12vDC wire shield ruptured

Discussion in 'General Electronics Chat' started by steelhead_bluesman, Aug 11, 2008.

  1. steelhead_bluesman

    Thread Starter New Member

    Aug 11, 2008
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    When locating a 12vDC source for an auxilliary fan to cool my RV fridge, I spliced into the wire supplying the fridge circuit board with a clamshell connector. I didn't realize it was a shielded wire, and when my idea didn't seem to work, I pulled the connector, and some of the foil shielding pulled out through the outer insulation. The shield is complete at top and bottom portions of wire, but pulled out a tiny bit at the sides where the metal "slicer" in the clamshell bit in. My question is, can I just tape over this wire where it got torn, or have I somehow compromised the integrity of the circuit and face future issues. If it is compromised, can I cut out the torn part (a sixteenth of an inch) and use a shielded connector? Or do I need to replace the entire wire? It is flowing current and the fridge seems to be unaffected. Any help would be great! Thanks
     
    Last edited: Aug 11, 2008
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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    At the very least you should wrap the damage with an insulator. Electrical tape would never be my first choice for such a thing, but if it is all you have access to, then it is better than nothing.

    Ideally, the cable should be replaced or repaired, if budget allows.

    What I would do if it were mine, and I were broke: carefully remove the outer insulation for about 1/2" to either side of the wound. Wrap with copper foil or aluminum foil. Wrap with polymer fiber tape. Apply multiple light coats of RTV silicon or other flexible adhesive, thinned with whatever the manufacturer suggests.
     
  3. steelhead_bluesman

    Thread Starter New Member

    Aug 11, 2008
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    TM3 - Thank you for your reply. I would have a hard time replacing this wire, because I cant trace it, but what about an in-line repair? Is there a connector (or other gizmo) that could be inserted after cutting out the bad part?
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
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    Probably.

    Can you describe the cable? Or provide a photo?
     
  5. steelhead_bluesman

    Thread Starter New Member

    Aug 11, 2008
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    Here's what I have: This wire enters the compartment through the floor, from where I don't know. It carries 12vDC either into or out of the circuit board that controls the fridge. I'm guessing it is about a 16, but it's hard to tell, because it is slightly larger diameter w/ shielding, but just a bit larger than other 16 wires. It is yellow and has this marking - 158889-01-000 <H> ET. Its companion wire is white and has the same marks, except it ends w/ EU rather than ET. Where the yellow wire enters the circuit board, it's marked 12V, and where the white companion wire enters the C-board casing, it is marked GND. Everything is still working fine, but.... I'd like to make it right. Thanks much for your assistance.:)
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
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    Is there a "drain" wire from the cable connected to the circuit board? This would be a bare wire wrapped outside the foil shield.

    Typically, the shield is grounded at only one end. (This practice eliminates a "ground loop" - an undesirable condition.) If the shield is not grounded at the circuit board, it is likely grounded at the power supply. If this is the case, you need not worry about repairing the shield. The shield is to prevent rf noise from getting into the power supply and from there into anything else. If the shield is mostly in-tact, and if the ground is at the end far from the damage, then the shield will still serve its purpose.
     
  7. steelhead_bluesman

    Thread Starter New Member

    Aug 11, 2008
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    There is no bare wire associated with either the yellow or the white wire. But the white wire is taped to (and therefore runs with) the yellow, and appears to be a ground wire where it enters the circuit board (as described above.) Since I did not cut the shielded yellow wire, but sliced into it with the clamshell connector on two sides, it would seem there is continuous shield material length-wise, albeit w/ small holes or tears on alternate sides.... Do you feel confidant that the circuit will function properly? I'm not trying to hold you to anything, of course, I'm just trying to get a rough sense of what might be done, if anything.... Thanks so much for your time, I do appreciate it.
     
  8. thingmaker3

    Retired Moderator

    May 16, 2005
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    Based on your description, I would be quite surprised if you had any problem as a result from the tears.
     
  9. steelhead_bluesman

    Thread Starter New Member

    Aug 11, 2008
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    Okay. Thanks for your interest in my problem. Guess I'll take a wait-and-see attitude.
     
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