27' iMac (2011) Screen turns off

I'm not sure what else to say; the Apple Store had it for two days, looked at it, and said the issue was the logic board, not the graphics card or the LCD.

Ok for no cost to yourself.

Lay the mac on a flat surface and keep it this way power off.

just remove the front glass, then 6 X screws from the lcd.

Lift the lcd out without disconnecting any cables and sit it onto of the mac 40mm above where it normally sits.

DO BE CAREFUL NOT TO LIFT TO HIGH AS THE CABLES ARE STILL CONNECTED UNDER SIDE.

look on I fix it for a tutorial with pics.

You can then power on and check the led status to tell you where the mac is at.

What is the serial number on your mac?

I can try get a few pics to show you how to remove the screen.

aboofhead wrote:

Ok for no cost to yourself.

Lay the mac on a flat surface and keep it this way power off.

just remove the front glass, then 6 X screws from the lcd.

Lift the lcd out without disconnecting any cables and sit it onto of the mac 40mm above where it normally sits.

DO BE CAREFUL NOT TO LIFT TO HIGH AS THE CABLES ARE STILL CONNECTED UNDER SIDE.

look on I fix it for a tutorial with pics.

You can then power on and check the led status to tell you where the mac is at.

What is the serial number on your mac?

I can try get a few pics to show you how to remove the screen.

I don't have the iMac anymore (sold it for parts) so I can't test it.

Hello,

Minor update on my side : the blackscreen happens repeatedly in a few seconds il the brigthness is set very low, but somewhat rarely when it is set at maximum. I just can't figure out the link between brigthness and logic board issues.

Daffodil

The issue is somehow connected to an auto brightness adjustment. Try turning it off.

How do you turn it off?

I can adjust the brightness but I didn't see where/how to set "auto brightness adjustement" in the System Preferences.

As I read it a while ago on this thread, one way to workaround this issue for some of us is to set the brightness to full max.

This is maybe what you mean.

Since I've forced the brightness to full max, I didn't get the issue anymore without having replaced/upgraded anything nor having brought the iMac to Apple. (27' iMac mid-2010 - OS X V10.9.2)

I couldn't be bothered trying anything else as I don't want to get stuck with no screen display anymore.

I've lived with my iMac/"Sun lamp" ever since hoping for the best. (^^,)

Hope this help...

Go to System Preferences - Displays - Automatically adjust brightness (checkbox) . I have been reading this forum for a wile and i think that its not a software problem. The problem occures when there is a brightness change - i have a windiws 8.1 on a bootcamp - same story. And i also think that its not a hardware fault in major, it might be a some sort of low level programing error in NVRAM.

Hello ! I already unchecked the brightness adjustment under windows 8.1, but the random screen shutdowns still happen (more rarely when at maximum brightness). For an unknown reason, the issue only appeared when I upgraded to Mavericks (I never had any problem with Lion or windows 8.1 before upgrading, but downgrading was useless) -> does the Maverick upgrade change anything to nvram programming that could not be undone by downgrading ?

Thx

Interesting. The screen on my 2009 27in iMac used to go black every few seconds. I have a "display sleep" hotspot in the lower right corner. So if it happens I go into the corner and back out again, wiggle the mouse, and the screen is back on.

Now what wasn't the interesting part.

Despite the hot corner it could go black every few seconds.However if after it comes back I set it to full brightness for a few seconds, then turn it back down, then it does not go black every few seconds. I can actually use the iMac for a few hours before it happens again. Hope that remains so.

I guess I'm the most recent guest at this party!

I bought a refurb 27" iMac (originally made in 2011) a year ago last January, and it has just begun blinking off in the past couple of weeks. I had been hard-rebooting it to get the display back. What I've noticed with mine is that the display dims for a period of time before it goes out. I'm updated to 10.9.6, and I have the auto brightness feature disabled.

After reading this depressing thread, it does seem to me like this is a big enough problem Apple should be taking care of it. It could be they don;t know what to do yet.

I have found the Shift-Control-Eject restores the screen the quickest.

I find that odd, given that that's supposed to be the keyboard shortcut for putting the display to sleep.

I think this is an O/S issue, because if it was an overheating issue, the display should shut down again after restoration, and it doesn't.

Just had this happen to me this morning. So far no luck getting the display running again.

I have to 27" iMacs (one mid 2011, the other late 2013) connected by a thunderbolt cable so I can use either as a second monitor for the other.

This morning just after I'd flicked the 2013 model to be the second monitor for the 2011, the 2011 gave a click and the screen wen black. The 2013 was still working as it's second desktop, so I knew it was still running.

The weird thing is that the 2011 will work as a second desktop for the 2013 now, but not as a primary desktop for itself.

Neither the ctrl-shift-eject or the cmd-opt-eject tips have worked for me. 😟

At least the second monitor allows me to continue working.😟

An update on my situation:

First, I believe this is a software issue.

I had dimmed my display brightness and got the SMC fan controller software (I still recommend having it). The combination seemed to lessen the frequency of incidence, but did not solve the problem.

One thing I hadn't done in a while is run Time Machine; my computer is away from my external hard drive at the moment, so I have to set it up to run a backup. I think this, plus no having enough RAM were somehow the cause of the problem.

I ran a backup, and my computer guy upgraded me from 4 to 12 GB of RAM. Now, I have the fan controller at the lowest setting, which restores the OS/X defaults, turned my brightness back up, and now it runs flawlessly. I apparently cleaned something out when I did the backup, and with no applications running, my RAM is running ~5.5GB.

So, my conclusion is, if you're not doing backups, start, and, upgrade your RAM.

One thing about the SMC fan controller: It gives you a readout of temperature. My computer guy says, under use of intense graphics applications, temperature can go as high as 190∘F, and running at 150 is normal. Mine never hit 150, even when we ran as many as 12 HD videos simultaneously, along with ripping a DVD, and having 16 windows open between Safari and Chrome. So, this is definitely NOT a temperature issue.

I´ve came across with the same problem and when I look out for solutions I found out that basically I had Three options

1.- Dim the brightness to the first 2 dots (that is the limit for me, anything above that shuts down again my screen)

2.- Replace an expensive part of the screen (about $900)

3.- Try with an external monitor to see if the problem was the screen or something else

What I did was to plug my flat screen to my mac with a Mini Display Port to VGA Adapter

http://store.apple.com/us/product/MB572Z/B/mini-displayport-to-vga-adapter?fnode =51

And… Problem Solved! now Im going to buy a Monitor that gonna cost me less than half of the replacement parts, my main monitor will keep siting down if i dim it above the 2 dots but at least I will have the other to work properly

So that´s that, I hope someone finds this helpful

P.S. Sorry if my english it´s not that good

I have had this and tried every possibility including getting apple to replace the graphics card under the rather hidden replacement program on that part. Nothing worked including the graphics card replacement till I finally replaced the backlight board ( part no will be one of these...661-5980, 605-3034, 605-3035, 612-0094).

Only two days so far but it seems fixed at last. It was turning off as fast as you turned it on before.

Backlight board is about £120.