[jpump5]

Do you know that you have 220v at the receptacle and
that the receptacle is wired correctly ?
Have you checked for continuity across the two blades of the
welder’s plug with the power switch in the on position?

 

[jpump5]

My buzz box and every other one I’ve used makes a fairly loud
buzzing sound when turned on. Also fans run continuously on
all transformer type that I’ve seen. With power at the receptacle
and continuity across plug, seems like either fan would run or
transformer would hum.Do you have a multimeter?
My next step would be to check for power at the switch.
Or measure resistance across plug with switch on.
(Should be very low, probably less than 10Ω)

 

[jpump5]

Have you checked for voltage at switch ?(as Hobbytime suggested).
I would suspect plug ,cord or wiring of them.