Lenovo ThinkCentre 3493 User Manual page 58

Although there are no moving parts in your computer after the power cord has been disconnected, the
following warnings are required for your safety and proper Underwriters Laboratories (UL) certification.
CAUTION:
Hazardous moving parts. Keep fingers and other body parts away.
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:
1. Turn off the computer and disconnect all power cords from electrical outlets.
2. Remove the computer cover. See "Removing the computer cover" on page 32.
3. Remove the front bezel. See "Removing and reinstalling the front bezel" on page 32.
4. Pivot the drive bay assembly upward. Then, pivot the two plastic retaining clips outward to remove
the heat sink fan duct from the failing heat sink and fan assembly.
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ThinkCentre User Guide