I have acquired a Linde Heli-arc HF250 welder that is in need of repair.
The welder currently has already had a numebr of parts replaced including all of the boards replaced/repairde, polarity switch replaced, etc. The current status is this: Replace the SCR's and you'll get about 5 minutes before they burn out. Does anyone have any idea where I may be able to obtain any internal schematic/wiring diagrams for this welder?

Thanks