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ccfl to led upgrade questions/idea's

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  • ccfl to led upgrade questions/idea's

    this isn't really car related, but i'm already signed up here, so it's easier..

    recently my work has had a bunch of lcd monitors go bad out of warranty. i have ended up with a total of 2-15", 5-17", and 1-21" so far, i had have gotten a couple of them working, but i have a total of 3 of them have similar problems..

    note: all of these monitors were used for computer-based surveillance systems, and stayed on all the time, so heat very possibly played a part in their demise..

    the 21" starts up and the backlight works for about 3 seconds,but the backlight shuts off, but the display still works-- i assume this is either ccfl tubes, or a bad power supply section. i took the screen apart, and all of the components appeared to be ok visibly-- no swollen caps..

    some of the resistors looked a little crispy, but most checked out fine on resistance-- except one, which swayed all over the place when checking.

    also, there is some dark marks from heat around some of the coil's, transformers, and fet's, but it is to be expected..

    there is also a 17" that does a similar problem, and a 15 that one of the ccfl tubes won't light..


    if there are any trouble shooting ideas anyone has i am open for suggestions!




    my original idea was to replace the ccfl tubes with led's-- i was thinking some pre-made flexible strips that use plcc-2 led's for light output..

    the monitors were free, so cost really isn't a issue at this point-- as long as the cost-per-monitor stays under $50...


    the problem here is the power supply requirements-- most of the strips take 12v dc..
    i was thinking of using this strip:
    http://search.digikey.com/scripts/Dk...=365-1504-2-ND

    i was thinking i could build a quick circuit(tried googling for 120vac to 12v circuit schematics/diagrams, but only came up with 12v plugins..)-- adding some leads off the power cord connections, and using a full wave rectifier, and a 12v regulator(probably a sharp model with the on/off pin, so i can use a transistor to control the back light off the power light leads).
    but, i have never used a full wave regulator, but assume that it puts out more then 16-20vdc. i am quite sure that anything more would result in burning up the 12v regulator real fast.

    the limitations for this is that i would prefer to not have a separate plug-in for the backlight, i would prefer for it to be integrated into the monitor, but if that is the way it has to be, i can do it..
    My OLD 2001 Mitsubishi Eclipse GT:
    "The Project That Never Ended, until it did"


    next project? subaru brz
    carpc undecided

  • #2
    8mm wide on that LED strip might not fit. Even in a dual lamp assembly, 5-6mm is about all the room you have inside the LCD to work with.

    You can power the strips directly off the LCD controller or even the monitor's power supply. There are 5 and 12v DC taps available. You can even tap the 12v on the inverter side of the PSU.

    The power board/inverter assembly is AC in, but the inverter is driven off 12v DC post converter on the PSU side of the board.

    What are the models of the monitors in question?

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    • #3
      the 15's are AG Neovo F-415

      the 17's are AG Neovo F-417

      what i originally thought was a 21" is really a 19" widescreen... the front says Medion, the back says HANNS-G, model HW191D

      thanks for the help so far!! i'll look into locating a spot to tap into the 5v and 12v rails.
      My OLD 2001 Mitsubishi Eclipse GT:
      "The Project That Never Ended, until it did"


      next project? subaru brz
      carpc undecided

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