So over break I was working on my suitcase computer and had a moment (which actually was more like a span of a day) where I experienced what can really only be described as a rapid divergance between a cost-effective self-manufactured parts, and a time-saving purchased part. This is an uncommon failure on my part, but I digress.
This particular failure started out as an effort to make a DVI-I extension cable that will plug in to the video card and extend the DVI-I ports to the edge of the case. For this cable I knew that making my own cables would be painfull and time-consuming, however a search for a usefull commercial product turned up nothing (initially).
The first thing I tried was to take a DVI-D cable that I bought, use a dremmel to cut off the plastic casing around the end connectors, cut the wire and solder it back together shorter. Bad idea. I stopped halfway through the plastic casing realizing I would never get the wires free enough to solder back together.
So I bought a pair each of solder-on DVI-I male and female connectors. This was my first mistake: the DVI cable was DVI-D, not DVI-I. At the time of purchase I did not research the difference, but upon splaying the cable open I discovered that it was 6 wires short of the needed 29 wires for DVI-I.
DVI comes in 3 basic types – DVI-D, DVI-A, and DVI-I – with an option for “Dual Link” in “D” and “I”. The D stands for Digital, and carries the video signal in 3 sets of LVDS (Low-Voltage Differential Signaling) wires, and 8 other signaling and shield wires. The A stands for analog, and uses another 6 wires, using the “+” on the connector and the 4 pins around it, along with the unused pin remaining on the grid of pins and shares a few of the signaling pins. The I stands for integrated, and is a combination of both D and A in one cable.
Now that we know the types, there’s the Dual-Link option. From what I’ve read, if you don’t know what it is… you don’t need it. Just skip to the next paragraph. It’s not worth your time. Ok, if you insist… Dual link adds 6 more pins carrying 3 more LVDS channels in order to increase the amount of data that can be sent. If you simply say that’s twice the data that can be sent, you would be mistaken. This is twice the data channels. From what I can tell, LVDS is bit-wise signaling, so that means that you increase the information from 2^3 parallel bits, to 2^6 parallel bits. 2^3 = 8, and 2^6 = 64. That’s 8 times the data capability. Not that it uses it. In reality, the largest resolution possible at 60 Hz is 2.75 megapixels (including blanking interval). For practical purposes, this allows a maximum screen resolution at 60 Hz of 1915 x 1436 pixels (standard 4:3 ratio), 1854 x 1483 pixels (5:4 ratio) or 2098 x 1311 (widescreen 8:5 ratio). -wikipedia on DVI If you want higher resolution than this, you will need dual-link. Since I don’t know anyone who can afford a monitor with resolution better than this… you just wasted your time reading… congratulations. Next paragraph.
Back to the topic of me failing. So as I sat there looking at the lack of wires needed to make a DVI-I extension cable, I decided to go ahead and try to solder it on, and maybe find some extra wires to make the analog connections. This was my second mistake. I spent a good 2 hours soldering on 24 connectors (D-Dual link). When I finished, I looked at the soldering connections, and realized that there was a better chance of a 1 legged rat making it across a 4 lane highway alive than my solder points having resistance within tolerance.
So I went back to the internet and started searching again. I found various sites that offered cables that I could probably rig up to work, but not exactly what I was looking for. So I went back to the mess of solder. I thought I still need the “A” connections, so I sacrificed a VGA cable that I had and removed the 3 component shielded cables to get the 6 necessary connections. I prepared to solder them on and simply gave up. I knew that there had to be an alternative.
So I went back online and searched some more. I finally found a solution. One site offered a panel mount DVI-I extension cable in lengths starting at 1 foot and up. Great! I now have a 1.5′ extension cable, but I have another problem: the distance between the video card and the side of the case is less than the length of the connector plus the minimum bend radius of the wire. NOW WHAT!
I went back to my combobulation of splayed wires and half cut up DVI-D cable and tried to weigh the chances of being able to cut enough of the panel mount extension plug away to get the bend radius needed to clear the case. Five minutes of holding the butchered connector and I was convinced there had to be a COTS part for this. (commercial off the shelf). So back to the interwebnet!
I finally landed on a site that sold 90 degree connectors for the exact purpose I needed. PHEW! Now the trouble was that the combined price of the 2 panel mount connectors and the 2 90 degree connectors was upwards of $90. One last look at the mess I made with a dremmel and soldering iron and I gladly laid down the cash.
Today the 90 degree connectors showed up in my mail, and I rejoyced. Success! …at a price.
I usually have no problem manufacturing something for less than the COTS alternative, but this is one case where I will pay the cash over the sweat. What made this such an epic event is the obscurity of the parts to complete this project, and their high price when I found them. So instead of simply finding them and buying them, I sunk time into making the part, knowing that there was more than a good chance it wouldn’t work, and in the end the time cost was too high to justify over the money cost. Fail. Success.
