Again, Kempy, not following you here. It seems you are replying to my questions or thoughts... but on a different plain. I never said set it to 15 volts. Set at 15 volts, and at that amp setting you will have issues. Reset the volts in synergic mode to 23V AFTER adjusting the amperage to 150 BEFORE you try to weld or take measurements. Please try to punctuate better because it's very, very hard to understand what is being said... Use fuller sentences as well. I am just not following you that well. I am really only trying to help, but its like we are both speaking English but somehow not communicating very well.
My guess is that when welding too hot initially, over the duty cycle of the gun, you MAY have burned up something inside the gun. That would account for the change and some of the issues you are seeing.
Burn back is caused by poor shielding, the wire staying energized after the gun quits feeding, holding too long of an arc at start. (The gun must be really close), Starting on oxidized metal with poor conductivity at the start, Too high of wire speed feed at the start resulting in a "blowing" off of the wire, Too long of an arc length at start (should be 3/4" or less, better at 1/2" or less) or poor contact between the contact tip and the wire, and even dragging/seizing between the contact tip and the wire, One more could be drive roll slippage.
The wire feed readings/amp readings on a gun without welding are not accurate. It would be best to have someone weld while you watch the changeover from IPM to actual amps while welding to compare the two.
Instead of worrying about gauging RPM, just measure wire spool off with the gun pressed for 15 seconds and multiply the length of the despooled wire by 4 to get inches per minute. Just roll it back on when you finish each test. This is a more accurate way.
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