No Backlight on LED screen

Discussion in 'VAIO / Sony' started by nebage, Sep 27, 2011.

  1. dinsdale79

    dinsdale79 Newbie

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    Hi, I have a problem with my asus zenbook ux31a. A friend of mine replaced a faulty power jack for me. After that while assembling the laptop I connected the LCD strip with the battery plugged in. I've heard some cracking noise and now backlight is gone.
    I showed the laptop to two different "laptop repair specialists", but it turned out they're not really that good. One told me that there's something wrong with the motherboard, but he doesnt know what (he checked all the fuses he said). The other said the led backlight is faulty and I have to replace the whole upper lid.
    Is damaged baclight itself possible in my case? Or it's rather the motherboard?
    Another interesting thing is that the laptop doesnt do anything after I close the lid, eventhough I set up in win10 that it should hibernate after lid closing. So it got my suspicious about the reed sensor. But the keyboard is working fine. Faulty reed sensor would block backlight and the keyboard, right?
    Also I can't power up the laptop normally. Every time after shut down I have to disconnect the battery, reconnect it and then plug in the ac adapter, then it starts automatically without even pressing the power button.
    Befor that unfortunate laptop assembly everything was working fine.
    Any help would be greatly appreciated.

    I checkd LVDS pins. Here are the values:
    pin 8: 19V
    pins 13 and 14: 0V
    pins 18,19,20: 3.3V
    Looks like faulty U4501? Anyone knows correct values for pins 13 and 14?
    [​IMG] [​IMG]
    Last edited: Sep 20, 2017
  2. SjoerdG

    SjoerdG Newbie

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    Hi everybody.

    incredible handy forum you have here. I searched the history of this thread in the hope
    of seeing the motherboard of my Vaio coming by, but no luck. Therefore I am writing this post.

    I purchased a Sony Vaio PCG-81313m (used but in great condition) for my fiancé as
    an extra Christmas present because her old notebook broke down. Unfortunatly the screen got
    cracked during transport.

    I installed a new screen, but hasty to do it while she was out of the house,
    forgot to take out the battery. Now the backlight does not function any more.

    So the model name is PCG-81313m, the product name is VPCF24P1E.
    Mainboard is the MBX-243 V081-MP_MB Rev 1.1. It has a 16,4" Full HD LED screen.
    The screen has a 40 pin connector, but no separate backlight connector.

    Here a picture of the front of the mainboard, with the connectors marked. The 40 pin connector
    on the screen leaves the screen area as 1 cable, but the cable is divided on the motherboard
    where it connects to those 2 plug-ins.

    Here a picture of the connector area.

    And a picture of the backside. Red are the connector area's on the other side.
    I did not paint over any writings or diode's/fuse's.

    Here also a picture of the backside of the screen, and the connector area on the screen.
    I noticed there is also a small fuse on the screen, so included this picture to be sure.

    Is there anybody who could guide me to the solution, by pointing out the possible fuses?
    Last edited: Dec 9, 2017 at 4:56 PM

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