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Old Feb 13, 2013, 05:55 PM   #1
totallytech
macrumors newbie
 
Join Date: Feb 2013
iMac 8,1 (2008 alu 24") blank screen

Hey Guys,

I've got a 2008 aluminimum 24" imac. 3.06GHz, 4GB, 250GB. The screen started to just turn off around 2 weeks ago. Sometimes the machine would power on and work for around 1-2 hours, but sometimes only around 15 minutes.

The screen just goes black. No funny flickering, no odd pixels etc. Just off.

The superdrive is still reading etc, if I put in a disk it spins and reads, I can also hear the hard drive reading etc.

I opened the imac and checked the graphics card. Its the 512MB Nvidia 880GS.

I sent the graphics card to a company to test it and it worked directly in one of their machines for an entire day.

I've replaced the ram and the lcd screen too.

When I power up the machine I check the little diagnostic leds and it shows

LED 1 - ON
LED 2 - ON
LED 3 - ON
LED 4 - OFF

but the screen is just black.

Any ideas - I'm thinking it may be the logicboard but surely the dvd drive and hard drive wouldnt power on?
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Old Feb 13, 2013, 06:17 PM   #2
kpgh554
macrumors regular
 
Join Date: Dec 2011
Quote:
Originally Posted by totallytech View Post
Hey Guys,

I've got a 2008 aluminimum 24" imac. 3.06GHz, 4GB, 250GB. The screen started to just turn off around 2 weeks ago. Sometimes the machine would power on and work for around 1-2 hours, but sometimes only around 15 minutes.

The screen just goes black. No funny flickering, no odd pixels etc. Just off.

The superdrive is still reading etc, if I put in a disk it spins and reads, I can also hear the hard drive reading etc.

I opened the imac and checked the graphics card. Its the 512MB Nvidia 880GS.



I sent the graphics card to a company to test it and it worked directly in one of their machines for an entire day.

I've replaced the ram and the lcd screen too.

When I power up the machine I check the little diagnostic leds and it shows

LED 1 - ON
LED 2 - ON
LED 3 - ON
LED 4 - OFF

but the screen is just black.

Any ideas - I'm thinking it may be the logicboard but surely the dvd drive and hard drive wouldnt power on?
LED off- means video card and logic board not communicating apple recommend replace either.{you have.} but have you tested the inverter not problem. and no wires loose or pinched. other than that sound like mother board to me.
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Old Feb 13, 2013, 06:25 PM   #3
totallytech
Thread Starter
macrumors newbie
 
Join Date: Feb 2013
Hey,

I've not checked the invertor, but I have tried two complete lcd screens - the LCD's have the inverters installed so I'm guessing they are fine...

If the logicboard / mainboard has failed would the dvd drive etc still power on?

----------

I have noticed though none of the fans are coming on when I turn on the machine....
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Old Feb 13, 2013, 06:35 PM   #4
kpgh554
macrumors regular
 
Join Date: Dec 2011
Quote:
Originally Posted by totallytech View Post
Hey,

I've not checked the invertor, but I have tried two complete lcd screens - the LCD's have the inverters installed so I'm guessing they are fine...

If the logicboard / mainboard has failed would the dvd drive etc still power on?

----------

I have noticed though none of the fans are coming on when I turn on the machine....
I think dvd drive and hdd powered by psu and only controlled by mother board and fans run by mother board, not sure but someone else may say different.
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