[mythtv-users] TV-tuner signal interference problem

[Joseph H. Fry]

Try shielding your card with aluminum foil grounded to your case... just
make a cardboard box that will surround your card without touching it
and line it with foil in all the places that the foil wont come in
contact with anything and connect the foil to the computer's case... I'm
not gonna guarantee that this will help but it might reduce emissions
caused  by components within the case.  Also make sure you are using
RG-6 coax cable (assuming your in the us) instead of the standard and
lightly shielded RG-59 to help reduce interference with the cable
itself.

Computer cases are generally pretty noisy (electronically speaking) and
they can often cause interference.  The reason that your composite input
might be cleaner is that the electronic interference might not be of the
right frequency to disrupt composite video.

Joe

Just my 2 cents, take them for what they are worth... practically
nothing.

-----Original Message-----
From: mythtv-users-bounces at snowman.net
[mailto:mythtv-users-bounces at snowman.net] On Behalf Of Alexander P.
Petkov
Sent: Friday, May 02, 2003 12:23 PM
To: mythtv-users at snowman.net
Subject: [mythtv-users] TV-tuner signal interference problem

TV-tuner card is Avermedia TV98 w/remote.

I can't watch TV through the tv-tuner card anymore, because the video
has lots of diagonal lines, and the sound frequently disappears
altogether.

It started having a lot of picture noise (lots of diagonal lines) and
dropping sound during a scheduled MythTV recording session (the
problem 1st occurred within that recording). Every consecutive
recording has garbled picture and choppy sound. The file size is also
over twice as big as it what it should be (around 900MB vs the usual
370 MB for a 1/2 hour recording).

Also, now when I watch regular (live) TV with xawtv, the video
interference and sound problem is persistent. Even when I boot into
Windows, the problem is there.

When I switch to composite (to use the VCR's tuner), the picture and
sound is normal. So that eliminates cable reception problems. This
leads me to believe that the problem is hardware related.


These are the things I tried in order to solve it:

1. I removed the TV-tuner card and installed it in a spare machine.
The result--video and sound were clear when using the card's on-board
TV tuner. So I think that the card itself is not defective.

2. I put the card back in the original machine, the problem of course
came back.

3. I removed the computer from its' current location (away from other
equipment), tried watching live TV, the problem is there. So it has
to
be something within my computer causing the interference.

4. I changed the power supply, it was getting hot actually. The
problem did not go away.

5. I removed every other card, except the tv-tuner card and graphics
card. Nothing was plugged into the tuner card except the composite
cable. No improvement.

6. I moved the tv-tuner card as far away as possible from the
graphics
card, the problem is still there. Although the pattern of the video
noise changes.


All this leads me to believe that the tv-tuner card itself is not
defective, but I have interference problem within my computer. The
spare machine is only P233 MMX, so using it for a myth PVR box is not
an option.

What else could be causing the garbled video and choppy sound? I am
out of ideas. Besides posting to the forum, it looks like the only
other thing I could do is call Miss Cleo.

It would be easy if the card didn't work well in another
computer--then I would just change the card. But now, even if I go
and
buy another one , it looks like the problem will persist.

Do you have any ideas as to what can fix this? The only things I
haven't removed are memory, processor and peripheral HD and CD-ROM
drives.

I can't go back and watch TV without Myth. I simply can't. I won't!!

If needed I can grab some screenies to better illustrate the problem.

Any ideas are appreciated, thanks in advance.


Alex

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