Experiences using CAT5-STP for long video cables using DSUB HD-15 (VGA) connectors

Discussion in 'Cables & Switches' started by Transwarp, Mar 18, 2006.

  1. Transwarp

    Transwarp
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    Hi All

    I just wanted to share my experiences and perhaps motivate others to try using CAT5-STP cable to make long video interconnects.

    My setup consists of a ceiling mounted projector that requires an 11m video cable to reach my DVD player / HTPC. The projector inputs include composite, s-video and HD-15 (standard computer VGA video connector). The image using the HD15 input is exceptional, the composite and s-video alternatives simply don't compare. I decided to construct a suitable HD15 to HD15 cable with the following design goals:

    1. The cable must be thin enough to route through walls
    2. The cable must be 11m long
    3. The cable must achieve better picture quality than both s-video and composite

    I found the wiring diagram and some great feedback on this page: this page.

    This page is also very interesting but uses UTP cable with no shield on pin 10 of the HD15 connector (bad idea in my experience see below).

    For my first attempt I used cat5-UTP to make an 11m (36ft) cable. Whilst the cable worked (term used loosely) the image was horrible with very noticeable ghosting and blurring - I was very disappointed.

    I then built a 12.5m (41ft) cable using CAT5-STP (shielded twisted pair) and metal DSUB hoods. I also terminated the STP shield wire to pin 10 on both ends.

    I tested this cable on two projectors and a 42" LCD TV, I used a HTPC (1280x1024x60Hertz), DVD player and XBOX to drive the image and the quality was exceptional. There is no visible ghosting, ringing or banding what-so-ever. I blind tested this cable (compared to a 5ft SONY moulded VGA cable) to a couple of "video-phile" friends and they immediately demanded that I build replicas for them.

    The total cost of building the cable (15m STP patch cable, 2 DSUB connectors, 2 shielded metal DSUB hoods, 10mm heatshrink wrap) was less that £10!

    Here are a few tips if you are planning to build these cables:

    1. Buy STP patch cables, it's actually cheaper than buying a reel of STP! I got 15m cables from expansys for £2 + shipping (£3 for black cable).

    2. Twist and tin the wires before soldering.

    3. Use a pair helping hands to hold the dsub connectors while soldering.

    4. Buy metallised hoods, the ones from Maplin are of a very high quality.

    5. Use 10mm shrink-wrap to strengthen the last 2-3 inches of cable as it enters the hoods, this really makes a difference.

    6. Use a continuity tester to check each pin before using the cable. The metal hoods should act as a shied so check that too.

    7. Don't waste your time with with CAT5-UTP (unshielded cable)
     
  2. JamesBird

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    Hi Transwarp

    My requirements are the same as yours. My pj needs a cable 10m in length and I need it to be routed through a wall and the ceiling space. I’m currently using composite over WF100 cable (I’ve tried RG6 cable too) but the image is barely acceptable. I’ve plugged my projector directly into my laptop using the vga port and the supplied 5ft cable and the image is stunning! I would really like to go down this route with my HTPC to pj.

    I have lots of cat5stp (I’m a network engineer) but I’m not sure of the other components I need to build this cable do you have a parts list from Maplin? There is a store just down the road so I can go and buy them and try this today.

    Thanks,

    James
     
  3. Transwarp

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    Hi James

    The reason the picture is so much better is because the VGA input uses RGBHV (Red, Green, Blue, Horizontal+Vertitcal sync) to drive the image, that's 5 channels of ‘data' as opposed to composite's 1 channel.

    The Maplin parts I used (in addition to CAT5-STP) are as follows:

    Code:
    Part    Description            Qty.
    ===================================
    YR17T   10mm Heatshrink 1m        1
    JB68Y   Metalise D Hood 9W        2
    JW77J   HD 15 Way D Plg           2
    As for tools, I used a 25w soldering iron, a pair of helping hands (part no: YK53H) and a continuity tester.

    Good luck! And let me know how you get along.
     
  4. Tee Tee

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    I've used CAT5 STP cable as well - using tips from both the pages linked to above. The difference being that I used phonos at one end to create a phono to VGA for my Panny 6 series plasma.

    I'm very pleased with the results - interesting project and cheap too!
     
  5. Transwarp

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    Hi Tee Tee,

    That sounds like an interesting solution. Did you ground the STP shield wire to one on the phono connectos (green I think) to bring down the cable impedence to ~75 ohm ?

    I might make one of these for my other projector which is pretty antique and has RGB phono inputs instead of VGA.

    TW
     
  6. Tee Tee

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    Hi TW,

    Yes, that's exactly what I did. Couldn't believe how easy it was to do - a little soldering experience is required though! and that helping hands tool is invlauable...

    TT
     
  7. JamesBird

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    Hi Transwarp

    YOU FREAKING RULE! :thumbsup:

    I had my friend (who can solder) put the ends on my cable and test it with his multimeter. All was well so we plugged it in and gave it a whirl.

    The picture quality is absolutely superb! I’m totally blown away.

    I can’t believe this isn’t the standard cable for this sort of installation, there must be loads of people using composite or s-video when they could be using this.

    I’ve actually got two vga inputs on my pj so I’ve run another length of cable which I’ll have soldered up tomorrow, this one is going to go into my freeview box. However, the freeview box only has an rgb scart output. Do you know if one end can be soldered to a scart connector instead of the vga? If so, what’s the pinout?

    Again, thanks for posting such brilliant info.

    James
     
  8. Transwarp

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    Hi James

    I'm really glad to hear about your success. Don't thank me though, it's was Mr.Wiggles and Thumper on the American AV forum that came up with the original idea and gave me the inspiration to try it out.

    I've made 2 more of these cables today for my friends and have enjoyed equally impressive results. I suspect I'll be making a few more for friends of friends etc once word gets around :rolleyes:

    I'm currently making a combined S-VIDEO and COMPOSITE cable to feed the other two inputs on my projector, there are 4 pairs plus the ground wire in the STP cable so there's plenty of scope to combine these sources. I don't actually need them but I figured I'd wire them in while I have the floor up – just in case…

    You can't connect SCART to VGA directly as the SCART connector does not supply the necessary separate H+V sync lines. You can build a simple circuit to extract the sync signal and separate it into H+V. It might be easier to buy one of these devices. It accepts RGB SCART on one side and outputs RGBHV VGA on the other. I installed one at a friends house to enable him to connect his SCART DVD player to his 42” LCD TV's VGA socket. It works great and for some reason gives a much better picture than directly plugging the SCART lead into the TV :confused:

    Be warned though, your projector / TV needs to be able to accept a 15.6 Khz signal. I've never had any problems with this on any of the equipment I tried but you might want to check the input frequency specifications of your projector's DSUB port.
     
  9. JamesBird

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    Hi TW

    That makes sense; I'll order one of those scart to vga boxes today.

    Once again, thanks for all your help. Your advice has improved my viewing pleasure dramatically.

    James
     
  10. ZippyCat

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    As said above you will need to be careful that your display devices can actually accept the synch rates from the converter box. My advice would be to purchase from a retailer with a good returns policy. I have had the misfortune of believing the specifications listed in user manuals where it stated my projector would accept the frequencies, however my projector only displayed ‘signal not supported’, yet both the horixontal and vertical rates were specified as within range.
     
  11. Transwarp

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    That sucks ZippyCat. I guess I've been lucky with the kit I've tried it on.

    It's a double slap in the face when the manual states that it will work!
     
  12. ZippyCat

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    Tell me about it, I now have a surplus JS Technology SCART Buffer and 10m Lindy VGA cable sitting around doing nothing (managed to return the QED converter although I still have yet to receive my refund). I suppose I could post them on the classified forum but it’s just been a load of unnecessary hassle, which I could do without.:thumbsdow
     
  13. ScottBaker

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    Transwarp

    I am really interested in buying one of these cables for my setup. I don't need to drill through walls as I have trunking built into my skirting board and up to the projector. The cable would need to be 31ft long.

    Soldering etc is totally beyond me. I know it's a bit of a cheek but I would be hugely grateful if you would be prepared to make and test me a cable for say £30 delivered?

    Scott
     
  14. Transwarp

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    Hi Scott

    If you practice your soldering skills for 30 mins you'll be able to do this on your own, seriously it's not that difficult.

    Also, I don't think the forum rules allow conversations about payment for work etc as it's not fair on the companies that sponsor this site. On that note, have you checked those guys out, they might have a long ready made VGA cable for less than £30!

    Remember, one of the key benefit of this DIY approach is for when you need to run cables through walls over long distances before attaching the ends. If you don't have any walls you might just as well buy a ready made cable.

