2011 27 inch iMac - Black Screen of death?

sgould

Registered
Doesn't time fly. I thought that my iMac was still under guarantee, but it's well over 2 years old!

Today it died. At least I thought that this was the problem, but it comes back on after a reboot. Further investigation shows that the computer is OK. It's just a black screen. I can access all the files by network sharing.

Anyone any idea of the problem? Is it the screen? Is it just the backlight? Is it a common issue?

I've read elsewhere that the 2011 iMac has a heat problem, but this turns the whole computer off.

If it needs a new 27 inch screen, is it the end?
 

DeltaMac

Tech
Be sure to try pressing f2 from a wired USB keyboard, to make sure that the brightness is not just all the way off.
Sometimes, I miss the simple stuff - so I always ask :D

Check for any video by shining a bright flashlight into the screen, and look for any screen elements (menus, dock, file-folder icons on the desktop) Those can be quite difficult to see, so make sure to move the light and look at the screen from several different angles.
Do you see _anything_ at all - or is the screen just completely black?
If you see any part of your screen, then it's the backlight (probably the LED backlight board)
Have you tried both a PRAM reset, and an SMC reset?

If no video at all (black screen) - do you have an external display that you can try? If an external display works, then likely it's the LCD panel. If there's no video on an external, then there's a good chance the video card is out (bad)...
 

sgould

Registered
Thanks!

I'll have a play the next time it goes out.

I've since read that it's a problem with 2011 iMacs. It may need a new screen.... But the temporary solution is to reduce the brightness a bit. I lowered that by two clicks and so far, it's stayed alive.

I'll check with a torch next time. I should have done that today, but my wife was in the middle of something important and I did a restart that worked for a while. Then we had to go to the shops...... ;)
 

sgould

Registered
A quick update. But no real progress.

Since dropping the level of the brightness a couple of clicks the screen has not failed. I'll leave it like that and see, but I'm off on holiday tomorrow and will not be home to use it. for a while.
 

sgould

Registered
Well it's lasted until now with us dropping the brightness lower and lower. But last night it decided that it was dead :(

Just got to sort a replacement. I thought of a new Apple screen in front, but that costs as much as a repair. So now to decide. A new one or something cheap and non-Apple....

My first thoughts are a £350 screen from eBay, dumped in front of the iMac.

Then later a Mac Mini to go with it, as i'm sure the double screen set-up will get on my nerves.
 

DeltaMac

Tech
Did you determine if it's really the screen? or is it simply the backlight?
You can tell because you will still have visible screen elements (Menubar, Dock, windows, etc) if you look carefully, perhaps by shining a bright light into the screen.
In that case, there's a backlight board that may be failing.
Or, could be a flaky power supply
Neither of those two parts are terribly expensive, and not too difficult to replace.
Those are likely failures, and you should end up spending 3 - 400 dollars, maybe less.

And, the video card is replaceable, too, and will be higher, depending on which one you have.
And, there's the possibility that the screen is failing, which will be considerably more.

And, it may be worth your time to talk to a "genius", as there are occasional service programs, that can provide repairs, if you ask for them. Some folks here seem to get the idea that Apple service is always tight-fisted, but there are (perhaps anecdotal) stories about getting free repairs. Doesn't hurt to ask! If you still have an independent Apple-Authorized service shop somewhere close to you (there still are a few), then that's where I would try first.
 

sgould

Registered
I've tried shining a torch into the screen, but seen nothing.

I can access all my files from the laptop over the network. The only thing inaccessible is the stored mail from our local ISP that is not on the Cloud. So the computer bit is OK.

On odd occasions the screen wakes and I see the password box on the screensaver, but as soon as I enter the password the screen goes dark.

I have an Apple store a mile down the road. I'm booked in for Wednesday with a "Genius". Let's see what they say. Here in the UK costs seem to be £1 = $1. So prices are around 50% higher than the USA.

If I get really desperate, I have an old laptop that I could wipe and restore that from the Time Machine backup, I suppose.

I'll let you know how I get on with the Genius.
 

sgould

Registered
OK. An update that may confuse more than help.

After reading through everything I could find on here and on the Apple support forums, I thought that I had better go through all the possible self help options again before taking the iMac to the Apple Store and finding that it wouldn't show the fault.

We have been away all weekend and the iMac has been switched off for three days. When turned on this morning it waited until the user password was entered (left for a minute), but as soon as the desktop appeared after the password entry, it was black within a couple of seconds.

Double checked the screen with a light and could not see anything. Computer still accessible over the network.

So I tried another PRAM reset. The bongs went twice and I let go of the keys. Then the screen went black and bonged a Restart. Screen came on, flashed on and off a few times, went off for 10 seconds. I was just about to give up when it came back up on full brightness and asked for a password. I put the password in and the screen has stayed on with no flicker or any untoward symptom for five hours now. I will leave it on, on full brightness to push the heat a bit. If it stays on overnight and through tomorrow morning, I will cancel the Genius appointment.

