[mythtv-users] HD-PVR horizontal bands

[Brian Wood]

On Wednesday, November 17, 2010 02:53:42 pm Christopher Meredith wrote:
> On Wed, Nov 17, 2010 at 3:31 PM, Brian Wood <beww at beww.org> wrote:
> > On Wednesday, November 17, 2010 02:08:31 pm Christopher Meredith 
wrote:
> > > > Yeah, you can get magnetic ferrules for the cables, but if your
> > > > hdpvr came with the same cables mine did (the 5 wire joined
> > > > cable), it is very high quality (at least mine is)...
> > > 
> > > Yeah, that's the one I'm using. I wonder what the problem is,
> > > then...
> > 
> > The problem is not cable quality, it's most likely common mode AC
> > hum.
> > 
> > Try re-orienting your cabling, especially if you are crossing AC
> > power wiring.
> > 
> > Make sure all of your gear is connected to the same AC power outlet
> > (as much as possible).
> > 
> > Make sure all your gear is grounded or, conversely, don't use
> > grounds except for the protective grounds in the power wiring.
> > 
> > A fairly good explanation of ground loops is here:
> > 
> > http://en.wikipedia.org/wiki/Ground_loop_(electricity)<http://en.wi
> > kipedia.org/wiki/Ground_loop_%28electricity%29>
> 
> In my case, the HD-PVR sits directly beside the STB and the component
> cable goes directly from one to the other. The excess is coiled and
> bound with a twist tie. Everything is plugged into a single power
> strip which is plugged into a single outlet. Come to think of it, I
> actually have a second power strip plugged into the first (I know, I
> know).
> 
> I do have the monitor output from the HD-PVR connected directly to
> the TV. I can't imagine how that could be causing it but I'll
> mention it anyway.

Try moving the HD-PVR farther away, it might be picking up some magnetic 
field from a transformer in the STB.

If you happen to have some Mu-Metal around, you could use it to try and 
shield the HD-PVR.