To prevent electrical shock from residual voltage, never touch the areas outlined below on PSU-A [A], PCU-B [B], and PCU-C [C].
Residual charge (100V to 400V) can remain on the AC circuits on the PSU board for several months even after the board has been removed safely from the machine.
Turning the machine off and unplugging from its power source discharges only the DC circuits. Residual charge will remain on the AC circuits.