Lenovo 3421 Personal Computer User Manual


 
Replacing the power supply assembly
Attention:
Do not open your computer or attempt any repair before reading and understanding the “Important safety information”
in the ThinkCentre Safety and Warranty Guide that came with your computer. To obtain a copy of the ThinkCentre
Safety and Warranty Guide, go to:
http://www.lenovo.com/support
This section provides instructions on how to replace the power supply assembly.
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 14.
3. Disconnect the power supply assembly cables from the system board and all drives. See “Locating
parts on the system board” on page 10.
4. Release the power supply assembly cables from the cable clips and ties in the chassis.
5. Lay the computer on its side and remove the four screws at the rear of the chassis that secure the
power supply assembly.
Figure20. Removing the screws for the power supply assembly
6. Slide the power supply assembly to the front of the computer and then lift it out of the chassis.
7. Ensure that the new power supply assembly is the correct replacement. If your new power supply
assembly has a voltage-selection switch, ensure that you set the voltage-selection switch to match the
voltage available at your electrical outlet. If necessary, use a ballpoint pen to slide the voltage-selection
switch to a different position.
If the voltage supply range in your local country or region is 100–127 V ac, set the switch to 115 V.
If the voltage supply range in your local country or region is 200–240 V ac, set the switch to 230 V.
8. Install the new power supply assembly into the chassis so that the screw holes in the power supply
assembly align with those in the chassis.
9. Install and tighten the four screws to secure the power supply assembly.
24 ThinkCentre User Guide