24" LED Cinema display won't wake from long sleep

Question

Level 1

8 points

24" LED Cinema display won't wake from long sleep

Just bought a brand new 24" iMac and matching 24" LED Cinema display. Clean 10.6 installation out of the box. Day one, everything working ok except if I let the system sleep for a while the iMac will wake up if a key is pressed or mouse moved, but the display will not. No problem if its been asleep for a few minutes or even half an hour but leave it say 6 hours (say I'm downloading something overnight) and I get this problem. It will work again if I reboot the iMac or disconnect the display's power though just disconecting the display from the iMac display port doesn't seem to fix it.

Has anyone got any ideas? Apple tech support had nothing except suggesting resetting the PRAM. At the time I wasn't aware the problem was only happening after an extended period of sleep so I thought it was fixed but its clearly still there. Help!

R

iMac 24", Mac OS X (10.6.1), 24" LED cinema Display

Posted on Sep 30, 2009 2:31 PM

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Answer 1

xvx29a

Level 1

0 points

Mar 5, 2010 7:44 PM in response to reid007

I was just having this issue myself and after going through a ton of thread I was able to solve my issue.

I installed Snow Leopard 10.6.0 and did the combo update to 10.6.2 and started having monitor issues. The display would not wake after sleep, and on reboot the display would still not awaken. I could still connect with Screen Sharing. The display would eventually start if I unplugged the display power and the connection to the video card and once the Mac Pro booted into 10.6.2 I could reconnect and the display would turn on, sometimes.

If you have similar issues what seemed to work for me was a SMC reset, http://support.apple.com/kb/HT3964

This resets the management control and seems to get the display to start responding again.

To reset the SMC:

1. Power Off The Mac Pro
2. Unplug the power from the back of the machine
3. Hold down the power button for 5 seconds
4. Plug in the power.
5. Hit the power button and it should work.

I hope this works for some people that may be having this issue.

Good luck.

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Answer 2

Jan 21, 2012 1:08 PM in response to xvx29a

I was having similar issues... nice 20" cinema display completely black with no signs of waking up...

I followed the SMC reset instructions here:

http://support.apple.com/kb/HT3964

(using the Mac Pro desktop instructions to turn off computer, unplug for 15 seconds, plug back in, wait 5 seconds, then power back up.) I did this and then unplugged and replugged the power source for my cinema display...

My first attempt at steps listed above led to high RPM fan and still screen life after reset... a bit odd....

Everything seems to be working normally again (for now).

Thanks to other posts for pointing me in the right direction.

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Answer 3

lupunus

Level 4

1,000 points

Sep 21, 2011 7:44 AM in response to jngilman

My two Cent's to the choir...

I stumbled upon this discussion while looking around to find eventually a glue for a person who has opened his own thread about a similar problem.

So I read thru the posts here and found many useful ideas but at least I missed one essentially thing.

OK, there may be a problem with the power management options, worth to try a SMC reset in some cases.

OK there may be rare cases with applications or 3rd party software preventing the graphic adapter from sending the signal or lowering the available amount of power due to extreme stressing the system.

But as you may have noticed, the problem comes up to one regardeless of the used Computer, OS X or Windows version, display type or brand.

For that, the mostly useless but common "yesterday with my -whatever you want to read here- all was well" attempt gives me the clue and start blinking a little red LED in my rotten brain.

Back in time when I worked as Tech on support desk, exactly the same problem had risen up several times.

The solution was (in the very most cases) neither the graphic card, the display nor the OS. It was the wake up signal itself.

The display expects a defined current pulse as wake up signal and graphic cards (if not broken) will transmit that signal normally.

But the point is, this signal must have also a specific signal strengh to trigger the displays internal adapter to switch on.

There are exact ISO/ANSI defined standards for that but there are also defined tolerances for the signal as well for the sender (graphic card) as for the receiver (display)

Even though these tolerance band is narrow, if the sensitiveness of the receiver is on the higher end of the tolerance and the signal from the transmitter on the lower end the displays internal adapter may not recognize it well and therefore fail to switch ON the display.

Not to forget: Also every changeover within a electrical line decreases the current!

