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RGB Switching through Component Video

Discussion in 'AV Receivers & Amplifiers' started by GarethRamsay, Jan 13, 2002.

  1. GarethRamsay

    GarethRamsay
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    I've just bought a new amp which has two component video in and one component video out. As my TV is some way away from my setup, it would require metres of ugly cabling to get an RGB signal from both the DVD player and the Sky box. Ideally I'd like to use the component video for AV switching.

    The question is, if I use a SCART to RGB on three phonos (I've seen a few companies selll these) cable, connected to the Sky box and plug it in to the component in of the amp and use another from component out to the TV will this simply pass the RGB signal through?

    This seems a little too obvious to me, and begs the question: why aren't these amps sold as coming with RGB swithing, if this is the case?

    Also, how does the three phono cable work? My understanding has always been that RGB requires four (or five) connectors, the extras for the sync.

    Is it possible to by SCART to four RGB phone leads? I haven't seen these anywhere. If so, would it be possible to use on and pass it through the composite in/out of the required channel?

    Any help would be appreciated.

    Thanks

    Gareth
     
  2. Greg Hook

    Greg Hook
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    Hi

    Not sure about the amp questions because that is beyond me but why don't you try this;

    scart from DVD to Sky box
    scart from Sky box to TV.

    I have got a Panasonic digibox and this is the setup I use. The digibox passes through the RGB signal from the DVD so I get RGB from both the DVD and Sky.

    Hope this helps.

    Greg
     
  3. Ian J

    Ian J
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    I am not 100% sure but I don't think that component video is compatible with RGB even though they are closely related.
     
  4. digital

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    Ian J's right, component video is not compatible with scart-rgb. They are similar quality (some say component is better?). The cable you've got in mind won't work (3 phono to scart). Greg's tip's your best bet I think. Otherwise try www.lektropacks.co.uk
    I've found them helpful with cabling problems before.
     
  5. GarethRamsay

    GarethRamsay
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    Sure, I realise the two formats are incompatible. For instance if I plugged RGB phonos into a Component Video screen I would not get a signal, however this is not what I'm trying to do.

    I'm hoping that the Component Video sockets do not interfere with the signal and simply pass it through. If so, the signal that goes in (RGB) should be the same as that which comes out (RGB) and when it heads to the TV should give an RGB picture.

    Gareth
     
  6. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    The switching of RGB through the COmponent inputs would, I am sure, work. However you also need another signal with it to make RGB work and that is composite video. The Composite video sugnal carries the sync signal required.

    So, if you could run 4 cables, RGB+composite and send composite to the associated composite video input then run composite out and component out to a scart it moght work. Providing the composite video switching works along side the component one. The new Arcam Pre-amp will have this facility....

    Gordon
     
  7. GarethRamsay

    GarethRamsay
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    I've seen SCART > RGB leads with only 3 phones at then end, RGsB, where the sync is contained in the green signal. Do you need a compatible TV to make this work, as this is what I primarily had in mind?

    Gareth
     
  8. brattle

    brattle
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    Gareth, can you point me in the direction of these leads. I've ordered one from Keene, but it is taking forever to arrive.
     
  9. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Sync on green is usually the domain of projectors and plasma's. The RGB signal coming out the back of a Sky box or DVD does not have sync on green. The sync is carried on the Composite signal........you need 4 cables switched......

    Gordon
     
  10. GarethRamsay

    GarethRamsay
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    I may have been mistaken about the three phono lead. This is what I asked for on Tottenham Court Road on Saturday and was shown a lead which I'm sure was by Profigold. However it wasn't long enough and when I phoned them today about a longer one, they said they didn't do such a lead!

    I only work two minutes from TCR, so I'll go back down and check at lunchtime.

    I phoned Philips (who make my TV) and they say that my RGB SCART sockets support both RGBS and RGsB. I'm still waiting to here from Yamaha on whether the amp will switch it, though. I'll keep you posted.

    Gareth
     
  11. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    The scart socket may well support sync on green but does the Sky box or your DVD output sync on green....I'm trying to help here...honest....

    Gordon
     
  12. bxd

    bxd
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    Gareth,

    I understand what you're trying to do but I haven't tried it myself.

    It should be possible to get Lecktropacks or someone to make you up three cables, I think that the following should work.

    If two of those are scart to phono cables and carry, composite video and r,g and b... out FROM the scart to four phono plugs.

    You wire the phonos into the composite AND red, green and blue (coloured) inputs on the amp.

    You then get a 4 phono to scart cable to carry the composite video (sync) with the signals on the red, green and blue to the tv.

    As far as I'm aware when you switch the amp to (say) video 1 it will switch all of the composite, s-video and "component" signals that are on that input at the same time.

    Presumably, if there is no rgb signal present, then the tv will default to the composite signal.

