[Shop-talk] high frequency welder capacitors

[Brad Kahler]

I have an older Linde / Union Carbide AC/DC Tig/Stick welder (weighs 800 
lbs!).  It is a great welder that I'm extremely happy with.  There are 
very few components that could go wrong with this welder since it has no 
electronics in it what so ever.  However there are a couple of 
capacitors that I have seen fail on similar welders.  The particular 
capacitors in question are in the high frequency circuit and are .002 
mfd Mica 5000 volt capacitors.  I've picked up the following capacitors 
as potential replacements should the original ones finally fail.  Later 
units used 10,000 volt capacitors probably due to failures of the lower 
voltage units.

The ones I have picked up are listed below:

Sangamo 
Mica .002 mfd 5000 volts 6.2 amps  1000 k.c.

Cornell-Dubilier
Mica .002 mfd 6000 volts 6.2 amps  1000 k.c.

Aerovox
Mica .002 mfd 6000 volts 13 amps @ 3000 k.c. or 11 amps @ 1000 k.c or 
7.5 amps at 300 k.c.

Sprague
Mica .002 mfd 10,000 volts 14 amps @ 1000 k.c. or 8 amps @ 300 k.c.

The Sangamo and the Cornell-Dubilier look identical, brown rectangles 
with terminals on top and the only difference being one has a potted 
assembly and the other has a little plate with 4 rivets on the bottom in 
stead of potting.

The Aerovox and the Sprague are transmitting capacitors and are 
cylindrical with mounting ears on top and bottom.  I am assuming the 
wires are attached to the top and bottom mounting holes.

What I'm wondering is whether the transmitting capacitors can be used in 
place of the original capacitor without either being destroyed or not 
functioning properly in the high frequency circuit of the welder.

Any thoughts?!

Thanks,

Brad