Lenovo ThinkPad 11e - Manual (Page 44)

Table 5. LCD-related symptoms
Symptom or error FRU or action, in sequence
No beep, system-status indicator on, and a blank LCD
during POST. System board
• LCD backlight not working.
• LCD too dark.
• LCD brightness cannot be adjusted.
• LCD contrast cannot be adjusted. 1. Reseat the LCD connectors.
2. LCD assembly
3. System board
• LCD screen unreadable.
• Characters missing pixels.
• Screen abnormal.
• Wrong color displayed. 1. See important note for “LCD-related symptoms.”
2. Reseat all LCD connectors.
3. LCD assembly
4. System board
Horizontal or vertical lines displayed on LCD. LCD assembly
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, electrostatic discharge, or software errors. FRU replacement should be
considered only when a problem recurs.
When analyzing an intermittent problem, do the following:
1. Run the diagnostic test for the system board in loop mode at least 10 times.
2. If no error is detected, do not replace any FRUs.
3. If any error is detected, replace the FRU shown by the FRU code. Rerun the test to verify that no
more errors exist.
Undetermined problems
If the diagnostic tests did not identify the adapter or 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 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
38 ThinkPad 11e and ThinkPad Yoga 11e Hardware Maintenance Manual