We have a 115v Hobart MIG welder that has been in the shop since I started there in '00. It's worked great for all these years, until the other day as soon as you plug it in, and switch it on, the gas is always on (coming out of the gun), and as soon as you're grounded and you touch the wire to the piece you're working on, it arcs like the button is down... but the wire feeds like it should. We took the gun apart and there's 2 switches (assuming there's one for wire feed and one for gas/arc), and they looked fine; and also blew out the line with compressed air. Anyone have this happen before/know the answer to fix it???

Thanks

 

I think there is a relay that sticks in these machines that sticks.. I have the same machine and had the same problem. Just take the side panel off and try lightly tapping around with a hammer handle and see if it will "unstick"

 

Interesting. Good to know, thanks!!!

 

If it arc'd and stuck it will probably do it again.

So if that fixes it (the light hammer tap), find someone with a soldering iron and change it out.