Lenovo ThinkPad A21e Hardware Maintenance Manual for ThinkPad A22m (wireless m - Page 56

LCD-related symptoms, Intermittent problems, Important, at least 10 times

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LCD-related symptoms Symptom-to-FRU index Important The TFT LCD for the notebook computer contains many thin-film transistors (TFTs). A small number of dots that are missing, discolored, or always lighted is characteristic of TFT LCD technology, but excessive pixel problems can cause viewing concerns. The LCD should be replaced if the number of missing, discolored, or lighted dots in any background is: v XGA: 8 or more bright dots, 8 or more dark dots, or a total of 9 or more bright and dark dots. Note: Bright dots means pixel is always on (white or color.) Dark dots means pixel is always off (black color.) Symptom or error No beep, power-on indicator on, and a blank LCD during POST. v LCD backlight not working. v LCD too dark. v LCD brightness cannot be adjusted. v LCD contrast cannot be adjusted. v LCD screen unreadable. v Characters missing pixels. v Screen abnormal. v Wrong color displayed. Horizontal or vertical lines displayed on LCD. FRU or action, in sequence System board. 1. Reseat the LCD connectors. 2. LCD assembly. 3. System board. 1. See important note for "LCD-related symptoms". 2. Reseat all LCD connectors. 3. LCD assembly. 4. System board. 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. 52 ThinkPad A22m wireless models

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LCD-related symptoms
Important
The TFT LCD for the notebook computer contains
many thin-film transistors (TFTs). A small number of
dots that are missing, discolored, or always lighted
is characteristic of TFT LCD technology, but
excessive pixel problems can cause viewing
concerns. The LCD should be replaced if the
number of missing, discolored, or lighted dots in any
background is:
v
XGA:
8 or more bright dots, 8 or more dark dots,
or a total of 9 or more bright and dark dots.
Note:
Bright dots means pixel is always on (white
or color.) Dark dots means pixel is always off
(black color.)
Symptom or error
FRU or action, in sequence
No beep, power-on indicator
on, and a blank LCD during
POST.
System board
.
v
LCD backlight not working.
v
LCD too dark.
v
LCD brightness cannot be
adjusted.
v
LCD contrast cannot be
adjusted.
1.
Reseat the LCD
connectors
.
2.
LCD assembly.
3.
System board.
v
LCD screen unreadable.
v
Characters missing pixels.
v
Screen abnormal.
v
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.
Symptom-to-FRU index
52
ThinkPad A22m wireless models