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Power System Checkout
To verify the symptom of the problem power on the com-
puter using each of the following power sources:
1. Remove the battery ASM.
2. Connect the AC Adapter and check that power is sup-
plied.
3. Disconnect the AC Adapter and install the charged
battery ASM; then check that power is supplied by the
battery ASM.
If you suspect a power problem, refer to the appropriate
power supply check listed below:
“Checking the AC Adapter”
“Checking the Operational Charging” on page 34
“Checking the Battery ASM” on page 34
Checking the AC Adapter: You are here
because the computer fails only when the AC Adapter is
used:
If the power problem occurs only when the ThinkPad
Port Replicator with Advanced Etherjet Feature.
If the power-on indicator does not turn on, check the
power cord of the AC Adapter for correct continuity
and installation.
If the operational charge does not work, go to
“Checking the Operational Charging” on page 34.
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.
If the voltage is not correct, replace the AC Adapter.
If the voltage is within the range, do the following:
Replace the DC-DC & BATT board.
Replace the system board.
If the problem is not corrected, go to “Undetermined
Problems” on page 47
Note: An audible noise from the AC Adapter does not
always indicate a defective adapter.
Pin Voltage (V dc)
1 +15.5 to +17.0
2 Ground
ThinkPad 390E 33