On September 9, 2017 at 09:57, highfigh said...
It's also possible that the feed to the cable box isn't grounded or their line is passing DC to the cable box. Try disconnecting the cable from the box and if the hum stops, use an isolator on the cable feed. Or, you could have the cable company fix the problem they caused.
Absolutely, 100%.
We just experienced this at a property. Cable tech on site insisted it was our problem and something was wrong with our gear or with the electrical in the house. He swore up and down all of his items were correctly grounded. I requested that he show me everything and while walking with him I asked to open the pedestal so he could show me it was grounded...low and behold it was not. Of course he didn't have the ability to ground it or to provide an isolator so I ordered one and the hum is gone.
