On Wed, Nov 17, 2010 at 2:00 PM, Greg <span dir="ltr"><<a href="mailto:greg12866@nycap.rr.com">greg12866@nycap.rr.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div><div></div><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 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></div></div></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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