or Connect
AVS › AVS Forum › Display Devices › Digital Hi-End Projectors - $3,000+ USD MSRP › RGBHV over shielded Cat 5 success!
New Posts  All Forums:Forum Nav:

RGBHV over shielded Cat 5 success! - Page 5

post #121 of 524

You might want to try moving to the USA I found the users manual for your DVD player, and it's certainly a different animal from anything we see around here. It sounds to me as if you are on the right track. I hope someone steps up with a circuit for you. Unfortunately I've been in the world of ones and zeros too long to be of any help.

- Chris
post #122 of 524
Thanks for looking into it Chris. I don't think it's an option moving to the USA. I wouldn't know what to do with all of my PAL and 220V equipment.

This has been a long night but it seems like I found a solution. I found this page describing my situation http://www.epanorama.net/documents/vga2rgb/scart.html This led me to order a few ICs and some components. It seems like I'm going to build my first circuit including an IC

A pdf file describing the IC can be seen here if anyone has the interest http://www.maplin.co.uk/PDF/LM1881.pdf

The IC extracts the V sync from the composite signal and outputs it separate. I hope this will be sufficient to get the projector to accept the RGB signal from my DVD player.

If someone is thinking OH NO !! this is not going to work because it will ????, please let me know

post #123 of 524
So tell us a little more about how you will input RGB to your projector. I now understand that your RGB does not have the sync signal embedded, that is called "sync on green" I believe, because the composite sync is mixed into the green signal. If your intent with this circuit is to combine the green and sync signals for input on pins 2 and 7, then set the projector for "component video" input, that sounds correct.

I presume you understand that there are two forms of this component video, the interlaced and the progressive, and the sync frequency for the progressive form is double the interlaced. The projector will accept both but the interlaced signal will get "line doubled" using the internal circuitry of the projector. This may or may not produce acceptable video quality. The alternatives to improve this would be 1) use a quality external line doubler like a DVDO with an RGBHV output or 2) get a real progressive scan DVD player with embedded "sync on green" component output.

post #124 of 524
Hi Gary. Nice that you care.

48 hours ago I didn't know anything about this at all. I just couldn't get my newly acquired LT150 to accept the RGB signal now matter what I tried. I took my DVD player to the store I bought it and had them test that there was indeed a signal when I choose RGB and there was and the DVD player played a DVD through RGB . By then I knew that the problem wasn't the DVD player.

When I investigated further I found the information posted earlier.

As you mention my RGB signal is not "Sync on green". That is called RGsB. My RGB signal is RGBS which means "sync on composite". When I connect the composite signal to V-sync I sometimes get a picture. The picture doesn't last long (at most ½ second then the image "tears apart" and a few seconds later I get blue screen. I learned that this is because the strength of the signal is not strong enough (only 0.3Vpp).

What I plan to do is to make a little electronic device which is feed with the composite signal. The device the reads the sync information and isolate it. It then amplifies the signal (up to 1.5Vpp) and outputs the V-sync signal. I can then take this signal and feed it together with the RGB from the DVD player.

I don't know about the H-sync because I can't find any information regarding this so I have to try with only V-sync. If it doesn't work I only spent about $6-7.

If I understand you correct you suggest that I combine the green signal with the composite signal and thereby make RGsB? Wouldn't that be dangerous and wouldn't I risk making a shortcut and fry my DVD player ? I ask because I honestly don't know.

Regarding the DVDOO and similar devises I have thought about it. It is just a little to expensive right now and furthermore I don't think the LT150 will accept a progressive PAL signal (I don't know this for sure but seem to remember someone mentioning it a while back)

post #125 of 524
Thanks to Mr Wiggles and Belmore, I have successfully put together some cables. I kind of question how long the solder joints will last (my first time soldering, what a pain in the @ss trying to solder 9 small wires into the HD-15 connector!), but it's working great right now. I have a 19 foot cable terminated in a HD-15 connector going into my LT-150 and the other end with an RJ-45 connector going into a coupler. I also made two more cables terminated with Canare F-10 RCA connectors for component connections to my Samsung HDTV STB and DVD player, so I have a fairly easy way to switch sources. Thanks!
post #126 of 524

You won't find 75 ohm "cat 5" since cat 5 is a specification, and that spec says it has to be 100 ohms. The theory is that connecting the shield with the signal grounds bring the characteristic impedance down closer to 75 ohms. It's not clear to me how this works when one end uses BNC connectors.

If you have a bit of length to spare for an experiment, you should try replacing the BNC end with another HD-15 and seeing how it works using the Computer 1 input of your D-ILA. If this looks good, then you'll know that the BNC connectors are the culprit. I know that you need to use Computer 2 for the HD, but this experiment will at least tell you if it's the BNCs that are giving you trouble. Keep in mind too that 40' is right about at the limit of where this solution works well. My first attempt at one of these cables was 50' long with a female HD-15 on one end, which I connected to my Computer 2 input via a HD15-to-5BNC breakout cable. I was quite disappointed with the ghosting. I then cut it down to 38.5' with a male HD-15 and connected it to Computer 1 and it looks great. I was never sure whether it was the length reduction or getting the breakout cable out that was responsible for most of the improvement. Fortunately for me, using Computer 2 is not a requirement.

