[Galaxieman]

One last question: Since several modders have commented that the arc tends to sputter for a few seconds until the cap is powered up......

If you want to get rid of the startup sputter COMPLETELY....install the time-delay relay modification. You will find all the details in the 151 mod thread.

 

[Galaxieman]

"When wiring the toggle switch in between the positive plate on the rectifier and positive end of the capacitor, which side is considered the line (power in) and load (power out)? Or does it even matter in this application?"

Does not matter...the current goes to the capacitor when charging and from the capacitor during discharge.

"I also noticed that there is already a 4d151k Varistor wired between the two rectifier plates on my version of this welder, does I still need to install the resistor also?"

The Varistor does NOT replace the function of the bleed resistor. I think that the Varistor's function is to 'satisfy' FCC requirements for suppression of radio frequency emissions from the welder. You could remove it and the welder would work fine.

"I'm also a little freaked out by how close these little things are to touching. Is there any reason they would be so close to each other, should I try and spread them a bit further apart? "

Close is OK. Remember that the voltage is 'low' so that there is no danger of arcing across the gap. It takes roughly 5000 volts to arc across 1/4 inch. The voltage in the welder is less than 100 volts in that area.

 

[Galaxieman]

IMHO the 50V rating on that capacitor is too low. To be safe you need at least 60V.