Lenovo T400S User Manual download pdf (Page 59)

Power system checkout

To verify a symptom, do the following:

1. Turn off the computer.

2. Remove the battery pack.

3. Connect the ac adapter.

4. Check that power is supplied when you turn on the computer.

5. Turn off the computer.

6. Disconnect the ac adapter and install the charged battery pack.

7. Check that the battery pack supplies power when you turn on the computer.

If you suspect a power problem, see the appropriate one of the following power

supply checkouts:

v “Checking the AC adapter”

v “Checking operational charging” on page 52

v “Checking the battery pack” on page 52

v “Checking the backup battery” on page 53

Checking the AC adapter

You are here because the computer fails only when the AC adapter is used.

v If the power problem occurs only when the docking station or the port replicator

is used, replace the docking station or the port replicator.

v If the power-on indicator does not turn on, check the power cord of the AC

adapter for correct continuity and installation.

v If the computer does not charge during operation, go to “Checking operational

charging” on page 52.

To check the AC adapter, do the following:

1. Unplug the AC adapter cable from the computer.

2. Measure the output voltage at the plug of the AC adapter cable. See the

following figure:

(20V)

Pin Voltage (V dc)

1 +20

3 Ground

Note: Output voltage of pin no.2 of the AC adapter may different from the one

you are servicing.

3. If the voltage is not correct, replace the AC adapter.

4. If the voltage is acceptable, do the following:

v Replace the system board.

v If the problem persists, go to “FRU tests” on page 49.

Note: Noise from the AC adapter does not always indicate a defect.

General checkout 51

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Lenovo T400S User Manual Page 59