Wake Macbook from Sleep -> Screen Stays Black

Discussion in 'MacBook' started by mister donut, Jul 27, 2011.

  1. mister donut macrumors newbie

    Joined:
    Jul 27, 2011
    #1
    Every time my 2007 MacBook wakes from sleep, the screen stays black. Even though it's almost impossible to see, the screen is active, which lets me save open documents before shutting down. If I try to adjust the contrast, I can faintly see the contrast bars changing. But the screen itself stays black, same as if I had turned the brightness to 0/16.

    I've reset the PRAM and the NVRAM multiple times. Each time, it briefly resolves the issue. But once I finish this post, if I close the Macbook or it goes to sleep, the screen will stay black next time it wakes up.

    Any ideas? Thanks!
     
  2. Intell macrumors P6

    Intell

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    Jan 24, 2010
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    #2
    This happens to my mid 07 Blackbook as well. It started with Snow Leopard. Apple knows of the issue, but I don't think they'll fix it. Not sure if Lion fixes it.
     
  3. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #3
    Just discovered that if I wake the MacBook, then open and partially close the screen several times, the screen comes back on. Sometimes the screen only wants to stay on if the computer is mostly closed. Luckily it stayed on when I opened it all the way this time.

    Some kind of sensor related to screen position, then? I saw something about that here, although not quite like this since I wasn't searching specifically for that. I'll take a look when I get home from work. Still appreciate any other input. Thanks!
     
  4. Intell macrumors P6

    Intell

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    #4
    The sensor is called a "reed" sensor. Its a small magnet about the size of a pencil eraser. It located on top of the headphone jack area. It can detect the screen in the "closed" position when the screen is about one inch away.
     
  5. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #5
    Thanks for the great information, Intell.

    I'm not sure if my problem is caused by the reed switch, because if I open the display too much, it turns black. That sounds like the opposite of normal reed switch function. Right now, in order to use the display, I can't open it any more than about a 60º angle. Which is not very useful, nor easy to read.

    The screen still turns black if I close [or nearly close] the display, which sounds like normal reed switch behavior. Sleep still functions, which also sounds normal for the reed switch. [unless display auto-dim is controlled separately from the reed switch sleep function.]

    Since I can't open my display wide without it autodimming itself, are there other sensors / switches that could be involved?
     
  6. Intell macrumors P6

    Intell

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    #6
    Nope, the only sensor on the 07 Macbook that could change the screen is the reed switch. What OS is your Macbook running?
     
  7. unixperience macrumors regular

    Joined:
    Jul 21, 2010
    #7
    well is your lcd on? and just the backlight off? just put it under a bright light and if you can see your desktop then just the backlight is off.

    if its just the backlight.....................
    Put the computer to sleep again (command_option_eject), wait till the comp is TRULY ASLEEP (the little white light is pulsing NOT steady), then press a button or something to wake it up, then the backlight should be on. it happens to my comp randomly every now and then.... thats my fix
     
  8. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #8
    Okay, I just misunderstood how the reed switch works. I'm still kind of confused since I thought the reed switch would only darken the screen or go to sleep if the magnet in the bezel got close enough to the switch element near the headphone jack, but I'm just starting to learn about all of this.

    It's running 10.4.11.

    The LCD is on, I can use the display. The backlight is off if I open the screen up all the way. I can get the backlight to stay on sometimes if I keep the screen open only partway. Late tonight I'll try your fix, uniexperience, thanks.
     
  9. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #9
    Unixperience - Tried manually putting it to sleep, but unfortunately that didn't get the backlight working. Thanks, though.

    Intell, would you mind explaning how the reed switch causes the display to only work at certain angles, please? I admit that this is the first time I've researched a problem with a Mac, so my understanding is limited. So weird that the backlight doesn't work when the display is fully open.

    Any chance my problem could be with the inverter cable? Only just discovered that term, will research more when I have time in a day or two. But I appreciate any direction you can point me in.
     
  10. Intell macrumors P6

    Intell

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    #10
    The reed switch works by using magnets. When the magnetic field is close to the switch in the base, it tell Mac OS X "hey the screen is being closed or is closed". When the magnetic field leaves it tell the Macbook to wake.

    What you're describing doesn't sound like a problem with the reed switch. I do believe that it is caused by hardware, but not the reed switch.
     
  11. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #11
    Thanks, Intell - Any idea what kind of hardware? I've never opened up a MacBook before, but I'm willing to give it a shot.
     
  12. Intell macrumors P6

    Intell

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    #12
    I'm guessing the inverter board or inverter cable. The the backlight itself could be going bad. All of these things are difficult to replace in a Macbook. They require it to be almost completely disassembled.
     
  13. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #13
    Thanks for your help, Intell. Researching the inverter and its cable right now.
     
  14. unixperience macrumors regular

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    Jul 21, 2010
    #14
    yes, in that case i too suspect its the inverter cable (not board) the reason for this is because it still works at certain angles. it's old and probably has a short in it.

    Think of it like an old pair of headphones, where only one ear works, but if you wiggle it enough the other side starts working, same idea. the speaker is good, the jack is good, just the cable is bad

    in any even i highly recommend this site for all your repair needs http://www.ifixit.com/Browse/Mac
    its great and in depth with step by step instructions with pictures :) good luck mate
     
  15. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #15
    Thanks, unixperience - The headphone analogy fits well with what's happening right now. I actually ended up on ifixit a few days ago to order a used inverter cable. Should arrive tomorrow, I'll post back with how it goes.
     
  16. mister donut thread starter macrumors newbie

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    Jul 27, 2011
    #16
    New inverter cable solved it. Thanks again, unixperience and Intell
     

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