Dell Dimension 8250 - Manual (Page 31)

Note the routing of the DC power cables underneath the tabs in the computer frame as you remove them from the system board and drives. It is
important to route these cables properly when you replace them to prevent them from being pinched or crimped.
6. Remove the two screws that secure the power supply to the back of the computer.
7. Press the "PUSH" button located on the floor of the computer frame.
8. Slide the power supply toward the front of the system approximately 1 inch.
9. Lift the power supply up and out of the computer.
Replacing the Power Supply
1. Slide the power supply into place.
2. Replace the two screws that secure the power supply to the back of the computer frame.
3. Reconnect the DC power cables.
4. Close the computer cover.
5. Connect your computer and devices to their electrical outlets, and turn them on.
System Board
Removing the System Board
1. Shut down the computer through the Start menu.
2. Ensure that your computer and attached devices are turned off. If your computer and attached devices did not automatically turn off when you shut
down your computer, turn them off now.
3. Disconnect any telephone or telecommunication lines from the computer.
4. Disconnect your computer and all attached devices from their electrical outlets, and then press the power button to ground the system board.
5. Open the computer cover .
6. Remove any components that restrict access to the system board.
7. Disconnect all cables from the system board.
8. Before you remove the existing system board assembly, visually compare the replacement system board to the existing system board to make sure
that you have the correct part.
9. Pull up on the tab and slide the system board assembly toward the front of the computer, and then lift it up and away.
NOTICE: To connect a network cable, first plug the cable into the network wall jack and then plug it into the computer.
CAUTION: Before you begin any of the procedures in this section, follow the steps in the safety instructions in your Owner's Manual.
NOTICE: To disconnect a network cable, first unplug the cable from your computer and then unplug it from the network wall jack.
CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before opening the cover.
NOTICE: Before touching anything inside your computer, ground yourself by touching an unpainted metal surface, such as the metal at the back of the
computer. While you work, periodically touch an unpainted metal surface to dissipate any static electricity that could harm internal components.
NOTICE: The system board and metal tray are connected and are removed as one piece.