dell latitude l400 User Manual

							support.dell.com Dell Latitude L400 Service Manual 17
NOTICE: The keycaps on the keyboard are fragile, easily dislodged, 
and time-consuming to replace. Be careful when removing and 
handling the keyboard.
6. Remove the keyboard assembly.
To replace the keyboard assembly, perform the following steps.
NOTICE: Position the keyboard cable so it is not twisted when it is 
connected to the system board.
1. Connect the keyboard cable to the connector on the system board.
NOTE: Five metal tabs retain the bottom of the keyboard in the palmrest 
assembly.
2. Fit the keyboard into place by sliding the five tabs on the bottom of the 
keyboard into the palmrest assembly.
It is important that the two tabs on the bottom right edge of the keyboard 
assembly fit correctly into the slotted holes in the palmrest assembly. To 
help align the tabs with the slotted holes, you can temporarily insert the 
hard-disk drive into the hard-disk drive bay before you place the keyboard 
assembly in the palmrest assembly. By resting the keyboard assembly on 
the hard-disk drive, the tabs will be at the correct height to enter the 
slotted holes. When the keyboard assembly is seated in the palmrest 
assembly, remove the hard-disk drive and look through the hard-disk drive 
bay to make sure the tabs are seated in the slot holes. 
3. Ensure that the top screw-hole tabs rest correctly in the screw slots on the 
palmrest assembly.
4. Verify that the keyboard is correctly installed. 
The keys should be flush with the left and right surfaces of the palmrest.
5. Reinstall the four M2 x 4-mm screws that secure the top of the keyboard 
assembly to the bottom assembly.
6. Reinstall the keyboard bezel. 
						

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Memory Module
Figure 13.  Memory Module Removal 
NOTICE: To avoid damaging the system board, you must remove the 
main battery before you service the computer.
1. Remove the keyboard bezel. 
2. Remove the keyboard assembly.
3. Ground yourself by touching the unpainted metal surface of an I/O 
connector on the computer’s back panel.
4. To release the memory module from its socket, carefully spread apart          
the inner tabs of the memory module socket just far enough for the 
memory module to disengage from the socket (it should pop up slightly)                
(see Figure 13).
5. Lift the memory module out of its socket.
To replace a memory module, perform the following steps:
1. Align the memory module’s edge connector with the slot in the center of 
the memory module socket. 
The memory module is keyed, or designed to fit into the socket in only one 
direction. The slot on the system board is notched so that the memory 
module can be firmly seated only one way.
2. With the module at a 45-degree angle, press the memory module’s edge 
connector firmly into the memory module socket. 
inner tabs (2)
memory module 
						

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3. Pivot the memory module down until it clicks into place. 
If you do not hear a click as each end of the memory module snaps into the 
tabs, remove the memory module and reinstall it (see Figure 13).
Palmrest Assembly 
Figure 14.  Removing the Palmrest Assembly Bottom Screws
The palmrest assembly consists of the palmrest, status lights, and touch pad 
assembly.
NOTICE: To avoid damaging the system board, you must remove the 
main battery before you service the computer.
1. Remove the keyboard bezel.
2. Remove the display assembly.
3. Remove the keyboard assembly.
4. Turn the computer upside down on a flat work surface.
5. Remove the six M2.6 x 1.6-mm screws located in the battery bay           
(see Figure 14).
NOTICE: Make sure that the work surface is clean to prevent    
scratching the computer cover.
6. Turn the computer right-side up.
M2.6 x 1.6-mm screws (6)  
						

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7. Remove the four black M2 x 4-mm screws across the top of the computer 
(see Figure 15). 
 
Figure 15.  Removing the Palmrest Assembly Top Screws
8. Remove the three silver M2 x 6-mm screws in the keyboard-assembly  
area that secure the middle of the palmrest assembly to the bottom case 
(see Figure 15).
9. Disconnect the status lights flex cable from the ZIF connector on the 
system board.
10. Disconnect the touch pad flex cable from the ZIF connector on the system 
board. 
11. Carefully remove the palmrest assembly from the bottom assembly.
M2 x 4-mm screws (4 black)
palmrest 
assembly
M2 x 6-mm screws 
(3 silver)
status lights 
flex cable
touch pad
flex cable 
						

							support.dell.com Dell Latitude L400 Service Manual 21
To replace the palmrest assembly, perform the following steps:
1. Place the palmrest assembly on the bottom assembly.
2. Reinstall the three silver M2 x 6-mm screws in the keyboard-assembly area 
that secure the middle of the palmrest assembly to the bottom-case 
assembly (see Figure 15).
3. Reinstall the four black M2 x 4-mm screws that secure the top of the 
palmrest assembly to the bottom-case assembly (see Figure 15).
4. Connect the touch pad flex cable to the ZIF connector on the system 
board.
5. Connect the status lights flex cable to the ZIF connector on the system 
board.
6. Turn the computer upside down.
7. Reinstall the six M2.6 x 1.6-mm screws in the battery bay that secure      
the bottom of the palmrest assembly to the bottom-case assembly        
(see Figure 14).
8. Turn the computer right-side up.
9. Reinstall the keyboard assembly.
10. Reinstall the display assembly.
11. Reinstall the keyboard bezel.
Touch Pad Assembly
Figure 16.  Touch Pad Removal
NOTICE: To avoid damaging the system board, you must remove the 
main battery before you service the computer.
1. Remove the keyboard bezel.
M2 x 3.5-mm screws (3)
flex cable ZIF connector
touch pad
touch pad holder 
assembly 
						

