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Laptop TFT cable extension, strange problem

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  • Laptop TFT cable extension, strange problem

    I want to use a JVC MP-XV941 Laptop for my new install, almost everything is finished and working but I got a strange problem with the display cable extension. I already read the FAQ-thread and whatever else I got as search-results but couldn't find a solution.
    The screen is a LTM09C362W Toshiba/Matsu****a TFT (8.9" Widescreen 1024x600), already searched for a datasheet or any more precise specifications without success.
    There are four shielded pairs of wires (two wires in one shield) and four non-shielded single wires running from the mobo to the screen (inverter got extra cable) with the four non-shielded wires all being ground. So probably itís a LVDS connection but i don't know where the display gets its power from, the shielded wires are really tiny and it doesn't make sense to run power through shielded twisted pair wires.
    Basically for just extending the cable I don't need to know whatís running through which wire but here's the problem:
    I soldered nine short pieces of wire to each end of the original cable (one for each shielded wire and one for the four ground wires) and then soldered a rj45 plug to them. I use a cat5e patch cable to connect the to rj45 plugs with ground running over the shield (just like on the original cable).
    Powering on the laptop results in no picture and the laptop trying to boot again and again (the sound and the light flash on beginning of boot sequence are repeated) till I switch it off by holding the power-button for a few seconds. same behavior without anything plugged into the rj45 plug but without the display cable plugged in at all (original connecter removed from mobo) the laptop boots up normal (as far as I can tell from hdd access) and powers itself down by a short press of the power button (configured it to switch the laptop to suspend to disk) as normal.
    I got only one explanation for this, there is a sensing pin for the plug on the mobo so the laptop knows, that the screen is connected and then it refuses to boot unless it can find the tft. But then it should work with the screen being connected by the extension cable...
    I checked the cable multiple times, all wires are connected and there is no short circuit between the signal wires.
    I don't know what to do now, maybe somebody here has some knowledge about LVDS or just any idea what could cause the problem. I'd appreciate any help.

  • #2
    Originally posted by predator1
    I want to use a JVC MP-XV941 Laptop for my new install, almost everything is finished and working but I got a strange problem with the display cable extension. I already read the FAQ-thread and whatever else I got as search-results but couldn't find a solution.
    The screen is a LTM09C362W Toshiba/Matsu****a TFT (8.9" Widescreen 1024x600), already searched for a datasheet or any more precise specifications without success.
    There are four shielded pairs of wires (two wires in one shield) and four non-shielded single wires running from the mobo to the screen (inverter got extra cable) with the four non-shielded wires all being ground. So probably itís a LVDS connection but i don't know where the display gets its power from, the shielded wires are really tiny and it doesn't make sense to run power through shielded twisted pair wires.
    Basically for just extending the cable I don't need to know whatís running through which wire but here's the problem:
    I soldered nine short pieces of wire to each end of the original cable (one for each shielded wire and one for the four ground wires) and then soldered a rj45 plug to them. I use a cat5e patch cable to connect the to rj45 plugs with ground running over the shield (just like on the original cable).
    Powering on the laptop results in no picture and the laptop trying to boot again and again (the sound and the light flash on beginning of boot sequence are repeated) till I switch it off by holding the power-button for a few seconds. same behavior without anything plugged into the rj45 plug but without the display cable plugged in at all (original connecter removed from mobo) the laptop boots up normal (as far as I can tell from hdd access) and powers itself down by a short press of the power button (configured it to switch the laptop to suspend to disk) as normal.
    I got only one explanation for this, there is a sensing pin for the plug on the mobo so the laptop knows, that the screen is connected and then it refuses to boot unless it can find the tft. But then it should work with the screen being connected by the extension cable...
    I checked the cable multiple times, all wires are connected and there is no short circuit between the signal wires.
    I don't know what to do now, maybe somebody here has some knowledge about LVDS or just any idea what could cause the problem. I'd appreciate any help.
    there is a reason why the forums are full of such posts with the answer being: can't be done.

    the maximum lenght for such connectors is just a few inches. shielded or not, you won't get much out of it.
    Welcome, cdm.
    You last visited: 09-13-2006 at 02:42 AM
    Private Messages: Unread 0, Total 3.

    Wow.. how things have changed in 4 years. Gone are the days of mcgyver and datalux

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    • #3
      Originally posted by cdm
      there is a reason why the forums are full of such posts with the answer being: can't be done.

      the maximum lenght for such connectors is just a few inches. shielded or not, you won't get much out of it.
      No, it isn't. Even if the LCD was connected via TTL, it can be considerably longer than a few inches. Just thought I'd bump this so the OP can get some other opinions, I'm personally not sure what's wrong.

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      • #4
        Thanks for bumping the thread, fortunately I just found the problem and it seems to work now (got to wait for the new plugs to test it with extension cable).
        The ground wires had tiny supply voltage wires in them (just like the shielded signal wires) and I didn't see them, quite embarrassing
        After testing I will post the result.

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