We now have our four white wires pulled out and in the clear. This is what our setup in our jig should look like - the four white wires (two from the two cables and two from the two telco jacks) ready to be stripped, soldered and shrink-tubed.
The first step is to remove about 1/2" of insulation from the two white wires from the telco jack. I ALWAYS use a BBQ lighter and burn off the insulation. I've tried using wire strippers, pliers, cutters, etc and I've always regretted it. My BBQ lighter always does the job - no muss, no fuss, no broken strands of wire.
I first burn about 1/2" of the insulation off of the two wires from the telco jacks. The plastic insulation may either melt, or it may simply burn and leave black charred plastic behind. If it's black charred plastic, simply scrape it off of the wires with your cutters or some sandpaper.
Next I twist the two telco jack wires together - WHITE-to WHITE!!! Always the same colour!
The two white wires from the cable might be a bit long (you don't want them short!) so I cut them back so that they lie flat on the body of the jack with a 90 degree bend where they'll join the two wires from the telco jacks that I just twisted together. Using my Sharpie marker, in turn, I mark the white wires at a point where I will melt the plastic so that I will have bare wires. I melt the plastic with my BBQ lighter. I next twist these two wires from the cable around the two wires from the jack
install this telco jack into our module.
PS - You may have recently bought your crimper and you're all set to crimp an RJ12 plug onto the end of the wire. Only problem is, which wire goes into which side. Does the blue wire go into the left side, or, does it go into the right side. And after you've got the first plug crimped and you're all set to crimp on the 10th plug, how can you remember whether the white wire goes on the left or the blue wire goes on the right. Here's an easy memory jogger tip that will solve that problem. I take a dab of white paint (for the white wire) and a dab of blue paint (for the blue wire) and put the dab of paint on the crimper.
And just in case you want to get your head around the Digitrax LocoNet wiring standard, here's my schematic of the standards. If you twist your head sideways and upside-down, and look at the male plug, you'll see why, when facing the front of the crimper, we put the blue dot on the left and the white dot on the right.
PS - Don't buy the plastic crimpers as they're only reliable 75% of the time. Its that other 25% that's gonna cause you lotsa grief. With plastic crimpers, you can't get that extra squeeze to lock the blades in the male plug tightly onto the coloured wires.