RE: More destroyed NST's How do I remove stubborn tar?

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

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi Ed,

Snip
>
> 	Has anyone ever tried using a heat gun (he-man hot air gun,
> that is) to
> melt the tar away from the ends of the transformer at the point where it
> connects to the insulators?  If the failure is indeed due to carbon
> tracking, this should allow selective removal of tar without as much
> mess and without concern of the transformer dropping out of the case and
> pulling out the leads to the windings.  Furthermore, since the melted
> tar would be liquid which can be kept hot by the air gun, would think
> that it would be a simple matter to keep it flowing into a can from
> which it could be trashed or remelting to restore the potting.
>
> Ed
>
>
>
I've tried it. If you heat the metal (case) it will loosen the tar enough to
be able to remove the insulator. Heating the tar directly with the heat gun
does not work very well. The very surface will melt, but then the heat does
not seem to penetrate well. You get a small puddle of smoking tar. If the
NST is tilted so that the puddle runs off, it is still very slow going. A
lot of smoke, way to much for my taste. I just stick 'em in the oven. BTW I
have tried various settings for the air damper.

later
deano