On Sunday, May 24, 2015 at 11:41:22 AM UTC-4, Karl Townsend wrote:
I tore the machine apart. Pot runs smooth 0 - 12K ohms. Also tested
panel/remote switch, its fine.

Other ideas before the scrap man gets it?

Karl


pics here
http://www.hobby-machinist.com/threa...-repair.35668/

Several years ago I helped the owner of a TIG welder find why he had no current control. The machine was not a Linco[n , but I expect most welders of that age used the same general idea. The current control in his case was done by a saturable reactor. There was a circuit similar to a light dimmer that varied the current thru the saturable reactor. The SCR was bad. I forget if it was open or shorted. After we had trouble shot the welder, he got a new scr and that fixed the welder. He was not as tight as I am. I think he got the SCR at Radio Shack for about $5.

It sounds as if you have about the same problem. We did have a schematic and just used a DMM for measurements. Any kind of a scope would have made finding it much faster.

I would advertise in Craigslist for someone to fix it. I am thinking of high school kid or someone in college. And if you have no luck with that, I would give it to some kid before letting the scrap man have it.

I would help you but am on the East Coast.

Dan