Before working on an AC-powered device or near
power supplies, unplug the power cord.
To disconnect the AC power cord:
Unplug the power cord from the power source receptacle.
Attach an electrostatic discharge (ESD) grounding strap to your bare
wrist and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage.
Move the AC switch next to the appliance
inlet on the power supply to the off position (O).
Unplug the power
cord from the appliance inlet on the power supply.