Re: [TCML] Subject: Overheated Secondary

["Brian Foley" <ka1bbg@xxxxxxxxxxx>]

Hi, well i went and got a gallon of paint thinner over 6 dollars a gallon so
gasoline is cheap compared to mineral spirits... i am used to paying $2.50
for a gallon..cul brian f.


      www.genapro.com
----- Original Message -----
From: "mark olson" <kc5gym@xxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, January 04, 2008 10:41 PM
Subject: Re: [TCML] Subject: Overheated Secondary


> At 11:35 PM 1/3/08 -0800, you wrote:
> Thanks again Bart,
>
> I will begin repairs tomorrow (Saturday). Surely I will post the results
of
> this venture.  Most of the tar is gone,
> but even with gasoline I am not sure that it is possible to get all of the
> residue out.  I have been a mechanic
> of one kind or another for most of 50 years, so gasoline is no strange
> solvent for me, but it is rather expensive.
>
> later later,
>
> Marko
>
>
> >Hi Marko,
> >
> >Inner windings are connected to the core (which is center tap
> >configuration). Each secondary puts out about 6kVrms in your tranny. The
> >outer portion of the secondary winding is the high voltage end. This is
> >the area which usually shorts and your tranny appears to be no exception.
> >Typically a 2 or 3 layer removal will solve the problem. Some damage
> >occurs just in the depotting process itself from mechanical stress of
> >removing the tar. But, after a few layers of unwinding the damaged area
of
> >the effected secondary, it's good as new again.
> >
> >I like to use new GTO cable on the hv outer secondary windings (which the
> >tranny originally used). It's good for 15kV insulation and perfect for
NST
> >rebuilds. I bought like 100 feet of this stuff a year ago and it's come
in
> >real handy (not all that expensive either). You may have found some
gasket
> >or cardboard material in the potting compound. Insert something similar
> >when you repot the tranny. Allow the cardboard to keep the GTO cable out
> >of harms way (mechanically and electrically meaning more space away from

> >core and case is good).
> >
> >Removing 1/2 the shunts will put your transformer into major power mode.
> >The tranny will push a lot of current to the cap bank. It's not linear
(if
> >you remove about 1/2 the shunts your current may go up x3). However,
> >that's what I did on my 12/60 and achieved about 200mA (big jump in
> >current). My shunts where divided into two sets. Yours looks a bit
> >different, but regardless, remove 1/3 to 1/2 of the shunts to boost the
> >current. The difference is night and day.
> >
> >Something I did was to remove several secondary layers to reduce the
> >output voltage. When I removed 1/2 the shunts, I got a big current boost
> >and reduced the voltage to a manageable level. Don't remove more than say
> >15 layers however. That will reduce your voltage down to about 10.5kVrms
> >and it's nice to keep the output voltage near the original value as much
> >as possible. However, if you find yourself unwinding more than you
> >actually wanted to, don't worry about it too much. Simply adjust the gap
> >for the new lower arc voltage. It will do fine and due to the current
> >increase, much better than previously realized.
> >
> >Try the tranny dry during shunt reduction. If you like it, pot it with
> >your flavor of potting compound (wax, oil, whatever). Use trial and error
> >with the shunts. If it seems like a bit much, add a few more shunt slabs
> >in there until you find what your coils happy with. But definitely, while
> >you have it apart, now is the time to beef it up by removing 1/3 to 1/2
of
> >the shunts. That's exactly what I would do.
> >
> >Take care,
> >Bart
> >
> >>Thanks Bart,
> >>
> >>My photos are here:  http://members.cox.net/kc5gym/
> >>
> >>I have a question or two, maybe a million.
> >>There is a picture of the shunt in my hand. I should remove 1/2 of
these?
> >>
> >>I was not able to preserve the original "angel hair" wire terminations
on
> >>the secondaries.  Are the inner windings
> >>connected to center tap or are they the hv ends?  I suspect the outer
> >>ends are the outputs.
> >>
> >>Thanks
> >>Marko
> >
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> >
> >
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