The "color smearing" may be a different problem. If you mean by this that it appears that the R,G, and B don't appear to be perfectly converged, then this is probably caused by the "pair skew" that Dizzman brought up in an earlier post in this thread, and which has been discussed some more in another thread.
If you have Dilard, you can use the Pixel Alignment Wizard to check this and adjust for it. One thought I've had is that with the proper choice of which pair is used for which color, you might even be able to use the pair skew to your advantage to compensate for slight panel misalignment that most D-ILAs have.

- Chris
post #127 of 524
Has anyone tried to make a cable with an EVC connector on one end. I've got a Davis clone and would like to try this if anyone's had success. Anyone know where to get EVC connectors? I'll give it a try if I can find a connector.
post #128 of 524
Well, I've made a cable using the CDW STP cat5 cable. I got my HD15 connector from Radio Shack and bought some BNC connectors (I'm connecting an HTPC to a D-ILA and want to do both HDTV and SXGA on the same projector input which is RGBHV). The BNC conectors are Radio Shack part number 278-126. They were fairly easy to solder and attach. The signal part attaches with a screw and the grounding part needs to be soldered.

The cable is about 40 feet. I tested it and while I did see improvement over my cheap extension cables, I did notice faint ghosting and a little smearing of colors. I'm wondering if the cables are not right or do I have an impedance mismatch... or both. I know the impedence of the cable is different that the standard 75 ohm that is used in video equipment connections and cables. I'm not sure of the impedence of the BNC connectors or the HD15 connector but there is a problem. I could also have bad solder joints since but I've checked those and they look good. The only solder joints that are suspect are the BNC grounding joints but that is not used for the signal so i should not see any ghosting due to that.

Any suggestions or help? Does anyone sell 75 ohm stp cat5 cable?


-- John

[This message has been edited by brzez (edited 08-22-2001).]
post #129 of 524

I bought a 25 conductor cable that doesnt seem to have twisted pairs, but it is indeed shielded. Would this be usable? Here's the item I'm talking about:

My first attempt is a 35-40' long cable, but I get quite a bit of ghosting at 1024x768, is this the result of noise caused by the lack of twisting, or is this more of an impedance or out of phase problem?


post #130 of 524
Could you use the following combinations in order to build an easy RJ45-HD15 adapter:
http://www.national-tech.com/specs/31d1-17200.htm http://www.national-tech.com/specs/31d1-17400.htm
http://www.national-tech.com/specs/30h1-06100.htm http://www.national-tech.com/specs/30h1-06400.htm

For under $38 (plus shipping) I can get a 14' patch cable, the adapters above, a shielded coupler, and a 50' cable (all shielded). I don't know if the connectors are shielded or if they even need to be. Since the CAT5 is shielded that may (or may not) work.

Tell me if I am off my rocker. The adapters would be cheaper than the HD-15 connector with the shielded cover.

Hmm, cheap and quick with much less soldering.
post #131 of 524
Oh, here is something else at RatShack that may be of some use....

Then again, it may just be Monday
post #132 of 524
** bump **

I'm sure that this was lost during the events of last Tuesday.
post #133 of 524
Anyone running this mod with VGA to BNC successfully.
Wondering how the picture quality differ.
If any.
Thanks Hugo
post #134 of 524

Why bother? All DVD players sold in Europe worth mentioning have component output. Only rock-bottom players don't. So why not upgrade to a new player, especially considering that you should run a progressive signal to your LT150 anyway.
post #135 of 524
I'll be going from my VGA-HTPC to BNC-DILA G11U.
Using a CAT 5 Cable
Anyone tried this .


[This message has been edited by Hugomed (edited 10-12-2001).]
post #136 of 524

I would be concerned about losig shielding once you break-out of the Cat5 for the individual connectors. As I understand it, a large part of the sucess of this method relies on maintaining the shielding throughout the cable. Thus the shielded compact connectors are recommended, like the VGA D-Subs.

But hey, who knows how bad it will be till you try?

Ken B.
post #137 of 524
I see what you are saying, Between the CAt5 cables strands there is no Shield introducing maybe some noise.

If there is no risk to my projector I would like to try it.

post #138 of 524
Anyone tryed VGA <-> RGBHV(5*BNC)?

Maybe the cat5 shield could be connected to one of the BNCs ground like MrWigggles suggested with the Y connector on the Y-Pr-Pb breakout.

Thanks in advance.
post #139 of 524
Noone tryed this?
post #140 of 524
Are there alternative reasons (besides cost) for doing all of this work to get video over CAT5? I think CAT5 is something like $0.20/foot whereas very good 75 ohm 5-conductor cabling is $1.40/foot. Granted, that's a huge difference, but when you're looking at, say, 30 ft, it's only $36. Compared to the cost of the rest of the system, I'd say this was a pittance.

