I have had my TB302 for several years and it runs and welds great but after reading several post on here I bought a multimeter with a Hz. scale on it and thought I would check the RPM by the Hz as recommended on here.

When I plug it in to the outlets on the welder it jumps around so much you can't tell what it's reading. When I plug it into an outlet in the shop it shows a steady 59.9.

What am I doing wrong?

Guess I wont worry to much about as it runs and welds great as is, but just curious.