I mean, the simplest answer is to lay a new cable, and that is definitely what I am going to do - that’s not my question.

But this is a long run, and it would be neat if I could salvage some of that cable. How can I discover where the cable is damaged?

One stupid solution would be to halve the cable and crimp each end, and then test each new cable. Repeat iteratively. I would end up with a few broken cables and a bunch of tested cables, but they might be short.

How do the pro’s do this? (Short of throwing the whole thing away!)

  • myogg@lemmy.world
    link
    fedilink
    English
    arrow-up
    38
    arrow-down
    1
    ·
    1 year ago

    Higher end cable testers can show you where the break is, but it will be far more expensive that a new cable.

    • InformalTrifle@lemmy.world
      link
      fedilink
      English
      arrow-up
      15
      ·
      1 year ago

      My TP link switch can detect faults and cable length. I’m not sure it can do both together but it’s possible. Worth checking if you have a switch with those features

    • Num10ck@lemmy.world
      link
      fedilink
      English
      arrow-up
      3
      ·
      1 year ago

      you can rent a time domain reflectometer for this purpose… it sends out a signal and then listens for the echos back and calculates the distance. problem is they arent accurate the first like 500 feet so you have to add a reel of 500 ft of matching cable to the end first. electrorent.com rents them.

    • azdle@news.idlestate.org
      link
      fedilink
      English
      arrow-up
      3
      arrow-down
      2
      ·
      1 year ago

      I had an AMD Phenom-II era motherboard that claimed it would be able to do that. OP, you might be able to find an old NIC/mobo that could do this for cheap.

  • False@lemmy.world
    link
    fedilink
    English
    arrow-up
    13
    arrow-down
    1
    ·
    edit-2
    1 year ago

    You can only do 100M runs max anyways, just replace the whole thing? 100M of CAT6 is pretty cheap if you already have a box for it.

    Or is this an academic question?

    • PlutoniumAcid@lemmy.worldOP
      link
      fedilink
      English
      arrow-up
      7
      ·
      1 year ago

      Actual, not academic. And I agree that a new cable is cheap, which is what I will do. My question is about avoiding throwing a mostly good cable in the trash.

      • cevn@lemmy.world
        link
        fedilink
        English
        arrow-up
        5
        arrow-down
        2
        ·
        edit-2
        1 year ago

        Pull it, cut into quarters. Add jacks to each end and test the lines.

        Nvm, I see you suggested this…

        • Lem453@lemmy.ca
          link
          fedilink
          English
          arrow-up
          6
          arrow-down
          2
          ·
          1 year ago

          m = meters. M = mega (x 1 000 000).

          That’s why Km is 1 thousand meters and Mm is 1 million meters.

          The actual unit is lower case, the multiplier is uppercase.

          • neumast@lemmy.world
            link
            fedilink
            English
            arrow-up
            2
            arrow-down
            1
            ·
            edit-2
            1 year ago

            The actual unit is lower case, the multiplier is uppercase.

            Wouldn’t agree with that… There are many different units and multipliers. the letter being uppercase or lowercase has nothing to do with it.

            Examples:

            letters for prefixes/multipliers being uppercase and lowercase: P, T, G, M, k, h, da, d, c, m, u, n (trillion, billion, million, thousand, hundred, ten, one tenth, one hundredth, one thousandth, one millionth, one billionth)

            Letters for units being uppercase and lowercase: s, m, g, N, W, J, A, K, V, h, Hz (seconds, meter, gram, Newton, Watt, Joule, Ampere, Kelvin, Volt, hour, Hertz) (just recognised, that most units, which are named after scientists, are written with capital letters…)

            km = thousand meters/kilometer

            K = Kelvin (unit for temperature)

            M = Mega (prefix for one million)

            kJ = thousand joules

            s = second

            ms = millisecond (one thousandth)

            S = siemens (electrical conductivity)

            mS = milli siemens

            mm = millimeter (one thousandth of a meter)

            Mm = megameter (one million meters or thousand kilometers)

          • El Barto@lemmy.world
            link
            fedilink
            English
            arrow-up
            1
            arrow-down
            1
            ·
            edit-2
            1 year ago

            For reals? Where can I read more about this?

