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Laptop display connections etc

Discussion in 'General Electronics Discussion' started by nobelium98, Jan 10, 2015.

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  1. nobelium98

    nobelium98

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    Jan 7, 2015
    This all is for this project - https://www.electronicspoint.com/threads/portable-playstation-2-project.272126/

    So I got myself an old laptop and managed to get the screen out of it. Now I have some questions about the wires.

    http://gyazo.com/5e04015f7e9e3b9a35b7abd4bcca8a88 - Here is the LVDS connector, that much I know.

    http://gyazo.com/1356e62969104f92cf64eefa1aefe0b4 - Also there is this contraption that ends

    with this - http://gyazo.com/08218c53c759b906533039e88f2ef7f8

    and also this thing that was just mounted on the display housing and doesn´t do much I guess. Id still like to know what that is for. http://gyazo.com/015b52966acb4ca207c65a10a59bcf51

    My guess is that these have something to do with powering the display. Anyway if they are then that is going to be a problem because Im planning to use this controller board - http://ebay.to/1tQE10R which already needs a power input and I was guessing I could power the display through LVDS also. Or is the power only meant for the controller board signal processing?
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Right. It probably also carries power to the TFT driver circuitry.

    That's the CCFL backlight power supply. It generates the high voltage for the cold cathode fluorescent light that backlights the display. The connector carries power and control signals (normally an ON/OFF signal and a brightness control signal). Look for markings on the CCFL power supply board itself and try Googling the part numbers. I doubt you'll find documentation on it; you may be able to get documentation on the ICs that are used in the power supply, then figure out the connector pinout from that. You may also be able to figure it out from how it's connected at the laptop. If the laptop still works, you can measure the voltages on the connector pins and try to figure it out that way.

    That looks like a microphone, to go with the webcam.
    The TFT driver circuit gets its power through the same connector that the LVDS pairs go through. You'll need to adapt that connector to the connector on that controller board - I guess it's the 30-pin header at the back left? I don't think there's a standard pinout for the laptop end of the LVDS cable so you'll probably have to do some figuring out. Can you upload a good clear picture of the TFT driver circuit board (on the back of the panel) in the area where the LVDS cable connects to it?
     
  3. nobelium98

    nobelium98

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    Jan 7, 2015

    here are some pictures of the areas on the back of the display that has any little piece of information about something:

    http://gyazo.com/0000534f07b306a46702e58febf4cf9f

    http://gyazo.com/f658c7023ebc6a3431d9d0bff819ed40

    http://gyazo.com/0460b1d5c978e39cb03d0fa134656c91

    Also the LVDS connector seems to have the same amount of pins than on the controller board but my connector seems to be smaller. Also there is http://gyazo.com/dd9d19ab7c817476f9da1bbb94054a68 this contraption included with some other controller boards that seems to be the CCFL backlight powe supply. On my chosen controller board this isnt included but there is a connection that says http://gyazo.com/dcf089444333eaf80d421fed7b79fe9f and Im guessing thats for connecting to CCFL power supply. But my connector from the CCFL psu has 8pins instead of 6 on the board...

    I have heard that you have to contact the seller and tell you specs and they will tweak the controller board to the needed condition altough I think they wont get one with different connections´ sizes. I could get one with LVDS cable included so it would be 100% compatible with the controller board and the other end to the panel itself seems to be universal, no?
     
  4. nobelium98

    nobelium98

    10
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    Jan 7, 2015
    Do I need to power the VGA to LVDS controller board only or does the CCFL backlight psu need a separate power input also?
     
  5. Calmore

    Calmore

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    9
    Jan 19, 2015
    Generally, there are a variety of different connections for the motherboard end of the cable. A 30 pin cable *may* work OK on a motherboard with a 30 pin connector (Or might not).

    Have a look at the other end of the LVDS cable, where it attaches to the LCD. This will probably be an FFP type of connector and there is a lot more standardisation here, than at the other end. If you can get the datasheet for the LCD panel in question, as this will tell you what the pin out is. You'll then be able to get a cable made (Or buy one - ebay?) to interface the two together. (I seem to recall somewhere like Farnell did make your own LVDS cable kits)

    Similarly, you'll need a cable to go between the backlight converter and the interface board you have seen on ebay. It would be possible to wire the backlight control cable directly to a power source but then you'd lose the ability to control the brightness from the ebay board.

    HTH
     
  6. Calmore

    Calmore

    28
    9
    Jan 19, 2015
    In theory you'd apply power to the ebay board only. The LCD and backlight inverter should take power from the ebay board.
     
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