For (extreme) example:

Wake up signal definition may be: Current pulse on line (pin) Y have to be 5 V +-1.5 V / 200 mA +- 50 mA to trigger "wake up"

The transmitter (graphic adapter) sends 3.5 V 150 mA (passing factory tests with o.k. "in tolerance")

The receiver (display interface) passed factory tests as o.k. "in tolerance" with a sensitiveness for wake up current pulse on 6,5 V / 250 mA.

Even as both systems are passed as O.K., the customer expierience of the above (when connecting this two units) is clear: "No wake up after sleep"

Some may have had a quite similar experience with external USB hard drives. Some spin up after plug in, some with a different cable, some never "but on my other computer..." and even in some cases the computers USB interface displays a "shoot off" error.

So what can one do?

Swap Display until you found one that works, even of same brand and model
Swap graphic card until u find one matching (not a good idea with onboard graphic)
Swap computer until ... (Mostly not a usable way)
Try a cable with less resistance; e.g. a shorter one, better fitting contacts, larger cross-sectional area.

Best: Try a direct connection e.g. a MDP to DVI-I or MDP to HDMI cable.

For example: http://www.amazon.com/Mini-Displayport-Male-Cable-White/dp/B003ES241I/ref=sr_1_1 6?s=electronics&ie=UTF8&qid=1316614414&sr=1-16

or

http://www.amazon.com/Mini-DisplayPort-Male-32AWG-Cable/dp/B003L18YG2/ref=sr_1_1 1?s=electronics&ie=UTF8&qid=1316614414&sr=1-11

At least, never use a adaptor-cable-adaptor solution.

I hope that will help some people with this problem.

Cheers - Lupunus

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Answer 4

dkardell

Level 1

21 points

Jun 14, 2015 11:20 AM in response to reid007

5 years later and this is still an issue!

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Answer 5

alpa

Level 1

0 points

Nov 29, 2009 11:19 PM in response to reid007

This is a 'me too' reply. I see the same problem with my 24" iMac with an older 20" cinema display with a mini-DP to DVI adaptor. The 'Detect Display' function still detects the external display but will not wake it up from sleep. Plugging in and un-plug the external display does not help. The only way to get it working again is to reboot the iMac.

Sorry, no solution from me, just another fellow frustrated user.

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Answer 6

manic

Level 1

0 points

Mar 3, 2010 7:30 AM in response to reid007

Hate to be another "me too" but me too on this issue! I've got a 24" Cinema display that I have connected to a Mac Pro via a mini-dp to DVI adapter from Atona Technologies.
http://www.atlona.com/Atlona-Dual-Link-DVI-to-Mini-DisplayPort-Converter-USB-Pow ered-p-17922.html
I thought that the issue might be from using this adapter, but it sounds like you guys are having very similar problems as well.
Will keep searching for a solution.

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Answer 7

Mar 3, 2010 11:29 PM in response to reid007

I am really not convinced that this is a "display" problem in and of itself now since I have seen scores of posts throughout the Apple Forums with various Macs and Displays that complain of the same symptom.

I have been chasing this problem now for 3 months (looks like it started for some people going back to at least September 2009). I have (3) identical SONY 23" CRTs connected to my Mac Pro via two PCI video cards, but I am having trouble with only ONE monitor so far (doing the same thing you describe in previous posts - won't wake up from a long sleep - a few hours).

• First I purchased a new monitor cable for the monitor in question - no change
• Next, I purchased a new VGA to DVI Apple Adapter - no change
• Next, after talking to AppleCare Tech support and trying SMC reset, PRAM reset, etc. they sent me a NEW ATI 2600 video card - installed new card - no change
• Tried swapping suspect monitor to connection on other card (known good card) - same monitor would not wake up!!!
• Purchased new GT-120 video card to replace the new ATI-2600 - same problem.

This leads me to believe that it is either a problem with the OS somehow or perhaps some monitors just need a stronger signal to wake up??? Maybe my 3rd monitor is just getting tired compared to the other two and need a bigger kick to wake up?? Maybe some of these new flat screen LCD/LEDs need that extra kick out of the box?.

All I know is that I have seen scores of complaints on this issue all over these forums with different Macs, Different types of displays (new and old) and various video cards - the only common denominator I can find is the OS.

