ralphf@not. said:
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?
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).
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/1502526_PM_EN.pdf
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.
http://www.caraudiocentre.co.uk/productimages/zoom/3-5mm-phono.jpg
*******
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 imageshack.us 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.
HTH,
Paul
