Repairing A Data Cable

Discussion in 'General Electronics Chat' started by RdAdr, Jun 5, 2016.

  1. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    How would you go about repairing a data cable that does not work anymore?
    It has two end connectors and it is not cut in half or anything.

    I would first cut the ends and see if the pins of the connectors and the wires inside the cable are making connection. If the connections are good, then the fault must come from the cable itself.
    Thus I would cut the cable in two and check for continuity. Thus, one half of the cable should be broken, while the other half hopefully good. Then cut the bad half again in two and check again for continuity.

    And I do this until I find the location of the fault. Or maybe if I am satisfied with a shorter cable, I would just use the good half, maybe the good half plus the other good half and stop the cutting.

    Is there a better method?
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,501
    380
    hi,
    Cables usually fail close to the connectors.
    Remove the cable connector clamp, unscrew the connector cover.
    Inspect the solder pins for any broken connections.
    LIGHTLY pull on each wire in turn, if the wire is broken close to the connector, the pulled wire will come out.
    Repeat for both ends.
    Which type of cable is it.?
    Good Luck.
    E
     
    cmartinez likes this.
  3. tom_s

    Member

    Jun 27, 2014
    285
    333
    post 2 is great for broken connections

    the cable you should be able to check for continuity with a multimeter

    my question - is it worth spending the time to repair it?

    data patch cables - cat4/5/6/sata/esata/hdmi/ribbon etc are cheaper to buy new than to repair.

    from my experience, cables are not the issue, sockets are normally at fault, bent pins, dry/cold joints/oxidised contacts
     
  4. #12

    Expert

    Nov 30, 2010
    16,261
    6,768
    There are ways to inject an oscillating signal and search for where it stops radiating. Problem: Data cable isn't rated for 120 VAC so the cheap electricians pen style detector is a risky method. You have already defined the, "half interval search", but the ends are almost always the culprit. I have seen exactly one cable that was broken in the middle in 40 years of doing this kind of repairs.
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    A Time Domain Reflectometer could indicate where the fault is, but you need to know the velocity of propagation for the cable.
     
  6. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    Some cable used in automotive engineering when testing ECUs through HIL simulation. I do not know its particular name. I don't think it has one. One end is a D-Sub connector, while the other end is a Lemo connector.

    Good method. i did not think about pulling out the wires.
     
    Last edited: Jun 5, 2016
  7. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    So to look first at the connectors. Thanks.
    It is worth spending time, why not. It is a good cable.
     
  8. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    Thanks for answers. So the connectors might be the problem with high probability.

    Now the question is. Which connector from the two connectors to cut first and verify?

    Maybe just try my luck.
     
  9. dl324

    Distinguished Member

    Mar 30, 2015
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    A TDR will eliminate the guesswork.
     
  10. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    I don't have a TDR.
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    Do you have an oscilloscope?
     
  12. #12

    Expert

    Nov 30, 2010
    16,261
    6,768
    I'm surprised you can buy one for less than $200, but you can.
    http://www.testequipmentdepot.com/megger/tdr/cfl510f.htm

    My advice is to quit agonizing and look inside an end connector.
    Even if the problem is at the other end, looking twice still costs less than $200.
     
  13. dl324

    Distinguished Member

    Mar 30, 2015
    3,242
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    If you have a scope, you can make one with a suitable hex inverter, a handful of R's, C's, and misc hardware.

    If the connectors aren't meant to be opened, knowing which one was bad would be an advantage.

    I wish I had one 35 years ago when I had some contractors install multiple 400' runs of cable from a computer room to offices. The gorillas pulled for all they were worth and damaged a number of the ends. Fortunately, the connectors could be disassembled. But it was a hassle having to do both ends on multiple 7 conductor, 25 pair, and 40 pair cables.
     
  14. #12

    Expert

    Nov 30, 2010
    16,261
    6,768
    Since we're still beating this horse, I would mention that you can find the propagation speed by measuring one of the good wires.
     
  15. RdAdr

    Thread Starter Member

    May 19, 2013
    214
    1
    I saw that the connectors were meant to be open. I opened them and one was bad. The pins of the connector weren't making contact with the wires inside the cable no more. But I fixed it.
     
    RichardO likes this.
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