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Thread: IBM 4820 touch screen

  1. #1
    lez
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    IBM 4820 touch screen

    Well on the grounds that bigger is better I went and found one of the ibm 4820 touch screens on ebay, often used on shop counters / POS areas etc.

    If you get the 4820 4ft, it takes analog rgb (vga), and serial for the touch screen, power is 12-16 volt(yippee!).
    They also do usb, and DFP signal versions, make sure you get one that will work on your graphix card, as most of these POS units are digital.(vga)

    Problem?

    LOTS! AS YOU CANT BUY ANY DAMN CABLES!!!! IF YOU FIND THEM THEY COST MORE THAN THE MONITOR!!!!!!!

    the connectors are non standard, small 20 pin thing for the vga which vesa have decided is a DFP digital panal connector, and not designed for analog, so vesa website has only a digital signal pinout, ibm has no pinout, and after 6 hours of downloading pdf files from ibm I still have no pinout.....

    Does anyone have a diagram for a 4820 analog imput socket?

    Next option is to open it (very simple) and see what chipset is used for the A/D conversion, get a data sheet, trace input pins back to socket, and solder a long cable on as I cant buy a plug either....

    Then I have to work out the rs232 connections from the silly 8 pin socket they have fitted.

  2. #2
    cvi
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    Any of these connectors?
    take a pic of the connectors and the screen, and someone might be able to help you.
    Attached Images Attached Images  

  3. #3
    lez
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    Oh yes its the one marked digital only, thats why ibm are using it for analog vga........

    They do produce this screen in analog only and digital only versions, and use the same connector for each, no doubt in my mind thats to save money.
    Problem is I can only find how to connect it up for digital input, which is no good as this monitor is analog only and so is my gfx card!
    The vesa site has the pinout for the digital type, thats a vesa standard called dfp


    At this point in time its in bits all over the front room floor, I've taken lots of photo's, scanned the boards, googled away for hours getting datasheets for all its chips, now I have to work out how its all put together.(diagram style)

    It has a tmc 1203 (http://www.fairchildsemi.com/ds/TM/TMC1203x20.pdf) a/d converter so the rgb side is now under investigation, it has 2(2) 232cb serial converters so that will give some idea of where the rs232 is going for the touch screen, just not found anything for the h/sync v/sync yet.

    will try to get all this on web later.

  4. #4
    lez
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    just like to add ibm have got back to me on how to connect this monitor to a standard graphics card, and have two options, one is to /buy/ their cable, two is to /pay/ for tech support with my credit card.

    I'm still running on option 3, trace the signals back to the plug.

  5. #5
    lez
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    Ok I have the vga side working now got to win the fight with the touch controller....

    inside it has 2 rs232 converters, so it can support 2 channels of serial, but I dont know why....

    I have tried both and the software from the ibm/3m website, nothing working so far, if anyone knows of /any/ touchscreen software that works in XP with a screen on a serial port can you tell me where to download it, maybe it will see this screen etc as most serial software is fairly generic.

    What software is used on lilliput, thats probably good enough etc

  6. #6
    FLAC Skraggy_uk's Avatar
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    Probabley already been here but Is this of any use to you?
    4x4 in a turbo stylee.

  7. #7
    lez
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    yup started their, got them, says no screen detected.

    I think I have an rs232 problem between pc and screen but cant work it out.

    Boy I wish I could find a 4820 cable for an hour!

  8. #8
    lez
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    Just worked out the pinouts and posted them on the uk site, you can find them their.



  9. #9
    lez
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    Grief I'm still fighting with this damn display, beginning to wonder if touch side is dead etc and that why I cant build a working cable.

    But, as my cables are experimental having no diagram to follow, could be bad wiring.

    but if any one sees a cable or can buy a cable(cheap!) part number 07K6156
    or part number 10J0860 help me out here!

    even if its too far to ship etc its only the information needed to wire it.

    these things must have been sold by ibm in thousands, 12 inch epos units etc with serial touch, some one must have an old one somewhere.

  10. #10
    lez
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    And a year later I still have not got this to work!

    tonight is last attempt, kill or cure...

    going to start with rxd and txd from com2 and just connect to every pin on the socket in turn till the software says screen attached or I run out of pins.

    (or the mb com port dies!)

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