27' iMac (2011) Screen turns off

I have confirmed that the LCD panel still works by shining a work light on the screen. Only the backlight turns off.

johnny10k wrote:

Thanks

I found another thread (this issue is far too common) where someone had some success by disabling bluetooth devices.

There are definitely several different problems that manifest into a black screen (logic board, graphics card, led, memory, etc). Bluetooth seems like a stretch, but I've seen stranger. I'll post my results back on here.

I asume you are following that threads, could you, please link them. I think it can help other users to check quick other related threats.

Thanks in advance

I I am too with black screen as well in an imac mid 2011, 27inch. But sometimes problem makes worst cause it becomes to a hard shut off. So, loosing all job done unsaved.

As well I will share everything I discover.

HI all. at least its comforting to see that were all in this together. i think its s software issue that apple will (hopefully) deal with. mine is a mid 2011 imac with upgraded processor and RAM. screen goes black within a few minutes mostly. i replaced the backlight at the apple store in slc ut. 2 days after i got ot home it went black again. i was assigned a senior apple care service manager. shes been very nice and communicative, but still no fix here. i took it to my local appl authorized servicelace, simply mac in jackson wyoming. ( no apple stores within hundreds of miles.). the tech at simply mac ran bench tests for 3 days, and the screen never went out for him! he thought pram reset fixed everything. of course like clockwork i got it home, turned it on, opened a safari window amd bam within about 2 minutes black screen. i took it back to hiim, and hes running tests again. he suggested 'dirty power' at my house. im thinking it may be tied to weak BT keyboard/trackpad batteries? anyway my assigned service tech hasnt been able to suggest anything better. i cannot in good conscience replace the display, because i truly think this is a software thing. at the end of the day, i am up the creek with no paddle

Problem with v-Sync cable. You must open imac and disconnect it. After, black screen problem is will be gone!

Hi guys!

Been having exactly the same problem in the last couple of weeks, mine is a 2010 27' imac.

I started using the HDD Fan Control app today. I set the Preferences as follows:

45 ºC (113 ºF) as the temperature that Fan Speed starts to increase. 49 ºC (121 ºF) when it hits the maximum.

So far the screen only went black once. It's been 4 hours since I started using it. Before that it went black like 10 times during the afternoon.

Hope this helps!

Well I have almost had enough of this screen turning off on my 27" Imac, i have tried a lot of things to stop it from happening. I contacted Apple four time to no avail, they seemed like they hadn't heard of it before.

Today I downloaded OnyX software and ran it through all the 5 or six scans and fix & repair scans, it maybe early in the piece to say it's fixed, but I have run it, restarted the computer and watched video's from youtube, been on my website, Facebook, etc etc, all with the volume going too, and it's looking like the diagnosis repair software has stopped the screen from turning off. I will report back tomorrow with the verdict. I ran the maintenance first then the OnyX next.

Looking good guys, I hope it works for you all.

Regards Hamish

Sorry go to go this computer has been doing this for the last three weeks so much to do.

http://www.titanium.free.fr/onyx.html

I Think this software has solved it, now Day 2 computer running as one would expect excellent its 's longer a sea anchor.

Cheers Hamish

Well said Lex. I have the same problem with my mid 2011 27" and can't seem to fix it. Apple were totally useless - if only they would come out with the truth so we could all move on, but maybe they don't know.

I've had this problem too! iMac 27", maxed out model from 2011. I installed some upgrades myself like a new HDD, and an SSD underneath the optical drive. I was worried that I had damaged something when going in but I guess it's a common problem!

I run both Windows and OSX on my machine. Because of the HDD I installed myself, I also installed Macs Fan Control, this was all in 2013. Since then I've had the fans kick in much earlier than Apple's own fan control for a cooler-running system. So in my case I don't think it's temperature related. (in Windows the fans kick in at 40 degrees C, on OSX its 50 and both "go black" at a similar frequency)

My solution:

Windows: I'm using NIRCMD.exe, this turns the LCD off. I've attached this to a keyboard shortcut (CTRL+Shift+Caps). If the display goes black I press those keys, move the mouse, and it's back on. If it happens rapidly, say every 5 seconds, I'll cycle the brightness of the display from brightest to darkest. INTERESTINGLY (I think!) the backlight goes off when this cycle is going down at about 33%.

