Is there significant voltage present inside the machine after I turn it off?

Yes — significant DC voltage exists in inverter welding power sources after removal of input power. You must turn off the inverter, disconnect input power, and discharge the input capacitors according to the instructions in the Maintenance Section before touching any internal parts. Always wait at least 60 seconds after power is turned off, or check that input capacitor voltage is near 0 before touching any parts. (Page 10)