    Brian.

    OOPS......sorry, I hadn't spotted Gordons post which say's the same thing as I'm suggesting here.
     
  13. GarethRamsay

    GarethRamsay
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    OK, tried it tonight by bastardising an old SCART > 3 Phono leads using a connection diagram fropm the Net and the SCART - RGB lead from Profigold and..... nothing.

    This could be because I did a ridiculously bad job of the home-made lead, it may be that the SCART - RGB lead is incorrect, it may be that... hell, it could be any number of reasons, including that the whole affair is fruitless from the offset :)

    As I need to get a new lead anyway, I might see about getting a special one made up and try again, price permitting.

    It's a real shame 'cos I really wanted this to work ;)

    Checked out Lectropacks, although I'm not sure if I'm willing to spend all that cash on something that might not work! If it did, I'd have no objection to parting with my cash, but for £80 - £100 to find out... Does anyone know of anywhere to get cheapo, budget leads made up? I'd give them a try.

    Gareth
     
  14. brattle

    brattle
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    I've just recieved my lead from Keene today :). It cost me £22.50.

    Check this link http://www.keene.co.uk/pages/cat/11lea/111-4.html . I ordered the Scart to 3 Phonos (Sync on Green). It's fourth from the bottom of the drop down list. A word of warning though, it has taken over a month receive the lead :(.

    Did you actually buy the Profigold lead Gareth? If so what would you say the quality of the lead was actually like. The Keene lead does the job, but it is fairly basic.
     
  15. Stewart C

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    I have a philips ITV Digital Box. How do you know if scart 2 on the digi box allows a throughput of RGB from the DVD player to the TV?
     
  16. GarethRamsay

    GarethRamsay
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    The lead weas fine and sturdy, gold plated and seemed to be of pretty good quality. I too it back, though, when my home made lead didn't work.

    Have you tried it, Brattle? Does it work?

    Gareth
     
  17. brattle

    brattle
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    I haven’t. I’m using the lead for a different purpose, which is connecting my Toshiba DVD via component to the scart component input on my Loewe and it works fine. I would like to try your suggestion, but I can’t yet as my Denon hasn’t arrived yet. Anyway, I think Gordon is right and it won’t work unless you do something with the composite.

    I was a little disappointed with the overall quality of the Keene lead. It works fine, but it looks below spec when next to my QED Scarts.

    Today I popped into the local Sevenoaks today to buy some banana plugs, when the Ixos man was in there. I asked him if they could build me a lead to spec and he agreed. He was after quite a bit of cash at the start, but I knocked him down to £40 which didn’t seem to bad for a Gold standard lead.

    I’ve just ordered one from him, so I have a spare Keene lead to sell at a knock down price if you are interested?

    Brats
     
  18. bxd

    bxd
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    Gareth,

    Check that your two scarts are wired differently for the video connections. You should be using pin 19 on one and pin 20 on the other.

    If you're not happy about doing it yourself, why don't you get four (video) 'phono to phono' cables from somewhere (I suspect that you could get away with four old audio cables to try it out) and buy two cheap scart plugs from maplin (or somewhere).

    Cut the cables in half and take them into your local cheap TV repair store and ask them to solder them up so you have the following :

    One Scart wired to accept : Video "out" from the dvd player along with the red, green and blue out from the dvd player. That's a total of eight connections ..video out + ground and r,g and b + grounds.

    The other scart should be wired as video "into" the TV along with the rgb connections wired up as before.

    The other thing to do is to talk to Denon and as them about the switching of these inputs.

    If it does work , you can get Ixos or someone to make you up some decent connectors. If it doesn't then you haven't wasted too much cash.

    Brian.
     
  19. Kramer

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    I've tried to put this as simply as possible, but on reading it still sounds complex. I have a Yamaha RVX620, which has component video switching, but I haven't tried this yet. The points made already are correct, re the sync signal. I'll try this scenario & let you know the results, but I'm very busy at present, so it'll be a while. I can make the appropriate leads myself.
    Here's my read on the situation:
    SCART connectors used with many European video equipments is designed to carry composite video and RGB video signals. If the equipment which outputs picture outputs RGB-signal, it will output RGB signal from the RGB pins and a complete composite video signal at the same time.