            Edit: nevermind, I just googled it. TIL!

  • Steve@communick.news
    link
    fedilink
    English
    arrow-up
    8
    arrow-down
    1
    ·
    1 year ago

    If you just want some spare cable. I’d make 5x 20M pieces. The one that doesn’t work becomes 2x 10M. That bad one becomes 2x 5M … As far down as you like.

    • pjhenry1216@kbin.social
      link
      fedilink
      arrow-up
      2
      ·
      1 year ago

      Isn’t that almost what they suggested except starting at a different size and doing a binary search basically? You’re just starting the binary search after the first step of cutting into 5 lengths instead of 2.

  • redcalcium@lemmy.institute
    link
    fedilink
    English
    arrow-up
    3
    ·
    edit-2
    1 year ago

    Can’t you just use a cheap non-contact voltage tester to find where the cable is damaged? Just run the tester through the cable until it suddenly stop detecting any AC voltage, which is probably where the cable is broken. But if you’re talking about ethernet cable, then I have no idea.

    • Geometrinen_Gepardi@sopuli.xyz
      link
      fedilink
      English
      arrow-up
      3
      ·
      1 year ago

      I just learned about these things today when researching for a device to test that there’s no voltage present before installing a ceiling light. Such a great innovation since it works even through insulation, so no risk of getting shocked.

  • Haphazard9479@lemm.ee
    link
    fedilink
    English
    arrow-up
    3
    ·
    1 year ago

    How do you know the cable is damaged? If you have a toner you can hook the generator to the damaged pair and listen along the length of the cable to where the tone changes. It’s not as fool-proof as a tester, but much cheaper.

    • PlutoniumAcid@lemmy.worldOP
      link
      fedilink
      English
      arrow-up
      4
      ·
      1 year ago

      I wanted to post a photo of my network tester but Lemmy gives me a JSON error.

      Anyway, the tester is supposed to light up each strand one at a time, but what I get is disco fever.

      • Haphazard9479@lemm.ee
        link
        fedilink
        English
        arrow-up
        3
        ·
        1 year ago

        I assume the disco fever is all the pairs shorted together. Is this cable buried or run through the house? I would start by redoing your ends. Make sure they are crimped fully and both sides are identical.

        • jrburkh@lemmy.world
          link
          fedilink
          English
          arrow-up
          2
          ·
          1 year ago

          I agree. If that doesn’t work, I’d give the whole line a visual inspection for any more obvious signs of damage. If that doesn’t work there are other options to troubleshoot, but I’d probably just replace the line and attempt to recycle the old cord into shorter lines for device connections, patching, etc.

      • jake_jake_jake_@lemmy.world
        link
        fedilink
        English
        arrow-up
        2
        ·
        1 year ago

        short between pairs probably. tdr (time domain reflectometer) cable tester should help locate fault. might be pinched somewhere or something else

        there are “casts” you can get to repair buried cable. usually used in copper telephone plant, i wouldn’t trust it to certify to a gig but you could use it for a backup link or if you play with pots at some point. or “temporary repair”

  • SheeEttin@lemmy.world
    link
    fedilink
    English
    arrow-up
    3
    ·
    1 year ago

    The easiest thing to do would just be to pull it out and look at it. The break might be obvious.

    • PlutoniumAcid@lemmy.worldOP
      link
      fedilink
      English
      arrow-up
      1
      ·
      1 year ago

      Yeah, that’s not that easy, unfortunately, because each end of the network cable passes through an insulated wall, through a hole equal to the cable width = smaller than the plug. Even if I find the break, it is likely in the outdoors part of the cable where I would want an unbroken cable without a field repair.

  • InverseParallax@lemmy.world
    link
    fedilink
    English
    arrow-up
    2
    ·
    1 year ago

    You only need 2 pairs for 100base-t, try forcing a lower negotiation, see if the pairs you need work? Maybe unbundle the other set of pairs and try them?

  • TitanLaGrange@lemmy.world
    link
    fedilink
    English
    arrow-up
    1
    ·
    edit-2
    1 year ago

    Wire tracker maybe? You might want a higher quality version than that particular one if the cable run is long, one of the reviews suggest that the distance is limited.