27' iMac (2011) Screen turns off

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.

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.

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 😝

Thanks for the brightness tip, mine was turning off every 2 minutes and now it's just a flicker now and again. Not ideal, there should definately be a product recall but your tip really helped.

Welcome to the club I could say to myself...

I have a 27" iMAC from Mid 2010 with the same problem.

I have read all the posts and so much for my patient. It is in a relatively cool office, it still runs Lion 10.7.5 and has never been upgraded to 10.8. I hardly believe it has to do with power supply because the problem seems to come from all over the place. i.e. USA with 110V/60Hz and Europe with 220V/50Hz.

My black screen is so bad now that the iMAC stays on for hardly longer than a few minutes after startup. I put the brightness down to minimum and this works but the problem is still there. Interrestingly does the Safe Mode not change anything.

I would like to reinstall the OS with Bootcamp and using windows7. Wonder if that changes anything.

I am still convinced that this is a software problem because the Screen works fine... if it works.

N.B: I just saw the video on Youtube. My iMAC does not seem to have the problem with backlit. It goes pitchblack as if the monitor is turned off. It does not come cack either. I tried the "Shift+CTRL+Eject" and the screen comes back for a few seconds. The only way to get it back is "REBOOT".

Hi,

I have a late 2009 27in iMac. Apple did the Samsung 1 TB harddisk replacement, but since then I have the problem that the monitor keeps going to sleep. It can be every 2 minutes, or it can be 3 days till it happens, but happen it will.

The Mac is running, I can see the desktop dimly when I shine a light on it, and by making the bottom right corner activate the screen saver I can get it back to working by moving the mouse to the bottom right corner and out again, thereby activating and deactivating the screen saver.

The problem doesn't seem to be temperature related. After reading

http://blog.macsales.com/16878-imac-hard-drive-upgradeability-expanded/comment-p age-1#comment-63865

I wonder if Apple put a "not completely compatible" drive in …

Mid 2011 iMac 27" with extra display memory, etc, same problem with screen going blank.

Work-around was to set a screen save hot corner bottom right. This worked well enough so I could get work done. I have Apple care, but not sure all the replacements will sort it out. So phoned Apple support and after a good technical and friendly discussion I was asked to reset PRAM according to this link:

support.apple.com/kb/ht1379

This has solved it for me for now.

Henk

I applied resetting the NVRAM as suggested in http://support.apple.com/kb/ht1379 two days ago.

I decided then to re-set the brightness to a normal level as I was using the only trick that have worked so far which is to set the brightness to the max level.

As a consequence, I just got a blank screen again this evening.

So I conclude resetting the NVRAM does not solve the problem and does not even improve the situation.

Back to a very bright screen...

I need some sunscreen and sun glasses! (^^,)

Pascal

Thanks for that feedback Pascal. Will go check my machine when I'm back at office to see if brightness setting changes induce the problem for me.

Just a note: It took me two tries to actually reset the PRAM using my wireless keyboard. On the first try It did not work and I checked procedure carefully before getting it right using a USB keyboard.

Henk

Note: make sure you actually reset PRAM. You know it worked when you are asked to set some core system parameters after the procedure.

It is possible with wireless keyboard from Apple, but try and use a USB one for this exercise.

Keen to hear if this works for someone, or if my one was a once-off.

Henk

Henk,

I only have a Bluetooth keyboard but I can to borrow one...

When I held [Command (⌘)] + [Option] + [P] + [R] while cold booting the PC, the behavior was as described in step 5.

The computer restarted once again and I heard the startup sound for the second time.

Then I was not asked to reset parameters such as speaker volume, screen resolution, startup disk selection, and time zone information as described in the procedure.

I double checked those just in case and I actually had to reset the time zone that was changed from Central Europe (I live near Paris) to one of the American ones.

My speaker volume, screen resolution were set to the max values anyway and I only have on disk.

So I thought it all worked. Maybe not...

I'll try it again with a USB keyboard and I'll get back to you.

On your side how long has it been working since you did reset NVRAM/PRAM?

Pascal

Add me to the list. Mid-2010 iMac 27" still under AppleCare.

I have had 32gb of Crucial RAM in it since I purchased it. (Upgraded immediately)

I've had nothing but problems with this iMac. Ever since Lion, I had WiFi dropping issues that never really got resolved. They are better in Mountain Lion, and much more tolerable... but not perfect like my other apple products.

The screen blackout is happening more and more over past month. Now I feel like I've spent more time trouble shooting this machine than it's worth... which is frustrating when you buy a top of the line machine at the time of purchase.

Anyway, hope this info helps someone:

HACK FIX (Not ideal, but makes it more manageable):

After 3 calls with Applecare and a trip to Apple Store genius bar, still not fixed. I actually "RE-ENABLED" hot corner to make it a little bit more tolerable. (I previously deactivated hot corner to see if that was the issue)

When the display blacks out, which it does several times a day... usually 3-8 times in a row in a short period of time... I just drag my mouse to the corner and out of the corner and then the display wakes up. I also changed the setting so I didn't have to re-enter my password immediately on display wake up.

Here's what I've tried, with no success:

-Reset SMC (numerous times)

-Reset PRAM (numerous times)

-Adjusted Energy Saver settings

-Turned on Caffeine (screen blackout still occurs)

-Turned off FileVault -- allowed hard drive to decrypt

-Re-installed OSX Mountain Lion

-Ran Apple Hardware Test that came on DVD. (The first time, the screen would black out and not wake up. Waited for hours. The next day, I tried it again and everything passed).

