Lenovo ThinkPad T470 20HD, Hardware Maintenance Manual, Page: 35 / 116

3. Restart the computer.
4. When the logo screen is displayed, repeatedly press and release the F12 key. When the Boot Menu
window opens, release the F12 key.
5. Use the arrow keys to select ATAPI CDx (x: 0, 1, ...) and then press Enter. The diagnostic program will
be launched automatically.
6. Follow the instructions on the screen to use the diagnostic program.
Power system checkout
To verify if a battery or an ac power adapter is functional, do the following:
1. Turn off the computer.
2. Connect the ac power adapter.
3. Turn on the computer. If the computer can be turned on, it means that either the battery or the ac power
adapter is functional.
4. Insert a straightened paper clip into the emergency-reset hole to reset the computer. If the computer is
still powered on, it means that the ac power adapter is functional.
5. Turn off the computer.
6. Disconnect the ac power adapter and turn on the computer. If the computer can be turned on, it means
that the battery is functional.
If you suspect a power problem, see the appropriate one of the following power supply checkouts:
• “Checking the ac power adapter” on page 29
• “Checking the removable battery and the operational charging” on page 30
• “Checking the coin-cell battery” on page 31
Checking the ac power adapter
You are here because the computer fails only when the ac power adapter is used.
• If the power problem occurs only when the docking station or the port replicator is used, replace the
docking station or the port replicator.
• If the system status indicator does not blink three times when an ac power source is connected, check the
power cord of the ac power adapter for correct continuity and installation.
• If the computer does not charge during operation, go to “Checking the removable battery and the
operational charging” on page 30.
Note: Noise from the ac power adapter does not always indicate a defect.
Checking the traditional ac power adapter
To check the ac power adapter, do the following:
1. Unplug the ac power adapter cable from the computer.
2. Measure the output voltage at the plug of the ac power adapter cable.
(20V)
1
3
2
Pin
Voltage (V dc)
1 +20
2 0
3 Ground
Note: Output voltage of pin 2 of the ac power adapter might differ from the one you are servicing.
3. If the voltage is not correct, replace the ac power adapter.
Chapter 3
.
General checkout
29