Hi,
I have mostly done sales & remote programming, & some install work as well. Now I am doing primarily install. I am having the same problem at 2 different customers houses. They both have a cable line runnimg into the house. Going into a 1 x 16 amplified cable distrbuter.
Each one of them has one tv with a line running up & down it and audio interference coming through the tv. On all other sources both tv's are fine. I tried switching cable boxes. Both tv's are not that long of runs. Any suggestions.
thanx,
matt

Ground loop

Try running an extension cord to power the TV and plug it in where the other TVs are fine. Does this clear it up? If so, have sparky move the breaker to the other phase.

...and or run an RG6 from one of the good drop/outlet to the TV with problem

If the noise goes away you are going to have to re-locate the drop – it could be running parallel with a voltage run…!

Good luck,

JC

I think what he is saying is that when using other sources on either one of those t.v's, the lines and audio interference go away. Am I understanding that correctly?

I think in this case, check the grounding for comcrap outside of the house. You sound like you are getting a 60hz hum bar problem.

Do the tv's have a gound on their power cord? If it is a ground loop (I think it is) lift the gound on the outlet - go to home depot & p/u an adapter female pwr and ground in, male pwr outs - 2 blades. Sell the customer a good surge.

And a good fire insurance policy

Bad idea. Lifting the ground will get rid of the hum bar at the expense of safety. Don't do this.

And, while I'm hammering you on this, where do you think the surge arrestor tries to dump its surges to? Oz? Shangrila? The surges go to ground, unless someone disabled the ground.

The problem is a disagreement between the ground the tv sees and the ground the cable company has on the shield of their coax. Make sure the coax is grounded outside the house, and make them do it if they didn't.

My bad.

This will only prove a ground loop.

True, and I should have pointed out that I use a cheater plug to do that very thing, as a test only. I'm sure you were just referring to a test, eh? :-)

Radio Shack sells a ground loop isolator for 10 bucks that goes on the cable that will sove the problem. The thing you will notice is the TV is probably not grounded and the loop can be coming from anywhere. Short of disconecting everything to troubleshoot it this is the best fix.

The problem with using a ground loop isolator is, most of them also isolate DC.

Some cable companies use the DC return for features such as pay per view and other services. Interupting the DC return with an isolator will cause the customer, and possibly you, more grief from the cable company.

It is best to search out the problem by disconnecting equipment one piece at a time and then isolate and repair the issue from there.

Don't overlook the obvious though. Make sure the cable company has grounded their service properly at the main dimarc enclosure on the residence. Many a time I have found poor, or worse yet, NO grounding of the service.

John

Yes, that is interesting. A while ago Comcast sent out contracted workers to ground every drop in our neighborhood. I don't even have their service by it did run down to my demarc so they did it anyway.

Dave

Grounding followup visits? NO - say it isn't so!

LOL


John

I'm having similar problems with a TV that is being driven with S-video over Cat 5 from a remote cable receiver. I'll have to think through ground loops further myself, but does such a problem carry through a balun? Using a Muxlab device...