Dell Precision T7400 User's Guide - Page 167

DC Power Connector FDD Pin Number 1 2 3 4 Signal name 5 V COM COM 12 VC 18-AWG Wire Red Black Black Blue/White Removing the Power Supply CAUTION: Before performing any of the procedures in this section, follow the safety instructions in the Product Information Guide. CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before opening the cover. NOTICE: To prevent static damage to components inside your computer, discharge static electricity from your body before you touch any of your computer's electronic components. You can do so by touching an unpainted metal surface on the computer. 1 Follow the procedures in "Before You Begin" on page 139. 2 Remove the computer cover. See "Removing the Computer Cover" on page 141. 3 Disconnect the DC power cables from the system board, the drives, and any other cards or devices to which they are connected. Note the routing of the DC power cables underneath the tabs in the computer frame as you release the tabs and remove the cables from the system board and drives. You must route these cables properly when you replace them to prevent their being pinched or crimped. 4 Remove the four screws that attach the power supply to the back of the computer chassis. Adding and Replacing Parts 167