Re: Aaaaaaa!! My NST is toast! Salvage tips?

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

Original poster: "George Erdel by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gerdell-at-comcast-dot-net>




If the unit has TAR as a compound that is used to pot the interior then 
place the entire unit into an oven set at 250 degrees  until the tar is 
completely melted and is able to flow.  Once the tar is liquefied then 
remove the unit and allow the unit to cool slowly until the tar once again 
sets.  When the tar breaks down and an arc starts to travel through the tar 
then it is no longer able to have the dielectric properties needed to 
work.  Melting the tar and allowing it to once again cool will get rid of 
the track or crack and it should once again start working.  This is NOT 
able to be used with the epoxy type of potting compounds.  I have seen many 
a NST saved in this manner.


Good Luck

George








At 07:23 PM 12/21/2002 -0700, you wrote:
>Original poster: "Mark Broker by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><mbroker-at-thegeekgroup-dot-org>
>
>I forget the technical term, but "goo" would tend to imply something along 
>the lines of warm caramel or chocolate,
>and not the more epoxy-like substance described.
>
>The chiselling technique works best if the compound is very cold.  If you 
>live in a cold climate, place it outseid for
>a couple days.  If not,  place it in a COLD freezer.  If you can turn the 
>freezer down to the lowest setting, it will
>work better.  I've heard of people taking a large hammer and just smashing 
>the thing really hard.  The majority of
>the resin then breaks into chunks, leaving only a little to be picked off 
>the core and windings.
>
>Good luck!
>
>Mark Broker
>Chief Engineer, The Geek Group
>
> >I removed the steel case but it made no difference, which suggests that
> >it's shorting to the core. I tested to see if I could melt the potting
> >compound, but it burns instead of melting. It is a very hard brittle amber
> >substance so I guess it must be some kind of thermosetting resin, not tar.
> >So that rules out the oven trick.
> >
> >My plan is to carefully chisel the resin off and see if I can find where
> >it's arcing. If I accidentally trash the windings while chiselling (more
> >than likely) plan 'B' is to just set fire to the whole lot in a trash can
> >in the yard. That way I should be able to salvage the core and I can try
> >winding my own transformer. I know it's easier to just get another NST, or
> >a couple of MOTs, but I fancy the challenge.
> >
> >Is this going to work? Does anyone know a better way? Can I salvage the
> >core like that or will the heat from the fire mess up its magnetic
> >properties? Your $.02 would be much appreciated. Merry Christmas!
> >
> >Steve C.
> >
> >
> >