Can't get PC to TV to work :-(

Discussion in 'Computer Information' started by ralphf, Feb 27, 2013.

  1. ralphf

    ralphf Guest

    I've recently been trying to get my PC signal to go through a TV down in the
    kitchen so I can use a wireless mouse from there and control the PC from the
    kitchen without having to go back up a few steps to the living room all the
    time. It works ok from the PC to the monitor, so I know that much of the device
    is good and also that it's getting power. But the TV doesn't show a clear
    signal. Something is getting to it because the snowy look of the screen changes
    when the signal cable is disconnected, but it doesn't show any sort of picture.
    It's an old TV and I'm using an addapter to go from the RCA output of the device
    to the coax input on the back of the TV. I would suspect the addapter except
    that the TV signal from the DVD player is using the same type and it works fine.
    Does anyone know what the problem might be?
    ralphf, Feb 27, 2013
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  2. ralphf

    Paul Guest

    This "diagram", shows the two sides of a TV set.

    A TV can have the inputs on the left (baseband video and audio). The yellow
    color of the video jack, is a hint that the input side is baseband.

    Or, it can have RF inputs from antennas. Of which there is a 75 ohm coaxial
    input for cable TV, or the older 300 ohm flat ribbon antenna (screw terminals) input.
    The right hand inputs, you sometimes use a 300 ohm Balun to 75 ohm coax,
    to connect an older TV antenna ("rabbit ears") to a newer 75 ohm RF input set.

    Mini-DIN 4 pin (S-VHS baseband)\____
    Red+White RCA audio / RF Modulator ----> 75 ohm antenna input or
    Channel 3 or 4 300 ohm flat ribbon
    Yellow coax (composite baseband)\___ antenna input
    Red+White RCA audio /

    Note that it's possible to confuse 75 ohm antenna input (not yellow in color),
    for the composite input which uses yellow plastic. The docs for the TV
    set may not explain the difference. The connector types will be different,
    with the yellow baseband one being RCA/Cinch (big pin in the center). While
    the TV is F-series and uses a thin wire for the center pin. But they're both
    coaxial, and with the right adapters, you could mix them up. (I own adapters
    that convert RCA to F-series and vice versa, so I could confuse them
    without too much trouble.)

    This device, converts from the left hand input format (baseband, not a TV
    station signal as such), to the antenna terminal input type (RF modulated).
    I use this device, when I connect my baseband-only DVD player, to my old TV
    set that has RF antenna terminals (just the 75 ohm input channel3/channel4).

    You have to determine, whether you're mixing "like with like". If you're
    connecting baseband, to one of the two antenna terminal types, that
    won't work. The RF modulator fixes that for you.

    If you connect composite (yellow) video from computer or mini-DIN 4 pin video
    from computer, to the TV inputs, sometimes the DC restoration doesn't work that
    well, the colors can be off, and the picture generally looks lousy. Run the
    computer output through the RF modulator, to make a much nicer looking picture.
    If you don't connect audio to the inputs of the RF modulator, then you'll
    get no sound out of the TV speaker(s). You can continue listening to the
    computer speakers if you want.

    Computer audio is 1/8" (3.5mm) plugs. TV uses RCA/Cinch connectors. You can find
    adapter cables, if you need something to connect a red+white coax cable set
    for audio. For example, I would use this, if connecting computer audio, to my
    RF modulator inputs.


    If the above isn't helping, please provide either more description
    of what your connectors look like, or a link to the TV manual on the
    web. You also have the option of posting a picture of the connector
    area of the TV set, on a site like or equivalent (like
    Picasa). Then post the URL here.

    The PC will not send a signal to the TV set if:

    1) The "impedance sensing" doesn't work on the computer video card.
    Some Display control panels, in the custom section, include a
    "force TV" check box, which turns on the signal for you. You can
    use that, if you've verified you're feeding composite to composite
    on the TV set.

    2) If you attempt to "mirror" output, for movie playback purposes,
    some video drivers neuter this (in an attempt to prevent the user
    from "copying" computer output). It's foolish, and the display
    control panel will tell you this, by virtue of the fact that
    two displays can't be enabled in there. So if you only see the
    one icon in the Display control panel, that can be the reason.
    Windows has disabled "mirror" modes, if they exist. On older setups,
    the TV outputs still worked.

    Paul, Feb 27, 2013
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  3. ralphf

    Roger Mills Guest

    Presumably the 'adapter' is an RF modulator, which provides the same
    sort of signal as would come from an aerial? If so, its output will be
    on a particular frequency channel, and the TV will need to be tuned to
    that channel.

    Have you done that?
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Feb 27, 2013
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