Toshiba Satellite U900 Maintenance Manual page 81

Troubleshooting Procedures
The LED board or system board may be the reason of a LED fault. Either of these two
components may be damaged. To determine if the computer's LED is functioning properly,
perform the following procedures. Figure 2-20 outlines the process. Start with Procedure 1
and continue with the other procedures as instructed.
Procedure 1: Diagnostic test
Procedure 2: Connector and replacement check
Procedure 1 Diagnostic test
Run the Diagnostic Program, which will automatically execute the LED test. (Refer to
Chapter 3 system configuration check), Tests and Diagnostics for more information on the
program.
If an error is located, go to Procedure 2. If an error is not located, the LED function is
functioning properly.
Procedure 2 Connector and replacement check
The LED board 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 that the LED board FFC is securely slotted into the system board. If
the problem persists, go to Check 2.
Check 2 The LED board 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.
Satellite U900/U940/U945 Series Maintenance Manual
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