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VCR connection problems with Yamaha DSP-AX750SE

Discussion in 'AV Receivers & Amplifiers' started by NG66, Dec 30, 2004.

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  1. NG66

    NG66
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    Hi

    I have a Yamaha DSP-AX750SE connected to a Panny PW7 via Component. The 750 is doing video up conversion. This works fine for the Digital set top box (composite) but not for the VCR (also composite and yeah I know, but kid's videos, etc, etc!!). When the VCR (Sharp) is stopped you can view the TV channels outputting from the VCR's tuner fine but the screen goes blank (most of the time) when a video is played. (Audio comes through fine). VCR only has Scarts so am using a decent Scart to 6 x phono into the amp.

    If I daisy chain the VCR scart into the DVD recorder and view it's AV input then the VCR is fine - the DVD links to the amp in component, so the DVD is now doing the video up conversion.

    I assume this is something to do with the video conversion on the amp? But it seems strange that it only happens when a video is playing and not when viewing the tuner on the VCR?! :confused:

    Any help or ideas would be greatfully received!

    Thanks

    Nick
     
  2. Wasabi

    Wasabi
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    Nick,

    Unfortunately, I can't help you here to root the problem, but I thought of adding a comment so your thread moves to frontpage, and perhaps others that are more knowledgable will notice this thread.

    Cheers,

    Wasabi
     
  3. Zacabeb

    Zacabeb
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    I think it might have to do with the head switching and jitter in the VCR making it difficult for the video circuitry locking onto the signal.

    In the video drum of a VHS VCR, there is a video head in either half of the drum and the tape is looped a little more than 180° around it. The heads take turn in recording each video field from the picture signal as the drum spins. At the changeovers, there is usually some distortion to the picture signal, which may upset the synchronization in the video conversion.

    There is also some jitter caused by various factors which displaces each picture line, and the signal levels may sometimes be way off. Messy, messy, messy. :(

    The DVD recorder probably has a time-base corrector (TBC) built-in, which digitizes the signal, re-aligns the picture lines to remove jitter, restores video levels to normal, and cleans up the sync signals to form a new, stable signal. The DSP-AX720SE on the other hand, does not have a TBC.

    So, the DVD recorder loopthrough may be the best solution, especially if it doesn't protest when tapes are copy protected while just looping the signal through.
     
  4. Wasabi

    Wasabi
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    Zacabeb,

    Does it mean that with a TBC built in the amp and you route your video signals to it and then out to the panel source, you won't have any problems with lip-sync anymore?

    As I have discovered that the new Onkyo x02 amps doesn't have audio delay (which is unfortunately putting off some potential owners) but I noticed it does have TBC on the component output.

    Wasabi
     
  5. Zacabeb

    Zacabeb
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    It would not really improve lip sync since the audio is usually what's premature if I understand things correctly. How much delay the TBC adds to the video signal varies depending on how much of the signal is kept in memory, so I guess depending on how the TBC works it could be delayed anywhere from a few lines of video to a full field.
     
  6. pragmatic

    pragmatic
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    Are you sure your using the correct phono lead for the composite? Unlikely as it is coinsidering you get an output when the tv tuners on.
    Is the scart the only connection between the video and the outside world? No areil lead ect...
    Maybe your video has a dedicated in and out scart?

    Just some ideas, might not be any of them but worth a look. Otherwise see if you can get another video to try, or try it in a diffrent input on the amp (as the conection your using could have a fault, unlikely though)

    Otherwise if you can directly connect the video to the tv and the sound to the amp, if you have the connections on the TV and you souldn't get any audio delay really. I find I only get audio delay if i got through a component to get to the amp with the sound, but route the video strait to the tv.
     

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