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Table 6. LCD-related symptoms (continued)
Symptom or error
• LCD screen unreadable.
• Characters missing pixels.
• Screen abnormal.
• Wrong color displayed.
Horizontal or vertical lines displayed on LCD.
Intermittent problems
Intermittent system hang problems can be due to a variety of causes that have nothing to do with a hardware
defect, such as cosmic radiation, ESD, or software errors. FRU replacement should be considered only
when a problem recurs.
Undetermined problems
If the diagnostic tests did not identify the device that has failed, if wrong devices are installed, or if the
system simply is not operating, follow these procedures to isolate the failing FRU (do not isolate FRUs
that have no defects).
Verify that all attached devices are supported by the computer.
Verify that the power supply being used at the time of the failure is operating correctly. (See "Power system
checkout" on page 30)
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. Battery pack
d. Hard disk drive
e. External diskette drive or optical drive
f. DIMM
g. Optical disk or diskette in the internal drive
h. PC 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
FRU or action, in sequence
1. See important note for "LCD-related symptoms."
2. Reseat all LCD connectors.
3. LCD assembly.
4. System board.
LCD assembly.
Chapter 4
.
Related service information
43
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