Serious hum problem. Help

I had no luck with the grounding solution you're trying. I had the cable company install a new ground to the service, tested the continuity of the ground, installed another ground wire myself to the cable splitter in my listening room. None of it had any effect. The ground loop isolator recommended above was the solution - totally eliminated the hum I spent months fighting with.

One caution though, I tried multiple isolator options, including one recommended by another audiogoner that's "cobbled together" from 2 Ratshack antenna dividers, and one from Parts Express. The first didn't work at all (though I didn't use the same exact parts the other guy used . . . sorry I don't recall who), and the Parts express part suppressed bandwith causing graininess to the picture, and preventing access to the digital on demand functions of my cable service.
Here's the Parts Express isolator I tried:
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=180-075&CFID=22979&CFTOKEN=23734557
It worked effectively to remove the hum,and is only $9.85, but lacks the bandwith to handle my Comcast digital cable service (which btw is really squirrelly and act up at the slightest difficiency in inside wiring).

So, Nsgarch - while your compliments are appreciated, if I had sprung for one of the more expensive transformers months ago, I coulda saved myself hours of time I wasted fighting with penny-wise fixes ;-]

Bd -- forgive me, I failed to mention the cheap fix (i.e. any kind of 75 ohm isolation transformer, homemade or commercial) doesn't pass digital cable signals.

I knew that, just forgot to say so. I don't know how the new isolator units work or if they can even be duplicated by DIY.

Bdgregory,

Thanks for the "heads up" on the MCM Ground Loop Isolator.
Had the same problem with the coax cable causing the hum (and I also have Comcast as my digital cable), that you were having, and was considering getting the Mondial MAGIC Box ($99) but MCM Ground Loop Isolator solved the problem for much less money.

Once again, thanks.

i had the same problem and eliminated it at no extra cost to me. i used the power conditioner's (power strip's) coaxial "in" and "out" between the wall and the cable box. i suppose you need this coaxial feature on your strip or conditioner, but it works for little or no money. maybe it is grounded separately. dunno.

revision on that last comment. i too have comcast digital cable and there is a problem transfering information when using the power conditioner's coax in and out. back to the drawing board. the mcm product looks like the best option.