This is probably a silly question, but have you checked the consistency of your mains power? Mains power is usually pretty solid, but given that two separate machines have had the same problem, it may suggest something outside the machine causing the issue. If your mains power shows steady when the machine isn't plugged in, another thing you can do is clip some tiny alligator clips to the prongs on the plug, then plug it in to the wall, sandwiching the alligator clips between the plug and the wall. I can usually get the plug in far enough to make contact while still leaving the alligator clips attached. This allows me (or a helper) to monitor the line voltage while welding. Obviously, use some common sense when doing this and don't electrocute yourself or anybody else.
If you care to remove the cover of your machine, you could also clip a multimeter on to the lugs where the power line goes into the machine. This would also allow you to confirm that your plug and your receptacle were wired up correctly.
Reply With Quote