For anyone in the future reading this thread...just buy a dang inverter welder. Even if you rig it up somehow to your current welding equipment. They're cheap. Probably cheaper than adding your own MASSIVE capacitors and inductors. (The higher the switching/alternating frequency, the smaller of an inductor you can use. 60hz -sssslllllloooooowwww - at 100s of amps, you need a really big inductor. Inverter welders switch at high frequency.)
I second Chipresitor's view that you shouldn't be messing with a power supply if you don't know the basic components...but testing if the bridge rectifier is working is pretty simple...power it up, see if you've got the proper output on the rectifier.
Of course, that means having the dang thing open and live. Not recommended if you don't know what you're doing.
I have GFCI's on my shop's plugs, just in case I'm doing something stupid like that.
