TV Issues

[FLASHMSTRC]

I have a 40" Sony LCD HDTV. Picture was great and about a month ago I pulled the trigger on a Home Theater System (Onkyo HT-SR800). Love the sound quality, but ever since I am have two random lines slowly run up the screen.

It is especially obvious during dark moments in movies. I unplugged all video from the receiver and ran them directly through the TV and the lines are gone.

I'd like to use my receiver for the video switching because it is convenient and gives me more inputs...is this a reciever issue or a cable issue?

Anybody had the same/similar problem I would appreciate some help. Thanks in advance!

 

[FLASHMSTRC]

Moderator, can you please move this to the Noobie section so it will actually get looked at...Thank you.

 

[Mort Corey]

You're on the right track....it's either the receiver or the cable. I think I'd try a different cable first and if that didn't correct the problem, just bypass the receiver for video (or exchange it) and live with changing inputs on the TV. Another (remote) possibility is interference by a power cord or the like that's running adjacent to the video cable.

Mort

 

[MDS]

The problem sounds like a ground loop and most ground loop problems are caused by cable TV.

You could contact the cable company and have them make sure the cable entering the house is properly grounded. If it is grounded properly or the problem doesn't go away you can always by an isolation transformer to put in-line between the cable wall outlet and the cable box.

 

[mtrycrafts]

I have a 40" Sony LCD HDTV. Picture was great and about a month ago I pulled the trigger on a Home Theater System (Onkyo HT-SR800). Love the sound quality, but ever since I am have two random lines slowly run up the screen.

It is especially obvious during dark moments in movies. I unplugged all video from the receiver and ran them directly through the TV and the lines are gone.

I'd like to use my receiver for the video switching because it is convenient and gives me more inputs...is this a reciever issue or a cable issue?

Anybody had the same/similar problem I would appreciate some help. Thanks in advance!

I'd follow MDS' input, you have a ground loop issue

 

[FLASHMSTRC]

MDS, do you have a link or a rough estimate of the price for that isolation transformer?

The only reason I doubt that it is from the cable box is that I had the lines when playing Xbox 360 feeding the video through the receiver as well.

Only input that has no issues is my DVD player because I run HDMI straight to the TV.

 

[MDS]

http://www.audioholics.com/tweaks/connecting-your-system/ground-loops-eliminating-system-hum-and-buzz

See the bottom of the page where it talks about cable tv ground loops. There is a link to the Jensen isolation transformer. There are others that are cheaper but at least you can see what it is you need.

 

[FLASHMSTRC]

So the ground loop not only causes the humming noise that I experience, but also the lines on the screen as well?

 

[MDS]

So the ground loop not only causes the humming noise that I experience, but also the lines on the screen as well?

Yes it can, assuming that is your problem. The rolling lines on the TV is what makes me think it is indeed a ground loop.

Another thing that you should do is buy 75 Ohm terminators and put them on every unused cable outlet in the house. They prevent reflections and that may be part of the problem too. A box of 10 is about $6 at Home Depot.

 

[FLASHMSTRC]

Thanks, seems like the ground isolator is going for about $50, does that seem right?

 

[mtrycrafts]

So the ground loop not only causes the humming noise that I experience, but also the lines on the screen as well?

If you totally disconnect the cable TV at the wall and if you have a cable box, disconnect the power as well, the hum goes away, it is ground loop issue.
The rolling lines are the 60Hz/120Hz issues from a ground loop.

 

[FLASHMSTRC]

Which are corrected with a ground isolator, correct?

 

[mtrycrafts]

Which are corrected with a ground isolator, correct?

Yes, in the cable TV run, preferably at the wall so there is the least chance of the fault sneaking in another path not so obvious, like an audio interconnect that has a path back to the TV someplace, some how.

 

[jliedeka]

Most cable installations are competently done and there shouldn't be a ground loop. The cable should be well grounded.

However, if you only have the symptom with cable and not with other sources, chances are it's the cable. I would get the cable company to fix the problem but you might be able to solve it with a power conditioner that also cleans up coax inputs.