Unpotting my Neon (started today)

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Unpotting my Neon (started today)
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 5 Nov 1997 06:33:28 -0600
Approved: tesla-at-stic-dot-net

From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Tuesday, November 04, 1997 11:24 PM
To: 	tesla list
Subject: 	Unpotting my Neon (started today)


Today, I dealt with the messiest part of coiling- unpotting a neon sign 
transformer.  I have done this 3 times before, but every one is 
different, and it's always messy.  I did learn a few things with this one 
however, read on...

I started by freezing the neon overnight, and chiseling off the frozen 
tar.  This did not work very well (never has for me), and I damaged one 
of the secondary windings after finding the transformer.  I was about 300 
or so strokes into it at this time.  So, I decided to try something new.  
I got an aluminum baking pan, the disposable kind, and put the block in 
it.  Then, I put this directly onto a portable hotplate, outdoors.  Well, 
it smoked like a small factory, and caught fire twice, but overall the 
effect was good- the core got hot and the tar melted and was easy to just 
"spoon" off the core and windings.  In future, I will probably leave the 
block of tar in the original transformer case, heat it on a hotplate, and 
attempt to pour the liquid tar out.  The melted tar will not just run out 
like water, but it is a free flowing liquid nonetheless.

What I was left with in the end was a very messy transformer.  
Fortunately, the core was not welded, so I was able to separate the core 
pieces.  The windings would not budge (thing was cool now) so I put it 
back on the heat.  After 10 minutes of heating and smoking, all the 
windings just slid off easily.

Now I have:

     2 Secondaries (1 with the outside winding damaged)
     1 Primary (Also with a damaged outside winding)
     2 "E" cores
     4 shunting pieces

Everything is covered with tar and hideously filthy at this point.  I 
decided to attack the filth with mineral spirits- no luck.  Kerosene? 
Nope, not satisfactory.  Next, I tried d-Limonene (a lemon oil extract).  
Too my surprise, when I put the cores in d-Limonene, the tar just floated 
off!!! Amazing!  This is definitely _THE_ solvent for this stuff.

Now, I am going to wait overnight for the pieces to soak, and I will 
continue cleaning and repairing them tommorrow.  It looks like I will 
have to remove 14 turns from the 224 turn primary (piece of cake), and at 
least one layer from the damaged secondary (not so easy).  I'm not sure 
how this will affect performance, but we'll see soon enough.  I hope to 
re-insulate the secondaries with 30mil LDPE and electrical tape, in place 
of the cardboard and mica that was on there.  Then I will make yet 
another of my "mini pigs" by putting the tranformer into a sealed 6" PVC 
tube with transformer oil, and putting the original ceramic insulators 
through the top end cap.  They are pretty cute when they're finished :-)

-Adam



--------------------------------------------------------------------------
Adam Smith
absmith-at-tiac-dot-net
Epoch, Inc. Digital Music Project

www.tiac-dot-net/users/absmith/     Now with MP3!     Musik. Macht. Macintosh.
--------------------------------------------------------------------------