IBM THINKPAD S05L-1270-01 - Manual (Page 549)

If the voltage is not correct, the backup battery has
been discharged. Replace the backup battery.
If the backup battery discharges quickly after
replacement, replace the system board.
Checking the Standby Battery
(Rechargeable)
1. Power off the computer and unplug the AC Adapter
from the computer.
2. Remove the battery pack and keyboard.
3. Remove the standby battery. (Refer to “1100
Standby Battery” on page 586 to remove the battery.)
Attention
Be careful not to cause a short circuit when
measuring the voltage.
4. Measure the voltage of the standby battery.
If the voltage between red and black wire of the
battery is 3.5 V dc or greater, the voltage is
correct. Go to step 10 to verify standby battery
operation.
If the voltage is less than 3.5 V dc, go to the
next step.
5. Plug the AC Adapter into the computer and power on
the computer.
Attention
Be careful not to cause a short circuit when
measuring the voltage.
6. With the battery unplugged, measure the output
voltage at the connector.
If the voltage is less than + 4.0 V dc, replace the
DC/DC card. If the voltage is still low, replace
the system board.
If the voltage is more than
+ 4.0 V dc, power off
the computer, replace the standby battery, and
go to the next step.
Pin Voltage (V dc)
+ + 4.0
− Ground
ThinkPad 770 (9548, 9549) 537