In a previous installment, we had cut holes in the side of our module frame so that we could install either Digitrax UP5 panels or RJ12 telco jacks. We also demonstrated how we had modified RJ12 telco jacks so that we had a nice slim package. Now that we've got the module all finished with the track power buss (with pigtails installed), it's time to install our last major component before we lay track - the RJ12 telco jacks.
When I first started installing telco jacks, I simply stuck the wires from the cables underneath the screws and spade terminals. This resulted in a veritable mess of spaghetti, particularly when trying to keep 24 wires in the right order. These types of connections really weren't reliable, to say nothing of the strands of wire that got ripped out as I tried to tighten the screws on two spade terminals and two wires for each connection.
So now I my first step is to discard the screws, cut off the spade terminals, solder and shrink-tube everything. I end up with a much neater and more reliable package.
However, before we get down to brass tacks, we're going to make a couple of jigs - those handy-dandy gadgets that make the work easier and stops us from getting the air blue with our cursing when things don't go right.
Telco Jack Jig
The first jig we're going to make is a "jack holder". It's simply a piece of 1/4" or 3/8" plywood cut to a bit larger than the jack faceplate with a hole cut in the middle so that the telco jacks sits flush in the plywood. As we wire up the telco jack, we're going to have the jack, two telephone cables and 24 wires hanging out all over the place. Trying to hang onto the jack, the cables and the wires while we try to strip, solder, and shrink-tube the 24 wires would turn the job into a nightmare. Our jack-holder jig makes life a lot easier for us.
To make the jig, I took a scrap piece of 3/8" plywood left over from fabricating our carry-plates and cut it so that it was a bit larger than the faceplate of our telco jack.
I then turned the jack over on its back so that the plugs were staring at me and marked off the outer edges of the lugs that hold the plugs in place.
Next, I drew a rectangle around the pencil marks and clearly marked the four corners (when you're running your work through a band saw, a jig-saw, or a hacksaw, the corners can be difficult to see with all of the vibration, commotion and concentration).
Using my band saw, I then cut out the centre piece that I had just marked. The tools you use to do this will depend on what you have in your workshop. A jig-saw, fret-saw, hack-saw works just as well. Remember, it's a jig so accuracy and fanciness aren't important factors.
I next test-fitted the jig to make sure that it sat flush against the backside of the face-plate. You might have to do a bit of filing around the inside edges. We're now ready to get down to the task of wiring our telco jack.
The Tool & The Routes
As with any job, it's best to gather up the necessary tools before we start. Here's the tools we're going to need to wire some RJ12 6-wire cable to our RJ12 telco jacks.
Our wiring is going to take place in two or three steps, depending on whether we install one telco jack or two telco jacks on our module. In both cases, we'll first run our telephone cable from one end of the module to the closest telco jack. If we only install one jack, we'll run a cable from the jack we just soldered through the notch in our middle cross member and down to the other end of our module.
If we install two, we'll run the cable from the jack we just soldered through the notch in our middle cross member and over to the second jack, in which case, we have a third step to run another cable from the second jack to the other end of the module. We'll be soldering and installing these cables and jacks as we work from one end of our module to the other.
If you install one telco jack on one side of the module, this is the path our cables will take.
If you install two telco jacks - one on each side of the module, this is the path that our cables will take.
So we're going to do the more difficult and install two telco jacks. The cables and wires for Step 1 and Step 2 will be soldered at the workbench and then installed in our module. The wires for Step 3 will be soldered on the module. So let's get started.
Wiring The Cables For Step 1 and Step 2
Our first step is to measure and cut the two pieces of cable for Step 1 and Step 2. Cut these two cables at least 24" longer than necessary. We may make some mistakes and this extra bit of cable might save us some headaches.
As you can see from the photo below, our 6-wire cable is coiled up and needs to be straightened out. To do this we run the cable across the edge of our work bench or some other sharp corner and alternately stretch the plastic sheathing so that the cable lies reasonably flat.
Now that we have our two pieces of cable reasonably flat, we need to remove about 3" of the plastic sheathing from the end of each cable so that we expose the 6 wires. We first turn the cable on edge and slice through the top 1/2" of the sheathing. Turn the cable over to the other edge and slice 1/2" of the sheathing. We now have two "tabs" that we can pull back on to expose 3" of the six coloured wires. Patience is a must in this operation.
We next insert our telco jack into our jig and tape it in place. Recall that in one of our previous posts, we had removed and discarded the terminal screws and cut off the spade terminals. The short wires coming out of the back of the telco jacks are usually twisted all over each other. Straighten the short wires so that we have the wires in order - white, black, red, green, yellow, blue.
We next take one of our cables, and holding it in place so that the end of the coloured wires touch the edge of the jack, we tape the cable to the jig. We then repeat the process for the other cable.
Make sure that the white wires are all aligned on one side of the jig!! It makes our soldering work that much easier. (Do you see our error in the above photo!?)
We want to reduce the number of wires in our work area (we'll have a total of 24!!). Tape the wires from the cables back onto themselves as shown in the photo below with a piece of masking tape. Next pull out the white wires from each of the two cables (we'll pull out each wire in turn as we need them). Straighten out the two short white wires coming from the telco jacks and push the other wires to the side. We want a clear and open work space for what comes next.
This is what our "package" of cables, telco jacks, and wires should look like.
Next, we get down to work and start soldering the wires together - white-to-white, black-to-black, red-to-red, green-to-green, yellow-to-yellow, blue-to-blue. All nice and neatly packaged.