radically with my late-2011 "black out prone" 27" iMac.
My first experiment (now in progress) was to return the iMac to it's original operating system - Mac OS 10.6 (Snow Leopard). Since most users started experiencing the video blackout problem AFTER an OS upgrade to Lion or Mt. Lion (mine started on Sept 4, 2012, soon after I upgraded to Mt. Lion), I wanted to see if the problem could be elimated by returning to the machine's original OS: Mac OS 10.6 Snow Leopard.
So... 1 week ago I inserted the orignal image DVD (that came with the machine), repartitioned the drive and installed a pristine Snow Leopard image, did all the software updates from Apple (bringing the OS up to 10.6.8), and reinstalled all original applications. As for OS and software, the machine was like it came out of the box.
Now, one week later, with the display running full brightness, and often used... the DISPLAY HAS NOT BLACKED OUT! As I said, this experiment is on-going. BUT, when this data point is added to the fact that most of us had the problem start AFTER we upgraded to Lion or Mt. Lion, it would seem that these new operating systems are negatively impacting the Late-2011 27" iMac's video hardware. I could personally put forth several hypotheses as to the "Why?", but the bottom line is that this is most surely a design issue and not random component failure.
So, one work-around for those of us without AppleCare, is to backup, wipe, and reload the original Mac OS 10.6 OS. Of course, this means you have to forget iCloud and the neat new features introduced in Lion and Mt. Lion. But, as of right now anyway, it seems that this will at least return your Late-2011 27" iMac to it's original functionality.
No, it's not the ideal solution that we all want (an Apple recall to fix the problem), but it may be better than spending half-the-price of a new iMac on a repair that you should not have to pay for in the first place.
I'll keep you all posted on the progress of this current experiment.
Ponca City, OK USA
Currently Being ModeratedMay 31, 2013 8:22 PM (in response to Ashadur)
Hey everyone. I too have been having this problem for about 8 months with a 2011 27inch Imac. Let me lay out what I have found out so far. I am out of warranty, do not have apple care, using 10.6.8 and never updated to Lion. With 2nd monitor attached computer works fine just no main display. Here are some important notes. I brought the computer in 3 times to the genius bar in Long Island NY. They were very nice, ran diagnostics, took the computer in the back and ran stress tests on it for 3 days. Screen didn't black out once and they were convinced it was something else I had connected to the computer that they couldn't duplicate. We wiped the OS 2x, still no luck.
This is where it get's interesting. I have another IMAC in the same studio, from the same time frame and luckily no problem. So the whole heat in the room, temperature thing is not playing into it. I brought the computer back from the apple store and turned it back on without any extra devices and the screen went black in about 5 hours. I really believed this was a power issue and realized, when they took my computer they did not take my power cable. My other IMAC that does not have problems is using an APC UPS Backup. This is where I will begin to test that I have not read about anywhere on the thread. I believe if the power coming to the computer is inconsistent it may cause the screen to turn off as protection since it pulls the most power. Tomorrow I will be buying the APC for the problem IMAC and see if it changes anything, if not I will then replace the power chord. Not sure this is right but since I have not read about anyone else trying this, I will and let you know how it turns out. I'm curious if anyone else is using a power conditioner or backup with their system.
The Apple store is close to me and they have been very receptive and have not charged me for any of the tests or time yet. I will try and bring this thread to their attention, not sure it will mean anything but it's worth a shot. I will report back with power results.
Currently Being ModeratedJun 5, 2013 5:55 AM (in response to mebyard)
Thanks Marc to keep this thread up and all the others for their contributions.
I have the same problem on My Imac 27" 2011since one week.
This Imac is a remplacement of an other Imac 27" 2009 who have the screen dust and DVD player failure hopefully under warranty. I was happy to bought 3 years warranty at this moment, but this one is finish for the new one...
So in 3 years 3 problems, on 2 imacs (1800 euros each)...
After reading all this thread we can admit that there's a major problem.
I hope we could find a alternate solution, i wait for your feedback Mark on the missing blackout with a old system version (because pullny has the problem with the 10.6.8), keep us inform please
Currently Being ModeratedJun 5, 2013 7:05 AM (in response to Ashadur)
I had the same problem and took my iMac to a premium apple service provider for repair (care pack).
I've got a new LCD panel 27 inch with BLC since yesterday.
I'm still using 10.8.3 at this moment.
I reply to this thread if the problem occurs again.
Currently Being ModeratedJun 5, 2013 7:22 AM (in response to Ashadur)
So, after a THIRD trip to the repair shop, we brought the Imac home. After 2 hours of use, the screen started going off and on and then just stopped working.
