1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

S-Video and how to make the best one

Discussion in 'Projectors, Screens & Video Processors' started by cutes6, Jan 21, 2002.

  1. cutes6

    cutes6
    Active Member

    Joined:
    Jan 3, 2001
    Messages:
    766
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Near Leeds
    Ratings:
    +10
    Hi I have copied this thread to here as it may be more applicable

    I have been getting interference recently from my 10 meter s-video cable - if I connect my DVD via a short expensive cable its ok so its my long lead that's the problem.

    So having had a bad experience of an expensive cable I bought that was not wired up correctly in the past I will make my own.

    I am not in the position of trying various 10mtr cables to make sure it will get rid of the interference I am going to have to make the best I can and hope it works!!

    So here is my plan - if I get some well sheilded 75ohm coax cable and make 2 runs to keep both sides well insulated I think that will give me the best chance. The bit I am not sure about is how to physicaly connect 2 thickish coax cables into a small s-video plug at each end.

    The inteference I am getting is a diagnal cross hatch pattern which remains constant - maybe someone knows what type of interference this might be and give me some clues as to how to solve it - I have looked at various sites on the web but cannot find a picture if this particular interference - all I know is that with a short good lead it dissapears - my worry is that over 10mtrs whatever I do that it will always be there.

    Any help on this matter will be of great help - I use an projector and s-video is the only connection I can use - please help as it's taking the pleasure away from my films

    Thanks
     
  2. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Your Idea of using two seperated cables is a good one and what the pros do in installs.

    Problem is that you will have to introdue more connectors which will deagrade the signal more. the other is the cables must be exactly the same length beacuse one carries the colour info the other the Lumance

    Realy S-Video should'nt be run over long distances. but that is no help in your case.

    Unless your amp boosts the signal avoid routing it that way it may give a stronger signal.

    After that there are some booster boxes around that may help.
     
  3. Mark Grant

    Mark Grant
    Member

    Joined:
    Oct 27, 2000
    Messages:
    1,357
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    63
    Location:
    East Yorkshire, England
    Ratings:
    +171
    Hello cute6,

    I made a good cable with two 12 metre lengths of 'broadcast quality' SDV cable, decent size RG6 stuff, terminated with high quality BNC's, then used an adapter lead at each end to go from BNC to S-video mini din plug.

    The Bodgers way is to buy a decent quality 1 Metre S-video lead, cut it in half, then extend it using 75 ohm coax of some sort. Soldered and shrink wrapped of course.

    Just make sure you keep the lengths of the cable the same, tape them together, to be sure.

    (Also in the other thread as well)

    Good luck,

    Mark G.
     
  4. laurie

    laurie
    Standard Member

    Joined:
    Nov 23, 2001
    Messages:
    145
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    16
    Location:
    Sydney Australia
    Ratings:
    +0
    I have made my own lead up to a total length of 6m from my denon 2800 to my Sony10ht projector without problems the secret I found in making these leads is:
    1.best quality cable
    2.GOOD quality connector
    3.when soldering the cable twist the shield for each pair around the colored conductor and keep the twist all the way to the lug I have found that CAPACITANCE(I'll keep it simple) causes the picture to be say b/w or not work at all!

    the first 2 goes without saying but the third is REALLY the secret having spent $$$$(sorry UK) on the cable/connector pointless screwing the actual soldering AND watch out for shorts between conductors.hope this helps
    cheers Laurie
     
  5. cutes6

    cutes6
    Active Member

    Joined:
    Jan 3, 2001
    Messages:
    766
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Near Leeds
    Ratings:
    +10
    Thanks for those replies very helpfull -

    I tried something last night which has worked ! I went to maplins and spoke to an ex bbc engineer and he is familiar with this problem - we went all around the houses anyway eventualy he gave me some twin speaker cable which is very similar to coax and each core is heavily screened and both cores fit in a good quality s-video plug. - Its not 75 ohms(how important is this) - I made the cable up and routed it in the ceiling - it does get close to elctric cables - then switched everything on and hey presto the interference has completely gone and all for the cost of £7 for 11 mtrs.

    DVD plays perfectly - now I know I have a Chroma delay issue mainly from Sky plus so I tried channel 413 Sports news and the logo in the bottom right hand corner shows this up - the logo is red and blue whith a white border and the red and blue bleed onto the border on the left hand side - any way it was not better or worse then before so I am very happy:p

    Comming back to the 75ohm issue - what impact does this have and now I know with well screened cable I am ok would it be worthwhile to upgrade to 75 ohms - what benefits would I get ??

