Checking The Backup Battery; Checking The Ac Power Adapter - Lenovo ThinkPad Hardware Maintenance Manual

2. Click the battery status icon in the Windows notification area. If the keyboard dock built-in battery is
functional, the item Battery #2 is displayed showing the battery status of the keyboard dock. If you
cannot find this item, continue with the next step.
3. Disconnect the tablet from the keyboard dock. Then replace the keyboard dock built-in battery with
another one.
4. Connect the tablet to the keyboard dock and check the battery status again. If the item Battery #2 is
displayed correctly, it means that the original battery of the keyboard dock fails.

Checking the backup battery

To check the backup battery, do the following:
1. Insert a straightened paper clip into the tablet emergency reset hole and press the Windows button on
the tablet at the same time to reset the backup battery.
2. Disconnect the tablet form the keyboard dock.
3. Disable the built-in battery. See "Disabling the built-in batteries" on page 48.
4. Remove the backup battery. See "1070 Backup battery" on page 54.
5. Measure the voltage of the backup battery.
• If the voltage is correct, replace the system board.
• If the voltage is not correct, replace the backup battery.
• If the backup battery discharges quickly after replacement, replace the system board.

Checking the ac power adapter

If the built-in batteries work properly but they cannot be charged when the ac power adapter is connected,
check the ac power adapter by doing the following:
1. Unplug the ac power adapter from the tablet or the keyboard dock.
2. Measure the output voltage at the plug of the ac power adapter cable.
Note: Output voltage of pin 2 of the ac power adapter might differ from the one you are servicing.
3. If the voltage is correct, replace the system board.
4. If the voltage is not correct, replace the ac power adapter.
5. If the voltage is acceptable, replace the system board.
Note: Noise from the ac power adapter does not always indicate a defect.
Wire Voltage (V dc)
Red +2.5 to +3.2
Black Ground
Pin Voltage (V dc)
1 +20
2 0
3 Ground
.
Chapter 3 General checkout
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