HEEEEEEE!!! Hee!!! HEEE!! HEE!!!! I'm sorry but, I just could'nt help it!!!
Man - O - Man!!! is that tooo funny!!!!
Hey DOCTOR! The Pow Con 300 St is a DC only inverter type power source primarily designed to perform SMAW and GTAW and you could hook up a voltage sensing wirefeeder to do some GMAW or FCAW with questionable results, but, that's another story...
Anywho, Many moons ago when these puppies first came out into the market, they were definitely ahead of their time and as with anything new, they had their fair share of problems... One of them were just putting up with their ungodly noisemaking ability from the High Frequency step up transformers inside which by the way have nothing to do with starting the arc for you on this machine, but that is another story too!!!
What you have is capacitive discharge!!! This is what starts your arc transfer and as Lawrence so eloquently put it, YOU NEED TO REVERSE THE WORK CLAMP and TORCH connection to the OPPOSITE LUGS on the machine...
Nonetheless, Whatever you do , DO NOT OPEN THE MACHINE IF YOU DON'T KNOW ANYTHING ABOUT THE INSIDES OF THIS MACHINE BECAUSE, THIS IS NO LAUGHING MATTER!!! YOU CAN EASILY GET ELECTROCUTED IF YOU DO'NT KNOW YOUR WAY AROUND!!!!!
Cyclomatics out of California used to make this power source but, then they changed so many hands as to who has updated info on that machine that I'm afraid I could only suggest bringing it to someone that is familiar with that line of power sources, in other words, a qualified independant welding equipment repair shop in case you needed any service to be performed on it.
Electrode or in your case GTAW(TIG) Torch Positive equals tungsten balling up or reverse polarity... For TIG, stick to Electrode or TIG Torch on Negative which btw, equals straight polarity and that's where you want to be!!!
BTW, does your call sign represent that you're some sort of Doctor?
I hope you do not mean a doctor of welding, do you? I ask this because I would not be convinced of that, to say the very least based on your query!!!
Respectfully,
SSBN727
Run Silent... Run Deep!!!