Lenovo ThinkPad 770 Hardware Maintenance Manual for 770 series notebooks(Janua - Page 42

Power Systems Checkout, Checking the AC Adapter

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CHECKOUT GUIDE by removing one of the devices, use the computer under the same condition, and see whether a power shutdown occurs. Do this procedure for all devices to determine the cause. Power Systems Checkout To verify the symptom of the problem, power on the computer using each of the following power sources: 1. Remove the battery pack. 2. Connect the AC Adapter and check that power is supplied. 3. Disconnect the AC Adapter and install the charged battery pack; then check that power is supplied by the battery pack. If you suspect a power problem, see the appropriate power supply checkout in the following list: "Checking the AC Adapter" "Checking Operational Charging" on page 37 "Checking the Battery Pack" on page 37 "Checking the Backup Battery" on page 38 Checking the AC Adapter: You are here because the computer fails only when the AC Adapter is used: 1. If the power problem occurs only when the port replicator is used, replace the port replicator. 2. If the power-on indicator does not turn on, check the power cord of the AC Adapter for correct continuity and installation. 3. If the operational charge does not work, go to Checking Operational Charging. 4. Unplug the AC Adapter cable from the computer and measure the output voltage at the plug of the AC Adapter cable. See the following figure: (16 - 10 V) Pin Voltage (V dc) 1 +15.5 to +17.0 2 Ground 5. If the voltage is not correct, replace the AC Adapter. 6. If the voltage is within the range, do the following: Replace the system board. 36

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CHECKOUT GUIDE
by removing one of the devices, use the computer under
the same condition, and see whether a power shutdown
occurs.
Do this procedure for all devices to determine the
cause.
Power Systems Checkout
To verify the symptom of the problem, power on the
computer using each of the following power sources:
1.
Remove the battery pack.
2.
Connect the AC Adapter and check that power is
supplied.
3.
Disconnect the AC Adapter and install the charged
battery pack; then check that power is supplied by the
battery pack.
If you suspect a power problem, see the appropriate power
supply checkout in the following list:
±
“Checking the AC Adapter”
±
“Checking Operational Charging” on page
37
±
“Checking the Battery Pack” on page
37
±
“Checking the Backup Battery” on page
38
Checking the AC Adapter:
You are here
because the computer fails only when the AC Adapter is
used:
1.
If the power problem occurs only when the port
replicator is used, replace the port replicator.
2.
If the power-on indicator does not turn on, check the
power cord of the AC Adapter for correct continuity
and installation.
3.
If the operational charge does not work, go to
Checking Operational Charging.
4.
Unplug the AC Adapter cable from the computer and
measure the output voltage at the plug of the AC
Adapter cable.
See the following figure:
(16 - 10 V)
5.
If the voltage is not correct, replace the AC Adapter.
6.
If the voltage is within the range, do the following:
±
Replace the system board.
Pin
Voltage (V dc)
1
+
15.5 to
+
17.0
2
Ground
36