    I want to take this opportunity to thank AndyF - he lives near me and when I had this problem I thought it was my DVD player so he brought me his Pioneer 737 and proved that my 636d was fine so he saved me £400 !! Thanks for your help mate

    I would be gratefull to hear any thoughts on the 75 ohm issue
     
  6. RichardA

    RichardA
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Cutes6,

    The difference you are likely to see with true 75Ohm is better chroma/luma delay !

    The original problem you had with the diagonal cross hatch sounds very much like problems I've been asked about exactly this problem with a variety of consumer and professional kit by some of my contacts - I believe the problem is crosstalk between the Y and C parts where the colour information is bleeding onto the black and white signal. You would get a similar, but more intense, effect by connecting composite video directly to the Y connection of an S-Video connector. The normal reason for this is either poor screening on the cables and/or screens joined in the connector. This has been reported with some pretty expensive cables and kit, while some less-than-esoteric kit has no problems at all - S-Video is the one signal type that has to be treated properly - the combination of poor connection integrity (small contact area) small size (difficult to get cable in/terminated) poor cable avaiability (physical size/configuration) and seriously different frequencies on the two cables makes it very difficult to get the information to remain in the same time relationship, and cable length just makes it worse!

    If we are using S-Video we always use a short s-video to two BNC cable (custom made for us) and then run SDI spec cables. We have gone as far as to pull a player apart and fit 2 BNC panel connectors instead of the mini-din socket simply due to the poor reliability of the connectors!

    If you have to use S-Video, use the best individual 75Ohm co-ax for as much of the run as possible, and use break out cables at the end - or, if you can support the connector in the socket, bodge the co-ax directly to the socket without the cover (use very short lengths of Tinned Copper Wire (TCW) to link the connector pins to the co-ax (including the screen), remembering to insulate each pin, wire and solder joint from each other, and the use heat shrink over all - the weight and lack of flexibility in the cable will mean that it will have to be supported to stop it falling out, but it will give the best signal transmission)


    Hope this helps
     
  7. cutes6

    cutes6
    Active Member

    Joined:
    Jan 3, 2001
    Messages:
    766
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Near Leeds
    Ratings:
    +10
    Richard - thanks for that very informative reply

    It begs the question why a manufacturer doesn't make these bespoke cables there must be a market for them !!

    Any way you have me realy thinking about this now - I am wondering wether I can replace the s-video socket on the Ellie projector even if I made a little box to sit ontop of the unit to take individual BNC cables if there wasn't enough room in the back of the unit - although I would still have the issue of s-video at the other end

    The other way is to use the s-video to BNC breakout cables that you use - you say you get them made for you could I buy some from you - even to the point if I wanted a 10mtr set up like you use could you supply the whole lot for me and how much ?

    I would be happy to look at this route if possible with you as I have had a very poor experience in the past of buying so called "expensive quality" cables off the shelf in the past where they are not soldered,sheilded or even wired up correctly !!

    On the issue of s-video signal amplifiers the guy at maplins mentioned these to me at around £70 but I presume all these do is amplify the strength of the signal to start with and have no effect on the chroma delay issue ?

    Am I right in thinking the chroma delay issue is caused by the way the various chips deal with this signal and that it is also made worse by the fact that s-video signal is transmitted down 2 individual wires and it's the length of time the 2 signals take to get down their respective wire ie, if they were different lengths or had different resistance

    Now that I know I can get rid off the interference I am prepared to spend good money on improving the cables for the Chroma delay issue - I know some dvd's like the Pioneer 737 have a chroma delay adjustment so thats 1 answer but I do watch a lot of sky so rather than spend money on a new dvd - which would't solve the Sky issue - I will work on the cable issue hence your set up you use would be of interest,

    thanks
     
  8. ian_guinan

    ian_guinan
    Member

    Joined:
    Apr 14, 2001
    Messages:
    1,163
    Products Owned:
    0
    Products Wanted:
    1
    Trophy Points:
    38
    Location:
    Australia
    Ratings:
    +18
    Has anyone tried shielded Cat5 for s-video cables. There is an excellent thread thrashing out the technical aspects of using it for RGB/component on avsforum

    http://www.avsforum.com/ubb/Forum10/HTML/006683.html

    Would it be worthwile trying it for s-video too?

    Regards,

    Ian Guinan
     
  9. RichardA

    RichardA
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Cutes6,

    Sorry, we can't really supply cables directly - It would cost us more in paperwork than we could ever charge! (that's the down-side of a company turning multi-million pound deals)

    We generally use some of the Broadcast suppliers for cables and stuff - Composite Video in Sutton, Surrey do minidin to 2 BNC cables of a similar spec to ours - 2m long at £16.11+VAT (part 3123505) Telephone 020 8641 4044

    They also do Kramer products (including the VM-3Sxl S-Video DA for £85+VAT)

    An alternate source is Canford Audio in Washington, Tyne & Wear on 0191 418 1122.

