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Claws224, IEEE Network Engineer, Microsoft
Category: Computer
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Experience:  approx 20 years of experience from software to hardware design
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24 iMac starts to black screen

Customer Question

iMac worked fine for 3 months-Now startup or wake from sleep results in black screen. Unplugging all cords and waiting results in full startup. Have run all Disk Utility and TechTool dig and fix options. Problem persists-HELP
Submitted: 9 years ago.
Category: Computer
Expert:  RoeIncarnate replied 9 years ago.
This is a known issue with the newer iMacs.

I think it may have been fixed in the 10.5 updates

If you are using 10.5 (Leopard), then please make sure your system is up to date by running "Software Update" from the Apple menu.

If you are running 10.4, then you may want to look at upgrading to 10.5.

If this is the answer to your question, please kindly select * ACCEPT * so I can be rewarded for my efforts.
Customer: replied 9 years ago.
Reply to RoeIncarnate's Post: No mention of this problem on Apple site.

Have up to date Tiger and Leopard OS on separate internal HD volumes.

I removed all connections from external devices and power - Waited- Then plugged only power cord back in. Boots fine. Connected printer and 3 external HD's back in and all is still fine - For now anyway!

Here is log from this morning when initially startup again didn't work:

4/16/08 8:59:07 AM[2] launchctl: Please convert the following to launchd: /etc/mach_init.d/dashboardadvisoryd.plist
4/16/08 8:59:07 AM[1] (org.cups.cups-lpd) Unknown key: SHAuthorizationRight
4/16/08 8:59:07 AM[1] (org.cups.cupsd) Unknown key: SHAuthorizationRight
4/16/08 8:59:07 AM[1] (org.ntp.ntpd) Unknown key: SHAuthorizationRight
4/16/08 8:59:14 AM org.ntp.ntpd[26] Error : nodename nor servname provided, or not known
4/16/08 8:59:21 AM[1] ([80]) Exited: Terminated
4/16/08 8:59:22 AM[88] launchctl: Please convert the following to launchd: /etc/mach_init_per_user.d/RemoteUI.plist
4/16/08 9:25:18 AM[75] (0x1095d0.Locum[276]) Exited: Terminated
4/16/08 10:00:58 AM[353] failed to find start of cross-reference table.
4/16/08 10:00:58 AM[353] missing or invalid cross-reference trailer.
4/16/08 10:04:46 AM[75] (0x10b0e0.Locum[359]) Exited: Terminated
4/16/08 10:04:51 AM[75] (0x10b150.Locum[360]) Exited: Terminated

Sad to say I don't know what to make of this.

Also, on short term sleep and restart, both versions of OSX will restart fine.

24" iMac is three months old and has been a dream all along.

We were away for a week and iMac wouldn't startup when we got back.

Had left a 17" Powerbook running and it was still fast asleep and runs fine.

All cheap surge "protectors" were still on.
Expert:  RoeIncarnate replied 9 years ago.
I wouldn't worry about those meessages. 10.5 seems to spit more stuff into the logs than 10.4 did.

The "convert the following to launchd" is a warning to the developers to use Apple's new system for starting system processes. That is a harmless warning message.
More info on launchd is here:

org.cups is the printing system in OS X.

I don't think I'd worry about any of the other messages either.

Maybe trying Reseting the PRAM, it can fix all kinds of weird problems:

-Restart the iMac
-Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
Hold the keys down until the computer restarts and you hear the startup sound for the second time.
More detail here

I found one person that says a workaround for the black screen it to turn on the "Require password XXXXX wake this computer from sleep or screen saver" in the "Security Preference Pane".
More info:
Customer: replied 9 years ago.
"Answers" were not helpful as they covered very basic fix options which I had already done. It would seem the author would have known I must know a fair amount about my Mac as I stated I had already run all TechTool and Disk Utility options.
Expert:  RoeIncarnate replied 9 years ago.
I'll opt-out so others can chime in if they have ideas.
Expert:  Claws224 replied 9 years ago.


Could you perform a test for me?

Could you prior to walking away from the machine disable the airport card or whatever networking device you use and then see if it still does the black screen upon wake.

Let me know



Customer: replied 9 years ago.
Hello RoeIncarnate & Eric--

Per earliest post is was both reboot from shutdown and awake from sleep after a varying periods of time that machine would turn "on" and stay black.

Took it back to Apple store, which was a blow to my fragile ego (frist time in 20 years of Macs that I couldn't resolve a Mac problem), and after exhaustive review of many logs "Genius Bar" guy decided it is probably a defective power source.

He has ordered one and we will see.

Back on my "tiny" 17" Powerbook that I promised my new wife I would sell :-)

Thanks for trying, all of us!