Graphics corruption and no boot on iMac G5 ALS

Discussion in 'PowerPC Macs' started by LukeHarrison, Jul 28, 2015.

  1. LukeHarrison macrumors regular

    LukeHarrison

    Joined:
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    Location:
    Selby, UK
    #1
    So, I've been given an iMac G5 ALS, with a couple of issues. First problem, it doesn't boot past the Apple logo and spinning wheel. It will not move past this screen, and after a couple of minutes, the fans start spinning at full speed.

    At the same time, the graphics are corrupted, with lines down the screen, and green and yellow blocks in bands all over the screen.

    Video here:
    https://goo.gl/photos/huWSF2BH3Q4UWAsc8
    (the red lines going down the screen are quite difficult to make out in the video, but the other blocking is easy to see)

    I've taken the back off, and all the capacitors look fine, and the diagnostic LEDs light up as they should, so I don't know what's causing this.

    Could anybody shed any light onto this?

    Many thanks :)
     
  2. MacCubed macrumors 68000

    MacCubed

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  3. MagicBoy macrumors 68040

    MagicBoy

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    #3
    GPU or VRAM failure most likely, which means the logic board is basically a write off...
     
  4. MacCubed macrumors 68000

    MacCubed

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    #4
    Yeah, you could replace the GPU, but that would require specialist equipment
     
  5. LukeHarrison thread starter macrumors regular

    LukeHarrison

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    #5
    Tried booting into safe mode last night, that didn't work either. I've been trying to dig out my old copy of Tiger to see if I can boot into Disk Utility and check the disk, but if the logic board is a write off, is it worth it? How much is a new logic board? I've replaced them in later models before, and this one on the inside looks much easier to work on.
     
  6. MacCubed macrumors 68000

    MacCubed

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    #6
    Not too sure how much it would be as there are very few good ones out there anymore. I would try a reflow and see what that will do
     
  7. LukeHarrison thread starter macrumors regular

    LukeHarrison

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    #7
    Fair enough, thanks for the info. :) I'll give the reflow a go next week when I've a bit more time. Gives me time to get some thermal paste too.
     
  8. MagicBoy macrumors 68040

    MagicBoy

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    #8
    Possible - there were repair companies with BGA rework stations that were replacing the GPU on 2011 15" MacBook Pros prior to the belated repair extension. Given the age of the iMac G5 it's not really a viable solution - likely needle in a haystack stuff to find a the part, plus the labour would cost more than the machine is worth. Better to find a used logic board and swap that.
     
  9. MacCubed macrumors 68000

    MacCubed

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    #9
    Also it could be possible that the GPU isn't bad and it's just the solder. You could get the chip reballed and reflowed back onto the board
     
  10. MagicBoy macrumors 68040

    MagicBoy

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  11. MacCubed macrumors 68000

    MacCubed

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    #11
    Exactly, same goes for MacBook pros from 06-08
     
  12. California macrumors 68040

    California

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    #12
  13. LukeHarrison thread starter macrumors regular

    LukeHarrison

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    #13

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