Re: [TCML] Burnt Joint (Cap Bank)

[Michael Gray <graymp89@xxxxxxxxx>]

The strike rail is actually not a complete loop, the two ends are hidden
inside one of the supports, however I will check that they are not touching
and could actually put some insulation between them just to be sure. Thanks
for the advice.

The break out point is a great idea, I'll try that as well as soon as I get
home. I was thinking I could try making a longer secondary - do you think
making it wider would be a better idea?


On 6 May 2013 19:02, Mark X2 <susax2@xxxxxxxxx> wrote:

> 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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