"Eric R Snow" tesnow@whidbeyDOTcom wrote in message
...
Last week Ernie Leimkuhler held a mig welding tutorial at Grant's
place ( Thanks again Grant and ernie!). Ernie told me that the high
voltage caps in the high frequency circuit go bad and it is hard to
find replacements for them. I had noticed that something was dripping
on the floor underneath the Miller Goldstar welder. I searched in
without success for the source of the drips. Then yesterday I found
the source while wiring in an extra relay and receptacle. The relay
connects the receptacle to 115 volts which then powers up the water
cooler for tig welding. The source is the high voltage capacitors.
some kind of oily substance is coming out of them and dripping down
the red phenolic mounting board. Ernie was right, these caps are hard
to find. In fact, using google tonight to find these caps was
fruitless. They are mica capacitors. Can types other than mica be
used? And can they be paralleled to increase the value? Is there a
better type than mica? And finally, does anybody here have some to
sell?
Thanks,
Eric R Snow

I would expect Miller to have the parts available, at least unless the
welder is an antique. It's a big part of why I bought a Miller instead of
an off-shore el-cheapo. That being said, in order to find a suitable
replacement from other sources, you need to know the characteristics of the
capacitor you are trying to replace. And it is more than just the
capacitance and voltage. Many types of capacitors don't take kindly to
being charged backward and, if you put AC across them, they'll literally
explode. Even if they have enough of a DC charge on them that they never
see a reverse polarity, if they have a significant effective series
resistance (ESR), they'll get hot and blow if there is a substantial AC
signal riding on the DC. And this just scratches the surface...

Jerry