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Re: [TCML] How to Fix Damaged Secondary



Hi Carl, 


Thanks for describing the procedure. The wire surgery does not seem to be too difficult, and I admire it's precision delicacy and thoroughness. My coil burn is not yet bad enough to require this, but I will do it after I test the coil now that I have cleaned it and re varnished it and possibly reduced the coupling. However, I will definitely take to this measure if my coil burn gets worse. 


Thank you for your help Carl, 


Amir Mojarradi




-----Original Message-----
From: Carl Noggle <cn@xxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wed, Oct 26, 2011 5:22 am
Subject: Re: [TCML] How to Fix Damaged Secondary


Hello, Amir,

You probably have a shorted turn.  I have fixed several of these.  It's 
not hard, but requires the drastic delicacy of a brain surgeon.  Find 
all the turns that have burned insulation and carefully cut them back at 
least 1/2 inch each way from the burn, then cut the ends in a staggered 
fashion.  Be very careful not to nick any insulation.  Then take the 
first good turn on each side and cut it so that there is overlap between 
the ends.  Carefully scrape the insulation back 1/4 inch on each.  Then 
drill a small hole through the form and put both ends through to the 
inside of the form.  Reach inside the form and pull them tight and twist 
them together.  Solder them inside the form.  This leaves a point, but 
it's in a relatively field-free region.  Smoothe and dress the wire ends 
in the surgery area on the outside, and coat them all with epoxy.  Heat 
it with a heat gun or hair dryer to remove bubbles, but not too hot.

This leaves a visible injury on the coil, but I have never had one 
fail.  If it is a shorted turn, fixing it will greatly improve the 
performance o your coil.  The final step is to turn the coil so the 
injury is away from the audience.

This kind of problem is usually due to secondary arcs attaching to the 
side of the coil.  Avoid this like the plague.  The burns will be worse 
with higher power, of course.

I wind my coils with monofilament nylon fishing line of about the same 
diameter between the turns.  This is surprisingly easy.

Good luck.

---Carl



> Hi everyone!
>
>
> I recently finished completion of a fairly large Tesla coil, (specs and video 
below), and have been testing it.
>
>
> Maximum Arc Length (so far) 9 feet
> Secondary Diameter: 12"
> Secondary Coil Winding Height: 57"
> Wire Gauge: 18awg
> Number of Turns: 1400
> Toroid Minor Diameter: 12in
> Toroid Major Diameter: 60in
> Power Supply: 14.4kv 10kw Pole Pig
> Ballast: Lincoln Arc Welder (240 Volts @~ 26 amps)
> Primary Capacitance: 0.1289 uf
> Asynchronous Rotary Spark Gap
>
>
>
> Video: http://www.youtube.com/watch?v=KfQYHF6Z62c&feature=related
>
>
>
> When testing at about 5 Kw, I noticed some arcing one individual turn at 
exactly one point about 12" on the secondary. Upon examination, there is a small 
burn mark at the point on the turn where it was arcing. At this point on the 
wire, the varnish is melted and has left the point exposed. I have re-varnished 
the entire coil already. Is there anything I can do to "heal" the damaged point 
to prevent further arcing? I was originally planning to step up the power to 
about 12 Kw, but I might have to hold off, or possibly reduce coupling. Any 
suggestions or advice would be much appreciated.
>
>
> Thank you for your kindness,
>
>
> Amir Mojarradi
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla

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