    If you get really stuck then send me a private message (click my name in the left column) and I'll see if I can help.

    Dan
     
  15. Barton1967

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    Can anyone see why this technique can't be used to create phono to phono component cables?

    If it can what would be the best way to wire it?

    Thanks.


    Chris
     
  16. Transwarp

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    Hi Chris

    The yanks are making component cables out of cat5, there a bit about it on the middle of this page.

    Hope that helps

    TW
     
  17. SteveBot

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    Hi,

    I've worked back through this thread with interest as I have a problem plumbing in a plasma.

    I have an Arcam AVR300 with RGBs output to a Scart card on a Panasonic TH 42PW6 plasma.

    With a short 4 phono to Scart connector the picture is fine.

    I now want to chase the plasma cables into the wall and hide all boxes etc in a cupboard.

    I made up a 10m fully connnected scart lead to test the signal over a long run and got sound but virtually no video signal.

    If I read the posts right I could work out which Scart pins my RGBs cable is using and connect STP cat5 accordingly.

    My question is what to do with the Cat 5 shielding? Tee Tee mentions connecting it to the green phono. Is that to the Green gnd connection at both ends?

    Any help is appreciated as I want to get the connections working before chasing into walls.
     
  18. Transwarp

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    Hi Steve

    I would start by working out the current pin-out of your working lead using a continuity tester.

    I think the STP shied wire can be connected to SCART pin 21, at least according to this diagram.

    TW
     
  19. SteveBot

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    Thanks TW,

    That's what I was planning to do.

    What do you recommend I connect the shield to on the 4 x phono end?
     
  20. Transwarp

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    I would first try NOT grounding the shiled on the phono end, just bend the shied wire back on its self. I know that sounds odd, but if you read the American AV forum they offer some good reasons why this might work.

    If the image quality is poor then I wound ground it with the green phono connector's regualr ground.

    Good luck, and do post back with your results.

    TW
     
  21. RBJTech

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    If you're going to bother chasing walls for the cable - then why are you even contemplating using STP ? For a 'thin' quick and dirty cable 'it works' but for the best quality you need to use shielded coax for the analogue signals - in your case the RG and B (with sync going over composite/yellow).

    I've just done a similar thing for a long (10m) VGA connection, I tried with STP and the result was IMO nasty - I then used Van Damme 'thin' video Coax for the analogue signals (RG & B) and used the STP for the sync and monitor signals only - picture difference was night and day vs just STP.

    If you do plan to try it, then your common ground doesn't really need to be connected at the phono end - the shield is just acting as a RF shield, it is not carrying signals so grounding at one end is fine.

    This is assuming :-

    SCART 5 & 7 (Blue) - Pair 1
    SCART 9 & 11 (Green) - Pair 2
    SCART 13 & 15 (Red) - Pair 3
    SCART 17 & 19 (Composite/Sync) - Pair 4
    SCART 21 - STP Shield.

    All IMO of course .. hope this helps.

    Richard.
     
  22. Transwarp

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    Hi Teerex

    Are you sure you wired your original STP cable correctly? I only ask because I've made 6 of these cables now, raging in length from 10m to 13.5m and they have given me terrific results. I've used them on all sorts of kit with no problems what-so-ever. I did however have really awful results with UTP cable.

    Whilst I agree that running 4 lengths of coax will offer the best possible image quality I personally cannot see the difference. Then again I suppose your millage will always vary with a bespoke solution like this.

    SteveBot, I think I'd make up a test STP cable before committing to the multi-coax option as you'll need to chase out your walls a fair bit more to install 4 lengths of cable.

    Do let us know how you get on,

    TW
     
  23. SteveBot

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    Thanks guys,

    I was originally told that good quality Scart cable would be OK for this but obviously not (my 10m test lead produces no watchable image).

    I was also advised to try to lay DVI cables for future proofing but these won't handle the run either.

    I scrabbled around to find some reliable advice and stumbled upon Cat 5 DVI and RGB extenders at c£450 the set. Then found the threads about STP Cat5.

    I thought I would run 3 x STP and 1 ordinary for IR signals and if necessary use the DVI extenders later.

    I estimate the run to be between 20 and 25 metres. Would the Van Damme coax carry a signal that length (their website says 100m but does that depend on the strength of signal source)?

    Given the potential for this to go wrong I'll probably test the STP solution (I already have patch cables) as well as the Van Damme coax.