    If the receiving equipment uses RGB, it will take picture from RGB pins and sync from the composite video pin.
    If the receiving equipment understands only composite video, it will use the picture in it.
    Not all equipments are capable of outputting RGB signals. For example typical VCRs usually only output composite video. The equipment from where you might expect to get RGB are some DVD players, some computer to TV interfaces and similar devices.
    SCART pins used in RGB mode:

    5 RGB Blue Ground
    7 RGB Blue Signal (0.7Vpp 75 ohm)
    9 RGB Green Ground
    11 RGB Green Signal (0.7Vpp 75 ohm)
    13 RGB Red Ground
    15 RGB Red Signal (1Vpp 75 ohm)
    17 Composite Video Ground
    19 Composite Video Out (1Vpp 75 ohm)
    20 Composite Video In (1Vpp 75 ohm)

    On pins 19 and 20 please notice that a typical standard SCART cable the pins 19 and 20 are crossed with each other. The equipment which outputs RGB or composite video signal, the composite video is available on pin 19 at the female connector on the back of the signal sending equipment. The same signal is then available on the pin 20 at the other end of the SCART cable.
    The composite video signal has amolitude of 1Vpp, which consists of 0.3Vpp composite sync signal plus 0.7Vpp picture signal.


    SCART RGB to 4 Phono inputs
    You might in some cases want to feed the RGB from SCART to some video equipment with other type of interface. One example of such equipment would be a video projector with RGB inputs with phono connectors. The following diagram shows the wiring used for connecting an RGB signal from SCART connector to a video equipment with RGB and composite sync input.
    Hope this helps.
     
  20. bxd

    bxd
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    Gareth

    Kramer has "laid things out" a bit better than I had the time for.

    I don't see why this shouldn't work. When you select (say) Video 1 on the amp it should switch all three inputs together (composite video, s-video and component video). However these should all be independent of each other and the component inputs should be "transparent" to the rgb signal. Provided that you bring the composite video signal back together (with the rgb) at the scart input on the tv then everything should be OK.

    If manufacturers like Denon and Yamaha had thought about it they could have included a composite video input/output next to the component inputs/outputs just for the purpose of rgb switching without using a scart socket. (Doing it this way wouldn't 'tie-up' the composite output to the monitor). This sort of thing would allow people to 'switch' high quality rgb +comp sync (and probably progressive rgb) thru the amplifier. I'm sure the manufacturers don't want to put scarts on their amps (I can agree with that) but they seem to forget about the european market in this regard.

    OK, the inclusion of this type of socket might be a bit confusing for some people.... but no more so than the situation where people think that rgb and component ARE the same thing. It would also open up a NEW cable 'opportunity' for the cable manufacturers.

    Brian
     
  21. bxd

    bxd
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    Hi,

    I was just having a look at the CPC catalogue and just happened to spot the fact that they sell scart to 4 bnc (rgb+sync) cables which would be suitable for this job ( if you add bnc to phono adapters). They are sold in two forms_ one has signal out of the scart plug and the other has signal in. Unfortunately they are relatively expensive (£35 +vat for 1m / £47+vat for 5m) but do use Van Damme Red Series cable.

    Brian.
     
  22. T_Strife

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    Well it bloody works!! (On a 3802 at least).

    I Followed Kramer's excellent info and at first had no joy...only composite was passed thru.

    After studying a scart diagram i noticed pins 14+16 are 'RGB Status' Pins so i connected these up (bypassing the receiver of course) and hey presto RGB switched thru.

    Quality was good, no obvious interference could be seen despite the materials i used to bodge it together....cheap scarts, sticky tape, alarm wire and appalling soldering!

    I've no use for this feature at the mo but its good to know the ability to switch rgb is there.

    For those that want to bodge one together but are still unsure
    then this walk-thru might help:-

    The hardest part of this job is reading the numbers on the scart plug (VERY small) and ensuring with the aid of a simple multi-meter/bulb/circuit tester that you identify the correct wire at the other end.

    Take a cheap scart lead (all 21 pins connected) and cut it in 2 (this first lead you make will connect source to amp - make sure its long enough). Then take 4 male phono plugs and label them RED,GREEN,BLUE and VIDEO and connect these as follows:-

    Take your snipped scart lead and find the wire that is connected to:

    1) Pin 5 - connect this to BLUE phono OUTER
    2) Pin 7 - connect this to BLUE phono INNER (centre pin)
    3) Pin 9 - connect this to GREEN phono OUTER
    4) Pin 11 - connect this to GREEN phono INNER
    5) Pin 13 - connect this to RED phono OUTER
    6) Pin 15 - connect this to RED phono INNER
    7) Pin 17 - connect this to VIDEO phono OUTER
    8) Pin 19 - connect this to VIDEO phono INNER
    9) Pin 14 - attach a good length of wire to this and label it RGB STATUS GROUND
    10) Pin 16 - attach a good length of wire to this and label it RGB STATUS IN/OUT

    Okay thats the first part done you can now connect this to your amp, for example (if source is a dvd player) -

    Scart plug to dvd player and red/green/blue phonos to corresponding colours on amp DVD COMPONENT IN and the VIDEO phono to amp DVD VIDEO/COMPOSITE IN. Ignore the RGB STATUS wires for now.

