iMac g4 Help

Discussion in 'PowerPC Macs' started by jaydennz, Jul 30, 2014.

  1. jaydennz, Jul 30, 2014
    Last edited: Jul 30, 2014

    jaydennz macrumors member

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    Jul 30, 2014
    Location:
    Wellington, New Zealand
    #1
    Hi,

    I'm having big issues with an iMac g4 I recently upgraded the HDD, RAM and PRAM battery in and thought you guys could help.

    I installed a new HDD and 2 gb ram in it yesterday, applied the thermal paste and what not. I then booted into the installer and began to install OS X Leopard. This hung with about 1 hour to go. I turned it off after letting it hang for about an hour. I then tried again, this time I think it had a Kernel Panic ( black lines with white text on the screen, didn't take a photo though dammit). Tried one more time and this time it froze at the choose boot disk screen.

    Since then powering on simply turns on the fan and I think I can hear the hdd spinning but nothing on the display. If I hold on the power button I get one long tone. I tried all possible configurations of ram but this hasn't helped. The only thing I haven't tried is putting the old HDD back in.

    The red LED on the logic board still lights up so I believe it is still getting power. I have tried the logic board reset button on the underside of the mac.

    Any help with this problem would be much appreciated as I am stuck and I just bought it for a toy so am a little gutted I've possibly ruined it.

    Thanks,

    Jayden

    PS its a 1.25 GHz 17" imac G4 USB 2.0
     
  2. jrsx, Jul 30, 2014
    Last edited: Jul 30, 2014

    jrsx macrumors 65816

    jrsx

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    #2
    I'm wondering if it hasn't overheated.. this could cause the fans to rev on startup with a GPU failure. This was an issue I've read about on G4 iBooks, but I have no idea about G4 iMacs. Have you put all the original RAM and the old PRAM battery back in?


    EDIT: Here is a very similar issue to the one you have: http://forums.macrumors.com/showthread.php?t=1311704
     
  3. jaydennz thread starter macrumors member

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    Wellington, New Zealand
    #3
    I will give that a try when I get home and post back. Although I'm not confident as I don't get the start up chime, and it was working for a small time after the upgrade.

    Thanks
     
  4. jrsx macrumors 65816

    jrsx

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    #4
    Unplug it and hold down the startup button for 30 seconds or more, this may fix the startup noise. As for no video, I'm not certain as you saw it before, but it mysteriously stopped. Good luck!


    Another issue very similar: https://discussions.apple.com/message/10769619
     
  5. jaydennz thread starter macrumors member

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    Wellington, New Zealand
    #5
    Thanks for the tips,

    I tried putting the starting it up from the stock configuration. Still the same response. Tried the holding in the power button, no luck. Im going to put the old hdd in again, as that is the only non stock piece of hardware. Do I have to close it up every time I boot or can I boot with the base open just to check?

    Thanks
     
  6. jaydennz thread starter macrumors member

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    Wellington, New Zealand
    #6
    Put all the stock parts back in, still nothing other than the fans and a long flat tone. Might be a goner.

    Thanks for the help though
     
  7. fhall1 macrumors 68040

    fhall1

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    Dec 18, 2007
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    #7
    Did you go through some of the Youtube or ifixit videos? Make sure all the connectors are well seated? any pinched wires? RAM is properly seated?
     
  8. Intell macrumors P6

    Intell

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    #8
    The power button may be sticking. The long beep is what OpenFirmware does when it looks for an update after being triggered to look by holding the power button. The iMac G4 line never had a firmware update, but the ability is still there. When you turn it on, do not leave the dome open for more than 30 seconds or the CPU will overheat and burn out.
     
  9. jaydennz thread starter macrumors member

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    #9
    All the connectors seem to be seated properly except one which is a black cable with HH on it, it's taped at the end though which makes me think it was always like that, I certainly didn't pull it out.

    Thanks intell, I no longer get the beep if I stop the power button sticking :) but now I get nothing except fans and HDD spin. Is there a possibility I've corrupted the firmware by the aborted installation?
     
  10. jrsx macrumors 65816

    jrsx

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    #10
    It sounds to me like a fried graphics chip. Did you apply thermal paste correctly? Too much will cause it to overheat, too little will cause it to not conduct heat to the heatsink properly, also resulting in high temperatures.
     
  11. Intell macrumors P6

    Intell

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    #11
    It's unlikely the GPU is fried. That model iMac has the hardy GeForce 5200. If it would/did get too hot, the imac's fan would have become very noticeable and spun at a very high speed. The HH connector is for the internal Bluetooth antenna. If you don't have Bluetooth in that machine, it's normal for it to be disconnected.
     
  12. jrsx macrumors 65816

    jrsx

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    #12
    I just guessed it did because I've heard of some PPC Mac's fans spin and you (obviously) would get no display when the GPU is dead.
     
  13. jaydennz thread starter macrumors member

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    Location:
    Wellington, New Zealand
    #13
    Hi again guys,

    Tried everything I can think of but no luck, still nothing.

    Any idea how I can diagnose what is wrong with it?

    If the display is still functional and something on the logic board is gone then I will try the TMDS - DVI mod from Dremel Junkie's blog.

    Thanks again,

    Jayden
     
  14. jrsx macrumors 65816

    jrsx

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  15. Altemose macrumors G3

    Altemose

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    #15
    When you put it back together did you freshly apply new thermal paste?
     
  16. jaydennz thread starter macrumors member

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    Jul 30, 2014
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    Wellington, New Zealand
    #16
    Hi guys,

    No luck unfortunately. I did apply the thermal paste but I think I've diagnosed the problem. I think when I opened the machine I think the old thermal paste sort of glued the heatsink to the heat pipe( I hope that explains it) which lifted the heatsink off the logic board when I opened it. This caused it to overheat I think
     
  17. Altemose macrumors G3

    Altemose

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    #17
    If there is limited or no contact between the heat sink and logic board there will be significant overheating very quickly on a G4.
     
  18. jaydennz thread starter macrumors member

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    #18
    Yeah I figured that would be the case, unfortunately I booted it before I realised the issue. That'll mean the whole logic board is a gonner now right?
     
  19. Altemose macrumors G3

    Altemose

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    #19
    You could try fixing it and putting it together with special care. Intell would know how long exactly it would take to damage parts with that happening.
     

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