Intermittent Problems; Undetermined Problems - IBM THINKPAD L460 Hardware Maintenance Manual

LCD technology, but excessive pixel problems can cause viewing concerns.If the LCD you are servicing has
two or less visible defective pixels, it should not be considered faulty. However, if the LCD has three or more
visible defective pixels, it will be deemed as defective by Lenovo and it should be replaced.
Notes:
• This policy applies to all ThinkPad notebooks purchased on 1 January, 2008 or later.
• Lenovo will not provide warranty replacement if the LCD is within specifications because we cannot
guarantee that any replacement LCD will have zero pixel defects.
• One pixel consists of R, G, B sub-pixels.
Table 6. LCD-related symptoms
Symptom or error
No beep, power-on indicator on, and a blank LCD during
POST.
• LCD backlight not working.
• LCD too dark.
• LCD brightness cannot be adjusted.
• LCD contrast cannot be adjusted.
• 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, 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. Devices attached to the docking station or the port replicator
c. Printer, mouse, and other external devices
d. Battery pack
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ThinkPad L460 Hardware Maintenance Manual
FRU or action, in sequence
Replace the system board.
1. Reseat the LCD cable.
2. Replace the LCD unit.
3. Replace the system board.
1. See important note for "LCD-related symptoms."
2. Reseat all LCD cable.
3. Replace the LCD unit.
4. Replace the system board.
Replace the LCD unit.