Re: Warning about Magnetek(sp?) Jefferson NST's and a depotting question.

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

Original poster: "Mike Novak by way of Terry Fritz <twftesla-at-uswest-dot-net>" <acmnovak-at-email.msn-dot-com>

Garry,
If you paid a significant amount for this, I'd ask for a new one. It seems
it would've died no matter what application it was used in. I unpotted a
"Franceformer" about a year ago and it had an INCH thick sheet of mica on
each side of the xformer!!! It seems Jeffersons are not a good choice for
Tesla Coils after all... I've previously heard they were quite hearty, but I
guess not. Well, Good luck!

-Mike


----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, December 28, 2000 5:17 PM
Subject: Warning about Magnetek(sp?) Jefferson NST's and a depotting
question.


> Original poster: "Garry Freemyer by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <Garry-at-NDFC-dot-com>
>
>
> About a month ago, I acquired a used but relatively new brown 12/60 NST
from
> Magnatek Jefferson or something like this and it fried immediately when
put
> into service despite having a safety gap and two chokes like the ones
> reccommended by the coiler that wrote a book on making coils. I forgot his
> name but I've heard the book highly reccomended.
>
> During the course of depotting I noted a few significant things. ....
>
> The tar was severely cracked and dried out compared to the other trannys
> that were in the same sign and were of the same age.
>
> The tar did not extend around the entire transformer. The sides were clear
> of tar which led to the third observation ...
>
> One of the secondaries of the tranny was arching to the case that was MUCH
> LESS THAN AN EIGHTH OF AN INCH AWAY!!
>
> Obviously, the transformer should have been much farther from the case or
a
> sheet of insulation should have been placed between the secondarys and the
> case.
>
> When the unit fried, I could HEAR the arching inside and smoke arising out
> of the transformer after the lid was removed. Had tar been present, the
unit
> might not have shorted so easily.
>
> The arching of course melted the windings at the point of arching.
>
> I am posting this to warn coilers that if you get one of these units,
don't
> try to run it in the pot, depot it at once because you might ruin the unit
> by trying it out in a tesla app.
>
> I also have my suspicions that the reason the sign failed and had to be
> dismantled was because this particular tranformer was shorting to the
case.
>
> ---
>
> Also, what is the correct temp for melting tar out of a tranny in an oven
> without having the tar smoke a lot? I seem to remember 200 degrees, but
the
> tar wasn't even soft with this temperature after 45 minutes.
>
>
>
>