iMac 27" Black Screen?

Mine stayed good for 7 months after setting the monitor on FULL brightness and not one block less. unfotunatly today it occurred again one time. 😠

Im not sure how it wil develop now but setting it on full brightness was at least good for a very descent time.

Loose connection somewhere is my best guess. A friend asked me to look into his problem, so I went to have a look. Bad – after the first hour problem free, it occurred every few minutes and became unusable. Took it home with me, and the problem disappeared. Returned it to him, and it was okay for a few months, then got so bad he put the computer in the car to take to Apple. Was unable to deliver that day, so used it that night. No problems. Good for another several weeks. Then got bad again.

How else to explain that moving the computer can fix the problem, other than a loose connection?

Also, mine has never displayed the problem, but maybe once in 20 turn-ons I can hear an arcing noise for half a second. Don't know where it's coming from (could be the mains cable). The screen's never gone black but I'm thinking: there's a loose connection somewhere in my machine. I wonder if it's to do with the black screen problem?

I tried this and it has worked for a few days. And counting

For want of a better metaphor, it seems that the innards of the computer have only a tenuous grasp on the monitor. So, I set the desktop to change images every minute, and the screen saver to slow slides. Logic might say that this allows the brains to exert continuous control over the monitor and thus prevent it from lapsing.

Anyway, that is my logic, and my latest attempt to keep the monitor from going black.

OK I think I fixed it! Go to the display options, and turn of auto dimming. I think it's that dimming sensor that is faulty from being used over the years. In most cases, the computer is still on after the screen turns black, so that means just the computer screen is off.

You just have to manually control the brightness with the keyboard now.

I don't appear to have that functionality. I just have basic choices of DISPLAY, COLOR, RESOLUTION, SCALED, and SHOW MIRRORING OPTIONS.

I have an early 2009 24 inch on Mavericks, and a late 2009 27 inch on Yosemite. Neither one shows that functionality.

(the 27 is the one with the black screen problem)

?

I am a new black screen sufferer. Let me share the detail briefly. 27" iMac vintage 2011. Dragged it in to the local store a few weeks ago. They could not replicate fault despite running tests and having the machine on test for 18 hours so they handed it back. It was no better when I set it up again and I tried many of the suggestions on this thread. It got to a point when it was going black on start up before reaching the login screen. Dragged it back to the store and this time the fault repeated itself on the service counter so they said they would replace the video card (quoting UK consumer law but in actual fact Apple had already issued a notice on this particular video card in this manufacturing batch of machine). I got a call from the store asking if it was OK to clear down the HD and reload the operating system suggesting that installing a new video card had not cleared the black screen fault. I ok'ed this and picked the unit up last week. After 2 hours of use the fault has returned. I plan to couple the unit up to a second monitor to confirm it is just the video component dropping out (which seems to be confirmed by other people commenting on this issue) prior to returning to the Apple Store for the third (and last) time. Personally I think it disgraceful that a business this big with as much income as they generate cannot fix this problem effectively.

Here is an update to yesterday's post. Finished last night restarting the iMac after the black screen kept reappearing seconds after clearing via Cmd-Alt-Eject but couldn't get to the login screen before going black again. 8 hours later it booted normally. Connected to a second monitor and waited for the first black screen which came about 1/2 hour later but the second monitor stayed on playing YouTube. Downloaded Owly but the black screens continued periodically. Dropped the main screen brightness to 2 bars and black screens stopped appearing over a couple of hours. Added one bar to the screen intensity and got an immediate black screen. Went back to 2 bars and again ran without blackouts for a couple of hours. Decided to eliminate the wired keyboard as a cause so disconnected and used the mouse on preferences to increase intensity slightly and got an immediate black screen so recoupled keyboard and went back to 2 bars and again stability returned. Temperature monitoring shows GPU diode at 149 F, GPU heat sink at 138 F and CPU Core at 99 F and casing is warm but not boiling hot. The graphics card is new from last week and based on other posts the temperatures at not high. After several hours of playing YouTube videos I seem to have stability at 2 bars intensity and immediate black screen if I go over 2 bars. Anyone got a concrete cause for this? My next step is to upgrade from Mavericks to Yosemite after which it is either back to Apple store or live with 2 bar screen brightness until it goes phut completely.

