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My very first VGA cable

Discussion in 'Electronic Basics' started by Rene, Apr 20, 2004.

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  1. Rene

    Rene Guest

    I recently created a small 6" VGA cable for a little computer system that I
    am creating:



    http://home.comcast.net/~rene413/CC.JPG



    A couple of days ago, I asked a question regarding the creation of a VGA
    cable and there where some post pointing out some draw back that I may have
    due to not using a coax cable.



    Could someone tell me what are the drawbacks about using just plain soldered
    cables like I did? Aren't regular monitor cable created this way? Is there
    something I can do to improve on my cable quality?



    Thank you.
     
  2. John Larkin

    John Larkin Guest

    At 6", most anything will work. For longer runs, the RGB signals
    should be shielded and impedance matched, namely coax. Just wires in a
    ling cable run will look ugly on a computer monitor, but may be OK for
    a TV-resolution display.

    John
     
  3. soundman

    soundman Guest

    75 ohm balanced cable is the right stuff to use - normally a coax but it can
    be a twisted pair as well. But the problem with not using it only appears
    when the cable run starts getting longer than a few feet. The problem will
    appear normally as a ghost image to the right of the real image on the
    screen. It is caused by the signal reflecting from the end of the cable, to
    the beginning and back to the end so it appears as a faint image a little
    later than the first image. Using 75R cable will usually stop the effect
    appearing. However, there are some VGA outputs that don't drive the cable
    properly, so even with the right cable, the problem is still evident if the
    cable length is extended past 10 feet or so. I come across this problem
    from time to time but much less now than in the past. It seems that fewer
    manufacturers are cheating with their output drivers than before.

    Your cable length will have none of these problem, but if you aren't happy
    with the quality, you may find there is a problem with either the VGA output
    or the display itself. It won't be your cable as log as the soldered joints
    are good
     
  4. Rich Grise

    Rich Grise Guest

    No, the video is single-ended. A twisted pair will work, and just ordinary
    wires will work, and seeing the little link in the little link ( ;-) ), it
    certainly wouldn't be worth it to strip, tin, and solder six ends of 3/16"
    coax. Been there, done that. :)

    Until I saw the pic, I thought '6"' was a typo. :)

    But Rene, you're the one on the ground - how _does_ it work?

    Cheers!
    Rich
     
  5. Rene

    Rene Guest

    But Rene, you're the one on the ground - how _does_ it work?

    The cable actually works pretty good, the final cable length will be only 3"
    (half the size of what I have right now) so I expect to not have any
    problems there either.



    The reason why I posted this was mainly to see if I was missing something or
    simply to get general feedback.



    Thank you.
     
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