    Both these companies do broadcast spec stuff, and can make custom cables to your own specs. I have no involvement with either company - I've simply used them for parts when needed.

    The reason for the chroma/luma delay is down to delays created in the cable- the chroma bit is a higher frequency than the luma bit and there tends to be a difference in lag between the two signals - one arriving later than the other. In other formats with multiple wires, like component, the frequencies are similar on all the wires and therefore the lag is similar also, so the problem is not so visible.
     
  10. AndyF

    AndyF
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    No problems mate, anytime.

    Back in the late 80s, we used a very thin 75ohm co-ax in our datacoms cabinets. Overall diameter was about 3mm, so you could get 2 of them in an S plug easily. It was supposed to be very high quality - silver conductors and PTFE insulation - and it certainly wasn't cheap. I've been searching the web trying to find a supply of this stuff, but no one seems to have it. Anyone heard of it? I expect it would make great S-video and component leads.

    cheers,

    Andy.
     
  11. AndyF

    AndyF
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Exactly right. I saw that cable Mike had. There were 2 shielded conductors. They had used 1 conductor and it's shield for the Y and C. The other conductor/shield were connected to the Y/C shield pins. Crosstalk must have been horrendous.

    Mike, Have you thought about the optional component adapter for the Ellie? £350 I know, but it might solve all your problems in one fell swoop. Perhaps Jim will chip in and let us know what it can do.

    Engaging my brain for a second - could you not send RGB up to the projector, gaffa a convertor to the bracket and use the best short S-video cable you can find?. I seem to recall you have a spare convertor Mike, care to try it out?.

    Cheers,

    Andy.
     
  12. James McHugh

    James McHugh
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi Andy, I will send you spec tomorrow but remember using this converter will by-pass the Line Doubler. Mike called in today to collect some Lenses and have a look at the new projector so i have already expained this to him. Hope everything is OK.
     
  13. AndyF

    AndyF
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi Jim,

    Will that then mean I can switch on the progressive scan feature of my Pioneer 737?

    I've also thought about using a HTPC into the VGA port. Is this likely to be an improvement? I know it will bypass the line doubler, but the PC should take care of that. Any recommendations as to what video card to use? There's an ATI rage fury in there at the mo' but its DVD playback is dire. There's also a Hollywood plus, which works fine via its S-video output, but I haven't tried the VGA passthrough yet.

    I've sent you a private message about some other stuff.

    Cheers,

    Andy.
     
  14. cutes6

    cutes6
    Active Member

    Joined:
    Jan 3, 2001
    Messages:
    766
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Near Leeds
    Ratings:
    +10
    Richard -

    Thanks once again that information is brilliant
     
  15. James McHugh

    James McHugh
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi Jim,

    Will that then mean I can switch on the progressive scan feature of my Pioneer 737?


    Garry by using the RGBVH/Component Adaptor to vga port,will in deed mean you can use your progressive scan,not that it will be as good as the internal line doubler. Picture will look OK upto 6ft wide but over this you will start to see the line structure.
    Running your computer (HTPC) you will only need a VGA-VGA cable,I suggest you use a short one to try out first,as to what video card to use,we have limited information on what works best. Also you will have to install a small programme which i can email you,which allows adjustment (Only needed when running it at 800 -1024) its sweet spot is 800 which is about right for a 7" tube, but be aware that the picture projected is smaller than you would have normally 8ft wide becomes 6.5ft wide. Another interesting thread is " Help a man in need far,far away" He has just had an XS2000HT Intalled and is connecting the "Cinematrix" he said he would let us know as soon as hes tried it out. I have seen this tackled up to the XS3000HT at the High End Show in Athens and it i nice piece of kit. This inturn would be able to scale your picture ie have a 4:3 image inside a 16:9 and im sure the image will be good. At the moment they are built in to DVD players,satellite equipment and offer out RGBVH/VGA to your projector. The callibration is done through a computer that is pluged in to the DVD/SAT unit via a RS232 socket. Look out for the thread to see is it better than the internal line doulbler. Should be interesting!!!
     
  16. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Jim
    If the screen width has to reduce by 20% will it not follow that the resoloution an brightness will go by the same percentage.

    I agree that 800 lines is about right for a 4x3 image on a 7" Electroststaic tube but at 16x9 you are unlikey to resolve more than 600 lines.

    Why would the line structure visability be differnt at certain screen sizes? Whould this not be more affected by viewing distance?

    If I understand what you have said about the prgressive component feed correctly. converted to RGB (31.5Khz) this will give a poorer picture than s-video via the internal line doubler. I would have thought the opposite is true.
     

Share This Page

Loading...