They changed yet again the display AND the backlight controller. The tech at the store told me he thought the problem would be from the motherboard, concerning the signal that is sent to the backlight controller, but that he didn't have the tools or the expertise to properly act on that assumption. He asked that I called Apple, which I did.
Fortunately, service at Applecare was prompt in helping us get a replacement machine. So we threw the towel, brought the computer to the UPS store and are now waiting for a new Imac 27", hoping we don't encounter some other kind of problems... On and off, we haven't had a working Imac for 4-5 months now...
In any case, one thing apparently had SOME kind of effect on the frequency with which the screen turned itself black and it was to unplug the computer from our power bar and plug in into the wall directly. We've read somewhere that the power fluctuations might somehow disrupt the backlight and it worked to a certain degree. We got longer period of functionality when we did that. But the screen still toggled on and off sometimes, but not off completely for a few hours... Now, I don't know for sure if the issue is power related, but thought this might help some who don't have Apple Care.
Good luck to all of you with the same problem. I'm just happy I didn't get hernia carrying that computer so many times to the store. At least, the new Imac should be lighter...
Currently Being ModeratedJun 23, 2013 7:34 AM (in response to Kokoglace)
Same problem as everyone else on my mid 2011 27 inch. I do not believe it is a heat issue. I've had it happen under heavy loads (civ 5) and light loads. I've gone weeks in between incidents and I've had it switch on and off multiple times an hour. This is my second iMac to require an expensive out of warranty repair. I am very frustrated and will likely never buy an iMac again. At the least, an iMac requires apple care.
Has anyone had the blackouts when using the iMac as an external monitor to another computer? My backup plan is to live with this until the next Mac mini update and hook it to the iMac as the monitor.
Currently Being ModeratedJul 8, 2013 3:30 AM (in response to Ashadur)
Just a follow-up on my issue: about a month ago the screen would start shutting off, or at least I thought so. Kaos2K suggested I shine a flashlight onto the screen to see if I could make out any icons and, sure enough, they were visible. So it's a backlight issue.
This started happening so often that I could not use the computer. At one point I tried to lower the screen brightness to minimum and it has made a big difference. No more "blackouts" for now. As soon as I tried to raise the brightness a little, it started blacking out again...
So now I'm using the iMac at minimum brightness and my world is dark and gloomy...
On the plus side, you can't notice the dark left side of the screen now because everything is dark
I wish Apple would help us out here... Any official reps in the forums?
Currently Being ModeratedJul 9, 2013 7:56 AM (in response to Ashadur)
Same issue after upgrading to Mountain Lion. Backlight turns off randomly but external monitor is still working.
No Apple Care but I found out I was covered with software support because I'd just purchased Mountain Lion.
The lady told me there was no record of anyone else with this issue. Hmmm why has this thread had 10,000 views? It has to be a design fault, I feel ripped off.
Think it will be cheaper to get a cinema display to plug in then get this one fixed.
Currently Being ModeratedJul 14, 2013 11:16 AM (in response to Ashadur)
Having same issues here. I have a 27", Mid 2011, running Lion 10.7.4. Haven't done any updates since original purchase a year ago. Yes, a year ago, so I'm out of warranty and kicking myself for not taking care of it before it was too late. When it first started it would randomly black out a few times a day for just a few days and then behave for a long time. I guess that's why I let it slide so long. But of course, now that the warranty has expired, it's constant. I've been looking for tips and suggestions and have found these threads very helpful. I can use shift+control+eject to get it to come back on but sometimes not even long enough to log back in. I followed a tip of running very dim and found that my mac's sweet spot is at #2 brightness which isn't bright at all and gives me a headache from being so dark. So, then I tried the fan control app (smcFanControl) that has worked for others. It did not work for me. So, I've just tried turning my brightness all the way up as suggested by someone else...and so far so good! I'm far, far, far from tech savvy but that makes no sense to me. But since I can't afford a repair or a new computer, I'll take really bright over grey and gloomy.
Currently Being ModeratedJul 19, 2013 4:42 AM (in response to Ashadur)
I have taken it to a local shop to try to get it repaired. The guy tried but no luck. The screen has gotten to the point where it's unusable
I don't want to shell out the money for a new screen (which is what Apple seems to be suggesting through this thread). Now thinking whether to get a used external display instead, like Mirkin23 said.
Do you know if I can use other brands or only Apple? At this point I'm seriously nauseated by the idea of giving more money to Apple... It feels like the end of a beautiful love story
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