esab/linde mig went boom! help

I'm the maintenance mechanic at central washington university here in
ellensburg wa. Just today we had our mig welder scare the living crap
out of a sculpture student. I guess she was welding along and
BOOM!.... the prof tried it afterwards and was about an inch into her
first weld when again BOOM! (she said she could feel the concrete
floor in the foundery shake!) BTW she said it appeared to continue
welding.
Is this something that sounds repairable? or is it mostlikely one of
the coils on the powersupply shorting due to bad insulation?
The power supply is a linde vi-206. with a newer esab mig35 feeder.
I'm still a bit of a welding novice (done lots of oxy/act and mig on
steel but thats about all that is taught here) and have only a little
experiance fixing large amperage equpment such as this.
Thanks in advance for any help
Jeff Cleveland