Quote Originally Posted by Blaze View Post
Just a thought. What would cause the machine not to clean anymore. What makes the balance work correctly?
That is what I was talking about in the last post. Because of the way inverters usually work, there are separate parts that handle each portion of the waveform. The cleaning is from the DCEP portion and the penetration is from the DCEN portion. If you machine is only producing DCEN you would get no cleaning. But you might still get a buzzing noise if the DC was being turned on and off at the normal AC frequency. I'm not sure if it would even sustain an arc without continuous HF in that situation. But as I said, apart from putting the machine on a scope, I'm not sure there is an easy way for you to test that.
One thing you can do is setup a 1/16" tungsten at 100 amps AC and try to run a bead on something thick. Start with the balance control at 30%, then chance the balance to 70% and see if your tungsten melts down. If it does, you are getting AC, if not you have some kind of fault. Or if the tungsten melts down at 30% but not at 70% then your running reversed.
Cleaning also requires argon around the arc, you won't see any frosting, if the gas coverage is poor or has air in that area.

The thing is, most of the machine faults are not subtle things, but usually total failures of one kind or another. These are high powered circuits and even if something minor goes wrong, with that much current it usually lets the smoke out of something and you are dead in the water.

I am assuming you have checked welding steel with DCEN and it's all good? How about stick welding on DCEP, everything look good?