IBM ThinkPad X21 2660, Hardware Maintenance Manual

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If you have a torque driver, refer to the "Torque"
column with each step.
Make sure you use the correct screw. If you have a
torque screwdriver, tighten all screws firmly to the
torque shown in the table.
Never use a screw that
you removed. Use a new one. Make sure the
screws are tightened firmly
Retaining serial numbers
This section includes the following descriptions:
"Restoring the serial number of the system unit"
"Retaining the UUID"
Restoring the serial number of the system
unit:
When the computer was manufactured, the
EEPROM on the system board was loaded with the serial
numbers of the system and all major components. The
numbers need to remain the same throughout the life of
the computer.
If you replace the system board, you must restore serial
number of the system unit to its original value.
Before replacing the system board, save the original serial
number by doing the following:
1. Install the ThinkPad Hardware Maintenance Diskette
Version 1.60, and restart the computer.
2. From the main menu, select 1. Set System Identifi-
cation.
3. Select 2. Read S/N data from EEPROM.
The serial number for each device is displayed. Write
down the serial number of the system unit, designated as
follows:
20:System unit serial number
After you have replaced the system board, restore the
serial number by doing the following:
1. Install the ThinkPad Hardware Maintenance Diskette
Version 1.60 and restart the computer.
2. From the main menu, select 1. Set System Identifi-
cation.
3. Select 1. Add S/N data from EEPROM.
Follow the instructions on the screen.
Note: The serial number of the system unit is written
on the label attached on the bottom of the
computer.
ThinkPad X21
45