RE: Unpot

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>

I noticed the same thing as Gary, it looks like it would require a
complete teardown to change the current-limiting on my Jefferson. I will
look into finding a good wire. I know I might loose a volt or two by
that will be no problem because it I put this in a coil I will have up
to 140+ input with my  Varaic power control as my shop has high line
voltage also.

Rich

It's worth pointing out that with my Jefferson 15/60, the core
construction was such that there were no removable current-limiting
shunts that could be removed to increase output current.

Regards, Gary Lau
MA, USA

Subject: Re: Unpot

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

Often, the old used NSTs we get for free have either a burned out
wire between the secondary winding and the terminal or there is an
internal carbon short path through the tar.  These are very common
failures for NSTs.

Since NSTs can be very hard to get, may folks resort to the surgical
approach to repair them.

Also, once inside, one can remove a few of the core shunting bars to
increase the current of the NST.

The core needs to be insulated, but many folks put it back into an
oil bath rather than replace the tar to make any future repairs far far
easier.

Cheers,

         Terry

At 11:14 AM 11/27/2005, you wrote:
>I've come into this discussion very late.  Why would
>you want to unpot a transformer anyway?  Just
>curious...
>
>--- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> > Original poster: tesla popp <teslas_lab@xxxxxxxxx>
> >
> > I've to date unpoted more than 100 NST's, and in the
> > begining I used to kill TONS OF SECONDARY WINDINGS!
> > I
> > developed a few tricks to saving the transformers...
> >
> > In your case here's what it the most effective way
> > to
> > fix it:
> >
> > (1) using a tweasers, pull the broken peices of wire
> > away from the rest of the windings at least 3/4".
> > (2) use a lighter to QUICKLY burn away the enamel
> > coating from the wire.  You must move with causion
> > as
> > you will melt the wires easily.
> > (3) use the finest steel wool you can find to clean
> > the burnt enamel from the wire(s) in a pulling only
> > motion. "should require less than 3 passes" [note:
> > be
> > shure to "blow away" any powder left by the steel
> > wool*]
> > (4) now, take a peice if fine stranded wire
> > "#22-#18"
> > and wrap the super fine wire around the ends of the
> > stranded wire.
> > (5) carefully apply HIGH GRADE SILVER SOLDER* to the
> > ends of the stranded wire,  The solder will engulf
> > the
> > fine transformer wire in the process
> > (6) place a peice of plastic under the repaired
> > joint
> > so it dosen't arc to the windings underneath it.
> > (7) use hot glue of something similar to cover the
> > joint "and lead wire if you used one" so that
> > nothing
> > is pulling on the joint it self.
> >
> > I've used this repair technique on all the
> > transformers I've messed up in the depoting process.
> > If this is unclear, I will give more info and maby
> > some pics if you truely need them.
> > I would like to know if it worked for you, so please
> > tell me if it did.
> >
> > Good Luck
> > Coiler Forever: Jeremiah Popp
> >
> >
> >
> > --- Tesla list <tesla@xxxxxxxxxx> wrote:
> >
> >  > Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>
> >  >
> >  > I have had a transformer soaking in gas for
> > awhile,
> >  > I just took it
> >  > out and cleaned it up with lacquer thinner. What
> > a
> >  > mess! Now to my
> >  > question, the secondarys are a mess and nicked on
> >  > the outer windings.
> >  > , I goofed and was too rough a while back trying
> > to
> >  > remove the tar.
> >  > The transformer is a Jefferson 15Kv 60ma. The
> >  > secondarys are about
> >  > 36ga wire and I don't have any butt splices that
> >  > size but I do have
> >  > some .004 copper sheet from a transformer
> > winding.
> >  > My question is
> >  > would it work to lightly sand the outer windings
> > and
> >  > solder a strip
> >  > of the .004 copper to it for a lead point? I do
> > not
> >  > feel safe trying
> >  > to solder to the end of the 36ga.
> >  > If it works I plan on making a Lexan box for it.
> >  >
> >  > Rich
> >  >
> >  >
> >  >
> >
> >