Message was edited by: ChoreoGraphics

Message was edited by: ChoreoGraphics

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Answer 8

Pete1961

Level 1

25 points

Apr 2, 2010 7:45 PM in response to RichMBP

This may sound strange but after trying many things to fix this same problem I was able to wake my monitor by changing where it is plugged into my power strip. Seems a little strange but after a couple of SMC resets not helping, re-boots, etc. this actually did the trick!

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Answer 9

KAI51

Level 1

0 points

Jun 28, 2010 10:59 AM in response to reid007

I have a 23" display that is about 3 years old that is connected to a Mini that is about 4 years old. Software has been upgraded through the years to the current 10.6.4. My display would not wake from a long sleep. Everything everybody else has tried I did (unplugging and reconnecting, resetting PRAM, etc. etc.) would fix it for a while but eventually they no longer worked. Long story short after taking the display in and having it "fail" to wake during testing in an Apple store I sent the display back for repair. Approximately $400 and four days to replace an internal inverter (I think that was what they did) and the display has been working perfectly for the last few of months.

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Answer 10

Jul 2, 2010 10:57 PM in response to reid007

Ok so i too have had this issue, i tried all the suggestions on here with zero results...
The last three times i had this happen i did the following and it worked all three times:

1- Leave computer on
2- Unplug the monitor from the computer AND the power from its plug
3- Let monitor stay completely unplugged for roughly 15-30 min
4- First plug monitor into the computer then plug in the power

I noticed different results from different peoples setups... i'm merely
throwing in what has worked for me in hopes of helping another person
with this same issue..

Good Luck !
Justin

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Answer 11

Jul 7, 2010 7:47 PM in response to reid007

Same problem. I'm using the Gefen DVI to mini-display port adaptor and have started experiencing the problem where the 24 inch CD goes to sleep and never wakes up. It used to be that rebooting solved the problem, but now that doesn't work either.

Is this a problem with these displays and should I return mine? I thought it was the Gefen, but now suspect the Apple display.

-m

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Answer 12

Jul 15, 2010 11:32 PM in response to reid007

I had this problem. Just turn off your sleep mode. When you leave the computer, switch your display off at the side.
I have found the solution to the 23″ cinema screen not coming on when you start up. I had this problem for years. If there was a power failure or I switched my computer off, on start up the monitors would not light up. After reading countless blogs and taking the power cable in and out of the brick until it came on, I tried this. I have a high powered torch which I held on the brick for a minute or so, just enough to make it warm. It worked. Tried it on the brick for the second monitor and it worked. It has done ever since. 1st time, every time. I think that when the brick is cold, it doesn’t work properly. Just try warming it up. (NOT IN THE MICROWAVE!)

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Answer 13

patwl

Level 1

0 points

Jul 27, 2010 8:22 PM in response to reid007

I also have the same problem. I have found an odd "solution".

The problem first arose when I bought a new 20 inch display for an old G5, running the latest OS 10.5.8. It is a very mysterious problem.

Anyway, my "solution" is to temporarily swap displays (using the screen my MacPro - a 24inch). This has immediately fixed the problem every time.

But it's very much less than an ideal solution: the only reason I brought the G5 in to my work where the MacPro is, was to test whether the problem was with the display or the G5.

Any thoughts?

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Answer 14

Aug 15, 2010 2:19 PM in response to reid007

"Me Too" It started about 2 years ago. Finally I called Apple support they shipped me another video card it seemed to work for a period of time but then it re-appeared if the monitor was left on to long. Now I can not get it to wake. I tried another monitor to ensure the card worked - it did work. Plugged my monitor back in nothing. Got the short - long - short blinking which tells you to check the power adaptor - its the right power adaptor. Maybe my adaptor has gone bad?? Maybe not. I used to unplug the monitor from the computer and unplug the monitor and let it sit for 15 minutes. That always use to work. I am now in the middle of letting it sit to see if it works this time. I will report back if it works.

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Answer 15

Aug 30, 2010 7:45 AM in response to reid007

Not sure if I have a bad machine or not. It appears very slow at startup, it took me 11 hours to Load Logic Studio? It seems to take twice as long to startup vs my 23 inch iMac 4gb mem, 2.9ghz. Anyone else experiencing these issues. I would expect with Quad core and 16gb memory on the i7 would be lightening fast yet it appears to be turtle slow with basic operations - especially loading software.

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