-Avoided different programs.. but nothing consistently turns the screen off. e.g. at first I thought it was Chrome, so I switched to Safari.. same issues.

-Found reproducible logs on Console (see below). These also probably show that I'm waking up the screen with a hot corner.

Of note, the screen blackout is not true sleep mode:

-I can still "Share Screen" from my macbook to my iMac. If I am already sharing screen.. the macbook doesn't change at all.. but I can't wake up the screen on my iMac without the hot corner or SHIFT-CONTROL-MEDIA-EJECT (unresponsive to mouse, keyboard)

-If music is playing, it does not stop

-Pressing the power button in back puts the iMac into true sleep mode, then pushing it again in a few seconds wakes it up (including the screen)

Of course, the problem did not happen during my ~1 hour at Apple Store. Since decryption was going to take >1 day, I decided to take my iMac back hoping that decrypting and reinstalling would fix the issue. It didn't (I still haven't re-encrypted).

re: Heat -- I thought that was the issue too. Heat may or may not exacerbate it, but it definitely happens when the machine is cold or recently waken from a long sleep as well.

re: Logic board -- I've read lots of posts pointing to a problem with logic board.

re: Screen - I've also read lots of posts saying that replacing the screen can help, but doesn't always.

Here are some good links describing similar problems:

https://discussions.apple.com/thread/5118135?start=105&tstart=0

http://forums.macrumors.com/showthread.php?t=1234778

Console Logs that seem pretty reproducible:

8/7/13 4:50:17.109 PM WindowServer[89]: CGXSetWindowBackgroundBlurRadius: Invalid window 0xffffffff

8/7/13 4:50:17.109 PM loginwindow[41]: find_shared_window: WID -1

8/7/13 4:50:17.110 PM loginwindow[41]: CGSGetWindowTags: Invalid window 0xffffffff

8/7/13 4:50:17.110 PM loginwindow[41]: find_shared_window: WID -1

8/7/13 4:50:17.110 PM loginwindow[41]: CGSSetWindowTags: Invalid window 0xffffffff

8/7/13 4:50:17.276 PM WindowServer[89]: Created shield window 0x3a6 for display 0x042735c0

8/7/13 4:50:17.280 PM WindowServer[89]: device_generate_desktop_screenshot: authw 0x7f82b96471b0(2000), shield 0x7f82b8637990(2001)

8/7/13 4:50:17.360 PM WindowServer[89]: device_generate_lock_screen_screenshot: authw 0x7f82b96471b0(2000), shield 0x7f82b8637990(2001)

8/7/13 4:50:18.245 PM WindowServer[89]: handle_will_sleep_auth_and_shield_windows: releasing authw 0x7f82b96471b0(2000), shield 0x7f82b8637990(2001), lock state 2

8/7/13 4:50:18.246 PM WindowServer[89]: handle_will_sleep_auth_and_shield_windows: errs 0x0, 0x0, 0x0

8/7/13 4:50:18.248 PM WindowServer[89]: Created shield window 0x3a7 for display 0x003f003d

8/7/13 4:50:18.248 PM WindowServer[89]: handle_will_sleep_auth_and_shield_windows: releasing authw 0x7f82b96471b0(2000), shield 0x7f82b8637990(2001), lock state 2

8/7/13 4:50:18.249 PM WindowServer[89]: handle_will_sleep_auth_and_shield_windows: errs 0x0, 0x0, 0x0

Pascal, my system is now working for about two weeks. I am in New Zealand on 220V supply via a UPS. I have extra screen RAM. I bought the high-end display card at the time and I am driving a second display via Thunderbolt. That display stays on even when the iMac blinked.

I checked temperature, workload running several Apple approved packages, worked wit a clean install of ML, and only the PRAM reset recently changed anything. I do see the screen doing a slight flicker every so often, but it does not go black. Checked working temperature, room is at 18°C all the time via aircon. It is not a heat issue as far as I can tell.

I wonder how many people here have that specific expanded display card with the extra RAM. Also had my HDD recalled and replaced.

One thing is clear, if this happens again I will ask for a replacement machine under NZ law. The machine is not working as intended, and given that I have Apple Care I have done my bit. It is not my job to fix or trouble shoot a product that was sold to me.

Will keep you posted

Henk

So, I did a time machine backup and then completely reinstalled a fresh copy of osx (deleted everything)... it is still blacking out. no temperature warnings... does not feel hot at all. I'm managing to catch it on video so hopefully that works at genius bar if it cant be reproduced there....

Not a software issue if a complete reinstall doesnt take care of it.

Henk,

I borrowed a USB keyboard yesterday and re-applied the procedure twice to make sure I did it right.

I didn't had to reset/restaure the settings but the computer behaved as described in the procedure (again).

I did this yesterday and guess what tonight, so less than 24hours after I've reset the PRAM/NVRAM and dimmed the screen, ...

...got a black one again!

It used to take much longer before and this time I barely used the computer between the time I reset it yesterday evening and the second time I used afterward tonight. I was myself surprised it happened again so quickly.

So I am back in "Sunlamp" mode... (^^,)

Thanks anyway for the trick. It might have worked for me too...

So far the only "trick" that worked for sure (for me) is to set the brightness to the max.

It is still better than a totally black screen. (^^,)

Pascal