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2 Troubleshooting Procedures
NB250/NB255 Series Maintenance Manual
18
To determine if the computer’s keyboard is functioning properly, perform the following
procedures. Figure 2-5 outlines the process. Start with Procedure 1 and continue with the
other procedures as instructed.
Procedure 1: External keyboard check
Procedure 2: Diagnostic check
Procedure 3: Connector and replacement check
Procedure 1 External keyboard check
Connect a USB keyboard to one of the computer’s USB ports, and then boot the computer.
The computer automatically detects the external keyboard.
If the external keyboard works correctly, the internal keyboard or its connections may be
faulty. Go to Procedure 2.
If the external keyboard appears to have the same problem as the internal keyboard, the
system board may be having some problem. Replace it with a new one and following the
instructions in Chapter 4.
Procedure 2 Diagnostic check
Run the test and Diagnostics Program, which will automatically execute the Keyboard Test.
Refer to Chapter 3, Tests and Diagnostics for more information on how to run the program.
If an error is located, go to Procedure 3. If an error does not occur, the keyboard is
functioning ok.
Procedure 3 Connector and replacement check
The keyboard and/or system board may be disconnected or damaged. Disassemble the
computer following the steps described in Chapter 4, Replacement Procedures and perform
the following checks.
Check 1 Make sure the keyboard cable is firmly connected to the system board.
If the connection is loose, reconnect firmly and repeat Procedure 2. If there is still
an error, go to Check 2.
Check 2 The keyboard may be damaged. Replace it with a new one following the
instructions in Chapter 4.
If the problem still exists, perform Check 3.
Check 3 The system board may be damaged. Replace it with a new one following the
instructions in Chapter 4.