Is it safe to touch internal parts immediately after turning off the Dynasty 350?

No — 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 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 verify that input capacitor voltage is near 0 before touching any parts. (Pages 9, 18)