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System Board

Dell™ Latitude™ C840 Service Manual

NOTICE: Disconnect the computer and attached devices from electrical outlets and remove any installed batteries.

NOTICE: To avoid ESD, ground yourself by using a wrist grounding strap or by periodically touching unpainted metal on the computer.

1	M2.5 x 4-mm captive-washer screws (3)
2	system board
3	network connector
4	modem connector
5	network cable cover
6	M2.5 x 20-mm screw

The BIOS chip on the system board contains the service tag sequence, which is also visible on a bar code label on the bottom of the computer.

The replacement kit for the system board includes a floppy disk or CD that provides a utility for transferring the service tag sequence to the replacement system board.

NOTICE: If you received a flash BIOS update floppy disk or CD with the replacement microprocessor, you must update the BIOS after replacing the microprocessor module.

Removing the System Board

1. Follow the instructions in "Preparing to Work Inside the Computer."
   
   
2. Remove the hard drive and the fixed optical drive.
   
   
3. Remove any installed Mini PCI Cards.
   
   
4. If migrating the memory, remove all installed memory modules.
   
   
5. Remove (if migrating) or disconnect the modem daughter card.
   
   
6. Remove the keyboard.
   
   
7. Remove the hinge cover.
   
   
8. Remove the display assembly.
   
   
9. Remove the palm rest.
   
   
10. Remove the video graphics board.
    
    
11. Remove the microprocessor thermal-cooling assembly.
    
    
12. If migrating the microprocessor, remove the microprocessor module.
    
    
13. Separate the network cable from the system board:
    
    
    1. First remove the network cable cover: Insert a narrow plastic scribe or small screwdriver just barely into the slot that faces the back of the computer (do not insert the scribe far enough to catch on the wires inside), press down on the cover lightly to secure it, and pry upward to release the cover.
       
       

1	network cable cover

2. Disconnect the network cable. Do not pull on the cable wires. Instead, pry up the outer corner of the upper connector until the connectors start to separate.
   
   

1	outer corner of upper connector
2	network cable

14. Remove the three M2.5 x 4-mm captive-washer screws from the system board.
    
    
15. Remove the M2.5 x 20-mm screw from the center of the LED board.
    
    
16. Lift the front of the system board and work it out of the back panel.
    
    

If necessary to help release the system board, pull outward on the top of the plastic near the back left corner of the bottom case (see the small arrow at the far left in the following figure).

System Board

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