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I have several light strands that I'd like to effectively seen cut in half, and make two shorter lengths out of, but I've only succeeded in seriously confusing myself so far.

The lights I'm working with are wired in such a way that I'm able to pull out completely quite a few lights without affecting the rest of the strand so long as the ones pulled aren't next to each other, if they are next to each other I can pull a max of three before the entire strand goes dark.

The wiring has me completely confused because it has three wires coming out of its plug and three going into its socket end, but following each lead seems to have two wires that simply go from one end to the other without ever being jumped into the lights wiring, and those two wires show continuity to the prongs on the plugs.

But the third wire is the one that ties into the daisy-chained lights and I'm not seeing any continuity from it to the plugs. Which I really don't understand, but they work just fine when plugged in. I'm unsure how to properly measure them with a multi-meter to discern which wires are doing what so that's not helping me either.

I've sketched up a crude diagram showing how the strand leads are, the dips and then double dips between the diodes are depicting the wires that jump from one light to the next.

The only labeling for the wires I've found show them as:

    Neutral
    V-
    V+

led light strand

But that does nothing to tell me what's going on with them. I do generally understand wiring that I'm dissecting, but these have me completely lost.

I'm sure they're nothing too uncommon but simply something I just haven't encountered up to now, and would very much like to be educated on how it works, and to know if I'm even able to do what I was set on to begin with.

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2 Answers 2

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There are some resistors buried in the sockets or wiring somewhere. Sometimes like 3 total (Big Clive video link). You won't sense continuity measuring the series LEDs+resistors because of the nonlinearity of the LEDs.

Presumably the sets can be daisy-chained so they need the two mains wires running along the length.

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  • \$\begingroup\$ I get how the ones Clive is showing works, seeing the rectifier in-line and them run in a series on a single wire. But the links between the bulbs on mine start with a single wire then two, then back to one, alternating all the way down the line, what does the extra lead every other light achieve? As for resistors being buried inside, that's entirely possible as it does have a rather chunky plug. Is there a way to use a meter to know for sure, and figure out the values of them so I can split the strand in half and still provide the resistance the leds require? \$\endgroup\$
    – Demon Seed
    Dec 8, 2023 at 6:05
  • \$\begingroup\$ ok, it didn't give up it's secrets without a fight but I've managed to gut out it's plug and yes it has a fat capacitor and two resistors along with a diode inside, so that part's answered. So now here's my goal. I don't really need 2 separate strands from my cut lights as much as I need two lengths powered by the same plug. Think it'll work if cut the series in half but re-add it back in parallel to the plug with the resistors? \$\endgroup\$
    – Demon Seed
    Dec 8, 2023 at 6:54
  • \$\begingroup\$ Or should I just add a length of wire tied to the cut end of the strand that doubles back all the way to the socket then reconnect the cut off half back into it's original series configuration except with a bit of extra resistance from the extension? None of this still helps me understand the wiring circuit but if I can just make them be what I need, I guess that'll be good enough. \$\endgroup\$
    – Demon Seed
    Dec 8, 2023 at 7:02
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    \$\begingroup\$ Without a good schematic, I have to say I think it quite possible it will burn out and perhaps cause a fire. \$\endgroup\$ Dec 8, 2023 at 7:03
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Ours have a rectifier first in line at the plug, then 25 led, another rectifier and another 25 led... Between the last of the 25 led and the next rectifier there are only 2 wires, they are the hot and neutral. The rest of the wiring consists of 3 wires, the 120 volt feed to the next rectifier, the power from the last rectifier and a neutral. The strings may be safely cut at any location where there are only 2 wires. A fused plug can be spliced in and the lights will work. Make sure that the appropriate fuses are installed.

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  • \$\begingroup\$ Thanks for trying to help, but I did eventually figure out the ones I had were wired in a series parallel configuration that also had a hot and neutral wire that ran the entire length uninterrupted that provided power to the daisy chain plug on the opposite end. So provided the resistance was adjusted on the socket I technically could have cut mine anywhere along the strand at any odd numbered bulb. \$\endgroup\$
    – Demon Seed
    Dec 30, 2023 at 2:48

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