New(?) twist on ground loop hum/digital cable

Video Asylum

TVs, VCRs, DVD players, Home Theater systems and more.

Hi,
Have run into (and solved) CATV ground loop hum problem in the past.
I originally ran into this problem when integrating a Rotel 200W amp with my system. Its the only component in my audio/HT system with a 3-prong plug. I eventually (thanks to posters here) eliminated the hum with a transformer-style ground isolator (Jensen VR-1FF, also tried the Radio Shack dual-balun-for-cheap solution, which likewise worked well.)
A few weeks ago, I got digital cable. This comes via a Scientific Atlanta cable decoder. Was very glad to get this as I can at last do full video switching on my Onkyo 787, thanks to the S-Video out on the cable box.
The problem I had was that I couldn't get the digital portion of the cable signal. None of the cool features (menus, digital channels, Dolby audio, etc) worked.
Finally have traced the problem back to the Jensen transformer. Eliminating it restored the digital features of my cable service. Replace it, and they are gone again. Apparently the transformer either introduces too much noise, or else drops the frequncy at which these digital signals are sent, or something...
So... off this morning to my local radio shack to buy the bits to make a capacitance-type hum reducer thing, a'la the good info at http://www.smr-home-theatre.org/Ground-Loops/Ground-Loops.html
A brief test indicates that my new homemade isolator it works as well as the Jensen in eliminating hum (and for about $2.50!) but sadly, blocks the digital signal just as effectively as the Jensen.
Anyone have any ideas? I'm about to try defeating the ground on the Rotel, but I'd prefer to avoid that if possible. Hate to zap the kids or the dog.
Regards,
Chris Leger

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Topic - New(?) twist on ground loop hum/digital cable - cleger 10:39:36 12/28/01 (5)

Re: New(?) twist on ground loop hum/digital cable - Old Guy 13:03:12 12/28/01 (1)

Re: New(?) twist on ground loop hum/digital cable - cleger 13:41:49 12/28/01 (0)

Cheater plugs and cable hum - Lasermeister 11:33:07 12/28/01 (2)

Re: Cheater plugs and cable hum - cleger 11:56:19 12/28/01 (1)

Re: Cheater plugs and cable hum - john 19:05:46 12/30/01 (0)

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