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So I took the computer plug and took the end off which left me stumped.

3 sets of strands each insulated from each other however which is which?
Mmm, well, I'd say it's time to dig out the old multimeter . . . ;)

And, FWIW, I've come to believe that "stumped" may pretty much be my new normal when tackling new things . . . or even old. :sneaky:
 

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Yep, still looks like coaxial cable, but with concentric inner layers rather than either a single inner conductor (like that used for TV, other RF or older computer network wiring), or a single shield around braided conductors. Still not a clue why they would go to the trouble and expense of using such an unusual configuration for a pedestrian power supply connection, though.
 

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Well, I'm pretty sure the outer braid would be ground, and if the power supply offered multiple voltages, I'd guess the inner braid and center conductor will each show varying voltages to ground, and likely between them as well. As I said, time to break out the multimeter -- this is not something you want to trust to analysis alone!
 

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Well, I can think of no reason to make a doubly-shielded inner wire a ground (since the ground is usually the conductor closest to the outside, to avoid a short if the outer insulation is penetrated), but since I don't understand why such a fancy cable was used in the first place, I suppose anything is possible. I don't know your multimeter, but yes, you're almost certainly looking for a relatively low DC voltage (so I doubt your life or limbs are at risk!), and you want to be sure to test all possible pairs for their potential. For instance, on a tutorial I saw about recycling an old computer power supply to provide multiple output voltages, stacking the various power taps can yield a startling range of output voltages, and something similar might be happening in with your "universal" power supply. In any event, good luck!
 

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The receptacle plug suggests it has no ground wire, just like a floor lamp.
If there is a wide blade and narrower blade on the plug, the wide is neutral (white), the narrow is the line/load side (black). If you can check for continuity between the line/load blade(prong) and the center conductor you’ll figure out which is white & black.
No need for “live” wires when checking continuity. One probe on the narrow plug blade, put the other probe on the central conductor. If 0, try on the surrounding shield wires.

The outer most steel mesh is probably reinforcement and nothing more.
Whoa -- just to be clear, be sure the power supply is unplugged from the wall before you test for continuity between either prong of the input plug and any output conductor! o_O
 
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