Starting up an old Lincoln MIG welder

I've got a Lincoln SP-125 Plus MIG welder that was last used about 10 years ago. Does anyone know if I can just fire it up or do I need to reform the capacitors like I had to do with a VFD that sat for a couple of years. I'll probably call Lincoln on Monday but thought someone might know.

Thanks.
Steve

If it's an old fashioned three phase it may not even have capacitors, might be worth taking the covers off and looking. The unit I fixed up last week didn't have any capacitors but did need a major service to get going again.

I Picked up a three phase UNI MIG 3023 for $50 in a scrap yard as a gamble: it was absolutely filthy internally and what I thought was burnt insulation was a thick coating of black crud on the woven glass fibre spaghetti insulation. I sat it out on the concrete in the open and used a garden hose with a nozzle to hose the years of crusted up dust and dirt from the cooling fan off the internals. I blew off the visible water with compressed air and sat it in a shed where the afternoon sun could warm it and left it for two weeks while I got on with rebuilding the rectifier stack.

The three phase rectifier has 36 diodes with six diodes in parallel for each positive and negative terminal times the three phases. The diodes were all electrically connected with silver plated steel nuts and plated steel washers on silver plated brass threaded rod and some silver plated copper bussbars. Over the 20 odd years the silver plating had badly corroded leaving only rusty steel nuts and washers to connect the diode stacks, so I used all new copper and brass hardware to reassemble the bridge rectifier stack. The diodes were masked off and the aluminium heatsinks were bead blasted to remove oxide and put back together with 2" wide by 20 thou copper sheet conductors and machined brass washers and nuts. For some reason brass hardware is expensive and almost non existent so I had to machine the nuts and washers from scratch which gave nice flat surfaces to connect the diodes together. The fan was also seized (before washing) and needed few drops of oil to get running again. The 400 Amp Tweco handle was a total write off and cost $200 to replace with a copy.

I'm not saying your MIG would be in such an extreme case, I was only gambling $50 ($300 fully up and serviced) and it paid off with a solid 300 Amp welder that ran perfectly fine after the clean up and service.






Internals after wash down, compressed air and drying for for two weeks: the transformer winding insulation tested fine at 500 V: 8 Megohms resistance.

For the size of the machine, just plug it in and see what happens.
You might need to get fresh wire if it was flux core. That stuff doesn't age very well.

I always open up old welders and check for muce nests. they live to chew wire insulation off. no harm no foul if you tape it up before energizing. not so good if you got a couple hot leads laying on chassis.

mice......

It's been sitting quietly in the corner of a climate controlled shop for the whole time so it's clean and doesn't have any mice in it.

Did check the wiring diagram and it has a capacitor. Guess I need to get in the habit of firing up every piece of electronic equipment at least once a year so I don't have to mess with this again.

Steve

If it is that old, it was probably made before the onslaught of crappy chinese capacitors. Was discussing this with a friend who is an HVAC guy just yesterday. The old caps would go for decades with no problems. New chinese ones often don't make it a year in brand new AC units. I'd fire it up and see if it welds. If it does, use it until it doesn't. I would open it and visually inspect and blow clear of dust, even if it has been in climate control. Takes just minutes and you get to make sure nothing is loose inside.