Toshiba Satellite M640 Maintenance Manual page 48

2 Troubleshooting Procedures
Procedure 3 Connector and replacement check
The LCD module and system board are connected to the display circuits. Any of these
components may be damaged. Refer to Chapter 4, Replacement Procedures, for instructions
on how to disassemble the computer and then perform the following checks:
Check 1 Make sure the DDR RAM module is seated properly. Test display again. If the
problem still exits, replace the DDR RAM module. If the problem still exists,
perform Check 2.
Check 2 Replace the LCD module with a new one and test display again. If the problem
still exists, perform Check 3.
Check 3 Replace the LCD/FL cable with a new one and test display again. If the problem
still exists, perform Check 4.
Check 4 Replace the CPU with another of the same specifications. If the problem still
exists, perform Check 5.
Check 5 The system board may be damaged. Replace it with a new one.
Satellite/Satellite Pro M600/M640/M645/M647 Series/Dynabook TX/AX Series Maintenance Manual 16