Powerbook G4 screen stopped working

Discussion in 'PowerPC Macs' started by parendox, Jun 3, 2016.

  1. parendox macrumors newbie

    Joined:
    Jun 3, 2016
    #1
    Hi all, wonder if anyone can help diagnose my issue. My powerbook g4's screen won't work - well it is working because the backlights come on but nothing displays on the screen. I think it's the LVDS cable but I'd like a second opinion;

    What happens is if I turn the Mac on the screen backlights come on but the screen is still black almost as if it's turned off. I've verified that it isn't the brightness control, after waiting for the Mac to boot into OS X I can control the screens brightness via the keyboard controls and can see the backlight dimming or brightening but the screen remains black.

    The display plugs into the logic board in two different places:

    invertor..PNG

    In the picture above, that cable on the left hand side of the powerbook which the manual says it's the inverter cable. And;

    lvds.PNG

    This one on the right hand side, called the LVDS cable apparently (note I took these pictures from the apple manual not my powerbook but they are identical, except my logicboard is green, not red).

    I did some tests and when the I unplug the LVDS cable and turn the Mac on the screen lights up grey like it normally should do but, stays that way (kind of expected given the cable is unplugged). I reckon because it does this and doesn't go black like when the lvds cable is plugged in, that the actual LCD panel is OK and a it isn't anything to do with the inverter board due to the backlights working.

    So I've narrowed it down to something to do with the LVDS cable, but I'm not sure. I mean, it could be the cable, it could be the board it plugs into on the LCD panel, or it could be the logic board connector? Does anyone have any clues as to what might cause the screen to be black (ie if damaged lvds cable causes this exact symptom, or perhaps it's something else that's related to the lvds cable).

    Thanks!
     
  2. 128keaton macrumors 68020

    128keaton

    Joined:
    Jan 13, 2013
    #2
    It might, I'm no expert. However, I have a spare cable from a DLSD PowerBook 17". It worked at some point, and it is yours for shipping.
     
  3. parendox thread starter macrumors newbie

    Joined:
    Jun 3, 2016
    #3
    That's kind of you, thanks you very much! Though are you in the US though? Only I'm in Europe so the shipping cost might actually end up being more expensive that if I were to simply buy one from my local Mac specialist (they usually have all sorts of parts like this in stock and sell them for peanuts, I got the case and a clutch cover for less than 20 euros).

    Still having said that I don't want to go hopping down there to to buy a cable only to come back and find out it wasn't the problem because they don't do refunds on used goods and also it's not particularly easy for me to get to at the moment. Though it probably is the cable but then again that's why I posted this topic to see if anyone else could say what the possible causes for the symptoms are.
     
  4. Adamscomputerrepair macrumors 6502

    Adamscomputerrepair

    Joined:
    Aug 9, 2015
    #4
    Hook it up to an external screen. If it comes on, it's the LVDS
     
  5. 128keaton macrumors 68020

    128keaton

    Joined:
    Jan 13, 2013
    #5
    Also, you didn't mention what PowerBook you have, its obviously an Alum, but you might also have the chance of a failed GPU, which can be sorta remedied. You can do a reflow, but that is a last-ditch effort, and hopefully it won't come to that.
     
  6. parendox thread starter macrumors newbie

    Joined:
    Jun 3, 2016
    #6
    Hmm, that's a good idea! I have to find a dvi cable (got one somewhere) then I'll try it.

    Ah sorry! I completely forgot to mention it was a DLSD "hi-res" 15" model (A1139). I think I know what a reflow is (cooking the chip or something so it melts solder?), not sure this things worth bothering to go to that sort of trouble. Still if I hook up a monitor to the dvi out and that shows a screen I suppose that would narrow it down at least to not being the gpu?
     
  7. 128keaton macrumors 68020

    128keaton

    Joined:
    Jan 13, 2013
    #7
    Reflowing isn't that bad. just remove the board, and pop it in the oven for a while. Yes, if its the same on the monitor, its a GPU flaw.
     
  8. parendox thread starter macrumors newbie

    Joined:
    Jun 3, 2016
    #8
    It's not the gpu. I found a cable and plugged it into my monitor and it displays the desktop fine. Next stop then is to get another lvds cable.
     
  9. parendox thread starter macrumors newbie

    Joined:
    Jun 3, 2016
    #9
    Just to follow this up, I got round to getting another LVDS cable and tried it and was pleased to find it all works fine now. I guess when I was fiddling around with the monitor I must have damaged the old cable around the hinge area since I can't see where else it's been damaged. Eh anyway that's that.
     
  10. eyoungren macrumors P6

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    Phoenix • 85037
    #10
    Over time the action of opening and closing the lid can wear down the cable. Then you get your problem.

    There are tight tolerances inside PowerBooks.
     

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