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Is this a crosstalk problem?


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Old 17-12-2003, 01:08
tichtich
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Any help with the following problem would be appreciated.

Until recently I was experiencing ghosting when playing back from my DVD recorder. In this forum it was suggested that this was probably caused by crosstalk on the Scart, and I should buy a fully shielded Scart cable (to replace the cheap cable supplied with the DVD recorder). I bought a £10 Cambridge Ausio cable from Richer Sounds, which gave a considerable improvement. I can no longer see ghostly images. But I can still see a faint vertical line moving across the screen, at fixed intervals (of about a second).

My first question: is this still probably crosstalk, and if so would it help to buy a better cable still?

My second question: do good cables have shielding around every individual conductor? Looking at this page (http://www.playserver2.com/play247.a...G&title=137545) about the Thor cable, it says "Separate shielding between audio and video conductors for improved overall performance", which suggests something less than shielding around every conductor.
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Old 17-12-2003, 09:15
wicket
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It is definitely interference of some kind. I had the same problem and know exactly what you are on about. I solved it by purchasing a good scart cable. I bought one that was RGB compliant and shielded.
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Old 17-12-2003, 09:23
GaryB
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It could well be crosstalk. The line that you see is probably the sync signal from the video that is output from the TV mixing with your DVD input signal. To see if it is crosstalk, tune the set to an unused channel (so that you get noise on screen) and then play a DVD. What you may then see is a slightly noisy picture but without the line that you see now. This is the noise being picked up by the tuner mixing with your DVD signal. If you see the slightly noisy picture it is pretty much certain that you have crosstalk.

The best cables do generally have individual screening. One of the best cables i have found is sold by RS Components. It is not sold as a specialist AV cable but does have excellent screening.
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Old 17-12-2003, 12:37
flagpole
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Every time i've seen this it's been interference from the TV's own tuner.

It tends to occur when the channels are tuned in but there is a bad signal. if you have cable/ sattelite then you could just completely un tune the the tele. or if you don't then you just make sure you turn to a channel that has a good or no signal before you watch the dvd.

one final thing... you say dvd recorder... you aren't watching a dvd you recorded before you got the new cable are you??
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Old 17-12-2003, 13:58
tichtich
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Originally posted by GaryB
To see if it is crosstalk, tune the set to an unused channel (so that you get noise on screen) and then play a DVD.
I'd already tried this, and it didn't make any difference. (Sorry, forgot to mention it before.) Further experimentation has revealed the following:

1. The lines are not present when playing a commercial DVD.

2. The lines are present when watching a TV programme via the DVD recorder (but not playing a DVD), i.e. with the signal going to the recorder and immediately back again (via a single cable). By the way, I have an IDTV (Panasonic TX-28DT30).

3. In the case of a home-recorded DVD (which is what I mostly watch), the lines are recorded to the DVD. I can see them when playing the DVD back on my PC. However, the lines are only recorded if the TV is displaying the signal from the recorder while recording, rather than displaying its own picture. I do a lot of Timeslip viewing with my DVD recorder (a Panasonic E50) which is why I've been noticing the effect a lot.

4. The problem is the same regardless of whether the DVD recorder's output is composite, S-video or RGB. There are no options for controlling the output type of the TV, so I'm not sure what it's outputting.

I'm wondering if the problem could be related to another problem which I've been aware of for some time but thought was unrelated. When watching a TV programme (but not a DVD) there is a static vertical line present all the time. Like the moving lines it's only visible against certain types of background (it shows up well on the gray banners of the Freeview radio channels). If the problems are related, then perhaps it's the TV's tuner which is producing these lines, i.e. it produces a static line most of the time, but a moving line when the TV is in AV mode (displaying the signal from a scart socket). Does this sound plausible? Any other ideas?
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Old 18-12-2003, 19:52
GaryB
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I've read your second post a couple of times and the only thing I can think of is that the high voltage from the line output stage of the TV is leaking into either the SCART cable or the DVD. Can you try moving them apart to see if that helps.
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Old 19-12-2003, 13:26
JamboUK
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Had a similar problem..... solved by cutting pin. Check out this thread.


Previous Digi link
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Old 19-12-2003, 15:28
tichtich
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Thanks for the suggestions.
Originally posted by GaryB I've read your second post a couple of times and the only thing I can think of is that the high voltage from the line output stage of the TV is leaking into either the SCART cable or the DVD. Can you try moving them apart to see if that helps.
OK, I just tried moving the DVD recorder as far as the 2m scart cable would allow. But it made no difference. I also tried using alternative scart sockets on both the TV and DVD recorder. That made no difference either.

I suppose it might be worth making or buying a one-way scart cable, to absolutely rule out cross-talk. But I'm becoming more and more convinced that this is a problem with the TV's digital tuner. (The TV always directs its digital tuner's output to the scarts, never the analogue tuner's output, so I can't check whether the moving lines are present on analogue channels. But I've never noticed the static line on analogue channels.)
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Old 19-12-2003, 15:32
tichtich
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Originally posted by flagpole
one final thing... you say dvd recorder... you aren't watching a dvd you recorded before you got the new cable are you??
Good idea. But no, that's not it.
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