IBM ThinkPad 340 Series Hardware Maintenance Manual page 221

Checking the Quick Charger:
types of chargers, but checkout procedures are the same
for both of them.
1. Ensure that the battery pack is operating correctly.
(See "Checking the Battery Pack" on page 208.)
2. Connect the power cord to the quick charger and the
other end to an ac power outlet. Ensure that the
power-on indicator is on.
If the power-on indicator does not turn on, check
the power cord for correct continuity and
installation.
If the problem is not corrected, replace the quick
charger or the power cord.
3. Install the battery pack into the quick charger.
If the charging indicator does not start blinking,
replace the quick charger.
Checking the Backup Battery
1. Power-off the computer and unplug the AC Adapter
from the computer.
2. Open the keyboard, and remove the battery pack and
the diskette drive.
3. Remove the backup battery from the system board.
4. Measure the voltage of the backup battery. See the
following figure.
Red
Wire
Red
Black
If the voltage is correct, replace the system board.
If the voltage is not correct, the backup battery has
been discharged. Replace the backup battery.
ThinkPad 355x, 360x, 370C, 750x, 755C, 755Cs
Black
There are two
Voltage (V dc)
+2.5 to +3.7
Ground
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