[Amps] opening up a transformer

[Pete Lancashire]

Be careful for what you use as a separator/insulator. Plumbers tape is
made with very very low quality standards. Quite a long time ago the tape
manufactures stopped using DuPont Teflon and switched over to other
makers of the PTFE powder base. And the only requirement of the tape is
to act as a cavity filler. It can be very porous and its its thickness can vary
down to zero.

If your in a good size city or near one, check out a few large motor rebuilding
shops, you should find at least one that if you let them know it is for a hobby
will let you buy small quantities of tape, papers, wire, etc.

In a past life at 17 I worked in a shop that made their own transformers for
large welders. On of my first jobs was building transformers, including the
wonderful job of putting the coil assemblies in the 40 gallon heated varnish
tank, and a few times having to reach in and find one that had dropped of
its hook .. gloves .. back then .. now way, and just clean your arm and hand
of with solvent.

-pete

On Fri, Jun 15, 2012 at 8:57 AM, Jerry Kaidor <jerry at tr2.com> wrote:
>> Just cuz I can I plan to open the defunct Hunter Bandit 2000c transformer
>> to see if I can find the fault.  Working one day and not the next I think
>> a
>> power surge hit it....the only piece of equipment plugged in, but there
>> were not TS around.  Anyway, any advice on going into a transformer?
> *** Once you get the wraparound sheetmetal cover off, the core will consist
> of "E" laminations and "I" laminations.  Use a little knife or whatever to
> tease off the first lamination.  The first few will be hard, the rest are
> easy.  Generally they're stuck together with some sort of lacquer.  Once
> you get all the laminations out, you're left with a coil wound on a form.
> Just unwind until you find the offending wire. It helps if you make a
> holder for the coil form - something with a wooden stand and a bolt
> through it and something on the bolt to hold the coil - that way you can
> just pull,
> and it will turn.
>
>   I actually did this once.  I had a big surplus low-voltage transformer,
> and what I actually needed was a filament/bias/plate transformer for a
> Galaxy 5 that I had picked up at the flea market sans PS.  So I bought
> a big roll of appropriate magnet wire and wound the needed HV windings.
> Magnet wire, BTW is not cheap.  I seem to remember paying $30 for enough
> to do the job 20 years ago.  Probably more now.  Traditionally, the layers
> are insulated with paper - wind a layer, put on some paper, wind another
> layer, more paper etc.  Now I would be tempted to try teflon plumbers tape
> instead of the paper.
>
>   After you wind the coil, you put back the laminations.  Possibly with
> lacquer or varnish to stick them together.  Messy job.  You will not be
> able to get them together as neatly as they were originally, and you might
> have to leave out one or two.  But it will still work.
>
>                              - Jerry Kaidor, KF6VB
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps