TB350D HF251 problem

[dendog69]

Hello, I hope someone can help me out. I'm having an unusual problem when welding AC tig on aluminum. I'm using a Trailblazer 350d with an hf251 freq box. I have used this combo many times before without any problems, now something is wrong. The arc seems to surge so much that is displaces the puddle and makes hard ridges in the weld bead. I'm thinking the ac output is out of balance. This is something new that I've never had a problem with. The Machine has 2800hrs, 1/8" aluminum, 1/8" ceriated tungsten, machine dial set @230 amps. Any ideas?

[cruizer]

Check your engine rpm no load via the frequency (HZ) at the auxillary 120Vac terminals

Warm engine 62hz high idle no load, and about 43hz low idle no load

Bet its way out....

[dendog69]

Thanks, I'll try that. If that is the case, why do you think it would've caused a sudden change? I used this set up about a month ago with no issues.