IBM N51 Series, Hardware Maintenance Manual

Page: 133 / 503

Testing the Battery Pack
1. Remove each battery pack and measure the voltage
at the battery terminals between (
+
) and (
−
).
(T)
( )
(+)
Ÿ
If the voltage is less than
+
12 V dc, the battery
pack is discharged or defective.
Ÿ
If the voltage is more than
+
12 V dc, go to the
next step.
2. Using a low-power ohm meter, measure the
resistance at the battery terminals between
(T) and (
−
). The resistance must be
500 ohms to 20 kilohms.
If the resistance is out of range, replace the battery
pack.
Testing the Backup Battery
1. Remove the keyboard and the top cover.
2. Disconnect the battery connector from the system
board.
3. Measure the voltage of the backup battery.
+(Red)
(Black)
If the voltage is correct, replace the system board. If it is
not, the backup battery is discharged by a short circuit or
is defective.
Terminal Voltage (V dc)
(
+
)
+
12 to
+
18
( T ) Thermal Detection
( - ) Ground
Wire Voltage (V dc)
Red
+
2.5 to
+
3.7
Black Ground
Model CL57 (8554)
121