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Re: Franceformer repair

At 12:04 PM 12/20/99 -0700, you wrote:
>Original Poster: Apollo <ollopa-at-jps-dot-net>
>
>I got a nice little 15-60 Franceformer the other day to add to my
>NST collection, but there were a couple of problems with it.  It was
>only putting out 50ma of current, so the guy gave it to me for free.
>It looked like cleaning the heavy corrosion off the terminals was all it
>would need to be a-ok, but when I fired it up the lights flickered like mad
>and some smoke puffed out the lid.  I shut it off quick and checked it out
>with my ohm meter.  The primary and secondaries were looking good, but I
>noticed that the primary winding is shorted to the ground, and thus
>connected to
>the secondaries.  Not a good condition!  I don't want to run it without a
>ground
>OR with the secondaries tied to the primary through the core.
Your primary is probably not just shorted to ground, its probably just 
plain shorted. I have a France 15/30 that had the same problem. It would 
draw about 18 amps at 120 V Causing smoke and other undesirable phenomena. 
:-( It was fairly easy to rewind though. about it was made of about 250 
turns of #14

>I've got the core out and about 98% unpotted.  There were four bolts (one
>in each
>corner) holding the core together.  I also noticed that the core seems to
>be made
>of two sideways U shaped parts with the seam going right down the middle
>(where the
>primary winding is).
>   I've got the bolts out, but I can't figure out how to
>get the
>core apart.  Am I going to have to peel each layer of laminate off
>carefully, or should
>it pop apart with a screwdriver or two?

It is probably being held together with tar I would try cleaning the core. 
soak it in kerosene for a few days and tap on it with a mallet that should 
break it loose. I wouldn't separate the laminations if I could help it.


>Also, there are four banks of shunts (two per side).  How many shunts is it
>safe to
>remove from each bank?
>
>Y.T. -
>Rick Richard

Your guess is as good as mine there. I took out about 25% of mine and it 
increased the output from 28 to 40 ma
Other tips that would have saved me some time and made  the repair easier:

  be sure to note the orientation  of the secondary coils before you take 
the core apart.( if you take them off the iron )

  careful with those insulators

If you clean the case up and seal it fairly well you can repot the nst with 
paraffin wax. ( You can get at your local grocery store for about $1.30/lb 
and its a lot easier to work with than that nasty smelly tar stuff  YUCK! )

add a couple of turns of 18 or 20 awg to your secondarys and hold in place 
with a little dab of hot melt or epoxy to give you a lead wire that's easy 
to work with instead of that super fragile angel hair thin stuff its wound 
with.

Hope this helps, good luck
Bruce