15-PIN PC Video Cable

A patch cable on the cable? Stuff the big cable where no one can touch it.

Replace the cable. CDW has vga cables 75' 100' etc. Expect to pay over $100 for it.

Cheers

If I read the facts correctly and if I were in your position, I'd do it this way:

Cut off the HUGE cable. Use a smaller cable on the 15-pin connector. Join the two cables by soldering the corresponding wires together. Put a heat-shrink sleeving on each wire. If possible, put a large heat shrink over the whole joint. For the smaller cable and the 15-pin connector, you can use an off-the-shelf VGA cable.

I've done similar patch work a few times in the past. The loss of video quality isn't noticeable.

That sounds like a good idea; use a small aluminum box instead of the DE-15 size shroud, and mount a female DE-15 socket there. Your box can then be screwed to the wall, and a limp 15-to-15 cable can run the last yard.

In a few years, it'll have to be replaced with DVI or HDMI or optical, anyhow... so I wouldn't make a big project out of it.

--- If it's been working all these years, then I wouldn't replace the cable, I'd just make a map of what goes where, viz-a-viz the 15 pin connector.

Next, I'd get a metal enclosure:

two 8 circuit, 16 position terminal blocks:

a cable clamp:

And a 15 pin D-SUB female chassis mount video connector:

View using a fixed font, and mount them in the box something like this:

. BOX . \ ___________________________________________ . | _________________________________________ | . || || . || TB1 +-+-+-+-+-+-+-+----+ || . || \ | | | | | | | | | || . || CABLE +-|-|-|-|-|-|-|-|-+ | || . || CLAMP | O O O O O O O O | | VGA || . __||_/ | O O O O O O O O | | FEMALE || . | || |_ +-|-|-|-|-|-|-|-|-+ | \ _|| .---|__||_| |--+ | | | | | | | | | _| ||_ . | || | | |----+-+-+-+-+-+-+-+ +-/8/--| | || | . | || | | |-----------------/ | | || | . |__||_| | |----+-+-+-+-+-+-+ +-/7/--|_| ||_| .---| || |_|--+ | | | | | | | | |_|| . \ |__||_| +-|-|-|-|-|-|-|---+ | || . BIG || | O O O O O O O O | | || . ASS || | O O O O O O O O | | || .CABLE || +-|-|-|-|-|-|-|---+ | || . || / | | | | | | | | || . || TB2 +-+-+-+-+-+-+------+ || . ||_________________________________________|| . |___________________________________________| .

Then, what you'll have will be, essentially, a VGA-to-huge-cable adapter which you can connect to your PC with a standard VGA cable.

I showed the connector on the box as a VGA female because I couldn't find any cheap male chassis-mounts so, unless you can, there are gender changers on the same link which which will do the trick.

Unfortunately, I read your requirements wrong so I showed signal flow from right to left. :-(

It'll work, but the graphics are clumsy...

The price is right, though ;)

--- JF

Religion. Nothing but trouble :-)

150 feet is a lot so you'll need really good cable. Is the outer shell of the cable very thick or are the internal coax cables very thick? If the internal coax cables fit into a D-shell you could use heatshrink tube to make the cable thinner.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

Not going to happen. No budget - plus the labor costs would be enormous! Think: 30-foot high ceilings.

Good suggestion, though. Thanks!

This was my thinking as well. I'm not going to make my own PCB, though. If I can do one of those $49 proto boards (PCBExpress, etc..) then that might be the best option. The board obviously wouldn't need to be very big, as I know those "specials" have strict dimension guidelines.

So, if I hear you right, fanning out on a PCB shouldn't hurt the video that much, right? If I do layout a board, anything special I should consider? It's been a real long time (since college) when I did any serious video work, and honestly, I think I forgot all that stuff.

Option-B, as mentioned here by others, is the heat-shrink approach. My only beef with that option is a) time to do it, and b) the internal video conductor are small diameter SOLID wire. I really don't want to mess with it in the first place, truthfully....

Someone else asked about cable diameter: The outer jacket is pushing 7/8". The 3 colors inside are individual shielded (small, solid conductors each), and I would guess these are about 1/4" each in diameter. Maybe a little less, but not by much.

You can imagine: Put all that on a 15-pin shell, and it's a ticking time bomb. The cable is not flexible at all.

Thanks for the ideas and suggestions guys! I was really hoping there was an off-the-shelf item for exactly this purpose...

