powerbook G4 12" back light not working

Discussion in 'PowerPC Macs' started by traviscope, Jul 21, 2009.

  1. traviscope macrumors newbie

    Joined:
    Jul 15, 2009
    #1
    ok guys, here the problem:

    the backlight on my 1.5gh 12" powerbook G4 will sometimes work and sometimes not. it will not cut out while in use, but when i try to wake it from sleep or on power up. it is completely random, and does not appear to be a short in wiring, as i can move the screen around while it is on and it does not cut out. i have replaced the dc-dc board and that did not change anything. My next shot was going to replace the LCD inverter board. is this a good guess? i just want to check with you guys before i buy it.

    i also tried reseting the pram and no luck.:mad:

    thanks
     
  2. California macrumors 68040

    California

    Joined:
    Aug 21, 2004
    #2
    It's either the inverter, the backlight itself or the video chip is coming loose.

    Google around.
     
  3. boiee macrumors member

    Joined:
    Oct 22, 2005
    #3
    I believe the 12 inch Powerbook did not have a backlit keyboard. At least mine doesn't.
     
  4. OrangeSVTguy macrumors 601

    OrangeSVTguy

    Joined:
    Sep 16, 2007
    Location:
    Northeastern Ohio
    #4
    He's talking about the LCD display. No 12" PBs had the backlit keyboard... damn you Apple.:mad:

    Since you took it apart already, maybe you didn't connect something back in tightly? It's probably just a little loose.
     
  5. traviscope thread starter macrumors newbie

    Joined:
    Jul 15, 2009
    #5
    alright, thanks for the info.

    i will tear it back down again tonight and have a look around. i'm usually very meticulous so i don't think i left any thing undone (but who knows!) i will check out the video card too.

    i don't think the back light it's self is going out because it works every now and then. or would a bad backlight go in and out too?

    thanks
     
  6. simonhead666 macrumors newbie

    simonhead666

    Joined:
    Sep 28, 2008
    Location:
    Uxbridge Ontario
    #6
    Don't be fooled thinking it's the LCD

    Hi
    I know this is an old thread, but I have since bought 2 1.5gHz Logic boards that were in old broken 12" PowerBooks with no screen.. both sellers told me that the screens were broken and the computer worked fine with an external monitor.. both had 'back light' issues with the LCD's

    It's the Logic board on both of them.. apparently there is a lack of 5V coming from the LogicBoard connector (PMU controller maybe) that will not power the Back light.. so If you loose BackLight on your machine.. don't be fooled into getting a used LCD from EBAY or craigslist thinking it will fix your problem.. your odds in repairing the problem are much more slim then if you had the same issue with a 15" or 17"..

    Just thought I would let you know :)
     
  7. California macrumors 68040

    California

    Joined:
    Aug 21, 2004
    #7
    Well I have my old 1.5ghz Powerbook 12" logic board that I personally pulled off one of the plugs off the board when I was trying to upgrade a hard drive.

    It worked perfectly with video etc., before this.

    If you can solder the plug back onto the board, (i have the plug) let me know because it has just been sitting here for months and months.
     

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