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Model A1200 with 2.16 or 2.33 GHz Core 2 Duo processor

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Won't Boot - 3 LEDs, no chime, keyboard not responding

I know, sounds like a repeat topic, but I've read (& tried) much of what has been posted. There are some super thoughtful posts, but nothing has helped my situation just yet. Here are the facts:

  • LED 1 is on when plugged in
  • LED 2 & 3 light up immediately when powered on.
  • LED 4 never lights up
  • There is NO CHIME
  • The 2 fans spin.
  • The HD spins.
  • The display is black and shows no life.
  • The wired keyboard is not responsive - THE CAPS LOCK won't even light up.
  • The CD drive won't accept a CD.

THINGS I HAVE TRIED:

  • Replaced the HD yesterday with a new one.
  • Completely disconnected the display.
  • Tried all the keyboard tricks at startup (but the keyboard is not responsive)
  • Reseated each of the 2 memory cards, including removing one, then the other, even swapping positions, one at a time and both at the same time.

WHAT I HAVE NOT TRIED:

  • Replacing the graphics card
  • Replacing the PSU or the GSU or the logic board

I'm definitely at the point where I'm close to calling it quits...don't want to spend too much more trying to get this dinosaur functional for my kids. Any new thoughts are most welcome. I have the machine open and ready for surgery!!!

Thanks much for any insights you might have.

Cheers,

David

Answered! View the answer I have this problem too

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Its worth noting that the 24" white iMac range suffered from 2 very common problems. Failed GPU and faulty PSU.

From the sounds of it, you may have an issue with the GPU.

Its worth trying to remove both ram modules, then power it on to see if you get a single loud beep. This indicates that its not too far gone to initialise the pre-boot test sequence. if it doesn't even do that, then the damage or the short is preventing it from completing that process.

Because of how common the fault is, i'd suspect the GPU is at fault, as the 4th LED is display related (LCD specifically) but at this point, it is just an educated guess. its hard to complete diagnostics without being in front of a machine, but i hope this proves helpful.

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David Mac Daddy will be eternally grateful.
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