Heath potted transformers

[Roy Morgan]

At 09:55 AM 4/24/2007, Taylor Jim-CJT001 wrote:
>I have a question for the list regarding the potted transformers that
>Heath (and others) used in power supplies ...
>
>Has anyone ever tried to remove the potting material ? It appears to be
>an epoxy type material,

Jim,

Yes. I have a pair of heath W-5M amplifiers. They are known for power 
transformer failures (leakage to case from the HV winding).  So I took one 
of the transformers out and de-potted it. The potting in them is tar.

I suspended the transformer with coat hanger wire in a (Metal!) coffee can 
with the underside down, and put the can in to my simple backyard charcoal 
grille.  The heat melted the tar which dripped into the can.  It was fairly 
easly to get the transformer out of the drawn metal cover.  The metal cover 
had become charred a bit, and the paint partly came off.  I'd hoped to find 
a different transformer innards and melt the tar back in there, but have 
not gotten that far with the project yet.

There is at least one fellow doing transformer re-building (other than 
Peter Dahl, Company):


Transformer rewinding service.

Materials used in the rewind of transformers include the following.

  Triple coated magnet wire rated at 200 degrees C.
Nomex insulation, 10 mil or 15 mil. Depends on application.
  Class "H" baking varnish.
  Hex-Flex glass sleeving used on all leads.
  Leads are always soldered, not crimped.

  http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/

That would be Gary, WZ1M. He's been rewinding iron for many years,
now. Seems some folks still aren't aware of his service.... He's a good man 
who does good work and stands by it. Prices are more affordable as well.


Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing
13033 Downey Mill Road, Lovettsville, VA 20180
Phone 540-822-5911   Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-975-6097
roy.morgan at nist.gov --  

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