Re: help NST potting

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 2/23/02 11:03:16 PM Eastern Standard Time, tesla-at-pupman-dot-com
writes:

Chris,

Certain NST brands, such as the Jefferson/Magnetek, use a silica
filling in the tar.  This makes them much harder to melt.  You may need
to remove just about all the tar to get rid of the carbon tracks.  I had
to do that with my NST's to get them working again.  I've used various
methods such as heating the tar outdoors with a propane torch and
scraping it away with a screwdriver, freezing it in the freezer and 
chipping it away, heating it with a heat-gun, etc.  When it looks
pretty clean, then I soak them in gasolene for about 2 weeks or
more, then scrub them with a brush.  I usually take the core apart,
and remove the coils, and soak them separately, etc.  A lot of work...
too much if you ask me.  I did two of them, and that was enough.
Sometimes simply heating them in an oven or in an outdoor 
controlled fire fixes them.  Sometimes the carbon track can be 
found by digging into the tar around the case or near the top. 
If not, I dump them in the garbage pronto.  

Cheers,
John


>
> I am in the middle of potting an NST i got a while back.  I first tried the 
> solvent method (gasoline).  And it didn't seem to affect the tar at all.  
> Then I tried the oven method, and even at 300 degrees for a few hours the 
> tar only got soft and flakey, like it was extra dry tar.  I almost got all 
> the tar off but there is still a significant amount tar coating on the 
> primary and secondary.  I think it has carbon tracks and I want to make sure 
> I fix the problem.  Is there something else i should try, like a different 
> solvent?  IS it necessary to get all the tar off around the primary and 
> secondary?  I can't even get close to chipping the stuff off at room 
> tempature.  Any suggestions?
> -chris
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