Lenovo 21FV Hardware Maintenance Manual page 45

Verify that the power supply being used at the time of the failure is operating correctly. See "Power system
checkout" on page 26.
1. Turn off the computer.
2. Visually check each FRU for damage. Replace any damaged FRU.
3. Remove or disconnect all of the following devices:
a. Non-ThinkPad devices
b. Printer, mouse, and other external devices
c. External diskette drive or optical drive
d. Wireless cards
4. Turn on the computer.
5. Determine whether the problem has been solved.
6. If the problem does not recur, reconnect the removed devices one at a time until you find the failing FRU.
7. If the problem remains, replace the following FRUs one at a time (do not replace a nondefective FRU):
a. System board
b. LCD assembly
.
Chapter 4 Related service information
39