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

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

Original poster: "Yurtle Turtle by way of Terry Fritz <twftesla-at-uswest-dot-net>" <yurtle_t-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Garry Freemyer by way of Terry
> Fritz <twftesla-at-uswest-dot-net>" <Garry-at-NDFC-dot-com>
> 
> Well, today I destroyed my fifth NST out of six
> tries and I am at whits end
> on how to prevent this nasty problem from recurring
> over and over and I want
> to ask people out there a few questions.
 
<snip>

Here's the method I've used successfully many times:
You need a large metal bowl, large enough to contain
the NST and all the potting tar. You need an oven with
good temperature control. Mine is a gas oven with
electronic controls. I set the temp for 175 F and let
it hum for 15-25 minutes. Then I check the tar. If
it's soft, I may increase the temp slightly. If not, I
may increase it 25 F. As I get the right temp, the tar
begins to soften. I then remove the high voltage
bushings, the low voltage terminals, and all wires.
Then I place it upside down in the bowl and let the
tar melt out. It usually takes an hour or so. If the
tar is just at the point that it starts to soften and
flow, there's no smoke and no smell. Again, my oven
turns on at 175 degrees F and allows increments of 5.
After most of the tar has melted away, I remove the
NST and remove the rest by hand. I don't let it get
hot enough to get runny, so I can now pull the rest
off in hunks. For final cleaning, a good bath in
gasoline does the trick. Be patient and allow a good
day of soaking before LIGHT brushing with a
toothbrush. It usually requires one additional day of
soaking to really get it clean.

It sounds like you may be rushing things a little too
much.

good luck
Adam

=====
Adam Minchey
yurtle_t-at-yahoo-dot-com
www.geocities-dot-com/yurtle_t/index.htm

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