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Re: More destroyed NST's How do I remove stubborn tar?
Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>
Tesla list wrote:
>
> 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
Roger. Results about what I expected, but surprised about the smoke.
I thought it would be possible to melt it without starting it to burn.
Ed