iMac 27" Screen goes black repeatedly, but then settles for a while?

Aha! I'm happy to hear that you have that problem sorted-out ... two thumbs-up for stick-to-itiveness and never-say-die.

It's weird that different folks keep stumbling-across such different Hail Mary fixes (a new keyboard, my "brightness slam", your recent memory tweak/re-set) for this one maddening symptom ... which even the Apple engineers/coders cannot cure/eliminate/diagnose.

Thanks for the closure. 🙂

Why would many different solutions be weird when a symptom can have many different causes?

Displaying information on screen is the final element in a long chain, and is therefore affected by many different components.

Yes, Grasshopper ...

But this is 'way too FN Zen for me.

F U ... y'all have a nice day. 🙂

HI guys,

Just an update, and my fix (explained on page 16) is still working. Better yet, I just received a congratulatory email from Apple Support this morning. On another thread here ... about exactly the same problem ... I had suggested my idea to Gaetanfromparis. That was maybe two or three weeks ago. It worked for him too, and it's still working today.

Here is the link ...

Re: imac 27 black screen

Hooray for me. 🙂

Mine worked for a month with the display brightness set to about 30%. I thought it was fixed, perhaps by some software update. But today, it happned again and I have a black screen that appears non-recoverable. It is INTERMITTENT so any "fix" cannot be verified by short term observation.

Murrfk,

Did you look at my post from yesterday, at the bottom of Page 17?

It worked for me, and for Gaetaninparis. And then I got a nice congratulatory email from Apple Support!

If you can once again get your iMac working at all ... even with a dim screen ... try my suggestion. It worked for me. And for Buddy in France.

And give us a report FFS.

Yes. I tried it. It did not work. And my point is that any solution that APPEARS to work might only be temporary. The problem is intermittent. It can appear every day, and then disappear for weeks, making it look like whatever one did, worked.

THat's what I've been saying too. There are many possible causes, there are many possible fixes. Some things work for a while (it might be days, or even weeks), some might make the problem less frequent (eg it only happens every few weeks instead of every few minutes).

if Boomer49's solution worked for him, then that's great. But that doesn't mean it is the solution to all our problems, and touting it as such is not what one should do.

I think that the object of the game is to keep an open mind, and experiment with any-and-all suggestions (within reason) that have worked for other folks who are experiencing the same problem. If Apple's engineers and coders are unable to track down and fix the root cause (or causes) of this issue, we normal (non-geek) folk have to be satisfied with fumbling-around and trying random stuff (changing-out the keyboard, removing supplemental aftermarket memory, my pedal-to-the-metal brightness surge, etc) that might at least treat the symptom (for at least the time being) and let the professionals worry about The Big Picture.

I never claimed that my lucky shot-in-the-dark was the be-all and end-all super-fix. It sounds so implausible that I felt that I had to make the point that ... if nothing else had worked ... it was at least worth a try.

And now some dude in Paris has his iMac working again. 🙂

Hi everyone,

I'm having the same problem for years now. I tried almost everything posted in this thread and some of the solutions worked, but just for a short period of time.

I'm just "living with it" since i can't find a solution

But i find a way to when it happens, bring it back up for weeks.

I do think that this is software but not hardware related. Maybe a combination of both.

The trick:

For me it works on OSX Yosemite 10.10

When the screen shuts down...

1. Restart you iMac and do a PRAM reset (Option+Cmd+P+R).
2. Restart you iMac again (Force restart with power button)
3. Then, press ALT key while starting the machine to enter boot selection menu (Startup manager)
4. Just leave it there running until the screen comes back

If hours pass and this not work, reinstalling OSX Yosemite 10.10 might help. You'll need the help of a flashlight to see the screen

After this steps, i get the screen back on with no blackouts for weeks.

I know it seems weird, but for me, it works.

I hope we can find a real solution

HI Mfacci,

Thank you for sharing this "tip" with us. It seems that we keep discovering new ways of dealing with this issue.

Maybe it it is just me, but I find your instructions a bit too brief and unclear. For example, in Step 1 you write "Restart your iMac and do a PRAM re-set" ... but you do not mention how you turned it off (with the power button I guess?) and "Restarted" it again ... With the power button I guess. More importantly, at exactly what point in time do you do the PRAM re-set. As it is loading in? After the process is complete and the screen shows what??

In Step 2 do you simply mean "Turn it off with the power button and then turn it back on with the power button"? And exactly WHEN in that booting-up process do you press the ALT key?

As you can see, I am not very computer-savvy and need as much step-by step detail as possible. Take your time. 🙂

Thanks!

My 27" iMac is a mid 2010 machine, running latest El Capitan. It's behaved pretty well up till a couple of days ago. At first the screen went black a few times, but this morning it was going off every few minutes. I used the "Alt, Command, Eject, then any key" trick to keep reviving it, but obviously couldn't get any work done like that. So I read forum posts. Boy, this has affected a LOT of people, hasn't it? Boo, Apple.

I did the recommended PRAM reset but it made no difference. Then I tried changing my keyboard and mouse batteries ...no change. Then I did the SMC reset ...still happening. I had no hot-spots set, but one person advised setting up a hot spot to sleep the screen, then wake up, so I did that.

Finally I saw your tip about whacking the screen brightness to 100%. YAY, it seems to have worked!! ...so far anyway. Thank you Boomer49. I'm finding 100% a bit too much so I'll experiment with reducing to 80% tomorrow. I wonder what the long term prognosis is? It doesn't seem fair that only 2011 machines got the free replacement. Really Apple, BOOOO.

General observation: Every time the screen went black and I revived it, the mouse pointer would be at the top left of the screen, regardless of where it was when the screen went black. I have no idea if that's normal or whether it's significant. What do you technical guys think?

My advice to anyone reading these threads ...don't panic. Don't spend a fortune replacing parts until you've tried all the suggested tricks.

Cheers!

Hi Soobret,

That's great to hear ... thank you for letting us know. My fix has been "holding" since November 15th, and on December 13th I received a congratulatory email from Apple Support after GaetaninParis reported that it worked for him too. And then on December 17th I received an email and then a phone call from Applecare Outreach (in Texas, I think) that said ...

Hello R,

My name is A********, and I'm with the AppleCare Help Desk. I'm reaching out to you on behalf of Apple Engineering who would like us to gather additional details/data about the issue you've reported to Apple Discussions.

https://discussions.apple.com/thread/4053857?start=225&tstart=0

I am available between 9am - 6pm EDT, Tuesday - Saturday. Please let me know the best telephone number you can be reached, and the best date+time you'd like to be contacted during those hours.

Sincerely,

A********

Finger crossed that our little fix continues to work for all three of us.

R.

Everything was working great for over 6 months, and then I stupidly increased the brightness--and immediately (like within 10 minutes) the screen started going black again. Read the various posts, and changed energy saver to never, and slid brightness to 100%. Let's see if this works. I love it at 100% and do not like when it's not bright. .but I also hate having it black out every 10 seconds!

Also, I've upgraded to El Capitan so it's not the old software.

Hi Marjorie,

You didn't provide any background history or description of the when and how and time of the problem, but I'm still curious to know if this little fix of mine continues to "hold" with your iMac. Please keep us posted.

And it would be much appreciated (by me, anyways) if you filled in the history/details with a bit more specificity. Thanks!

Ron