RE: 15000V/120 ma NSTs, other XFMRs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi Dave,

I ususally just chisle the case apart at the corners, then take out the 
large block of tar with the transformer inside.  Depending on the condition 
of the tar i may freeze it for an hour in the freezer.  Then i take a 
hammer, and flat screwdriver, and crack away at it, CAREFULLY of course.  
Once you know where each coil is, then its pretty easy to chip away all the 
tar.  Then i usually take the transformer apart.  I re-insulate the coils 
with new tape, and mica(or poly) for the secondaries.  Then i clean at least 
the outer surface of the core so that i dont have tar residue all over my 
coil.  I think thats about it, it usually takes me about 6 hours to complete 
a rebuild.  Anyone know if im slow or perhaps fast with this???  How long 
does it take everyone else?  Good luck Dave, and be carefull, i just got a 
1st class gash to my outer hand :(.

Steve Ward.


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: RE: 15000V/120 ma NSTs, other XFMRs
>Date: Sat, 27 Jul 2002 15:51:14 -0600
>
>Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><ddhartwick-at-earthlink-dot-net>
>
>Steve,
>All very interesting! These units are made by GE. The large sides are
>removable--dont know if that makes a difference. By the time futz around
>with  shipping one or both, I may as well have a shot at unpotting.
>What is the state of the art in unpotting?? Heat, solvents, dry ice...?
>Dave Hartwick
>
>
>
>Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>"
><srward16-at-hotmail-dot-com>
>
>About unpotting,
>
>What brand are the transformers??  Here is my list for good and bad
>transformers to unpot.
>
>BAD
>1, Allanson 15/30-couldnt seperate core, useless because of that
>2, Magnetek(jefferson)15/60 hard to insulate after repair(not enough room),
>shunts arent removable, actually part of the core!
>3, Transco-15/60 difficult to seperate core, and tar is unusually gross
>
>GOOD
>1, Any France!!  easy to remove tar after freezing with a screwdriver, core
>is simple and coils are wraped in tape so they dont get damaged from 
>pulling
>off tar,  All 4 of the transformers i rebuilt from them were a success. And
>i have about 6 more on my list to unpot
>
>It IS messy to de-pot them.  Use an ohm meter to check for normal secondary
>resistance.  If both test good, then the transformers is most likely ok.
>Most transformers i rebuilt had either DEAD or WEAK secondaries, but all
>work perfectly when unpotted.  Id love to get my hands on a 15/120,
>definitely worth the rebuild effort in my opinion. IF i had the money, and
>shipping were free :)  I would be one of those coilers who see those 
>15/120s
>as gold, but i have a supplier for all kinds fo 60ma units for free:).  
>Good
>luck,
>
>Steve Ward.
>
>
>
> >
> >...But the most interesting items in my collection are 2 - 15000V/120ma
> >NSTs. These must be rare, since I rarely read of other coilers using 
>them.
> >
> >The problem is that one is dead, the other weak. I assume un-potting will
> >fix this, but I wonder if it is worthwhile? I stopped using NSTs some 
>time
> >ago when I discovered MOTs would work--and then  finally bought a Piglet.
> >Still, for a smallish coil, one of those big NSTs would be ideal.
> >
> >I've never un-potted an NST. I know it can be a mess. Maybe I should 
>simply
> >sell these units as is for someone else to do the un-potting, but I 
>wonder
> >if coilers would be interested in NSTs of questionable operational 
>status?
> >Dave Hartwick




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