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Re: Melting tar out of NSTs with a Weber (grill)-thanks

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>

Hi all,

I depotted one a round Christmas. I used a single electric ring element.
I placed the NST metal case directly on the element and then covered the
whole thing in aluminum foil to keep the heat in.
Then left it on the lowest setting for more than three hours.
Note it takes a lot of time get the heat to the core. I bit like cooking
turkey or chicken.
Probably will not work very well with a propane torch unless your willing to
wave the torch round the NST for hours

The asphalt did get very soft but not runny.A higher temerature may have
helped but I did not want to damage the transformer's insulation.
When I inverted the case the transformer partly dropped out ripping the HT
leads out of the coils.
The power connections held it in. With a some persuasion the power
connections broke and the transformer was on paper on the floor.
I was able to scrap the asphalt off carefully with a screw driver and knife.
In particular as the out asphalt cooled and the transformer remained hot.
Pieces came of relatively cleanly from the transformer.
When the majority of asphalt was off. I placed the transformer in white
spirits and left it for more than a month.
With frequent brushing with an old paint brush. Apparently the white spirits
does not dissolve the asphalt it turns it in to a black gelatinous mass that
then can be washed or brushed away.
But it take times.

If I had to do it again. I would put the NEST on its side in say a large
dish or something to catch the asphalt.
Then place the whole thing in an oven say for four hours to let the asphalt
slowly flow out.
Then I would put the NST upside down with the transformer supported for say
an other four hours.
Again most of the asphalt would flow out.
By this time I would have access to the connections so I could cut them and
remove the transformer.
Then carefully remove the remaining asphalt.

For the white spirit cleaning I would want to fix the transformer in some
way in a tin can so I could shake the tin to dislodge the softened asphalt.
Unfortunately what I can not tell you is what temperature the NST got to or
what temperature you should not exceed  to avoid damage to the transformer.

Robert (R. A.) Jones
A1 Accounting, Inc., Fl
407 649 6400