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Old 08-01-2006, 03:11 PM   #1
nclou
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Join Date: Dec 2003
Posts: 40
Help with faint vertical scrolling lines

I have the following set up:

HR10-250
DVD Player
AV Receiver
Xbox
Toshiba 51" CRT HDTV

My Tivo and Xbox go into my receiver, which I use to switch between them on one of my TV's component inputs. (My Tivo started having HDMI problems like so many other people, and I am more than satisfied with the picture on component)

My DVD player runs directly into my television's second component input.

I only have two component inputs each on my receiver and my TV so this seems to be the most reasonable solution for me.

My problem is that when watching the Tivo, and only that, I get a faint scrolling vertical bar or line, running from right to left on my picture. It is almost always unnoticable when programming is on, so I've just lived with it, but I'd like to get rid of it. It is somewhat noticable on Tivo menus with the green background, but it is most clear on the gray screen that comes up for a second or two when switching channels.

It never happens with DVD, XBOX or over the air programming.

I can't be sure, but I suspect it has to do with the component inputs on my tv. I don't recall this being an issue before I started using both component inputs. I can't pin point it to that for sure, but it's my suspicion. It also never happened on my old SD Directv Tivo.

Yesterday, I had to move my TV slightly to get something behind it, and the scrolling bar became extremely heavy, visible through all programming, and impossible to watch, but by moving the TV back, and maybe jiggling it a little bit, it went back to it's previous faint and watchable quality.

I suspect someone is going to tell me it's a ground loop, but I'm not sure. Maybe it's just because I don't want it to be a ground loop, because I don't even really know what grounding of the Tivo means or how to look for it and fix it.

But moreso, I would have expected if the Tivo was not grounded correctly, it would have been doing this from day one. Maybe that idea illustrates my ignorance of grounding, I don't know.

Any suggestions you might have are greatly appreciated.
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Old 08-01-2006, 06:01 PM   #2
jfischer
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Posts: 578
Sounds like a ground loop to me

Probably wouldn't be a problem with DVI/HDMI, but on an analog connection it could be.
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Old 08-01-2006, 09:53 PM   #3
hdtvlover
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It is a ground loop, get a ground loop isolator from HDTV Supply
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Old 08-02-2006, 10:18 AM   #4
nclou
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I'll give it a try. Thanks!
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Old 08-02-2006, 11:24 AM   #5
nclou
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Ok, the only ground loop isolator at HDTV Supply has audio connections and is for eliminating hum in the audio, which I don't have. It's also $50. Is this really what I need? I don't have any audio inputs going in to my TV I don't think, but I could be wrong. Where would this be placed?

Is there another kind of ground loop isolator for the Tivo, and where in the line does it go?

Thanks.
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Old 08-04-2006, 11:43 PM   #6
A J Ricaud
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Join Date: Jun 2002
Location: Hacienda Heights, CA (Los Angeles County)
Posts: 1,065
Quote:
Originally Posted by nclou
I have the following set up:

HR10-250
DVD Player
AV Receiver
Xbox
Toshiba 51" CRT HDTV

My Tivo and Xbox go into my receiver, which I use to switch between them on one of my TV's component inputs. (My Tivo started having HDMI problems like so many other people, and I am more than satisfied with the picture on component)

My DVD player runs directly into my television's second component input.

I only have two component inputs each on my receiver and my TV so this seems to be the most reasonable solution for me.

My problem is that when watching the Tivo, and only that, I get a faint scrolling vertical bar or line, running from right to left on my picture. It is almost always unnoticable when programming is on, so I've just lived with it, but I'd like to get rid of it. It is somewhat noticable on Tivo menus with the green background, but it is most clear on the gray screen that comes up for a second or two when switching channels.

It never happens with DVD, XBOX or over the air programming.

I can't be sure, but I suspect it has to do with the component inputs on my tv. I don't recall this being an issue before I started using both component inputs. I can't pin point it to that for sure, but it's my suspicion. It also never happened on my old SD Directv Tivo.

Yesterday, I had to move my TV slightly to get something behind it, and the scrolling bar became extremely heavy, visible through all programming, and impossible to watch, but by moving the TV back, and maybe jiggling it a little bit, it went back to it's previous faint and watchable quality.

I suspect someone is going to tell me it's a ground loop, but I'm not sure. Maybe it's just because I don't want it to be a ground loop, because I don't even really know what grounding of the Tivo means or how to look for it and fix it.

But moreso, I would have expected if the Tivo was not grounded correctly, it would have been doing this from day one. Maybe that idea illustrates my ignorance of grounding, I don't know.

Any suggestions you might have are greatly appreciated.
I would try switching the HD Tivo with the DVD player and see if the problem persists. If it follows the HD Tivo that's where the problem is--and it needs
to be replaced.

If the problem now goes with the DVD player then it is a bad cable on that component input or the TV's input itself. Switch component cables. If it follows the cable, then the cable is bad. If not it's the TV's input.
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Old 08-06-2006, 02:00 AM   #7
TyroneShoes
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Join Date: Sep 2004
Posts: 3,604
It sounds to me more like interference than a GL issue. Usually a GL allows the ground to lift slightly above 0 volts at some point which results in video "hum", which is characteristically seen as one horizontal bar rolling slowly up the screen. This is due to the 60 Hz current (or 120 Hz from a failing power supply, which will display two bars) interfering with the 59.94 Hz frame rate, and the result is this slowly moving characteristic beat pattern. Lifting the ground could fix this, but in your case, lifting the ground on interconnecting cables would likely not improve things.

What you are describing is a beat pattern from another source, at another frequency. A poorly shielded cable can cause this, so I would first replace the cables one by one. Also, you could have interchassis interference, where two components stacked closely together can have an issue where one component radiates directly into the other. Try physically separating various components.
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