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On 11/17/2010 03:46 PM, Christopher Meredith wrote:
<blockquote
cite="mid:AANLkTikpP5-9O6=FEZbLp5SJpvyMj2f4Np_79U2L-q-A@mail.gmail.com"
type="cite">On Wed, Nov 17, 2010 at 2:00 PM, Greg <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:greg12866@nycap.rr.com">greg12866@nycap.rr.com</a>></span>
wrote:<br>
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<div class="h5">On 11/17/2010 12:20 PM, Brian Wood wrote:<br>
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On Wednesday, November 17, 2010 10:11:58 am Robert
McNamara wrote:<br>
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On Wed, Nov 17, 2010 at 9:09 AM, Christopher Meredith<br>
<br>
<<a moz-do-not-send="true"
href="mailto:chmeredith@gmail.com" target="_blank">chmeredith@gmail.com</a>>
wrote:<br>
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I've been noticing this for a while now and finally
want to fix it.<br>
I'm noticing that on any content captured by the
HD-PVR, there is<br>
a thick band of discoloration that slowly moves up
or down the<br>
screen. It's very faint, and the effect is usually
just to make<br>
the "banded" area a shade lighter. In complex or
fast-moving<br>
scenes, it's virtually indiscernible. But you can
definitely see<br>
it in slow pans or dark scenes. I've tried using a
different<br>
component cable but it still happens.<br>
<br>
Does anyone have suggestions about resolving this?<br>
</blockquote>
It's good that you tried a different cable as that
would have been my<br>
first suggestion. I don't see anything like this, and
given you've<br>
tried another cable, my next inclination would be to
say try<br>
capturing off of a totally different piece of hardware
(ie, a DVD<br>
player, XBox 360, whatever) and see if things are
different. My<br>
thought is that your current STB and the HD-PVR
disagree in some<br>
fashion.<br>
</blockquote>
With NTSC, 60Hz. "hum" will show up as a single or
double bar moving<br>
slowly up through the screen (because the NTSC field
rate is not quite<br>
the 60Hz. of the power mains).<br>
<br>
If you replaced the cable with an identical one, it
might not have<br>
helped. You might try one with better shielding.<br>
<br>
But the problem may be that all your grounds (earths)
are not at the<br>
same potential, and what you are seeing is AC hum, the
amount and<br>
direction would vary with the frame/field rate of the
video and the<br>
frequency of your AC power (50 or 60 Hz.).<br>
<br>
Grounding is a very complicated issue, and simply
grounding everything<br>
is site is usually not the best solution, as you get
multiple paths and<br>
varying potentials all over the place.<br>
<br>
The best treatment of grounding issues I have seen is in
Tremaine's<br>
"Audio Cyclopedia", but that section is hundreds pf
pages long.<br>
<br>
But I suspect your problem is either induced signals due
to bad cabling,<br>
or "common mode" problems due to poor grounding.</blockquote>
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</blockquote>
<div><br>
Thanks all for the good suggestions. I think I am going to
experiment with the cable more. The first one I was using was
the one Comcast gave me with the STB (because it was already
connected). Then I replaced it with the one that came with the
HD-PVR, since I assumed that would be best suited for the
device (since they included it, and all). <br>
<br>
Interestingly, I have had this same problem with two different
STBs (first was the SA3250HD, second is a Cisco RNG-150). I
think I'll see if I can find a higher quality, shorter
component cable, and if that doesn't work, look into the
ground loop isolator. As a side note, aren't there devices
that can be clipped on to an existing cable? I seem to recall
seeing these somewhere.</div>
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</blockquote>
I think you are thinking about a toroidal coil..Simple to make if
you have the parts...<br>
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