Yes, this has been a problem...more than once. It seems everyone who buys our welder claims to be an EE. More than one or two have taken said schematics and rigged stuff and done everything from turn diodes around backwards to overheat a chip when fixing this on their own. Guess who they call up and blame? And where does the complaint go? All over the place for sure, without a trace of accepting or mentioning even partial responsibility for the ensuing aftermath of a goof.