							22 Dell Latitude L400 Service Manual
2. Remove the display assembly.
3. Remove the keyboard assembly.
4. Remove the palmrest assembly.
5. Remove the three M2 x 3.5-mm screws that secure the touch pad 
assembly to the palmrest assembly (see Figure 16).
6. Slide the touch pad assembly out from under the two hold-down tabs.
7. Remove the touch pad assembly from the palmrest assembly.
8. Disconnect the flex cable from the ZIF connector on the back of the touch 
pad (see Figure 16).
The flex cable remains attached to the touch pad holder assembly.
Bottom Assembly
Figure 17.  Bottom Assembly    
The bottom assembly consists of the following field-replaceable components:
•Reserve battery
•Main battery
•Modem
•Fan assembly
•Speaker
•System board assembly
•Main battery release latch
•Bottom case assembly
reserve 
battery
fan
main battery 
compartment
system board assembly
bottom 
case covermain batter y release 
latch location
modemspeaker (shown with audio 
EMI shield removed) 
						

							support.dell.com Dell Latitude L400 Service Manual 23
Reserve Battery    
Figure 18.  Reserve Battery Removal
NOTICE: The reserve battery provides power to the computers RTC 
and nonvolatile random-access memory (NVRAM) when the com-
puter is turned off. Removing the battery causes the computer to lose 
the date and time information as well as all user-specified parame-
ters in the BIOS. If possible, make a copy of this information before 
you remove the reserve battery.
1. Remove the keyboard bezel.
2. Remove the keyboard assembly.
3. Peel the reserve battery away from the foam pad on the system board   
(see Figure 18).
The reserve battery is located between the memory module and the PC 
Card bay, and it is attached to the system board with an adhesive foam 
pad.
4. Disconnect the reserve battery cable from the connector on the system 
board.
5. Remove the remnants of the foam pad from the system board.
Main Battery
See the “Preparing to Work Inside Your Computer” section found earlier in this 
manual for detailed instructions for removing the battery.
reserve batter y cable reserve battery 
						

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Modem
Figure 19.  Modem Removal
1. Remove the keyboard bezel.
2. Remove the display assembly.
3. Remove the keyboard assembly.
4. Remove the palmrest assembly.
5. Use a 5-mm socket wrench to remove the four 5-mm socket screws for the 
VGA and parallel ports located on the back of the bottom assembly.
6. Use a small flat-blade screwdriver to remove the two integrated drive 
electronics (IDE) connector screws at both ends of the IDE (modular bay) 
connector located on the back of the bottom assembly.
7. Remove the M2 x 9.5-mm screw that secures the modem retainer bracket 
and modem to the system board (see Figure 19).
The screw is located by the VGA port.
8. Remove the modem retainer bracket from the system board.
9. Pull the modem straight up to disconnect it from the system board.
10. Disconnect the modem cable from the connector on the system board.
M2 x 9.5-mm screw
modem retainer 
bracket
modem 
						

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To replace the modem, perform the following steps:
1. Connect the modem cable to the connector on the system board.
2. Align the connector on the bottom of the modem with the connector on 
the system board, and carefully press the modem onto the system board.
3. Put the modem retainer bracket in place.
4. Reinstall the M2 x 9.5-mm screw to secure the modem retainer bracket 
and modem to the system board.
5. Reinstall the two IDE connector screws at both ends of the IDE (modular 
bay) connector located on the back of the bottom assembly.
6. Reinstall the four 5-mm socket screws for the VGA and parallel ports 
located on the back of the bottom assembly.
7. Reinstall the palmrest assembly.
8. Reinstall the keyboard assembly.
9. Reinstall the display assembly.
10. Reinstall the keyboard bezel.
Fan
 
Figure 20.  Fan Removal
1. Remove the keyboard bezel.
2. Remove the display assembly.
3. Remove the keyboard assembly.
connector fan
M2 x 8-mm screws 
with rubber washers (2) 
						

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4. Remove the palmrest assembly.
5. Carefully disconnect the fan wire connector from the system board       
(see Figure 20).
The male connector on the fan wire is keyed to fit into the female 
connector one way only.
6. Remove the two M2 x 8-mm screws with double rubber washers that 
secure the fan to the bottom assembly (see Figure 20). 
7. Remove the fan from the bottom assembly.
To replace the fan, perform the following steps:
1. Place the fan in the bottom assembly.
NOTE: Make sure that the fan wire is pointing toward the connector on the 
system board assembly.
2. Reinstall the M2 x 8-mm screws with double rubber washers to secure the 
fan to the bottom assembly.
NOTE: Make sure that the two M2 x 8-mm screws are installed with two rub-
ber washers apiece.
3. Reconnect the fan wire to the connector on the system board assembly.
4. Replace the palmrest assembly.
5. Replace the keyboard assembly.
6. Replace the display assembly.
7. Replace the keyboard bezel.