So, I ask -- am I missing something?

post #141 of 524
Thread Starter 

You have very good points.

For the people who are doing component video runs with coaxial connectors on the source and display, this cat5 solution won't have much benefit.

However, for others there are benefits:

1. Form factor - Shielded cat5 is thinner and lighter than multi-coax cable. this makes it a lot easier to pull through walls as well. I like putting on my connectors after running it through the walls. This leads to #2.

2. HD-15 connectors - getting coax wires to go on hd-15's takes shield terminators, big mouth backshells, and a ton of soldering time. Good shield terminators are a $1 a piece.

3. Cost - as you mentioned, but plenum coax is much more expensive than plenum cat5 when the building/fire codes come into play.

4. Signal switching - using shielded recepticles, manual switching is very possible. RJ-45's are easy to switch in and out. When more cost effective higher performance KVM switchers (without the V and M) are produced electronic switching will be a better option; but for now it isn't IMHO.

So for those who have multiple sources and displays with moderately long cable runs, using shielded cat5 is quality cost effective option.

-Mr. Wigggles
post #142 of 524
Or, if you dont want to spend a lot of time building them, and get some cables at ridiculously low prices go here:
post #143 of 524

Originally posted by MrWigggles
1. Form factor - Shielded cat5 is thinner and lighter than multi-coax cable. this makes it a lot easier to pull through walls as well. I like putting on my connectors after running it through the walls.

I've made this point many times before. The shielded cat5 is thin enough that you may be able to get away without going through walls at all! This is what made this such a killer solution for me. I glued it along the bottom edge of my crown moulding and painted it. It is virtually unnoticeable and does nothing to detract from the aesthetics of the room. The only way I could get HDTV into my system was to run another cable, and I was simply not going to tear up the room again. If it weren't for this thread, I would not be watching HDTV today. Thanks once again MrWigggles - it's great to have you back!

- Chris
post #144 of 524
OK ,

I recently got a DLP projector and haven't set it up properly so far, what I was lacking was a 'long-enough' VGA cable to connect it to my PC. The solution given here was pretty convenient for me as I'm in the IT business and can get RJ45 cables so easily ... So yesterday I took a 5m long cable: Cat 5e, FTP and made my cable. The result is quite decent regarding ghosting compared to the previous 3m VGA cable that I had and which was really worse, BUT I can see the 'beating' of my fans on my screen !!! Don't really know how to call this in English but it's quite annoying, is this normal or is there a way to get rid of it ? should I re-make my cable.

For Info, this was using res. 1024*768 @ 85Hz on my TFT monitor.

Thanks for your help
post #145 of 524
Are you using shielded cable? Sounds like it could be an induced voltage on your cable. If you do use a shield, make sure it is only grounded at the source (PC) end to avoid ground loops.

I built a 40' cable using unshielded Cat 5 and got good results.

A clamp on ferrite may also help, should be available at most electronics supply houses or on line at www.digi-key.com
post #146 of 524
I finally found a local supply of cat5e cable


It is base in Montreal. I was about to order when I notice they have some shielded cat5e with 5 pairs instead of 4. Will that be better? that way I could have the H an V with their own ground. Please let me know so I could make that cable ASAP.

I will like to know what are the rating for. Should I go for the 4 pairs 24 AWG solid or the 4 pairs 26 AWG stranded?

Thank you!

post #147 of 524
Do I need to beg?

Please! Please!
post #148 of 524
Just hooked up my recently built home-made 35' cable. Looks as good as my store bought 6' breakout cable with no ghosting. Get the 4-pair solid and you can't go wrong. You don't need the ground for the H & V sync. Just more soldering to do!

post #149 of 524
Thread Starter 
The thread that won't die. That is a good thing.

If you want 5, go with 5. The H and V shouldn't matter all that much if they have a seperate ground or not. Those lines only toggle during the black front and back porches of image. During the actual image those lines are stagnit. They simply don't need perfect impedance matching to operate correctly.

Also the 5 twisted-pair cable is going to have a thicker form factor than the 4 pair stuff. That is something to keep in mind.

-Mr. Wigggles
post #150 of 524
I just built a cable for my sanyo xp30, mounting it on a 20' ceiling tomorrow.

My problem is that With 20' up, +/- 40' to the back of the room, my run is going to be quite long.

I bought 100' of STP and did a test-solder with the whole roll, blurring is quite bad, not too much ghosting.

If I have to run 65 feet of cable, is there any way to increase the PQ? Will those little ferrite clamp-ons help? (I'm pretty sure they're just for noise, right?)

Anyway, even if it doesn't do what I need it to, it's still the best temporary solution until I can buy some good 75' cable.
New Posts  All Forums:Forum Nav:
  Return Home
AVS › AVS Forum › Display Devices › Digital Hi-End Projectors - $3,000+ USD MSRP › RGBHV over shielded Cat 5 success!