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

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)

[JamesBird]

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

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:

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.

[Tee Tee]

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!

Originally Posted by Tee Tee

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!

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

[Tee Tee]

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

[JamesBird]

Hi Transwarp

YOU FREAKING RULE!

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

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

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

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.

[JamesBird]

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

[ZippyCat]

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.

Originally Posted by ZippyCat

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.

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!

[ZippyCat]

Originally Posted by Transwarp

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!

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.

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

Originally Posted by ScottBaker

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

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

[Barton1967]

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