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iMac screen goes blank, iMac still running

Hi,

I have an iMac 20" Core2Duo (iMac7,1), 4GB running Snow Leopard (latest version/updates). From time to time the iMac's screen goes to black but keeps running (I can hear the fans). It's a bit like it goes to standby but not completely. I have to power it down using the power button (holding it 5 seconds). After that I can boot it up normally without any problems.

Log files are completely empty. No crash, nothing.

This happens only from time to time - today the first time after two weeks without problems. We did a complete reinstall two weeks ago thinking it's caused by some software. Reinstalled Adobe CS4 and some HTML/CSS developer tools like Transmit, Textmate, CSSEdit.. Nothing else.

Can't reproduce the problem. It just happens from time to time.

Any ideas on this?

Thank you,
Sebastian

iMac7,1, Mac OS X (10.6.3)

Posted on May 20, 2010 7:39 AM

Reply
Question marked as Best reply

Posted on May 20, 2010 4:35 PM

Hello taenzerme

Welcome to Apple Discussions

Reset the SMC > http://support.apple.com/kb/HT3964

+1. Shut down the computer.+
+2. Unplug the computer's power cord.+
+3. Press and hold the power button for 5 seconds.+
+4. Release the power button.+
+5. Attach the computers power cable.+
+6. Press the power button to turn on the computer.+

Dennis
33 replies
Question marked as Best reply

May 20, 2010 4:35 PM in response to taenzerme

Hello taenzerme

Welcome to Apple Discussions

Reset the SMC > http://support.apple.com/kb/HT3964

+1. Shut down the computer.+
+2. Unplug the computer's power cord.+
+3. Press and hold the power button for 5 seconds.+
+4. Release the power button.+
+5. Attach the computers power cable.+
+6. Press the power button to turn on the computer.+

Dennis

Jun 1, 2010 11:17 PM in response to taenzerme

I have been having the exact same issue with my screen the last two days. It also just goes black randomly. I attempted the mentioned fix and am still having the same problem with the screen going black.

I have not added any new software or downloaded anything from the net so I have to assume it is not a software issue.

When it went black the last time, I shut the computer down and restarted it but the screen was still black even though it turned on with the bong sound. I turned it off and waited a few hours before turning it back on and the screen appeared.

Jun 2, 2010 3:49 AM in response to taenzerme

Hi, I am having exactly the same issue you guys mention. My Mac just went blank but it was still running. I had to switch it off the mains. This has happened twice now. I am not sure if it is because I run quite a lot of apps and have Chrome and Safari running at the same time with lots of tabs open. Not sure but it happens when Mail is also running.
It really concerns me as it is very random. Any suggestions? I was thinking I might take it to the Genius bar in Southampton.
Hope any one of you guys out there have found a solution to this problem.
Thank you in advance for any assistance
Cheers
Andres

Jun 4, 2010 12:33 AM in response to aeloygut

I've had this for over a month now. Got my Early 2008 24" iMac back from the apple store yesterday. They'd had it there for a week and the 'Geniuses' couldn't replicated the problem. I got a black screen within the hour. Then another, then another, and since the third one, I haven't had the screen back since. Black,black,black - but the computer is working perfectly, apart from the fans sound a little different when waking from sleep or starting up.
I've also had this mac with an apple repair guy for a few weeks - replaced 2 screens, replaced screen power cable, replaced system power box, all to no avail. He put everything back to 'stock' before I took it to the apple store.
The really annoying thing is that I had black screen when showing them in the store, then they boxed it and took it upstairs to fix it, and since they unboxed it in the repair room it behaved completely normally and passed all tests with flying colours. Yesterday I turned it on the store, before boxing it and taking it home again - it was fine in the store, and fine when I got it home - for an hour. Now it's black again and I can't snap it out of it.
I should mention that I have 3.06 24 with Nvidia - other threads suggest that on the new 27 models the graphics drivers may be at fault, but that's with ATI - I have black screen, with Nvidia.

Jun 11, 2010 6:05 AM in response to aeloygut

HI
We rang the service center and they told us to turn the PC off, then back on and when it chimed we had to press the following keys "Command, Option, P and R " (all at once) then wait for the chime again.

It has not blacked out since but it still doesn't seem quite right. Time will tell but maybe it might help.
Cheers
AL

Jun 22, 2010 7:30 AM in response to taenzerme

I am also having this problem with my imac at this precise moment. The screen just goes blank as if it freezes. Sometimes it'll be fine for hours or won't do it at all and others it'll do it a couple.
At first I thought was update the new update I did for itunes because It seemed like every time I opened it would go blank but it's doing it on other things now.

I'm leaving it for a couple of hours and if it doesn't work by morning I will have to try some of these solutions. Glad i'm not the only one, hope can fix it. Cheers to those with solutions.

Jun 22, 2010 9:29 AM in response to taenzerme

I've been experiencing the above described iMac problems for some time now.

I suspected a hardware related problem in the beginning. All hardware has been extensively tested with the 'Apple Hardware Test', but with no abnormalities found. Next, the iMac returned to an 'Apple Authorised Service Provider' for some heavy and prolonged stress testing, but again no hardware errors were found. I was told the hardware should be perfectly stable. However, they gave me back one unreliable and unusable iMac back in my hands, making me an unhappy Apple customer.

Bizarre.

Meanwhile, a fresh install of Mac OS X 10.6 was forced (erasing everything). Resulting in a stable and usable system.
Next, the software-updates have been installed and rendered the iMac once again unusable (with the above described problems).

It is my believe this is a software related problem by one of the latest updates. Can other users please verify this statement by doing a clean install and NOT updating anything?

Oh, something magical happened recently! The iMac crashed once more and forcing me to shutdown (hangup with white screen). But I had the option to collect and sent a CRASH LOG to Apple after booting.

Apple, use this crash log and fix this ASAP! And next do some better QA when pushing updates.

One unhappy customer.

Message was edited by: tommie_c

Jun 24, 2010 8:41 AM in response to taenzerme

I am another user experiencing this --- same symptoms - black screen, mouse visible and working, i-tunes music still playing. Forced to power of and reboot. Have been watching the GPU heat display with a widget but blank screen does not seem to be heat related.

All MAC, Itunes and I-touch software is current.


Has Apple acknowledged this problem and provided advice?


Paul

iMac screen goes blank, iMac still running

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