Thursday, June 16, 2011

Motor Wire Repair – Part 1

I first inspected the wiring near the coils and one of the wires was completely exposed right up to the entrance to the coil – not a good thing!  You will notice in the photos below that there is a knot in the wiring just below the coils.  This is called an underwriters knot and is intentionally placed above the grommet to prevent strain on the coils.  I’ll discuss this more a little later.

Exposed-wiring-at-core_thumb4  More-bad-wiring_thumb

My assessment is that the wires will need to be recovered, at a minimum, and completely replaced, worst case.  So I decided to strip off the insulation of the current wiring to see the true condition of the wires.  The insulation was in such poor shape that it literally crumbled away when it was gently pinched between my fingers.  You can see just how bad it was in the next two pictures. I was even able to remove the insulation without even undoing the underwriters knot! 

   insulation_thumb5 Wires-after-removing-insulation_thum

Next came the wiring repair.  For this step I followed much of the advice given by Rain on the Vintage Singers group on Yahoo (see my Information Sources page).  However, instead of using 18 gauge wire as Rain suggested, my husband insisted on using 16 gauge wire because it would be less likely to overheat when I sew heavy duty cloth.  I don’t know if this is really necessary, but he is giving me his soldering gun, solder, and heat-shrink insulation to do this job, so I didn’t argue!Smile

The “black” wire (the one I previously labeled with orange tape) was in good shape, so I simple put heat-shrink over the length of that wire. I first trimmed “red” lead from the motor coil (the one I previously labeled with purple tape) to about 4 inches and soldered it end of new red wire.  Then I put a piece of heat-shrink insulation all the way up to the coil and well past the soldered joint. Wires with heat shrink insulation

I then soldered the brass ring off the piece of wire that had been trimmed from to other end of this new wire and applied heat-shrink insulation over the soldered joint and up to the brass ring.

Soldered ring end  Polished motor with repaired wires

The next step is to tie an underwriter's knot to secure the connection of the wire and prevent strain on the coils.  I’ll cover that in the next post – stay tuned!

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