OSX: I've set up a hot corner to turn the display off. It's not as fast as the Windows solution but it works.

Additionally the backlight never goes off when it's operating below 33% brightness. Even if I keep getting black out after black out, a dull brightness fixes it. Leaving it dark for a bit, or doing that brightness cycle, always fixes it for me. The cycle sometimes takes a few attempts though but once it's back I'll get at least an hour out of it.

my screen starting turning off recently. At first, i thought it was caused by a game i was playing, but then it happened again, then the problem got worse. Now the screen turns off like 30 minutes after i opened up the computer. After that, the screen turns off like every few minutes. I use a short cut for sleep mode in order to turn the screen on again. I also set sleep mode as a hot corner. I tried alot of things mentioned on these forums. Ive learned that this problem is caused by the computer heating up, and the brightness being set at 100%. It seems as if i am able to avoid the screen turning off for now by turning the brightness to 0. My computer is a iMac 27-inch, Mid 2010 model. Luckily, my computer has worked perfectly for 6 and a half years. Im assuming this problem is caused by my computer getting old and being on for too long. It would be great if there were a more easier solution to fix this problem. But If i cant solve this problem, then im just going to get a new computer.

Hi All, yep i got the same problem 2012 IMAC last year had a problem of a WHITE Screen was out of my 3yr warranty by 4 weeks and after some hard pushing to get it fixed Apple came to its senses and they paid for a new VIDEO CARD

Now exactly one year later, another problem just out of warranty again by 3 weeks, the IMAC boots up normally and after 10mins it heats up to over 40 degrees and then the screens goes BLACK. You cant do anything more other than shut it down.

Booked with Apple genius next Wed... gotta see what they have to say. If more money required THEN better go back and buy a WINDOWS machine

Went to Apple on the weekend, they said these issues are not common......lol...I said read the blogs............... anyway told me now that it is a Backlight' issue and the only thing u can do is to replace it at a cost of $217.

The problem did not occur at the time I was there. I went home with it and turned it on again and boom.....the problem occurred.

So then I had make another appointment even though we knew what the problem is. Went to a different apple location because no appointments available at the previous apple location, Another kick in the teeth and further pain encountered is that they could not replace it on the spot, so I had to leave the IMAC with them to repair. Come on Apple, what kind of customer experience is this!

'DIRTY POWER' might be the answer for at least some of us. After much frustration, I seem to have found the solution for my 27 inch 2011 iMac - a faulty power outlet at my home.

For 2-3 years now I've been having these same problems with my screen going blank (but running in the background). Sometimes okay for a few hours or even a day but lately so frequent I couldn't even shut it down to restart it. I've tried a number of different things and visited lots of forums but nothing has really resolved the issues.

I recently took it in to a highly recommended (by a Mac expert mate) apple authorised service centre near me and they ran all sorts of stress tests and diagnostics and were not able to fault it or find any sign of the problem. They had it for a few days, suggested it might need a new logic board and/or power supply but advised it might not be worth doing given its age. I brought it home, set it up and turned it on with a hopeful but sinking heart and within less than 5 minutes the screen had gone blank. So, on a hunch (must be/maybe it's the environment?) I moved it to a different power outlet and lo and behold... I haven't had a problem since - two weeks now. It's running as smoothly as it ever has.

p.s. for a description of dirty power: http://www.tesengineering.com/electrical-engineering-what-is-dirty-power/

I saw your conversation about 'dirty power' and had been using 5 outlets of an eight outlet power board. I switched to using another single use power point; this cured the problem of an extremely slow start-up for an iMac.

However, I had also:

(1) deleted 2 years of accumulated downloads (either stored separately or no longer of use) and

(2)installed a surge protector on the single use power point.

My iMac is now faster than it has ever been since new in 2012.

jardall