could my cables be the problem?

Discussion in 'Archived Threads 2001-2004' started by mike martin, Jan 17, 2002.

  1. mike martin

    mike martin Stunt Coordinator

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    I have what could only be called a "modest" home thater; but in general I am very happy with it. There is a problem though. When I run a cable directly from the dvd to the television set (27 in magnovox) there is a noticable ghost image the presents itself to the right of any sharp lines, especially dark agains light. When I run a cable through the vcr these lines are gone; however I get a slight fade in and out from the copy protection (presumably). The fade is less noticible that the ghost image so I generally go through the vcr. But why am a settling? It occured to me that it might be the cable I'm using from the dvd player directly to the tv, which came with the player (or tv, don't know). Is it possible or is it maybe just a shitty tv?

    Thanks for any insight any of you can bring.
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    Are you sure you are using a real VIDEO cable and not an audio cable? The ghost image sounds like reflection in the cable caused by using a cable that is not really 75 ohms. (My guess is you have a 50 ohm audio cable, is the connector WHITE or RED by chance? Video cables are usually yellow).

    Coax is designed to produce a specific Impedence. For Home Theater, you can find coax that all looks alike, but is made with 50/75/110 and even 300 ohm coax.

    The rule is that all video systems are designed to be connected with 75 ohm coax.

    The other rule is that the Coaxial Digital cable between a DVD player and a receiver should be a 75 ohm coax as well.

    Go buy an actual video cable and try again.
     
  3. Chu Gai

    Chu Gai Lead Actor

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    ghosts to the right of the image are invariably due to impedence mismatches. since you indicate it happened when you ran the cable from the dvd to the tv, i'd hazard a guess that you're using the wrong type of cable as Bob suggests. report back when you put the right type in.
     
  4. mike martin

    mike martin Stunt Coordinator

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    Thanks for the heads up guys. I'm -almost- sure that I am in fact using a yellow cable for the connection; but hope that I am in fact not. If all I have to do is get the correct cable in there to fix that problem, then I will be most pleased. I'll double check tonight and report back.

    Thanks!
     
  5. Bob McElfresh

    Bob McElfresh Producer

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    You could be using the correct cable, but a loose RCA plug or damage caused by heavy bending can damage a otherwise good cable and cause this problem.

    A simple test is to just use another fresh-out-of-the-box video cable. The AR brand is quite good, as is the Radio Shack versions.

    Please let us know. It's always good to hear of problems & solutions.
     
  6. SteveRS

    SteveRS Stunt Coordinator

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    Whenever I see a report of a ghost image where a dark object meets bright, SVM is my first thought.
    It is possible that the sharpness control is set too high.
     
  7. mike martin

    mike martin Stunt Coordinator

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    Okay, double check confirms that I am in fact using a video cable. Nontheless, I tried a seperate cable and purchased a new one just to be absolutely sure and the ghoast image persistes in all three. Not only that there seems to be no difference between the cables I used, one of which apears to be heavy duty that came with the DVD player.

    Just to reiterate, when I send the signal first to the VCR and then to the television (through the cable TV connection mind you) the ghost image is nowhere to be found. In fact the image looks pretty good save for the slight fade in and out. Personally this would lead me to believe that there is a physical problem with the direct video connection on the television. Mind you, this set has no S-video, component, or digital connections. It was the first piece of my HT I purchased well before I had any idea that I would even try to put together a HT and knew anything about what connections I would want.

    So, it's back in all of your hands I guess. Any other ideas are greatly apreciated.

    Thanks!
     
  8. Bob McElfresh

    Bob McElfresh Producer

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    Crap. This is a tough one.

    SteveRS had a good point - how high is your sharpness control set?

    Another thing to try is a setup DVD that has test patterns to help you adjust the brightness/contrast/color temp on your TV. If you have a good DVD rental place, ask for titles called "Video Essential" or "Avia". Both disks have various static test-patterns that should expose this "ghost" problem but give you time to try and adjust things to tune it out.

    And since this happens with the DVD direct connection, but not with the VCR, the problem points to the DVD Composite video output, not your TV input. (Or you would see the problem with the VCR as well).

    Do you have a friend that you could run the DVD player over to and direct-connect the Composite Video output to their TV to see if the problem stays with the DVD player?

    If the DVD player works fine on a friends TV, this points to mis-adjusted settings on the TV, but not a problem with the video-input.
     
  9. mike martin

    mike martin Stunt Coordinator

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    Bob:

    Many good points you bring up. Just to clarify some of them. I have dilegently attempted to fix the problem with the tv settings with no luck. The vcr connects to the cable coax while the dvd directly connects to the video input of the television. So they are seperate connections. At any rate, you have given me some ideas of how to isolate what exactly the problem is, ie, DVD or TV; but my suspicions lie firmly with the television. It is a far cry from "high end" and my dreams lie with a widscrean HDTV for the future; but for the moment I'm stuck with it.

    THANKS!
     
  10. Allan Jayne

    Allan Jayne Cinematographer

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    The yellow cable is the correct cable.
    The ghosting lines might not be appearing when the VCR is used because the VCR signal path has insufficient horizontal resolution.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     

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