IBM ThinkPad X20 Hardware Maintenance Manual page 40

v "Checking the AC adapter" 36
v "Checking operational charging" 36
v "Checking the battery pack" 37
v "Checking the backup battery" 37
Checking the AC adapter: If the computer fails only when
the AC adapter is used, check the following:
v If the power problem occurs only when the port
replicator is used, replace the port replicator.
v If the power-on indicator does not turn on, check the
power cord of the AC adapter for correct continuity and
installation.
v If the computer does not charge during operation, go to
"Checking operational charging."
1. Unplug the AC adapter cable from the computer and
measure the output voltage at the plug of the AC
adapter cable. See the following figure:
1
(16 - 10 V)
Pin
1
2
If the voltage is not correct, replace the AC adapter. If
the voltage is acceptable, do the following:
v Replace the system board.
v If the problem persists, go to "Product overview" on
page 41.
Note: Noise from the AC adapter does not always
indicate a defect.
Checking operational charging: To check operational
charging, use a discharged battery pack or a battery pack
that has less than 50% of the total power remaining when
installed in the computer.
Perform operational charging. If the battery status indicator
or icon does not turn on, remove the battery pack and let it
return to room temperature. Reinstall the battery pack.
36
ThinkPad X20, X21, X22, X23
2
Voltage (V dc)
+15.5 to +17.0
Ground