Picture gets blurry when using VGA splitter

Discussion in 'Amateur Video Production' started by ZalekBloom, Jan 6, 2007.

  1. ZalekBloom

    ZalekBloom Guest

    I purchased HDTV with VGA input entry and decided to have option to
    connect it to my PC.
    I bought VGA splitter and connect it to my PC.
    This is a simple draw what I did:

    Here is what happend:
    after I connected VGA splitter to PC and a PC monitor to a splitter -
    picture on PC monitor was OK.
    The moment I connected a second cable to a splitter (the one that goes
    to HDTV, nr 2 on the picture) - the picture on a PC monitor became
    very blurry. I made few tests - the picture on the PC monitor became
    blurry even when the connected cable was not connected to the HDTV.
    When PC is connected to a monitor through the splitter - picture on
    the monitor is OK.
    My question - why and how to solve this problem?


    ZalekBloom, Jan 6, 2007
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  2. Since you said nothing about what this "VGA splitter" is,
    it is difficult to offer any definite advice. If you want to
    actually explain what it is, we can likely help you.

    If this "VGA splitter" is merely a Y-cable with three
    connectors, throw it away and get a proper powered
    distibution amplifier. If your "VGA splitter" is already
    a powered distribution amplifier, then you need a
    better one.

    You simply cannot "split" a video signal with a passive
    cable. Not if you wish to retain any quality, at least.
    Also, the larger the screen, the more you can see any
    problems with the video signal, so the more critical to
    use quality devices/cable, etc. in the complete path.

    In the absense of the critical info, here are some general
    Use better quality cable(s).
    Keep the cable(s) as short as possible.
    The longer the cable, the more critical it is good quality.
    Avoid any "splices"/"adapters", etc.
    Use better quality distribution amplifier.
    Richard Crowley, Jan 6, 2007
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  3. ZalekBloom

    ZalekBloom Guest

    My VGA splitter is a simple Y-cable - this is the one I purcheased:

    Well - the distance between PC and the HDTV is not small - about 30
    feet. As matter of fact my project is more complicated - I need to
    connect 2 PCs to HDTV, but first I want to solve the "blurryeness"
    This is the full project:
    This is tha cable I am using in my project:
    It says about the cable:
    " 35ft Premium Tri-Shield VGA HD15 & 3.5mm Stereo Male to Male Combo
    Cable, Connects any VGA video with audio to any computer, switch or
    splitter with HD15/3.5mm stereo female ports. This premium combo cable
    eliminates clutter and improves cable management. Supports all VGA
    monitors including analog flat panel display, high resolution desktop,
    CAD and graphic workstations. It has color-coded connectors for
    error-free hook-up, triple shielding for maximum graphics performance,
    prevents signal loss, screen ghosting & loss of color and works up to
    200ft without a signal booster. Pin #9 is removed for universal VGA
    compatibility. This cable have matched impedance, PVC jacket, molded
    ends with thumbscrews and inner hood soldered 360 degrees to the
    connector for complete end to end shielding. Note: The stereo audio
    cable is 15inch on both ends. (Connectors: HD15/3.5mm Male to Male;
    Length: 35ft)".

    Can suggest a VGA amplifier? How I should connect it?


    ZalekBloom, Jan 6, 2007
  4. That gadget is a rip-off (IMHO) and is unsuitable for any
    but the most non-critical application. Some people think
    they shoud be illegal to sell. For the very reason you have
    discovered first-hand. What you are seeing is completely
    predictable from trying to use such a gadget. Hopefully you
    can return it for a refund.

    You cannot "split" video like you can do with audio or RF.
    Video must have a single 75-ohm load at the destination end.
    That kind of "Y-cable" puts TWO 75-ohm loads at the (multiple)
    ends, for a total of 37.5 ohms. That cuts your video in half
    all by itself, without also addressing the problem of multiple
    loads at different distances which is another source of your
    "blurry" video performance (multiple reflections from improper
    You can try cheaping it out with "Y-cable splitters"
    and inexpensive selector switches, I would likely try
    it myself. But don't be surprised to find significantly
    degraded video quality unless you use better-quality
    equipment in the video path. High-resolution video
    from computers is very much higher bandwidth than
    simple TV video and requires more serious ($$$)
    solutions to maintain the desired quality, particulary
    when viewing it on a big screen.
    That cable may be suitable, given a proper source.
    What happens if you plug that cable directly into
    your computer? If it looks good there, then your
    problem is the splitter and not the cable.
    Many people sell VGA amplifiers for a wide variety of
    prices. Radio Shack may even have them for all I know.
    Here are a couple (watch out for line-wrap)...



