Checking The Coin-Cell Battery; Checking The Ac Power Adapter - Lenovo ThinkPad Helix 20CG Hardware Maintenance Manual

• If the tablet cannot be turned on, replace the built-in battery with another one. If the tablet can start
up with the new battery installed, it means that the original battery fails.

Checking the coin-cell battery

To check the coin-cell battery, do the following:
1. Disable the internal battery pack. See "Disabling the built-in battery" on page 46.
2. Remove the coin-cell battery. See "1090 Coin-cell battery" on page 60.
3. Measure the voltage of the coin-cell battery. See the following illustration.
• If the voltage is correct, replace the system board.
• If the voltage is not correct, replace the coin-cell battery.
• If the coin-cell battery discharges quickly after replacement, replace the system board.

Checking the ac power adapter

When you use the ac power adapter to charge the tablet but no power is charged, see the instructions in this
topic to check the ac power adapter.
Note: Noise from the ac power adapter does not always indicate a defect.
To check the ac power adapter, do the following:
1. Disconnect the ac power adapter from the tablet.
2. Measure the output voltage at the plug of the ac power adapter. Refer to the following illustration:
3. If the voltage is not correct, replace the ac power adapter.
4. If the voltage is acceptable, replace the system board.
3
2
(12V)
1
Wire Voltage (V dc)
Red +2.5 to +3.2
Black
Ground
Pin
Voltage (V dc)
1 +12
2 0
3 Ground
.
Chapter 3 General checkout
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