Lenovo ThinkCentre M79 Hardware Maintenance Manual page 138

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:
1. Remove any 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 105.
3. Remove the front bezel. See "Removing and reinstalling the front bezel" on page 106.
4. Remove the two screws that secure the heat sink fan duct, and then lift the heat sink fan duct out of
the chassis.
Figure 46. Removing the heat sink fan duct
5. Disconnect the power supply assembly cables from the system board and all drives. See "Locating
parts on the system board" on page 34.
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. Ensure that you note the cable routing before disconnecting
the cables.
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ThinkCentre M79 Hardware Maintenance Manual