Billymick wrote:

Here is an update to yesterday's post. Finished last night restarting the iMac after the black screen kept reappearing seconds after clearing via Cmd-Alt-Eject but couldn't get to the login screen before going black again. 8 hours later it booted normally. Connected to a second monitor and waited for the first black screen which came about 1/2 hour later but the second monitor stayed on playing YouTube. Downloaded Owly but the black screens continued periodically. Dropped the main screen brightness to 2 bars and black screens stopped appearing over a couple of hours. Added one bar to the screen intensity and got an immediate black screen. Went back to 2 bars and again ran without blackouts for a couple of hours. Decided to eliminate the wired keyboard as a cause so disconnected and used the mouse on preferences to increase intensity slightly and got an immediate black screen so recoupled keyboard and went back to 2 bars and again stability returned. Temperature monitoring shows GPU diode at 149 F, GPU heat sink at 138 F and CPU Core at 99 F and casing is warm but not boiling hot. The graphics card is new from last week and based on other posts the temperatures at not high. After several hours of playing YouTube videos I seem to have stability at 2 bars intensity and immediate black screen if I go over 2 bars. Anyone got a concrete cause for this? My next step is to upgrade from Mavericks to Yosemite after which it is either back to Apple store or live with 2 bar screen brightness until it goes phut completely.

Upgrading OS X WILL NOT solve your issue, doing so will only make troubleshooting your problem much more difficult. If you had the computer serviced at an Apple Store, take it back immediately!

I'm dealing with the same issue. My computer is a 27" 2012 iMac with the 6970M graphics card. Everything was great until a month ago when randomly my iMac would flicker and go black. I have an external monitor hooked up to the device and this monitor always stays on when I'm experiencing the issue. Eventually the iMac screen comes back, sometimes its a few minutes other times its like an hour. Usually it goes black out of sleep when it does happen.

I took my computer to the store to have them look at it and they ran a bunch of test one of them being a VST test which it passed. The tech told me to have the faulty video card replaced it would have to fail the VST test 😟. After she ran more test I got a chance to try and show her the issue. We booted the computer to my drive and put it to sleep, no issues. We put it to sleep a second time and sure enough the iMac did not come up, the external display come up fine. After a couple of minutes the iMac came back up which is what I've been experiencing.

So will see how things turn out but I'm getting concerned about the iMac passing the VST test even though the tech saw the issue first hand.

I got same issue last week, 21'' model bought in 2012. It turns to same issue even into recovery mode.

I'm using a mini dvi adapter connecting another display as termporary solution to keep mac running.

I would follow to see how this issue walk out, but don't expect support says exchange your computer with new model, as it is not like a isolate problem at all.

I have a 27 inch Imac that I bought used with the same problem. I have read a lot of posts over the last few days. Some people have suggested running Apple Hardware Test Extended three times from Disk 2 of your original disks, which I am doing. One thing I noticed that I thought was significant was the fact that during the test, the screen remains bright and works fine. Which to me suggests that it is NOT a hardware problem, unless the test mode bypasses some hardare?.

I have mavericks on the computer, and the only thing that seems to work for me is to keep the brightness slider low. If I raise it up, it instantly black screens.

I have the same problem with my iMac 27" Late 2009, the only way to keep the screen on is to reduce the brightness to a minimum level, two days ago I tried to reinstall the combo update of El Capitan 10.11.1, At the moment I don't have any black screen with the brightness at maximum level, in my humble opinion this means that the black screen problem is not an hardware problem but a software bug, if someone want to try my solution and share the experience this could be useful.

I have a 2010 mid-year 27" iMac that started having the intermittent sudden "black screen" after upgrading to El Cap. I too thought the computer was shutting off but discovered quickly that the screen only was shutting down. I was watching some YouTube vid's and the sound was still coming through my headsets. Also discovered that holding down "Option" then "Command" and releasing would bring the monitor back up. Installed SmcFanControl and sped things up but that didn't seem to help.

I am using a wired, full size keyboard and BT Trackpad and Apple mouse. I have not tried a new/different keyboard but will give that a go and see what happens. I will also open her up and unplug and reattach all connectors.

I have a late 2009 27 iMac with the black screen problem. I tried everything, even a local repairman (I'm in Korea) to fix it for 6 months. I fought with it for over a year. New OS did not help, keyboards, settings, nothing. Installed fan application in computer, and put an 8 inch external fan directly on it. Nothing.

It appears to be heat related, and the only fix is another Mac.

I had hopes of a solution, (and for what t's worth) but ended up wasting a year of productivity.

The only solution I read in that whole year was some guy found a tech guy to open the Mac and disconnect and reconnect all the wires.

I have the issue with 'Black Screen' on my late 2010 27-inch iMac. Boots up fine, but then screen randomly goes black. The iMac is still alive as I can still hear things playing. Someone suggested I try putting the iMac to sleep using the cmd/alt/eject key commands. Well I tried this, then touching any key afterwards, the screen came back on. It did however go off again after a couple of minutes, but used the same tactics again and it worked again. Still a pain, but a solution.