Lenovo ThinkCentre A70 7099 Hardware Maintenance Manual page 104

DANGER
CAUTION:
Never remove the cover on a power supply or any part that has the following
label attached.
Hazardous voltage, current, and energy levels are present inside any component
that has this label attached. There are no serviceable parts inside these
components. If you suspect a problem with one of these parts, contact a service
technician.
To replace the power supply assembly, do the following:
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Hardware Maintenance Manual
Hazardous moving parts. Keep fingers and other body parts away.
1. Remove all media from the drives and turn off all attached devices and the
computer. Then, disconnect all power cords from electrical outlets and
disconnect all cables that are connected to the computer.
2. Remove the computer cover. See "Removing the computer cover" on page 88.
3. Disconnect the power supply assembly cables from all drives and from the
24-pin power connector and 4-pin power connector on the system board. See
"Locating parts on the system board" on page 86.
Note: You might also need to release the power supply assembly cables from
some cable clips or ties that secure the cables to the chassis.