Re: mysterious coil failure (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 28 Oct 2007 11:01:32 -0800
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: mysterious coil failure (fwd)

Hi Scott,

Yes, the glowing spot is either a shorted turn or carbon track. It may 
be a shorted turn and easy to fix if right on the bottom, and "if" it is 
like the very bottom turn, it's probably too much power for too long a 
period. I've had this happen on my 4" coil even with low coupling. If 
enough power is provided, it can cause extensive heating a greatest 
heating on the bottom of the secondary (highest current). If you were to 
continue running it, a nice little fire will begin. If it's a shorted 
turn, you'll have a nice black carbon ring around the entire turn. Real 
easy to fix obviously.

Take care,
Bart

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Sat, 27 Oct 2007 22:10:06 -0400
> From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: mysterious coil failure
>
>
> Hey guys,
>      I was running my 6-in MOT coil tonight for my little cousins, and it
> died and I cannot figure out what is wrong.  The spark gap fires fine, I
> did not adjust anything, it just died between runs, and won't arc except
> to a grounded rod (it acts like it is badly out of tune, but like I said,
> I adjusted nothing).  The only thing different I notice, is that there was
> very high humidity, and I could see a tiny spark at the base of the
> secondary.  It isn't arcing to anything, it is just a glowing spot, that
> melted through the electrical tape insulation.  I'm stumped, I guess I'll
> tear the insulation off of the bottom of the sec' coil and see if anything
> is amiss, but I've never had a failure like this before.  The only other
> possibility is that somehow my ballast malfunctioned, but I don't think
> so.
>
> Scott Bogard.
>
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