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    No screen backlight on MSI GT783 clone

    Discussion in 'MSI' started by johnbb, Oct 13, 2018.

  1. johnbb

    johnbb Notebook Consultant

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    Hi all,
    A friend of mine showed me his Medion Erazer X7813 (MSI GT783 clone) and the laptop works perfectly but there is absolutely no backlight on the internal screen.
    I thought at first that the panel was dead so we changed it but the problem is still there. So we change the LVDS cable and yet, no screen backlight.
    I heard that a blown fuse might be responsible for a no backlight issue.
    Does anyone has the schematics of the MS-1761 MSI motherboard?
    I'd like to know which one is the fuse connected to the LVDS socket.
    Thanks
     
    johnbb, Oct 13, 2018
    #1
  2. Danishblunt

    Danishblunt Guest

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    https://www.informaticanapoli.it/download/SCHEMIELETTRICI/MSI/MSI laptop schematic diagram.PDF
     
    Danishblunt, Oct 13, 2018
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  3. johnbb

    johnbb Notebook Consultant

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    Hi,
    Thank you but this block diagram is meant for i855gme (pentium 4 gen)
     
    johnbb, Oct 14, 2018
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  4. AU4U

    AU4U Notebook Evangelist

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    Follow the traces?!
     
    AU4U, Oct 14, 2018
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  5. Falkentyne

    Falkentyne Notebook Prophet

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    LMAO !!

    As I said schematics don't exist for these laptops.

    If the panel used isn't the original panel the laptop came with, you won't have backlight control. PM SVET on MSI forums for help with this.
     
    Falkentyne, Oct 14, 2018
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  6. johnbb

    johnbb Notebook Consultant

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    Wilco! Thanks.
    Honestly I already changed LCD panels on laptops and never had any problem of that kind...
     
    johnbb, Oct 15, 2018
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  7. johnbb

    johnbb Notebook Consultant

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    Hi and thanks for your help.
    It was not software related, just like I thought. But it was not a fuse either.
    It turns out the LED_EN signal on the LVDS ribbon was stuck at 0V, for an unknown reason. Maybe there's something wrong with the ENE chip. I really don't know. But I noticed if I connected the LED_EN signal with the PWM signal (next wire on the LVDS ribbon), the backlight comes on and the screen then works perfect.
    So I just bridged the 2 wires altogether. Now I have a working screen, I can even control the brightness level via the keyboard. Only downside is that when I turn off the screen, the LED backlight stays on for 1 or 2 seconds, which gives me a creepy white screen.
    Apart from that, it works nicely.
     
    johnbb, Nov 16, 2018
    #7