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First attempt at a cable repair

Discussion in 'The DIY Tool Shed' started by Gogogoch, Oct 30, 2020.

  1. Gogogoch

    Gogogoch TDPRI Member

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    Hi,

    In an effort to minimise waste (and save a little cash) I bought a Neutrik plug to repair a dodgy guitar cable. I've just soldered the sleeve and tip in place, but upon plugging it in and comparing it with a working Whirlwind cable the newly 'repaired' cable is giving less than half the volume. What have I done wrong?
     
  2. The Angry Possum

    The Angry Possum Tele-Holic

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    "What have I done wrong"
    Not buying a new one.

    Firstly, Do you have a good soldering iron? Maybe part of the wire you soldered is grounding out...
     
    Last edited: Oct 30, 2020
  3. kennl

    kennl Tele-Afflicted

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    While plugs account for the majority of cable issues, a cable can fail elsewhere.
    If, for instance, a cable suffered impact damage in the middle, the "HOT" insulation may have torn, and a strand of SHIELD conductor could touch the "HOT" conductor.
    That would cause part or all of the signal to shunt to ground.
    A multimeter could be used to check continuity, which might reveal if this is happening.
     
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  4. WalthamMoosical

    WalthamMoosical Tele-Holic Ad Free Member

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    Hate to be "that guy" but can we see some pics?
    Is the cable crackly, or is the "lower volume" pretty steady? Shorts are usually all or nothing, most typically in quick succession.
     
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  5. Peegoo

    Peegoo Poster Extraordinaire

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    If it's a low-noise instrument cable, chances are it has a carbon-impregnated sleeve, usually polyethylene, surrounding the center conductor's insulation. This sleeve is very thin and is designed to reduce handling noise caused by the braided shielding wire moving against the inner core's insulation. Look:

    [​IMG]

    When preparing the conductors for soldering to the plug's terminals, always make a very shallow slice along the central conductor's insulation and see if there's a thin film (you can peel it up) on the insulation. If there is, make sure to remove at least enough of it to prevent it contacting the center conductor's solder terminal. This conductive poly sleeve is usually black, and because many center conductor's insulation is also black, it's impossible to tell it's there simply by looking at it.

    This poly/carbon sleeve, in contact with the center pin's solder terminal, creates a resistive load on the signal; not a dead short, but similar to a volume pot rolled back about halfway. This is probably what's going on with your repair.

    Older low-noise cable (1980s and earlier) used cotton cloth impregnated with carbon, and you'll see it if that's the type of cable you have. All modern low-noise cable, however, uses the super-thin poly sleeve. It's not much thicker than plastic film (Saran, etc.) food wrap.

    Cheers and good onya for doing your own maintenance, rather than binning the cable and getting a new one.
     
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  6. tubegeek

    tubegeek Friend of Leo's

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    The most likely guess for "partial signal" is this:

    Your cable may have a black conductive layer that surrounds the insulation of the center conductor, it'd be the next layer underneath the braided shield. (If your cable only has a spiral shield, it's garbage cable and I wouldn't bother fixing it.) This layer is thin and can usually be removed with a fingernail. That layer is conductive and is there to reduce handling noise, if it is in contact with the inner conductor it'll cause this symptom.

    EDIT: if @Peegoo and I are giving you the exact same advice, you know you're in deep trouble.

    Otherwise:

    The original dodginess may have been damage inside the cable itself - but that's not the most likely reason. Look over the outer jacket of the whole cable and see if it got run over or pinched - if it's internally damaged, you'll usually be able to see evidence on the outside.

    If that't not it, then your soldering skills are in need of improvement - that's VERY common.

    Be sure that each of your solder joints is shiny and that the solder has passed through a loose, liquid phase as it fully heats and flows. Don't allow the parts to move while the solder cools, and don't blow on it to cool it faster.

    Be sure no stray strands of the outer shield are making contact with the inner conductor.
     
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  7. Peegoo

    Peegoo Poster Extraordinaire

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    Grab everything you can fit into your car and head for the hinterlands! It's the End of the World!

    Like...HRUN, Scoob!
     
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  8. tubegeek

    tubegeek Friend of Leo's

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    Ruh roh!
     
  9. Gogogoch

    Gogogoch TDPRI Member

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    Here's a photo. My soldering skills are shameful, but I figured it wouldn't hurt to try.
     

    Attached Files:

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  10. tubegeek

    tubegeek Friend of Leo's

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    Take a sharp object and carefully pick away the thin conductive layer. Those solder joints may possibly be fine.
     
  11. SRHmusic

    SRHmusic Tele-Meister Silver Supporter

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    I agree with the earlier comments, and good on you for doing a repair rather than throwing it out, assuming the cable is decent.

    If you have an ohmmeter, you can check the resistances first directly through the cable, then through the connectors. The point is to see if the cable is bad or the solder connections, (or the connectors, even), and different results point to different issues. Note: this won't tell you if the shielding is effective, just the basic integrity.
    1) Center conductor to center conductor at the other end. (0 ohms ?)
    2) Ground shield to ground shield at the other end (0 ohms?)
    3) Then check resistance from center conductor to the ground shield.(>100Mohm?)
    Repeat all three while probing at the connector tips and rings to see if it's a solder issue.
    If it is the carbon poly sleeve shorting to the center, then you'll get the same results for center to shield at the cable ends or at the connectors.

    If you don't have an ohmmeter... well, you can get a serviceable DMM at Harbor Freight or Northern Tool for pretty cheap, and it can help sort out stuff like this, isolating the problem. Good luck!
     
  12. Peegoo

    Peegoo Poster Extraordinaire

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    Cheap but good DMMs can also be gotten at most DIY shops and large builder-supply-big-box places too.
     
  13. Gogogoch

    Gogogoch TDPRI Member

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    Thanks for all the replies. I had another go at it this morning - stripped the conductive layer and resoldered the connections and it works!!

    Much appreciated.
     
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