Need to unwrap some wirewraps in a stereo receiver

Discussion in 'General Electronics Chat' started by programmer6502, Jul 28, 2015.

  1. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    Hi,

    I'm working on a stereo receiver and need to undo a few of the wirewraps in the power supply section, but don't have any experience with wirewraping as I always breadboard or solder my projects. Hence, I need help finding the right tool to accomplish the task.

    Here's some pics to give you an idea of what I'm dealing with:

    [​IMG]
    [​IMG]

    What I want to do is temporarily undo a few of these wraps and put them back in place in a later date as if they were never touched. I'm aware that there are manual wrapping tools and have a couple questions:

    #1 Can a regular wrapping tool also unwrap if turned the opposite direction?
    #2 The wires are 22 AWG (with very thick isolation), do you think a tool rated for 22 AWG will work okay judging by the photos?

    -Thanks
     
    Last edited: Jul 28, 2015
  2. JohnInTX

    Moderator

    Jun 26, 2012
    2,339
    1,019
    Digikey has what you need.

    1) You need an unwrapping tool to remove the wires.
    2) It should since those wraps don't wrap any of the insulation (that would be a 'modified wrap').

    Keep in mind that once a wire is wrapped around a square post, its essentially done - you pretty much have to discard the wire (cut off the wrapped end, restrip) that was around the post because of the stresses involved on the wire. Properly done, there is very high pressure on the corners which will fatigue the wire.

    Be careful unwrapping, occasionally, a semi-circular piece of wire will come off which has a real interest in creating unwanted shorts..
     
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  3. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    Perfect, that's some good info. Thanks for your help!
     
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  4. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    JohnInTX pretty much said it all except, I have removed wrapped wires with pliers, but the curly end is shot, no matter how you get it off. Not being experienced with wire wrap, I put the new wires on with one loop and some solder. This is based on the idea that wire wrapping is a production line method calculated to save time. The pins aren't going to fail if you solder the new wires on.
     
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  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    @programmer6502
    I guess another way to skin this cat would be to tell us what you hope to learn/test by unwrapping it. Maybe the crew can offer another solution.
     
  6. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    I'm currently looking to remove the PSU board (at least get enough clearance to poke around) and some of those wraps don't make that possible. I should go get one more good assessment before jumping to that conclusion though. I need to test the capacitors and look for shorts/cold joints, which can't be done with the board installed because the receiver's chassis covers a large portion of the board from below.

    But I like your thinking!
     
    Last edited: Jul 29, 2015
  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    928
    You could leave the wire wrap alone and cut the wire in a more accessible location and splice it back when done or add more wire to extend the length or put in a male female style crimp connector at the cut locations. This leaves the perfectly functional wire wrapped connections unmolested.
     
  8. programmer6502

    Thread Starter Member

    Feb 1, 2014
    126
    6
    What gets me is not the wraps themselves, but the costs for the tools! They aren't particular cheap especially for being manual tools. Unless I service more amps in the future as a hobby or something, they wouldn't be the best investment for myself. So I'll probably see if I can find a suitable alternative route like some of you are suggesting.
     
  9. Brevor

    Active Member

    Apr 9, 2011
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    I used to service wire wrapped circuitry, when we had to change a wire we would pull the old wire wrap off, then re-strip the wire and wrap a few turns on manually then solder the connection.
     
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