This is the first part of my forthcoming series of articles on classroom AV system installation. This article will specifically address, the thorny subject of how to get USB and VGA cables into wall plates. Firstly, we much prefer to use premade VGA cables, which have moulded plugs on each end of the cable and are supplied in standardised lengths. Making your own cable up is very fiddly due to the tiny little pins cramped close together being very hard to solder. I know of one organisation which found that the wires tend to break off and had to have both plugs resoldered on at considerable expense because of the difficulty in working on the plugs. So, even if you are installing a cable inside a wall, use premade cables if at all possible.
Second point is, don’t use flying leads except at the fixed end. That is, the end which connects to your ceiling mounted projector (or a wall mounted device such as an electronic whiteboard, etc). That’s OK because the connector won’t be disconnected that much and the equipment for the most part doesn’t get moved that often or is out of reach anyway. But it’s a different story for the end that connects to the PC. The cable will come out of the wall. The plug will be connected and disconnected often. The wear and tear is enough that the plug could get damaged easily as well as the flying cable. You don’t want that plug getting broken or that cable getting damaged because then you have to replace the whole cable.
Thirdly, use a female connector at the PC end of the cable, even though the PC requires a male plug. That is because male connectors have the small pins that can get bent or broken easily. Far better to have the fragile male connector on another attached lead that can be replaced easily rather than your in-wall cable.
Now, how to get the cable to come out into a faceplate. There are two ways that I have investigated. The first is a specialised faceplate connector made by Switchcraft called the EH Series. These are essentially a gender changer mounted onto a faceplate. You may be familiar with VGA gender changers already which are a male and a female plug or socket connected back to back in one metal shell. They make very handy cable joiners as well. Switchcraft make their EH series VGA faceplate adaptors in all possible combinations and they are reversible. The biggest issue is that they are not readily available in NZ, and will have to be shipped to you from Australia or the US at considerable expense. I was quoted around $12 each in a quantity of 10, but postage was a minimum of $40 from either Australia or the States.
The second option, which I have used before, is to mount a modified cable plug to a special plastic faceplate supplied by electrical manufacturers. PDL and HPM both make a special version of their standard faceplate series which have a VGA shaped cutout and the standard mounting hole spacing. HPM make variants which will carry two connectors. To fit a premade cable’s plug into one of these you have to modify the connector shell, which I’ll show how to do in a future article; basically you cut off the thumbscrews which gives you access to the plug’s mounting holes and you attach the plug to the faceplate using hex threaded nuts (which you can buy from Jaycar as cat no. PM0852).
Once you have this mated to the faceplate then you can use a standard male to male patch lead to connect the PC into the wall.
The USB connectors are also available in the same Switchcraft series, with the same availability and cost drawbacks. This time, however, I was able to find a similar product made by Neutrik which can be purchased by mail order from Farnell or over the counter from Jansen. The NAUSB is a reversible A-female to B-female gender changer mounted on a standard Neutrik faceplate assembly, designed to fit onto a standard XLR panel. Let’s suppose you have a standard USB cable coming out of, say, a projector or electronic whiteboard. There is a B female socket on the equipment which you connect using a standard A male to B male USB lead. The end to the PC will be an A male plug. Instead of bringing that out of the wall as a flylead, you set up one of these faceplate connectors so that it plugs into the NAUSB’s female A connector. On the open side is the female B connector. You connect another standard A male to B male USB cable to this connector and the A male plug goes right into the back of your PC without any other adaptors needed. The NAUSB costs $10 from Farnell (ex GST) or $12 over the counter from Jansen (incl GST).
The insert can be reversed to place the ends on whichever order suits your situation. For example suppose you want to use one of these to get the signal into the wall from the equipment. You would set it up so that the A end faces the equipment and the B end faces the wall cable. It works perfectly every time. The only other connector of this type I was able to locate on my travels of the Internet is an IP68 rated connector on a flying lead that Jaycar sells. Not only do they cost almost $20 each, they are on a short lead that terminates in a five way header. You would have to fit a matching plug on your USB lead to connect it to this adaptor. Both the Switchcraft and Neutrik adaptors have the advantage that the cables just plug in on both sides. The one issue for both these and the VGA connectors is the depth needed behind the panel in the wall. If you have limited space you may have to find an alternative way of mounting the faceplate to allow for this.