    Now take the remaining half of your scart lead (bearing in mind that it must reach from your amp to the TV's RGB scart socket - if not cut end off another one!) and get another 4 phono plug's - label em as before - RED,GREEN,BLUE + VIDEO
    and follow steps 1 to 7 above.

    For step 8 - connect Pin 20 to the VIDEO PHONO inner.

    Steps 9 & 10 (same as before) - find the wires which connect to Pins 14 & 16 and label em 14 - RGB STATUS GROUND 16 - RGB STATUS IN/OUT.

    Right were ready to go! Take this scart lead and label it "AMP to TV" to avoid any confusion with the first lead you made.
    Connect the red/green/blue phono's to your amp's COMPONENT MONITOR OUT,
    and the VIDEO phono to amp's VIDEO/COMPOSITE MONITOR OUT. Plug the scart end into your TV's RGB capable socket. Again ignore the RGB STATUS wires for now.
    TV on, AMP on, DVD on......check TV is on correct AV input and AMP is set to correct input (DVD in this example). If your amp puts out both COMPONENT & VIDEO at the same time like mine (denon 3802) you should now have a picture.

    Ascertain whether you are getting RGB or Composite - i was only getting a poor quality composite feed at this stage cos it turns out that my tv (Sony) requires the RGB STATUS pins wired to switch into RGB mode. If you are only getting composite then simply connect together the RGB STATUS wires from each part of your leads together and VOILA!!
     
  23. GarethRamsay

    GarethRamsay
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    ... yup, it does and all!

    After following the instructions I hashed together some cables and up popped the picture in RGB. Now all I have to do is get some decent leads made up and I'm laughing.

    Thanks everyone for the input,

    Gareth
     
  24. mja

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    That is really great news and thanks to everyone for their efforts and experimentation. If anyone (brattle or Gareth or ...) gets some good quality cables made up for this, I would be very interested to know that they work, and where they can be ordered from. Any cable manufacturers reading this? I don't know how many HT households are in the UK, but I suspect many would be delighted with this option.

    Now, I know I might be wishing for everything here, but hey... Would it be technically possible to have a cable that goes from amp to TV which does this RGB via Component sockets trick, and composite for sync, and S-video? That way I could switch all inputs from the amp to a single RGB and S-video enabled scart socket on the TV and no longer have to switch TV A/V channels. If so, what would the wiring diagram look like for that - Kramer?
     
  25. LV426

    LV426
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    FWIW, I consider lektropacks ( www.lektropacks.co.uk ) to be a good supplier of custom cables. My 10 metre component (3xRCA>3xRCA) cable was received 48 hrs after ordering.
     
  26. bxd

    bxd
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    mja,

    Sorry... you can't do what you're suggesting because the s-video connection uses some of the scart pins which are (normally) used for rgb. Therefore you can't get rgb AND s-video on the same input.

    You will need to use one tv input for rgb and another for s-video/ composite.

    Brian
     
  27. NapoleonGuitarSolo

    NapoleonGuitarSolo
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    You might not be able to pass both s-vid and RGB in this fashion but could you not use the s-vid socket to pass the RGB status signals thus allowing complete RGB loop through using your amp/receiver?
     
  28. GarethRamsay

    GarethRamsay
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    I've been thinking along the same lines. I have a need for Svideo switching, RGB switching and phono switching - could I get it all on one cable? I'm not so sure...

    Phono and RGB on one cable? No problem as the phono is needed for the sync, however this leaves the question of the RGB status wire, which is required by (i believe) most TVs. Now my initial thought was to pass this through on the Svideo channel, which would work fine; problem solved. However here lies the big prob - if I did this I would never be able to use my amp for Svideo switching as the Svideo out lead to TV would be wired up as an RGB Status lead. It works vice-versa using the phono lead as status, but two out of three ain't bad, is it?

    A solution to the Status wire problem is to find out if there is a way to get the status signal activated by either the R, G, B or Sync channel (not sure if this is at all possible) or, failing that, to have a lead which carries R, G, B, Sync and Status from the DVD to the amp although only passes R, G, B and Sync through the amp, passing the Status directly to the lead which goes to the TV. If both leads had Status on a phono, you could use a simple phono - phono connector to make the join.

    Now there is a downside to this in that whenever your DVD/Sky Box is switched on, that Status signal will be reaching your TV no matter what other component your using or what channel your amp is on. Would this be a problem? I don't know, but you could always make sure they were switched off, so the problem wouldn't arise.

    Now for the big question: can you get them all on one lead? Well, many of these wires are shared on SCART, so the initial thought would be "no". However could they not be wired up to share, and as you were only ever using one at a time the signal would be pure? You wouldn't, after all, have one component using both Svideo and RGB, now, would you?

    I shall endevour to find out!
     

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