Problem waking iMac from sleep

[Smashedbanana]

In my experience waking from sleep issues have always been related to graphics cards.

But a  couple of things to try,

create a new user
login as that user
put mac to sleep
see if you can wake it

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delete preferences
try again

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run Apple Diagnostics

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Ed

[ben schmidt]

I suspect the scheduler doesn't like being overridden by your wife, so it throws a tantrum.

Good point MacMoore! If the computer is already set to go to sleep when it is inactive for 1 hour, it seems that further scheduling a nightly shutdown at 10:35PM is redundant. Disabling that might be a good start. (As of course would be the earlier suggestions of PRAM reset and Combo updater too! <grin>)

[Dan Millar]

Wow, this is a common problem - see the Apple discussion boards for iMac.

When it isn't caused by a faulty backlight, it seems externals such as USB hubs or firewire drives may contribute to the problem - do you have any of these? Or wireless mice/keyboards?

How can you tell if it is a faulty backlight? "Wake" the machine and shine a flashlight - from the front or through the rear Apple cutaway - on the screen and if you see your desktop, albeit dimly, then you have a faulty backlight. The "caps lock" light may not light up on wireless keyboards, but the screen inspection is 100% fool-proof.

Others suggest the SCM/PRAM resets, but they often report the problem returns.

Another hint may be an issue with "migration" - if you migrated your user accounts from a previous install or another Mac (especially pre-intel), you may need to re-install fresh OS - sometimes older drivers may cause this problem - as Ben suggested, a Combo update (10.6.7 now available - thks Ben!) is better than the incremental updates.

One possible "trick" to wake it up properly if it is indeed awake, but dark - press CTRL-SHIFT-EJECT, followed by RETURN twice - this has worked for some people, but doesn't fix the underlying error.

I'm surprised to see how long this problem has been going on, according to the Apple Discussions, this has been an issue since the first Intel iMacs.

Hope something here helps with your issue,

Happy Mac'ing!

Dan
We have two iMacs here, neither has ever shown this error, though one has had a logic board replacement for other issues.

[Dan Millar]

Oh, and as Steve would say - one more thing.

If you have the original install disk that came with your iMac, it contains the AHT - Apple Hardware Test - for your iMac, which you can boot and run to see  if the backlight board tests OK or not. Hold down the D-key to boot AHT off the install disk and let it run all tests- takes quite a while so be prepared for a long wait - you can speed things up by NOT testing RAM or HDs.

Happy Mac'ing!

Dan

[HarmanyHank]

Thanks, everyone.

A lot of good suggestions in here. I will follow up on them and report back in a few days if the problem continues or disappears.

Dan, yes there is a USB hub but no wireless mouse/keyboard. And though there has not been any migration from another machine, there was an accidental delete of the only account on the machine (my bad!!) a  couple of years ago and it had to be restored from the external hard drive (I doubt that could have contributed to the problem though).

Anyway, as I said before, stay tuned... and thanks.

Hank

[HarmanyHank]

Well, it has now been 2 weeks since I tried some of the suggestions made here by various individuals and there has been no recurrence of "waking from sleep" issue. (With my luck, now that I'm posting this things will go south again the next time my wife tries to wake her computer from sleep!!)

Specifically, I followed Ben's suggestions and applied the Combo updater and reset the PRAM and I followed Dan's suggestion to disconnect the USB hub (I didn't do the Apple Hardware Test - AHT - but could still do that). Nevertheless, one or more of those moves may have made the difference. We shall see....

Thanks to all again for your help.

[HarmanyHank]

Well, it has now been about a month since I followed some of the suggestions posted here with regard to the "waking from sleep" issue for my wife's 20" Intel iMac running Leopard. As of a few days ago, the problem has re-surfaced.

To recap:  As before, after the computer has been on for a long session (say, 3 or 4 hours of livestreaming) she puts it to sleep manually. Then when she comes back to it - minutes or hours later, it doesn't matter - she is unable to wake it from sleep. She has to hold down the rear power button for 10 seconds, then press it again to reboot.

It only seems to happen when the computer has been on for a long session like that. If she uses it for a shorter session (for livestreaming or for actually working at the computer) this doesn't happen.

I did run the AHT (Apple Hardware Test) as recommended by Dan (?) and it showed no problems at all.

One new piece of information I can report (which I just noticed today) is that when she has this "unable to wake from sleep" situation, if I listen closely I can still hear what I think is the hard drive running. What this tells me, is that when she puts the computer to sleep after one of these long sessions, the display turns off but the hard drive is still on. (Then, while holding the power button down for 10 seconds to cut the power, I can hear the hard drive turn off, as one would expect when doing this kind of reboot).

Is it possible that at the end of one these longer sessions, something is preventing the hard drive from shutting down, even though everything else seems to go to sleep?

Thanks.

[ben schmidt]

Tweeted by Apple Spotlight  (@applespotlight)
iMac graphic firmware update 2.0 http://t.co/95zspJi (for lazy iMacs that won't wake from sleep)
Fri Jun 10 23:12:32 2011

...b