I have a Miller Shopmaster 300, s/n KD408963. My manual is January 1993.
It has worked fine until recently. Now it will sometimes mig weld, sometimes it pops the breaker. The breaker pops right when I pull the trigger, before the wire strikes an arc. I looked at my liner, it had a couple of minor kinks so I replaced it, no change in symptoms. I was welding 1/8" steel, it will weld fine for a bit, pause, pull the trigger again and the breaker pops.
Stick welding (reverse polarity, 170A) works fine.
I am using a 50A breaker which has always worked for me. I changed to the 50A circuit for my plasma cutter (different breaker), same problem.
Advice will be greatly appreciated.
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11-27-2013, 12:22 PM #1Junior Member
- Join Date
- Nov 2013
Shopmaster blows breaker MIG only