IBM Thinkpad T20 T21 T22 T23 Manual

							Intermittent problems
Intermittent system hang problems can be due to a variety
of causes that have nothing to do with a hardware defect,
such as cosmic radiation, electrostatic discharge, or
software errors. FRU replacement should be considered
only when a problem recurs.
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. Rerun the test to verify that no more errors
exist.
Undetermined problems
You are here because the diagnostic tests did not identify
which adapter or device failed, wrong devices are installed,
a short circuit is suspected, or the system is inoperative.
Follow these procedures to isolate the failing FRU (do not
isolate FRUs that have no defects).
Verify that all attached devices are supported by the
computer.
Verify that the power supply being used at the time of the
failure is operating correctly. (See“Power system
checkout”on page 35.)
1. Power off the computer.
2. Visually check each FRU for damage. Replace any
damaged FRU.
3. Remove or disconnect all of the following devices:
a. Non-IBM devices
b. Devices attached to the port replicator
c. Printer, mouse, and other external devices
d. Battery pack
e. Hard-disk drive
f. External diskette drive
g. DIMM
h. CD-ROM and diskette drive in the Ultrabay
i. PC Cards
4. Power on the computer.
5. Determine whether the problem has changed.
6. If the problem does not recur, reconnect the removed
devices one at a time until you find the failing FRU.
7. If the problem remains, replace the following FRUs one
at a time (do not replace a nondefective FRU):
a. System board
b. LCD assembly
Symptom-to-FRU index
ThinkPad T20, T21, T22 and T23 series55 
						

							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. In IBM
ThinkPad computer, this problem is addressed 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 when you service this machine:
vKeep the screw kit (for the P/N, see“Miscellaneous
parts”on page 167) in your tool bag.
vAlways use new screws.
vUse a torque screwdriver if you have one.
Tighten screws as follows:
vPlastic to plastic
Turn an additional90 degreesafter the screw head
touches the surface of the plastic part:
90 degrees more
(Cross-section)
vLogic card to plastic
Turn an additional180 degreesafter 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
for each step.
FRU replacement notices
56ThinkPad T20, T21, T22, T23 (MT 2647/2648) 
						

							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 descriptions:
v“Restoring the serial number of the system unit”
v“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. These numbers
need to remain the same throughout the life of the
computer.
If you replace the system board, you must restore the
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 1.62, and restart the computer.
2. From the main menu, select1. Set System
Identification.
3. Select2. 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 1.62 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 uniquely assigned to your computer at production
FRU replacement notices
ThinkPad T20, T21, T22 and T23 series57 
						

							and stored in the EEPROM of your system board. The
algorithm that generates the number is designed to provide
unique IDs until the year A.D. 3400. No two computers in
the world have the same number.
When you replace the system board, you must set the
UUID on the new system board as follows:
1. Install the ThinkPad hardware maintenance diskette
version 1.62, and restart the computer.
2. From the main menu, select4. Assign UUID.
A new UUID is created and written. If a valid UUID
already exists, it is not overwritten.
FRU replacement notices
58ThinkPad T20, T21, T22, T23 (MT 2647/2648) 
						

							Removing and replacing a FRU
This section presents directions and drawings for use in
removing and replacing a FRU. Be sure to observe the
following general rules:
1. Do not try to service any computer unless you have
been trained and certified. An untrained person runs
the risk of damaging parts.
2. Before replacing any FRU, review“FRU replacement
notices”on page 56.
3. Begin by removing any FRUs that have to be removed
before the failing FRU. Any such FRUs are listed at the
top of the page. Remove them in the order in which
they are listed.
4. Follow the correct sequence in the steps for removing
the FRU, as indicated in the drawings by the numbers
in square callouts.
5. When turning a screw to replace a FRU, turn it in the
direction indicated by the arrow in the drawing.
6. When removing the FRU, move it in the direction
indicated by the arrow in the drawing.
7. To put the new FRU in place, reverse the removal
procedure and follow any notes that pertain to
replacement. For information about connecting and
arranging internal cables, see“Locations”on page 140.
8. When replacing a FRU, use the correct screw as
shown in the procedures.
DANGER
Attention:Before the computer is powered on after FRU
replacement, make sure that all screws, springs, and other
small parts are in place and are not loose inside the
computer. Verify this by shaking the computer gently and
listening for rattling sounds. Metallic parts or metal flakes
can cause electrical short circuits.
Attention:The system board is sensitive to, and can be
damaged by, electrostatic discharge. Before touching it,
establish personal grounding by touching a ground point
with one hand or by using an electrostatic discharge (ESD)
strap (P/N 6405959).Before removing any FRU, power off the computer,
unplug all power cords from electrical outlets,
remove the battery pack, and then disconnect any
interconnecting cables.
Removing and replacing a FRU
ThinkPad T20, T21, T22 and T23 series59 
						

							1010 Battery pack
DANGER
1
2
Use only the battery in the parts listing for your
computer. Use of an incorrect battery can result in
ignition or explosion of the battery.
Removing and replacing a FRU
60ThinkPad T20, T21, T22, T23 (MT 2647/2648) 
						

							1020 Backup battery
DANGER
For access, remove this FRU:
v“1010 Battery pack”on page 60
1
2
Step Screw (quantity) Torque

1M2.5×3.5 mm, (1) 0.392 Nm
(4 kgfcm)
(continued)Use only the battery in the parts listing for your
computer. Use of an incorrect battery can result in
ignition or explosion of the battery.
Removing and replacing a FRU
ThinkPad T20, T21, T22 and T23 series61 
						

							Cable routing:When attaching the backup battery to the
holder, route the battery cable as in the
following figure.
Removing and replacing a FRU
62ThinkPad T20, T21, T22, T23 (MT 2647/2648) 
						

							1030 Hard-disk drive
AttentionDo not drop or apply any shock to the hard-disk
drive.The hard-disk drive is sensitive to physical
shock. Incorrect handling can cause damage and
permanent loss of data.
Before removing the drive, have the user make a
backup copy of all the information on the drive if
possible.
Never remove the drive while the system is
operating or is in suspend mode.
For access, remove this FRU:
v“1010 Battery pack”on page 60
1
Note:The hard disk is attached to the cover.
Step Screw (quantity)

1Coin screw (1) or security screw (1)
Note:Use a 2.5-mm Allen wrench to remove the security screw.
(continued)
Removing and replacing a FRU
ThinkPad T20, T21, T22 and T23 series63 
						

							When removing the hard-disk drive, open the LCD a little
as shown in the figure.
2
3
3
4
When installing:Make sure that the HDD connector is
firmly connected.
Removing and replacing a FRU
64ThinkPad T20, T21, T22, T23 (MT 2647/2648)