    Markertek has a whole bunch of them. The one above is just
    the first one in the list (and the cheapest). I would bet that
    it would solve your problem.

    There are many currently up for bid (or BuyItNow) on eBay.
    For example: eBay# 220068126159 Even one of those
    things at $12.45 is infinitely better than your "Y-cable".
    I might just buy one or two of those myself, They seem
    reasonable to me.
    They all have 1 input and two or more outputs. You can
    figure out how to hook them up just by looking at them.
    You would plug the output from your computer into the
    input of the VGA amplifier, and then each of the amplifier
    outputs to the corresponding destination.

    You may also find a "matrix switch" that would route your
    various inputs to your various outputs and will take care of
    the distribution amplification problem all in one box. But
    likely not cheap except maybe on eBay.
    Richard Crowley, Jan 6, 2007
  5. ZalekBloom

    J Brockley Guest

    VGA is an uncompressed format i.e. several 10s of mhz unlike component,
    svideo etc. Because of this poor quality cable or excessive length is going
    to be a severe problem. With the splitter you are using even an unterminated
    cable will still be putting on a capacitive load effectively knocking out
    the high frequencies. This would lead to the effect you are seeing. I
    suspect the only way this splitter is going to work at all is by using very
    short cable lengths.
    J Brockley, Jan 6, 2007
  6. ZalekBloom

    Franc Zabkar Guest

    It looks like the problem is with your Y-adapter. What you are
    effectively doing is terminating your 75 ohm source with a 37.5 ohm
    impedance (2 x 75 ohm devices in parallel). This results in
    reflections (ghosting) and a reduction in signal amplitude.

    The way that multiple studio monitors are connected is by daisy
    chaining them and terminating only the last monitor in the chain. All
    other monitors have their 75 ohm terminations switched off. If you are
    willing to hack your monitor, you might try to disconnect the internal
    75 ohm resistors. Otherwise purchase a distribution amp as suggested
    elsewhere in this thread.

    - Franc Zabkar
    Franc Zabkar, Jan 6, 2007
  7. ZalekBloom

    ZalekBloom Guest


    Thanks for your help. I ordered 2 VGA splitters from ebay - hope it
    will work.
    After receiving and installing it I will inform you guys about
    Thanks again for your help,

    ZalekBloom, Jan 6, 2007
  8. ZalekBloom

    Darkknight Guest

    what he said!
    Darkknight, Jan 7, 2007
  9. ZalekBloom

    Mike Ruskai Guest

    Get a graphics card with two outputs, and toss the splitter.
    Mike Ruskai, Jan 8, 2007
  10. ZalekBloom

    GMAN Guest

    Youd be much better off getting a late model NVIDIA or ATI video card that has
    dual heads. Almost all modern video cards have two outputs, a VGA and a DVI
    connector that can be used with simple $5 adapter to use as a second VGA
    GMAN, Jan 8, 2007
  11. ZalekBloom

    ZalekBloom Guest

    Well - I tried to do it cheap (I paid $40 for 2 splitters incl
    shipping) and as usually I am going to pay more...

    I purchased electronic 2 port video splitter PCI PC1400 400MHz and
    used it instead of my Y - cable. When I connect the VGA output to TV -
    the monitor picture still gets blurry, although not as bad as with the
    Y cable. But I notice another strange thing - while picture on the PC
    monitor look normal, the picture on the HDTV looks normal only in DOS
    screen or Win in a stretched mode, here are pictures I took:

    while in DOS regular mode:

    while in DOS i stretched mode

    while in Win regular mode:

    while in Win i stretched mode

    Any ideas why picture in Win regular mode is showed this way on HDTV,
    while on a PC monitor it looks normal?


    ZalekBloom, Jan 13, 2007
  12. Perhaps that is using a video mode that your HDTV can't display.

    My TV's manual has a chart near the back giving the supported
    resolutions - I definitely needed it in order to get my system going

    Now wait for a reply from someone who actually knows :)
    Gene E. Bloch, Jan 13, 2007
  13. One problem at a time. We assumed before that your
    TV actually works properly with computer video input.

    What makes you think your TV is not broken? Have
    you EVER seen a good picture out of it with the computer
    2 feet away and connected directly?
    Richard Crowley, Jan 14, 2007
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