    I don't mind how much cable goes in the wall as long as it stands a chance of being useful in the future. Scart obviously isn't.

    I'll report back in a few days.
     
  24. Transwarp

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    20-25 meters is a looooong run Steve. I think you will get noticeable signal loss over a run like that but it's a question of what's acceptable. Don't forget to uncoil the STP when you make your test cable!

    You can probably go a bit further using a VGA sync box (see earlier post) as the voltages are higher.

    Arcam Component out -> Component in | VGA out-> long STP VGA cable -> VGA in (on Plasma TV?)
     
  25. RBJTech

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    Transwarp - Hmmm, maybe I did wire it up wrong ! I used 3 pairs for the RGB signals (signal and return per pair), H & V sync on the remaining pair and sync return on the ground wire. I used decent metal enclosures so thought I did everything correctly but was disappointed with the result. Mind you, it was being blow up to a 120" via a projector so maybe I saw the ghosting/colour bleeding that remains hidden on a (relatively) small plasma ? I may try it again, you've nudged my curiousity ... :)

    For a 20-25 meter run, regardless of the above, it will be all about signal loss (via the cable resistance,capacitance etc) vs interference vs signal strength. If it were me, I would use full sized (ie non mini) decent coax for each analogue signal.

    Can't understand why the 10m SCART didn't give you reasonable quality tbh - was it a cheap lead using unscreened individual cores ?

    PS - Only way to 'really' future proof the cable run is to bury some hosepipe in the wall with shallow bends and put a pull string through it ready for the next time you need to replace the cable with the new standard ! (just don't use the corrigated stuff, cables snag on them something rotton) ...

    :)

    Richard.
     
  26. flash543

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    Not sure if this is straying too far off thread, if so I apologise, it was the network connection that got me thinking!

    I have numerous lengths of the old thin wire coax 10Base2 network cable and I was thinking of making up a component video cable using three of these "tied" together. They are currently terminated with BNC plugs but could be converted using adapters and I believe the cable is 50 ohm. The run of cable would be approx 10ft.

    Has anyone tried this or any views on problems that might arise or in fact any other possible AV uses for the cable.
     
  27. Transwarp

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    10ft! cripes that's a big screen. I project onto an 8ft screen using my cable with no problems. It could just be that you have a better eye than me, although I have had several of my rather picky video-nerd friends check my results before they used the same configuration for their projectors.

    I'm wondering if all STP cables are not equal. I've only used 15m cables from expansys (~£3) , these are machine terminated so I had to cut the original shielded rj45 connectors off.

    That's solid advice.

    Very true, though I usually use 1 inch plastic conduit, heat it to create soft bends around the corners and glue the straight couplers in place.
     
  28. Transwarp

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    Hi flash

    I've used thin-net in the past to make various cables with pretty good results. Unless your kit uses BNC connectors cut them off and directly solder your own plugs in place.

    TW
     
  29. SteveBot

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    Spent yesterday evening lifting floorboards to find a shorter cable run.

    Also discovered my Scart pinout diagram is suspect. Looks like a problem with the composite sync.

    I was planning to use conduit but the advice about the corrugated stuff is welcome as that's what I have available at the moment. I'm taking all the plaster off the wall (solid stone) so chasing a wider conduit is not a major problem (2 to separate mains from signals).

    Does anyone know of small mains connectors (preferably with surge protection) I can use in a cable box behind the plasma mount?

    I will run 2 x STP cables as well as UTP and will test these for RGBs anyway.

    That should keep me going to next week.

    Thanks again,
     
  30. Joe Fernand

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    Hello SteveBot

    01 DVI - there's no reason not to install a conventional 'copper' DVI cable - you can go to 15m with a 1080P signal without problems; see http://www.bettercables.com/index.asp?PageAction=VIEWCATS&Category=2

    02. Fibre DVI - you can also go with Fibre optic DVI and not require mains powered Transmitters and Receivers; see http://www.gefen.com/kvm/cables/fiberextreme.jsp#dvifo

    03. SCART at 10m - this should be possible though you can get inconsistent results even with a decent cable such as the SUPRA AV6 (RGB Only).

    04. Analogue Multicore - if your going to 25m and want to ensure you get no signal drop off use the VanDamme Red Series (268-315-020) not the Mini Red Series (268-305-020).

    If you use the five core Multicore you can use the cable for most analogue signal types.

    Best regards

    Joe
     

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