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What's wrong with this?

Discussion in 'Cables & Switches' started by melliott1963, Apr 13, 2004.

  1. melliott1963

    melliott1963
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    Hi,

    First, let me apologise for the length of this thread, but I want to try and get all the details right!

    I currently have a TV, Video and DVD player in my main room. I also have a couple of other TV's in other rooms.

    I have run an aerial cable from my main room into the two other rooms. This is plugged into the aerial out socket of my VCR.

    I have no problem, whatsoever, with normal TV viewing and video viewing in the other 2 rooms.

    BUT...

    I'd like to be able to watch DVD's in the other rooms. I have cabled the DVD player 2 different ways, but each time, whilst I do get a picture and sound, every second or two, the screen goes blue, then returns to normal, then goes blue again etc. etc. This happens on both the sets in the other rooms so would indicate a wiring problem.

    My actual wiring is as follows:-

    * External Aerial into my Digital TV's Aerial In socket.
    * TV aerial out into Video Aerial In.
    * Video aerial out to extension lead into other 2 rooms.
    * Video SCART In/Out into TV SCART In/Out.
    * DVD SCART into TV SCART

    My DVD has a 2nd output which I origianlly put into my video SCART In. I noticed the problem so I removed it and have now tried the following.

    My TV's SCART Out, which goes into the Video's SCART In, can be set-up so that the video can receive digital channels, or what is displaying on the TV screen, or what is being received from AV3 (My DVD).

    I can view Digital Channels in the other rooms with no problem using this method, but still have the same problem with my DVDs, regardless of whether or not I set the TV to output what is coming from the DVD, or just what it is displaying.

    Is there something about DVD signals that means they can not be broadcast over standard coax cables?

    Do I need, instead, to run a SCART extension lead to my other 2 rooms? If so, is there any maximum length of cable you can use for SCART or should I be OK.

    Or is my problem loss of signal due to the length of the cable? I estimate the cable length is about 50 foot.

    Any help/suggestions would be appreaciated.

    Thanks.
     
  2. LV426

    LV426
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    The problem, I suspect, is with Macrovision. DVDs (mostly) have a trigger code on them which makes the DVD player add a Macrovision signal to the video signal output.

    This signal, typically, is ignored by TVs. But VCRs have an automatic gain control on them which is affected by the signal. It's primary purpose is to stop copying onto tape. But it has the side effect you describe, whereby the VCR's AGC reacts to the signal as it goes in. When it then tries to output the signal via the aerial (RF) cable, the AGC effect becomes visible.

    So, in short, your problem, I guess, is that your VCR is being affected by Macrovision and is passing this effect along the chain.

    You can buy Macrovision-defeating cables. Put one between your DVD and other hardware. Or you could buy a standalone RF converter to use instead of the VCR. Or use a video signal connection to your other rooms in preference to RF.
     
  3. melliott1963

    melliott1963
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    Thanks Nigel.

    I'm sure you must be right because, now I come to think about it, when I did my inital testing a while ago, I was using a DVD that I created myself from home video and all appeared to be perfect. It's only now that I've tried playing commercial DVD's that this problem's occured.

    I'll have a look to see where I can get the cables you mention, unless you're able to help me with this as well.
     

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