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2. Turn the computer upside down.
3. Remove the backup battery (see “1030 Backup battery”
on page 60).
4. Measure the voltage of the backup battery. See the
following figure.
k(-)
@
Red(+)
Blac
Wire Voltage (V dc)
Red +2.5 to +3.2
Black Ground
a. If the voltage is correct, replace the system board.
b. If the voltage is not correct, replace the backup
battery.
c. If the backup battery discharges quickly after
replacement, replace the system board.
38 ThinkPad X20, X21, X22, X23, X24