Quote:
Originally Posted by
spearhead 
I am having a problem with hum on Comcast. I had a filter on the input to the STB (Motorola D2007) but that was causing problems receiving some channels after Comcast made some changes (it did work until something at their end changed). I get a really severe hum when using the STB. If I remove the power cord from the STB, I still get the hum. If I remove the audio cables from the STB, it disappears. I'm really frustrated and Comcast is no help. Suggestions?
The hum is indicative of a ground loop. Basically, at least two of your components are connected to two different grounds of unequal potential. In a perfect world, the potential on the grounding is zero. If it is indeed a ground loop, the offending component must be found. Perform a quick check of your incoming catv coaxial. Turn on your system as normal. When the hum appears, unplug only your coaxial cable from the wall. Indicate if the hum disappears. If so, an item like this may work:
http://www.markertek.com/SearchProdu...ff=0&sort=prod
If problem persists, list all components used, such as receivers, etc.,
You can purchase an item like this locally,
http://www.xitel.com/product_gli.htm
and return if not effective.