Finger crossed!!

Don't know why the original PRAM reset last month did nothing. Maybe I wasn't concentrating and did it all wrong...

I'll try and remember to update later, even if it stays working.

Thanks for all your help. :)
 

sgould

Registered
Well it was left on at full brightness for 24 hours and it was still working fine. :)

Shortly afterwards we decided that it looked good, so we cancelled the Genius appointment.

Half an hour after that, the screen went black :( It came back with a restart, so we left it for a while, but it went black again.

Dimming the screen again has allowed it to work continually since then, which is another 12 hours.

Tomorrow I will look at the Console to see if anything happened at the time. Maybe try another PRAM reset if necessary. I'm not sure about booking another Genius appointment if it's not going to be "reliably broken". Difficult to decide the best way forward as it needs to be reliable for our daily needs.

I'll shut it down in a minute for the night. It's bedtime in the UK!
 

sgould

Registered
Thanks for that. Alas, I don't think I qualify. We bought ours in December 2010, so just a bit early. And the symptoms are not the same. Pity. :(

After my last post, it started working after another PRAM/SMC reset. For a while. We booked another genius appointment, which was this afternoon - we are just back. Over the weekend it got worse and worse. So yet another PRAM/SMC rest and it started up OK again. But as expected. It has carried on working and the Genius could find nothing wrong!!

But it's been left with them to do an internal check and replace the display, if necessary.

I would be happy with a new display, if it's a fix. It seems to be the likely fault. The computer behind still works and can be accessed via the network. When the screen goes black there is no sign of any icons etc. on screen when a light is shone into it.

We have a price for the screen, labour and tax of £434. Which is equivalent to $680 at the moment. Still cheaper than a new computer and about the same as a separate 23 inch screen.

We shall see by the end of the week when I get it back.
 

sgould

Registered
Well that was quick! Taken in after lunch Monday. Text to say it's ready in less than 24 hours.

New display installed. Hard disc and settings undisturbed.
Back home and reinstalled, seems to be working, but time will tell.

Price at the Apple store was cheaper than a quote for a display from an independent repairer.
 

AlexEvans

Registered
Just joined to share my experience.

I bought a used 27 inch late 2009 iMac about a month ago. At first I was delighted with it. I went on holiday shortly after taking delivery of it and only when I returned and it was too late to return it a big problem showed up. The screen would go black after a short time, yet everything else worked, just the screen would switch itself off. Turning it on again with ctrl-shift-eject would have the screen display for a couple of seconds then switch off. Naturally I hit the Internet and researched what I could. I did the usual - PRAM reset, the S something, can't remember, installed an App called TG Pro to crank the 3 fans up, turned the brightness down much lower than I would like and all of this helped, but did not solve the problem. Turning the brightness up to maximum would cause the screen to go dark after a few seconds.

I have a wireless apple keyboard and it came with an aftermarket wireless usb mouse that plugs into the sots at the back of the iMac.

Anyway, what I have discovered is that moving the wireless usb mouse receiver thingy from one slot to another dramatically improves the problem. I now have the brightness at near maximum with no extra fan speed and I can use it for hours without the screen cutting out.

In fact whilst I began typing this post I thought the problem was completely solved, but it cut out whilst typing. Ctrl-shift-eject caused the screen to go on for 2 seconds then cut out. So I removed the mouse USB thing from the slots altogether and voila - I've been using it for several minutes on near max brightness with no problems.

Next step for me is to get a genuine mouse or trackpad, not use the aftermarket USB mouse at all and hope it solves the problem completely.

I'll post an update in case this helps someone because I know how frustrating this problem is.
 

AlexEvans

Registered
...several hours later, max brightness, no fans and so far no problem using an apple magic mouse and no usb peripherals. If you don't hear back from me you can assume that my problem is solved. I hope this works for someone else too.
 

sgould

Registered
It's interesting how different things affect these computers.

Over two years since our screen was replaced and it's been working with no problems since then. Used every day, all day.
 

Nine5Aero

Registered
Hi folks! Just registered. Two weeks ago, I got a great deal on a mid 2010 iMac 27. I soon found out why and I've been researching this issue ever since. Mine has the same symptoms- frequent black screen, can keep it on by lowering the brightness level, can see icons with a flashlight, 2nd screen continues to work. Cleaned it all out last night and checked all connections to the display. I'm going to try a new backlight inverter board. I really believe that's the issue. Ordered it today. I'll keep you updated.
 

kkaragitz

Registered
Hi folks! Just registered. Two weeks ago, I got a great deal on a mid 2010 iMac 27. I soon found out why and I've been researching this issue ever since. Mine has the same symptoms- frequent black screen, can keep it on by lowering the brightness level, can see icons with a flashlight, 2nd screen continues to work. Cleaned it all out last night and checked all connections to the display. I'm going to try a new backlight inverter board. I really believe that's the issue. Ordered it today. I'll keep you updated.
What's the update on this? Did the inverter board work?
 
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