I see it quite often: a sudden shorted wire on a shielded cable. It can be maddening to find the short, and it’s often intermittent. Most often, it happens when the jacket is scored. It seems impossible, but the knife cuts through the shield and scores the jacket on the conductor wire inside. Here is an “Old Guy” trick that works for shielded conductors or coax.
Mark the cable where the jacket should be scored for removal. Bend the cable to a U shape between two fingers with the mark at the top. Lightly touch a sharp razor to the line until the jacket splits. Bend the cable the opposite direction and repeat. The jacket should split all the way around without further scoring, but if not, just repeat where required. The idea is to split the jacket without touching the shield with the blade.
Next, we need to expose the center conductors. Slide the shield back to loosen it. Grab a dull pick—not a sharp one—we don’t want to poke a hole anywhere. Open a window in the shield and use the pick to pull the conductor(s) out one at a time. The rest is up to you. Twist the shield and use it, or trim it off. Take a close look and make sure you did not score a conductor. I usually test with an ohmmeter just to be certain while flexing the wires.
This is the same technique I have used for decades. I never liked the idea of trimming the shield short and then having to apply a solder sleeve or similar. I pull the wires through the shield, twist the shield a little and then twist the end of it very tight and then crimp o a ring terminal and your shield termination is done and is nice and neat. I do put a short length of shrink tubing over the cable before stripping and then shrink that over the cable jacket to cover the end of the cable jacket to keep things neat.
Indeed, a very good description of the technique I was taught as a ham radio kid back in the vacuum tube days.
As for “Twist the shield and use it, or trim it off.”
This may not be an issue with non-metal airframes or with very short runs, but I’ve chased more than my share of annoying static/hums back to a long cable with only one end properly grounded, especially a tail strobe. So I always use the shield as a backup ground wire on both ends.
you can set up ground loops by grounding both ends
These twisted triples are commonly used in capacitance fuel gauging and XYZ wiring from compass or vertical gyros to remote indicators. Solder sleeves are necessary if you want to pin the sleeve thru a connector. However, grounding both ends closes an induction loop for AC current, something you may not want.
Folks. The multi-conductor shielded wire was just what I had easily accessible for a photo. That’s why my tip doesn’t get into specifics on termination or treatment of the shield and conductors. It’s just a tip about removing the jacket and pulling the conductors out.
Regarding the use it or trim it off, I’d recommend folding the remaining shield back over the outer jacket before covering with heat shrink as I have seen a couple of occurrences of the short fibers of shielding actually penetrating the conductors over time.