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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.

    EDIT:
    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.

    https://drive.google.com/open?id=1JhGOXDqLW7IkhAkT19vHQTASBkqheg2m

    Here a picture of the connector area.

    https://drive.google.com/open?id=19GEw8m7rQYVjGF16gWJnQARXUrJY-gPz

    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.

    https://drive.google.com/open?id=1CsCj8FVd3TVI-as1b2CGPahVAc0bcd04

    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.

    https://drive.google.com/open?id=1WZrQ4WYQJy0QxZ3r0l_XblW4hVvGG6wn
    https://drive.google.com/open?id=1pAFgLo1WiV2Y0Kk1BEJjfE9D8Rokn2Zc

    Is there anybody who could guide me to the solution, by pointing out the possible fuses?
     
    Last edited: Dec 9, 2017
  3. Napalm_Death

    Napalm_Death Newbie

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    Do you know how to check continuity in fuses with a multimeter? Check P02 and similar fuses on the motherboard. on the lcd check the white ones, look like fuses to me.
     
  4. postfire

    postfire Newbie

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    hello anyone!!
    please help for my problem plz?
    i have a laptop clevo W251HN (turbo x) and it no backlight for the screen
    the screen is ok tested to another laptop
    maybe it has problem in fuse on backlight but i dont know where is the fuse on the motherboard for this laptop
    please can you help me to find the fuse?

    thank you!!
     
    Last edited: Jan 20, 2018
  5. zumnao

    zumnao Newbie

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    You can get a multimeter and start testing all fuse and little smd resistances, specially around screen plug on mother board.
    Check continuity on both poles (sides), if you get continuity fuse is right, if there is no then bingo.

    Good luck!

    Enviado desde mi SM-A520F mediante Tapatalk
     
  6. postfire

    postfire Newbie

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    finally i found the fuse and fix it
    the backlight screen is ok now

    i post photos to help another users
    thank you!!

    [​IMG]

    [​IMG]
     
    Last edited: Jan 22, 2018
  7. pawel_

    pawel_ Newbie

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    Hi there. Thank You guys for all the useful information in this topic!
    I have a problem with the backlight in my old VAIO SVE14A1S6EW and thanks to your knowledge i am close to solve it.

    However, I would like to get an advice before I'll start soldering :)
    The place at mobo where the LED fuse is supposed to looks slightly different from the one posted a few years ago. Probably different rev. The elements are arranged in different order.
    Could you please help me with identifying correct fuse to bridge here? Is it "S" ?
    I will be very grateful for any help.

    https://imageshack.com/a/img923/1294/2ckknO.jpg

    EDIT: Tried with the "s" one, and backlight is back. Info just in case anyone needs it in the future.
     
    Last edited: Feb 10, 2018
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