140 Will Only Weld to Ground Clamp!

[MR5X5]

First post. Hello all and cheers.

Me and my little 140 were welding up a hole in an old truck oil pan. Tedious, but was getting it done. Was spot welding and grinding for hours with no issues. .030 flux core, Voltage 1, Feed Rate 20. Low duty cycle...

Then, the welder stopped drawing an arc? I relocated my ground and attached it to wire brushed bight metal frame. Nothing. Replaced the tip. Nothing. Made sure the gun was fully inserted in the machine. It was. Broke and re-tightened the +/- feeds. Nothing. Broke and re-tightened clamp hardware. Nothing. Cables look perfect. Crimp terminations look perfect. Nothing seems out of sorts...

I can't draw an arc an inch away from the ground clamp connected to bright metal truck frame.

I can draw an arc on the ground clamp.

I can weld perfectly normally if clamped to say a piece of 12 gauge ****** material.

I'm stumped. This is essentially a new unit.

Seems to be some serious sensitivity to clamp resistance??

Am headed out to dig inside deeper, but thought I'd put this out for consideration in the mean time.

Thanks for any ideas.

-Mike

[MR5X5]

Spoke with Hobart Technical support. Verified 28-29Vdc across "polarity terminals" at high setting with trigger pulled = unit potential as expected. Took apart both ends of gun cable and verified termination qualities. Re-assembled gun components ensuring good contact of center conductor - particularly at gun tip. Unit seems to be working correctly again. My guess is intermittent contact between the center conductor and tip. Just a guess.

[Dale M.]

Early style ground clamp (jumper cable style) or better ground clamp (true welding style)....

Anybody mistreat whip, yanking on it or run over by car, not inserted it to wire feeded correctly and clamped tight?...

Dale