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Prob with 4x20 lcd: blank screen...

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  • Prob with 4x20 lcd: blank screen...

    Well I just got my 4x20 backlit lcd from eio.com...and I just soldered it using eio.com's schematic combined with this page: http://www.geocities.com/krebnarb/lcdguide2.htm ...but it doesn't seem to be powering up correctly. I should be seeing 2 bars, but all I notice is when I turn on the computer, I notice the backlight lights up ever so slightly...only barely noticebly. I checked my connections and soldering...I'm not worried about the parallel port (yet) as I want to get the power prob fixed first..

    Any suggestions? I have followed the schematic except that (as per the above site's instruction) I replaced the 100 ohm pot with a 10 ohm resistor and got rid of the 10k pot (so pin 15 on the lcd aka VE goes to the 5V).

    I'm stumped. Any help is seriously appreciated.
    1999 Plymouth Voyager (That's right, big-pimpin' in a minivan.)
    PC built into console
    worklog with pics: http://www.mp3car.com/vbulletin/showthread.php?t=46359

    Some of my music: http://www.myspace.com/markquestion

  • #2
    I have followed the schematic except that (as per the above site's instruction) I replaced the 100 ohm pot with a 10 ohm resistor and got rid of the 10k pot (so pin 15 on the lcd aka VE goes to the 5V).
    I Think there's the problem..
    I have a 4x40 and it really needs the 10k pot
    otherwise you won't have control over the contrast.
    When I turn it to zero resistance, I won't see anything on the display, I have to set it all the way to 10k to see the characters on the display.

    Put in a 10k pot and use it all the way,
    should solve your problem.

    Hope this helps you out.

    Greetz
    Raas - The Netherlands
    ME: VIA epia m10000, lilliput 7', opus 150w, 80gb<br>
    GF: IBM Thinkpad 380, ext. 3.5 80gb, 40x4, PB-IR

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    • #3
      ergh...I put the 10k pot back in the mix...but I still get the same results..here's what the schematic looks like now..


      Any ideas?
      1999 Plymouth Voyager (That's right, big-pimpin' in a minivan.)
      PC built into console
      worklog with pics: http://www.mp3car.com/vbulletin/showthread.php?t=46359

      Some of my music: http://www.myspace.com/markquestion

      Comment


      • #4
        ARGH! I replaced the 10 ohm resistor with a 100 ohm pot so that I followed the schematic exactly...but it still doesn't work...when I turn the resistance down on that pot, the screen turns completely orange...so I know it's being powered...but it's still blank. When I turn the other knob, nothing at all happens. Help?
        1999 Plymouth Voyager (That's right, big-pimpin' in a minivan.)
        PC built into console
        worklog with pics: http://www.mp3car.com/vbulletin/showthread.php?t=46359

        Some of my music: http://www.myspace.com/markquestion

        Comment

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