White Screen issues. Tried everything, even this forum!

OK, iMac Late 2009 - White Screen Problem

Caution: Lengthy notes - (Skip toward bottom to read current situation and refer back to what I have tried)

Have a buddy that gave me his iMac and asked that I fix it for him.

Symptoms were that it would not start, gray screen, Apple and a Bar.

Tried all of the known answers:

  • Tried Option in Target disk mode from a second iMac, nothing
  • Started in D: nothing
  • Reset the PRAM, OPT-CMD-P-R, got second tone
  • Tried all USB ports to verify that keyboard was working
  • Removed the screen, blew out the computer, then pulled and reseated the RAM
  • Target disk mode - no, bar and Apple
  • C - white screen only
  • D - Hard Drive clicking, Hardware test came up, no trouble found

I suspect the HD may be full at this point. Hard drive seemed to stop making noise after trying to boot, still did not start

  • Tried starting from CD, nothing, bar and apple present
  • Target mode again, nothing
  • Option key on startup, HD and CD showed, tried starting with CD, locked up

Did the same process but tried starting from HD, locked up

  • Reset PRAM - didn't work
  • Pulled the Hard Drive out of the iMac and installed it into a slot on my Mac Pro
  • 8 Partitions showing on the completely full hard disk! Ran disk utilities but it wouldn't work. Ran Drive Genius and got an error on all of them.
  • Ran Disk Utilities First Aid again and it appeared to work this time
  • Tried starting in Safe Mode (Shift/start) - nothing
  • CMD-S, single user mode, yes it came up, didn't know what to do at this point
  • Cmd-SHIFT-V, safe mode plus verbose mode, nothing

Created a restore image of OS X 10.6 Snow leopard on a thumb drive, Option start and got nothing

  • CMD -S again entered fsck -fy a dozen times, no luck
  • Tried resetting the PRAM again, nothing
  • Tried deleting multiple APS in Single user mode, no work!
  • Reset SMC

Tried some of the above steps multiple times. After this point I stopped keeping notes.

Took the machine apart, installed a new hard drive and tried installing a new OS, would not work.

Took out the CD, Hard Drive, power supply, mother board, lower right cooling fan, blew out a lot of dust around the vents and installed a new PRAM battery (button)

Was able to hook up my 2007 iMac and start the 2009 iMac (problem) in Target mode. After a couple of tries was able to get the OS installed on the problem machine from my 2007 iMac. Still would not start on its own.

I was able to start the problem Mac using Option start with my 2009 Mac in Target disk mode. My iMac screen now showed up on the problem iMac! Still would not start on its own

I was also able to start up my iMac using the Option startup with the problem iMac in Target disk mode. Ran disk utilities and verified disk was ok,

CURRENT SITUATION

OS on the iMac is installed and it works on a separate iMac using Target disk mode on the problem iMac and starting with Option on the 2009 iMac

On startup the problem iMac still displays a white screen and doesn't start.

If my mother board wasn't working, I would not have been able to start the computer from another computer in Target Disk Mode

If My graphics card wasn't working, I shouldn't see the Target Disk Mode icon?

The HD has been verified on a 2007 iMac and a 2009 Mac Pro and it has a fresh install of OS X 10.5 Leopard

I am out of ideas.... Can anyone help me here???

Answered! View the answer I have this problem too

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You do need to be careful when swapping HD's around or installing new ones. Remember these older system's need a SATA II (3.0 Gb/s) drive or one that auto senses the systems SATA ports I/O speed. Many newer drives are fixed SATA III (6.0 Gb/s) and won't play nice in your system.

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As to your problem here, I've seen this problem before!

It almost drove me to pull out my hair as things appeared not to add up as you have noted you could get the screen to show up when you put your working systems drive in target mode.

OK heres the deal: The logic board has support chips which interconnect the different parts of the system together. The chip here thats in trouble is the North bridge chip.

You might be able to find someone to repair your logic board or you'll need a new one. Here's the Apple P/N's for the logic bds:

  • 661-5305 - 3.06 GHz Integrated Graphics
  • 661-5306 - 3.33 GHz Integrated Graphics
  • 661-5307 - 3.06 GHz MXM (graphics card needed)
  • 661-5420 - 3.33 GHz MXM (graphics card needed)

Graphics card:

  • 661-5308 - ATI Radeon HD 4670 256 MB

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I should point out you really need to redo the drive. Bring it down to one or two partitions.

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I too have had this problem of Everything having to work and it can be a nightmare. The way i finally starting solving it was to be able to switch out parts on a known working machine. So i have several machines just for testing parts.

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Tad Browning will be eternally grateful.
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