I come home with it after testing fine before I bought it and wired a new plug at the end since the previous owner had it hard wired. So I turn the machine on today and turn it to DCEN, put a new tungsten in freshly ground, and start to weld 1/8 mild steel plate. Im set at 120 on the amperage and start to weld. NOPE. All I get it HF start and thats it no amperage control. Machine says 120 still with moving the pedal to all of the way either direction. I switch to my finger control and same results. Also I heard the HF kinda cutting in and out in the machine so I pull the side cover off and look and it is kinda sputtering during HF start. Also Voltage says 14.7 when hf comes on and does not move with pedal. Not sure what is going on here but sounds like a bad board. And I checked the gaps and they were good. Inside of the machine is very clean and no noticable problems.
Any ideas on what to check or test?