-mpm

From your description it sounds as if the thick cable is a low-loss video cable, which is very useful, considering its length. I would use a piece of experiment board to line up the wires from the thick cable as short as possible, and cut an old vga cable in two, and solder the wires from the useful side also to that board, again, short and straight. That way you minimize impedance mis-matches as much as you can. You can use the other halve of the vga cable to check out, which color/shield goes to where. As one of the other answers shows, tuck the board in a proper box, with both cable ends fixed immovable. When you find it works, you could pour in epoxy to fixate things.

Your idea of fanning out the cable wires in a box seems to be the ideal solution. Fan out to terminal strips, then from those strips to a standard size (manageable) cable with lotza length and maybe spring-loaded strain relief might be useful outside.

Addition: if this doesn't fit: put 75 Ohm BNCs on the existing cable and use a standard VGA to BNC cable plus BNC female-female couplers.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

ize

OK - I think I'll go with this approach (small PCB in a metal box of some sort). Rather than a pigtail on the PC end, I should probably just use a PCB thru-hole 15-connector of the right sex and fasten it to the box. Then, run a standard monitor cable from the PC to my new box. (One less thing to go wrong, and elimintes several soldering steps.)

-mpm

Why a PCB? To terminate a stiff cable to solder pads on a printed wiring board is VERY hard. Get the cable bolted to the box for strain relief, then either

(1) fan out the conductors and splice one wire from the DE-15 connector to each or (2) terminate each conductor to a terminal block then use convenient- size hookup wire to the DE-15 connector.

Really bad idea. You don't want impedance changes in a video signal. Reflections are very easy to see in the screen.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

Depending on the screen resolution and refresh rate he's running, his video bandwidth is likely well under 100MHz, so it's not quite as bad yet as one might think... assuming "small PCB" means something like an inch or so or smaller. Heck, I remember older video cards -- back around the 1024x768 days -- where there were multi-inch traces from some video IC to the VGA connector that weren't length match nor impedance controlled!

But hey, as you say... reflections are quite visible, so at least he'll know if he needs to be more careful! :-)

eo

e 8

now

The projector resolution is 1024 * 768 (the XGA standard, I believe). I don't know the refresh rate, but the PC is pretty sluggish. It is probably 4+ years old, maybe older.

What made it a "disaster waiting to happen?" Are the individual conductors solid, like that telephone trunk stuff (only about as fat as a man's thumb), individual coaxes? Just one shield over the whole thing? When you redid the connector, did you use heatshrink on each conductor for strain relief? Is there enough cable left over at the PC end to cut it back to clean new ends? What's the other end look like?

We need more info, man! :-)

Good Luck! Rich

Remember, though, he's hanging this at the end of a 100' cable. Any reflection is going to make a mess of the video. 300ns will make a mess of even 1024x768x60Hz (21ns bit time).

By the time he finds out he's past the point of no return.

There's a fat cable coming from the projector. It's pushing 150+ in total overall length. The projector is 30-feet up in the ceiling, and while I don't recall exactly how it's hooked up, I don't think the projector end is the same kind of thick cable, so it must be spliced somewhere..?

Anyway, back to the PC end of the cable -- What we had was this huge cable (stiff, inflexible, many shielded wires, etc...) and on the very end of it, someone has literally soldered a 15-pin connector and pushed that directly into the video card on the back of the PC. That's right - wires individually soldered to the terminal, with no housing (as if one would fit!), and no strain relief whatsoever. If you move the cable, you automatically stress the solder joints. There's no avoiding it.

Each color is individual shielded (R, G, B), and the blue signal wire had come off. The cable has been twisted in the past, so now all the other pins on the 15-pin shell are nearly touching each other. And, it's not a good solder job to begin with. It's a mess. But, there's really no way to put a 15-pin connector on this cable. It's just too damn big.

The Blue signal wire which had come off, is a solid center, and pretty small gauge. I'm guessing a stiff 24 ga, but it might be a little bigger than that?

The projector image looks perfect, and always has, even with this screwy connector. It's an InFocus IN21 DLP type, but for the money ($900 budget) it actually outperforms the $35k projector it replaced (a big Sanyo unit). I don't see an upgrade anytime in the next year or so, minimum, and either way, we'll have to fix this cable.

Does that give you a little more flavor? I wish I had taken a picture of it.