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  1. #1

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    Default iMac G4 black screen. VGA out working. LCD backlight failure?

    Today I managed to kill my old imac whilst migrating data to the new 24inch model.

    I was using firewire target mode (or trying to as it would not recognise the internal HD but did recognise the external) when rebooting the old imac resulted in a black screen.

    I reset the PRAM which resulted in a long tone, the usual chime and then the black screen. I turned the black screen into the light and saw the faintest outline of the login menu. I typed in my password and I managed to log in.

    I can control the computer using remote login, and also via an external monitor.

    The only problem seems to be a lack of backlight.

    I have reset the PMU (twice) to no avail.

    I tried getting the apple hardware test running on the old imac but it refuses to provide me with that option when i reboot holding down the option key during startup.

    So I am now at a loss as to what to do. Have I killed it proper, or is there some software/settings voodoo I can do with it to try and get it going again.

    Any suggestions appreciated.

    Thanks
    Len

  2. #2

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    sorry its a 1.25GHz imac g4 with extra RAM that takes it to 768MB.

  3. #3
    leon's Avatar leon is offline That TAM guy

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    If the backlight is dead, then it is hardware. No amount of PMU resetting will bring it back from the dead. Seems like it was just coincidental that it occurred during the transfer of your files. As far as I can see it you have 2 options.

    1) Use it as a headless system and control via Screen Sharing on your 24"
    2) Attempt to repair it by purchasing a replacement backlight from the interwebs. I have no idea which parts you will need though. It could simply be that your fluorescent tubes have gone, or the voltage board that is supposed to fire them up could have blown. I am not sure if you can even replace the backlighting in an iMac G4. You may need to replace the entire screen unit as a single part. $$$$$$$
    Something about Jimby.

  4. #4

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    hi

    further googling suggests that it is a dead inverter. Cost about $80 USD on the web. Pretty simple to install apparently.

    I would imagine thats cheaper than new monitor, or a more elegant approach at any rate.

    now that my new imac has taken over photo and music management, what good uses could a headlessimac have in a home network? Some sort of server? atime machine server perhaps?

  5. #5
    leon's Avatar leon is offline That TAM guy

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    I would use it as a backup server for iTunes and iPhoto. If mine blew I would try the inverter board first. If that didn't work, then I would try purchasing a replacement head for it.

    Check out this site. They appear to have a bunch of stuff for reasonable prices.
    G4 iMac USB 2.0 Parts
    Something about Jimby.

  6. #6

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    Thats the one - Inverter Assy for iMac USB/17"Flat Panel #922-5298

    worth a shot

    Thanks Leon

  7. #7

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    Dude be careful

    It could be the inverter, could be the cable from the inverter to the LCD, could be the logic board connector not supplying power to the inverter

    Trades: Clockwork, applecollector, Amzy, Brains, chris, samuelclarke, mrldigitalmedia
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  8. #8

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    hmm okay, will call repair centre to get their opinion as to whether its worth getting diagnosed properly

    cheers
    len

  9. #9

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    If you peer really carefully into the LCD and maybe shine a lamp onto it, can you see any picture at all? If so, then the inverter is most likely dead.

    If not, then it could be a bunch of things and probably not worth fixing.

  10. #10

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    Rip the guts out of it and put it in a tower case?
    Macintosh Portable

  11. #11

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    Quote Originally Posted by ~Coxy View Post
    If you peer really carefully into the LCD and maybe shine a lamp onto it, can you see any picture at all? If so, then the inverter is most likely dead.

    If not, then it could be a bunch of things and probably not worth fixing.
    Quote Originally Posted by lenman74 View Post
    ... when rebooting the old imac resulted in a black screen... I turned the black screen into the light and saw the faintest outline of the login menu. I typed in my password and I managed to log in....
    The inverter maybe.

  12. #12

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    yes I think it is the inverter as well

    I decided today to use it headless as an appletv using frontrow

    its been ages since I luanched frontrow and I just realised tonight it was broken and wont work. I suspect some apple update broke andrew escobars enabler.

    in any case would frontrow 1 (ala tiger) be able to access itunes from another computer over wireless? From memory I you can only access whats on the hard drive. Would an alias to the new imacs itunes library help?

  13. #13
    astr0b0y is offline Banned

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    Do what I did. Rip the monitor off and use it as a headless torrent bitch.

  14. #14
    Wally's Avatar Wally is offline King of the Carrot Flowers

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    Quote Originally Posted by astr0b0y View Post
    Do what I did. Rip the monitor off and use it as a headless torrent bitch.

    Why would you bother ripping a perfectly good screen off a working computer with a sick inverter board?

    Wally

  15. #15

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    Well an iMac G4 will fit into a bit less vertical space and be a lot less unwieldy with no screen on.

  16. #16

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    Yeah that backlight power unit for LCD's usually costs around $400-$800 to replace on alot of LCDS. Well thats how muhc it was about 2 years ago when I was doing tech repairs.

    If you can still see the image, its almost certainly the power unit for the LCD backlight.
    ** iMac 3.4ghz QCi7, 12GB RAM, 1TB HD, 6970 2GB **
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  17. #17

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    Quote Originally Posted by wally4000 View Post
    Why would you bother ripping a perfectly good screen off a working computer with a sick inverter board?

    Wally
    Im not.

    I want to use it with a VGA monitor/TV until I can get around to getting the part from the US and trying to fix the inverter board which I have seen online for about USD$70.

    Could be a couple of months so in the meantime, will try to run it with an external display.

    I checked out front row 1.0 on my macbook and it will pickup the shared music files from the new imac, but not the videos or photos. So running Tiger on the imac wont turn it into an AppleTV equivalent.

    Sounds like I will need to update to Leopard to get Frontrow 2 for its "sources" capability. Though I am not sure that it will show shared iphoto libraries and videos from the new Imac.

    Anyone know if the new front row can do that?

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