Ground loop problems

[Dick]

I have only rudimentary electrical - electronic education and
experience.

I appear to have a ground loop problem with my home entertainment -
computer system. Here is the nature of the problem:

I wanted to route all the audio signals (TV -Satellite, VCR, and
computer) through the AUX input on my stereo amp.

Whenever both the TV and computer are connected to this AUX input
(through use of a switching box) there is 60 hz. hum.

All appliances above receive power via a common Panamax power
stip/surge protection device.

Previously, I had a problem with hum when I connected an FM signal
(which is split off the VHS signal) to the stereo tuner ALONG WITH the
computer's audio signal. I solved this by installing a small inline
slider switch on the FM line, so I could break that connection when
not listening to the radio.

It would appear that the conflict is between the VHS signal and the
computer.

I have not yet confirmed this by disconnecting the VHS coax from the
splitter box - only disconnecting the coax from the back of the TV.

I do NOT suspect a conflict between the satellite signal and the
computer, because as soon as I throw that switch on the FM line, there
is no hum.

So.....what could the solution be?

Are rooftop antennas supposed to be grounded?

Dick

 

[Mark]

I appear to have a ground loop problem with my home entertainment -
computer system. Here is the nature of the problem:

I wanted to route all the audio signals (TV -Satellite, VCR, and
computer) through the AUX input on my stereo amp.

Whenever both the TV and computer are connected to this AUX input
(through use of a switching box) there is 60 hz. hum.

All appliances above receive power via a common Panamax power
stip/surge protection device.

If, in fact, they all have a common power source, than your
problem is Not a ground loop.

Previously, I had a problem with hum when I connected an FM signal
(which is split off the VHS signal) to the stereo tuner ALONG WITH the
computer's audio signal.

I've read that a number of times, and still can't make sense
of it. You're getting radio broadcasts from a VCR? Please
explain your connections.

It would appear that the conflict is between the VHS signal and the
computer.

I have not yet confirmed this by disconnecting the VHS coax from the
splitter box - only disconnecting the coax from the back of the TV.

By "coax" are you talking about a CATV or antenna feed, or
an audio or video cable?

I do NOT suspect a conflict between the satellite signal and the
computer, because as soon as I throw that switch on the FM line, there
is no hum.

Still confused by what this FM line is.

Are rooftop antennas supposed to be grounded?

Generally, no.

--
Mark

The truth as I perceive it to be.
Your perception may be different.

Triple Z is spam control.

 

[CJT]

If, in fact, they all have a common power source, than your
problem is Not a ground loop.

That's not necessarily true. It just makes a ground loop less likely.

 

[CJT]

That's not necessarily true. It just makes a ground loop less likely.

I should have said it makes a ground loop _problem_ less likely. The
loop will probably still be there, consisting of two (or more) power
cords and the A/V connection(s) between the equipment.