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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac 24' green & magenta vertical Lines will not boot.


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Bob Wolf

 
Member Since: Jan 22, 2011
Posts: 2
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Firstly let me say Hello all ^_^ Secondly, I hope this is posted in the right forum.

The problem started a few days ago when my iMac went into screen saver mode and the whole screen had frozen and become pixlated with squares and a general scrambling of the screen, noise, grain, etc.. It wouldn't awaken from it's slumber so I did a hard restart.

The familiar friendly chime greeted me but the screen was covered in Vertical Green lines that are full of pixels, moving almost like static. The apple logo appeared and the spinning gear but that stopped spinning after about 20 - 30 seconds.



When I tried to boot into Safe mode this happened to the Apple logo (after about 3 or 4 mins)


The apple genius' are booked solid till next Thursday (27th) so I decided research and trial an error were my best options.

The following are the steps I have tried and where I am currently. Sorry for the lack of punctuation, etc...

-----------------------------------------------

On startup, Chime sounds, green vertical lines with what appears to be static, sometimes with Magenta in.

Apple logo appears

spinning lines lock up after about 10 seconds. Freeze.

Will not boot into Safe mode (by holding Shift after chime)

Will not boot from Mac OSX disk (by holding C after Chime)

Tried zapping the Pram (Shift, option, p & r on chime, Wait for 3 chimes)

Removed RAM 1 at a time tested in other slots, no change.

WILL enter into single user mode (holding Shift & S after Chime) so ran fsck twice to receive the Hard drive OK message. PHew Hard drive is OK then.

Reboot from here, same Vertical Magenta and green (sometimes just Green) Lines with static, Apple Logo, Spinning gear and freeze.


So connected with firewire into target disk mode. (connect mac book pro to imac using firewire cable and hold down the T key on your target computer, in my case my iMac) This essentially makes the imacs hard drive into an external firewire drive. Hard drive OK. Backed up. YAY. (most relieved to get back photos & current work)

-------------------------

Thanks for bearing with me on this epic post. and thanks in advance for sharing the knowledge.


So, does anyone know what other steps can I take on the diagnostic road? or betterer still a solution
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chscag

 
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Member Since: Jan 23, 2008
Location: Fort Worth, Texas
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Mac Specs: 27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, 3 iPods, Yosemite

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Welcome to the Mac Forums.

If the iMac won't boot at all we can't really test to see if it's the graphics card that's failed, however, from the symptoms you posted, it looks like that's what happened. Which means a logic board swap out. Assuming you have Apple care, the genius bar will take care of that for you. If you don't have Apple care, prepare for an expensive repair. Apple does have a flat rate repair fee though so be sure to inquire about that.

Since Target Mode boot is working, make a backup of all your data before taking the machine on in.
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Bob Wolf

 
Member Since: Jan 22, 2011
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THanks for your reply chscag. No apple care unfortunately, although the mac is nearly 3 years old, so from what I've been hearing It's not done too bad, especially considering how much I punish it.

I'm not fancying taking it to the apple store, my credit card couldn't take the strain! Have you or anyone had any experience with 3rd party apple repair shops?

Can anyone recommend one in the Islington area?
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chscag

 
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Mac Specs: 27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, 3 iPods, Yosemite

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I don't have a good feeling about using any repair facility other than one authorized by Apple. Too many horror stories about botched repairs and call backs. I suggest going to the Apple store and using their flat rate repair option. I believe (could be wrong - so check first) their flat rate repair fee is $325 or maybe a bit more. They'll send it out to an Apple repair depot. Takes about a week.

Of course you need to weigh that against buying a new iMac. You may not be ready to pay that much. Tough decision either way.

I take it you're not in the US... I'm not sure what the flat rate repair fee or if they even do that outside the US. So be sure to call first.
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Puppy

 
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Same happened to me this morning. 24" 2009 iMac. Is there any update?
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Puppy

 
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OK update. iMac went off on a holiday to my nearest apple store. Diagnosed at the Genius Bar as posible graphics card failure. Maybe logic board. Well 10 days later I have it back with a replacement NVIDIA GeForce 8800 GS graphics board. I hadn't noticed before. But it looks like the display had been slowly deteriorating, as it now appears shaper and crisper.
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