HP ProBook 4540s Notebook PC Reference Guide - static ...

When you disconnect external AC power, the following events occur:
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The computer switches to battery power.
The display brightness is automatically decreased to save battery life.
Testing an AC adapter
Test the AC adapter if the computer exhibits any of the following symptoms when it is connected to
AC power:
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The computer does not turn on.
The display does not turn on.
The power lights are off.
To test the AC adapter:
NOTE:
The following instructions apply to computers with user-replaceable batteries.
1. Shut down the computer.
2. Remove the battery from the computer.
3. Connect the AC adapter to the computer, and then plug it into an AC outlet.
4. Turn on the computer.
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If the power lights turn on, the AC adapter is working properly.
If the power lights remain off, the AC adapter is not functioning and should be replaced.
Contact support for information on obtaining a replacement AC power adapter.
28 Chapter 4 Power management