My first 250EX was bought used, it was owned by a guy who worked on all brands of welders. He said the 250EX was not welding at factory specs, it would not pulse at .2pps and would not weld at 10 percent electrode positive so that's why the change of potentiometers. A local shop explained to me that electrical parts like resistors and capacitors have a tolerance of 0 to 10 percent, only the military can afford the 0 to 1 percent tolerance. After a series of capacitors and resistors at 5 to 7 percent tolerance, the needed resistance in the potentiometer may need to be adjusted.
After buying a new 250EX, it only took a minute to see the difference between the two. The modified 250EX can be adjusted to have no cleaning action and a super focused arc with no arc wandering, tungsten spitting or dingle berries while keeping a super sharp tip at 250 amps on AC. Also a 1 meg pot in the pulser makes it pulse at .2 or one pulse every five seconds, when it was new it would only truly pulse at 1 pps.
Oleg knows all of the mods done to my machines, surely be now the factory has tested them as well. I believe after these modifications, the 250EX is one of the very finest welders available at any cost.
http://i854.photobucket.com/albums/a...st250EX004.jpg
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