I have a small Lincoln MIG (sp130?). Today I was doing a little tack and it stubbed and then wouldn't feed. It looked like it had burned back and was stuck to the tip. I pulled it off and it just kept coming! WTF?? I looked under the hood and the wire was broken. Looking closely at the break, I could see that it had burned through - there were tiny balls on both ends. And it wasn't just one point - the wire had been heated in several spots over 6" or so.
How can this be!? The wire is hot when the trigger is pulled (Duh). But it is only hot relative to the the ground lead, which is isolated from everything. I did some poking around with a VOM and found nothing strange, even with the power on and trigger pulled. I wasn't feeding wire, but that shouldn't matter.
I can't believe that the wire was on the spool like that, but I can't think of how the machine could have done it either.
Any help will be greatly appreciated, Bob