HP C781TU, C721TU Memory modules see Memory module on page, WLAN module see WLAN module on page

When replacing the system board, be sure that the following components are removed from the defective system board and installed on the replacement system board:

●Memory modules (see Memory module on page 43)

●WLAN module (see WLAN module on page 45)

●RTC battery (see RTC battery on page 75)

●Card reader board (see Card reader board on page 77)

●Heat sink (see Heat sink on page 79)

●Processor (see Processor on page 81)

●Power connector cable (see Power connector cable on page 83) Remove the system board:

1. Remove the power connector (1) from the clip built into the base enclosure.

2. Remove the power connector cable (2) from the routing channel and clips built into the base enclosure.

3. Remove the black Phillips PM2.5×4.0 screw (3) that secures the system board to the base enclosure.

4. Disconnect the USB board cable (4) from the system board.

5. Flex the front edge of the base enclosure (1) outward to provide clearance for the audio connectors (2).

6. Use the optical drive connector (3) to lift the right side of the system board (4) until it rests at an angle.

Component replacement procedures 73