Cord Replacement - wires broken at motor

Discussion in 'Electric Horology' started by semiretiredman, Mar 1, 2017.

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  1. semiretiredman

    semiretiredman New Member

    Mar 1, 2017
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    There is little left of the wires on this 1934 Hammond clock. I need advice on making a safe and lasting repair.
     

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  2. shutterbug

    shutterbug Super Moderator
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    I never liked how they originally wired those things. To make a good repair, you'll have to carefully get back to the coil wires, make a connection with new wires, and secure it all again. I think they originally just used electrical tape to wrap around the coil after connection to keep things secure. I can't offer a better way, but wish I could!
     
  3. David S

    David S Registered User
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    Dec 18, 2011
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    davefr over in the electric forum may be able to give some advice.

    David
     
  4. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    Get the back cover off as best you can. Try to not move the
    power wires around. You don't want to stress them at the coil.
    Once you have a clear shot at them, cut them from the coil.
    Usually there is a lug or something that they are soldered to.
    I recommend replacing them with a smaller power cord. Many of the
    cords that are used with computer power packs are good.
    If the lugs are loose be especially careful. You might even use
    a little epoxy to secure them.
    Do not try to remove the old soldered wire left from the power
    cord. There is no safe way to do this without skills most don't have.
    If you break the fine coil wire, it will be a more serious issue.
    Tinker Dwight
     
  5. davefr

    davefr Registered User
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    Nov 29, 2008
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    #5 davefr, Mar 2, 2017
    Last edited: Mar 2, 2017
    ^^^Excellent advice.

    You do need to be extremely careful because the coil wires are about the thickness of a human hair and will break off very easily if stressed. It's best to do this under magnification.

    If all you have left is little stubs of the coil's magnet wire then don't try and solder on a thick power cord. Instead, attach some smaller wire like a 20-24 AWG stranded THHN to the coils magnet wires and then attach the power cord to the THHN. (less stress). You'll need to remove the varnish from the coil's magnet wires in order to solder to them. An Xacto knife will do this but you have to be extremely careful not to break off the wires.

    Heat shrink works well to insulate your splices.

    You'll likely need to rewrap the core of the coil to secure/insulate the wiring and provide some strain relief. I use 3M #27 glass cloth tape. (don't use common electricians tape).

    https://www.amazon.com/Corrosion-Resistant-High-Temperature-White-Glass/dp/B00O7S124E/ref=sr_1_3?s=sporting-goods&ie=UTF8&qid=1488479959&sr=8-3&keywords=3m+%2327+glass+cloth+tape

    An even better solution is to slip a piece of large diameter heat shrink over the core of the coil and heat it until it completely compresses around the coil's core. 35-40mm 2:1 heat shrink should be about the right size.

    https://www.amazon.com/uxcell-Meters-Polyolefin-Shrinking-Shrinkable/dp/B009INJX7G/ref=sr_1_1?ie=UTF8&qid=1488478835&sr=8-1&keywords=35mm+heat+shrink+tubing

    Once your repair is complete secure the power cord to the motor frame with tie wraps for stress relief.

    Good luck because this type of repair is pretty tough and unforgiving!!
     
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