Hello all, I recently acquired an old airco 180 msn ac/dc heliwelder. The problem is that the high frequency part doesn't seem to work. Everything else seems ok. There is a 3 pin plug on the front where the wire on the tig torch goes but only 2 pins have a wire connected. Is the the prob? Is there a way by taking the side panels off I will be able to test or check the parts relating to high frequency?

Any help will be great