IBM Thinkpad X20 X21 X22 X23 X24 Manual

Memory
1. If two DIMMs are installed, remove one
of them and runDiagnostics-->
Memory Test - Quick.
2. If the problem does not recur, replace
the DIMM, remove the other one, and
run the test again.
3. If the test does not detect the error, run
Diagnostics-->Memory Test - Full.
Fan
1. Turn on the computer and check the air
turbulence at the louver near the power
switch.
2. RunDiagnostics-->Other Devices-->
IBM Fan.
Fn key combinations
The following table shows the function of each combination
of Fn with a...

Symptom-to-FRU index
The symptom-to-FRU index lists symptoms and errors and
their possible causes. The most likely cause is listed first,
in boldface type.
Note:Do the FRU replacement or other actions in the
sequence shown in the column headed″FRU or
action, in Sequence″. If replacing a FRU does not
solve the problem, put the original part back in the
computer. Do not replace a non-defective FRU.
This index can also help you determine, during regular
servicing, what FRUs are likely to need to be...

0200
Fixed disk failure1.Reseat the hard disk
drive.
2. Load Setup Defaults in IBM
BIOS Setup Utility.
3. Hard disk drive.
4. System board.
021x
Monitor type does not match
CMOS1.Load Setup Defaults in
IBM BIOS Setup Utility.
0220
Shadow RAM failure at offset
nnnn1.System board.
0232
Extended RAM failure at offset
nnnn1.DIMM.
2. System board.
0250
System battery is dead—
replace and run setup1.Replace the backup
battery and run IBM BIOS
Setup Utility to reset the
time and date.
0251
System CMOS checksum...

02F4
EISA CMOS not writable.1.Load Setup Defaults in
IBM BIOS Setup
Utility.Replace the backup
battery.
2. System board.
02F5
DIMM test failure1.DIMM.
2. System board.
02F6
Software NMI failure1.DIMM.
2. System board.
02F7
Fail-safe timer NMI failure1.DIMM.
2. System board.
Error messages
Symptom or error FRU or action, in sequence
Device address conflict
1.Load Setup Defaults in
IBM BIOS Setup Utility.
2. Backup battery.
3. System board.
Allocation error for device
1.Load Setup Defaults in
IBM BIOS...

Hibernation error
1.Restore the system
configuration to what it
was the before the
computer entered
hibernation mode.
2. If memory size has been
changed, re-create the
hibernation file.
Operating system not found
1.Reseat the hard disk
drive.
2. Check the boot sequence
by use of IBM BIOS Setup
Fan error
1.Fan.
Beep symptoms
Symptom or error FRU or action, in sequence
One beep and a blank,
unreadable, or flashing LCD1.Reseat the LCD
connector.
2. LCD assembly.
3. System board.
One long and two short...

The power-on password prompt A power-on password or a
supervisor password is set.
Type the password and press
Enter.
The hard disk password prompt A hard disk password is set.
Type the password and press
Enter.
The DOS-full screen looks
smaller.Start the ThinkPad
Configuration program and set
theScreen expansion
function.
LCD-related symptoms
Important:
The TFT LCD for the notebook computer contains many
thin-film transistors (TFTs). A small number of dots that are
missing, discolored, or always lighted...

such as: cosmic radiation, electrostatic discharge, or
software errors. FRU replacement should be considered
only when a recurring problem exists.
When analyzing an intermittent problem, do the following:
1. Run the diagnostic test for the system board in loop
modeat least 10 times.
2. If no error is detected, donotreplace any FRUs.
3. If any error is detected, replace the FRU shown by the
FRU code. Re-run the test to verify that no more errors
exist.
Undetermined problems
If the diagnostic tests did not...

FRU replacement notices
This section contains notices related to removing and
replacing parts. Read this section carefully before replacing
any FRU.
Screw notices
Loose screws can cause a reliability problem. The IBM
ThinkPad computer addresses this problem with special
nylon-coated screws that have the following characteristics:
vThey maintain tight connections.
vThey do not easily come loose, even with shock or
vibration.
vThey are harder to tighten.
vThey should be used only once.
Do the following...

Turn an additional 180 degrees after the screw head
touches the surface of the logic card:
180 degrees more
(Cross section)
vTorque driver
If you have a torque driver, refer to the″Torque″column
with each step.
vMake 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...

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, select1. Set System
Identification.
3. Select1. 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.
Retaining the UUIDThe Universally Unique Identifier (UUID) is a 128-bit
number...