[mythtv-users] HD-PVR horizontal bands

[Douglas Peale]

On 11/17/2010 01:56 PM, Brian Wood wrote:
> 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.
> 


Get one of the grounding blocks used for antennas and ground the shield of your cable to the same ground as your power.