Here you see the very not so complicated wiring of the welder. A simple parallel circuit, nothing in series. Not even a ballast. The ballast I made out of a shorted secondary MOT transformer dropped 6V with its primary winding, costing me precious arc starting volts. The diagonal metal has been placed to have a minimum magnetic separation between the two transformers, the chassis is grounded. I sealed up all the little holes in the chassis, the only holes left being the air intake behind the blue fan and outlet behind the PSU fan.