Re: [TCML] Burnt Joint (Cap Bank)

[Mark X2 <susax2@xxxxxxxxx>]

Very well spotted Atomic, I agree with you.
If splitting the strike rail and adding a breakout point shouldn't work,
you might want to consider winding a wider secondary.
Mark

2013/5/6 Atomic <atomicrox@xxxxxxxxx>

> I'm no expert but I noticed your strike rail looks like a complete circle,
> it should have a gap to avoid eddy currents sapping the coil's power.
>
> Couple things you could test, in case it's working but a very low power:
> -Add a breakout point
> -See if it lights up a fluorescent lamp
>
> On Mon, May 6, 2013 at 8:34 AM, Michael Gray <graymp89@xxxxxxxxx> wrote:
>
> > Okay, I resoldered the cap bank board last night, and had another crack
> at
> > running the TC this morning. Still doesn't work...!
> >
> > Just a quick run through of what I did: first I connected the safety
> spark
> > gap directly across NST and adjusted so it was just wider than the NST
> > could arc across. I then did the same for the main spark gap, except this
> > time a tiny bit narrower than max. Then checked all connections with
> > continuity tester and checked the wiring was correct. Here's a pic of my
> > circuit diagram:
> >
> > http://imageshack.us/photo/my-images/211/20130504191918.jpg/
> >
> > Then I fired it up (variac was connected but I just had it on 100%), and
> > the main spark gap was going, very bright with a loud crackling sound
> which
> > I presume is about right. But the toroid wasn't doing anything. I left it
> > running like that for about 10 - 20 seconds and still nothing, so I
> > switched it off to investigate.
> >
> > Disconnected everything and re-tuned the spark gaps as described above.
> > Then connected the NST across the Terry filter, with the other end of the
> > Terry filter left open, and powered up - no sparks on safety gap (as
> > expected). Moved on to connect Terry filter up to the main spark gap,
> > powered up and the spark gap was arcing much quieter and continuously (as
> > expected). Then connected one end of the spark gap to one end of the
> > capacitor bank, with other end of cap bank left open, powered up and
> spark
> > gap continued to arc the same as before (as expected). Then connected the
> > other end of the spark gap to the base (inside most) tap point of the
> > primary, powered up and spark gap continued arcing as before (as
> expected).
> > Just to be thorough, I then disconnected the spark gap from the primary
> and
> > instead connected the other end of the capacitor bank to the outer tap
> > point on the primary, powered up and spark gap again arced as before (as
> > expected). So up until now everything seemed okay, until I completed the
> > circuit by connecting the spark gap to the primary again. On powering up,
> > the spark gap this time was arcing as I described earlier, i.e. much
> > brighter with a very loud crackling noise (as expected), but the toroid
> > wasn't up to much, in fact nothing whatsoever. I was quite disappointed
> to
> > be honest...!
> >
> > Anyway I've taken a load of pictures of it (below), does anyone have any
> > ideas?
> >
> > http://imageshack.us/photo/my-images/51/20130506121432.jpg/
> > http://imageshack.us/photo/my-images/138/20130506113409.jpg/
> > http://imageshack.us/photo/my-images/194/20130506113502.jpg/
> > http://imageshack.us/photo/my-images/199/20130506113443.jpg/
> > http://imageshack.us/photo/my-images/545/20130506113418.jpg/
> > http://imageshack.us/photo/my-images/405/20130506113427.jpg/
> > http://imageshack.us/photo/my-images/12/20130506113343.jpg/
> >
> >
> > On 5 May 2013 21:56, Michael Gray <graymp89@xxxxxxxxx> wrote:
> >
> > > Thanks for the advice everyone. I must have forgotten to include the
> > > bleeder resistors. This board is the second iteration of my cap bank;
> the
> > > first had bleeder resistors on it so I must have forgotten to include
> > them
> > > on this one. So I'm resoldering it completely, removing the red wiring
> > > between each cap and replacing with the legs of the resistors as they
> are
> > > long enough to adjoin each cap too. Good point about the trailing
> leads -
> > > I've now tied each trailing lead to the board with some magnet wire,
> > > through the board holes and twisted taught.
> > >
> > > When I first turned on the coil I did here what sounded like arcing as
> I
> > > was turning up the variac (before spark gap had fired), but I wasn't
> sure
> > > what it was as I couldn't see the cap bank from where I was standing,
> and
> > > of course it was my first go so I didn't know what to expect. So that
> was
> > > probably the dry solder joint as has been suggested. I'll hopefully
> have
> > > the board resoldered tonight, and will have another crack at it in the
> > > morning. Hopefully it works, very excited, thanks everyone!
> > >
> > >
> > > On 5 May 2013 08:54, Phil Tuck <phil@xxxxxxxxxxx> wrote:
> > >
> > >> Michael,
> > >> You need to physically anchor all of those 12 red 'trailing leads' to
> > the
> > >> board. Either by wrapping some wire around the lead itself and then
> > >> through
> > >> the board's holes, close to the edge of the board, or a spot of 'Hot
> > Glue'
> > >> to tack them to the board. Otherwise they are relying on the soldered
> > >> connections everytime the leads move or flex.
> > >> The original trouble, as the others say, was a 'dry joint' (solder not
> > >> properly melting onto the wire, or only being held there by the resin
> in
> > >> the
> > >> solder)
> > >> I have used that board to mount a string of diodes once, to rectify
> > 10kV,
> > >> and the board ending up tracking. I had to put it under oil to allow
> it
> > to
> > >> work (it was just a temporay test setup anyway).
> > >>
> > >> Regards
> > >> Phil Tuck
> > >>
> > >> www.hvtesla.com
> > >>
> > >> -----Original Message-----
> > >> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > >> Behalf
> > >> Of Michael Gray
> > >> Sent: 04 May 2013 22:05
> > >> To: Tesla Coil Mailing List
> > >> Subject: [TCML] Burnt Joint (Cap Bank)
> > >>
> > >> I fired up my (first) TC for the first time today, after months of
> > putting
> > >> everything together. Needless to say, it didn't work! I was slowly
> > turning
> > >> up the variac, the spark gap fired up, and then I saw some smoke
> coming
> > >> from the cap bank. So I powered down and investigated - turns out one
> of
> > >> the soldered joints had smoked. I kinda regret buying the caps I did,
> > the
> > >> legs on them are tiny and this makes it difficult to string them
> > together.
> > >> The caps are mounted on some Vector prototyping board, and because the
> > >> legs
> > >> are so small I've had to solder a very small length of high voltage
> wire
> > >> between each cap. I'm looking for some advice really on my cap bank -
> is
> > >> soldering prone to burning out like this? What's the best way to make
> > the
> > >> connection? Should I try to solder the legs directly together instead
> of
> > >> using an adjoining length of wire? Should I invest in different caps?
> > >>
> > >> The caps are rated at 0.047uF at 2kV:
> > >>
> > >>
> >
> http://uk.mouser.com/ProductDetail/Kemet/PHE450SD5470JR06L2/?qs=s4t14sB06yQT
> > >> V0lacTv0rw==
> > >>
> > >> In 6 strings of 10 their total capacitance should be in the region of
> > >> 28.2nF.
> > >>
> > >> Here are a couple of pictures of it, you can see the burnt out joint
> on
> > >> the
> > >> right:
> > >>
> > >> http://imageshack.us/photo/my-images/841/20130504212930.jpg/
> > >> http://imageshack.us/photo/my-images/713/20130504212952.jpg/
> > >> _______________________________________________
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> > >>
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> > >>
> > >
> > >
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