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Re: [TCML] Burnt Joint (Cap Bank)

Em 04/05/2013 18:04, Michael Gray escreveu:
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:

In 6 strings of 10 their total capacitance should be in the region of

Here are a couple of pictures of it, you can see the burnt out joint on the


Wrap at least one turn of the wires around the capacitor terminals before soldering. This side soldering may not hold the large currents,
or even the mechanical stress in the assembly.
Avoid points in the conductors and solder joints to minimize corona losses.
I don't see bleeder resistors in parallel with the capacitors, that should exist for safety and residual DC voltage equalization. I am not sure if the board has good insulation at high voltages. I have made similar constructions, but used an acrylic plate as support.

Antonio Carlos M. de Queiroz
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