Im having a problem with my syncrowave 180 sd tig welder, when its on dc electrod negitive it sets help code 1. it will weld fine when on ac. i have a friend with the same welder and i put my control board in his welder and it works fine in his. I also used my pedal on his welder and it work fine as well. we then put my current transducer and both rectifier thyristors in his welder and it still worked fine, could not get the help code to set, so my question is what else can cause this problem.