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 SVGA: 5 or more bright dots, 5 or more dark
dots, or a total of 9 or more bright and dark dots.
v XGA: 8 or more bright dots, 8 or more dark dots,
or a total of 9 or more bright and dark dots.
v SXGA+: 11 or more bright dots, 13 or more dark
dots, or a total of 16 or more bright and dark
dots.
v UXGA: 11 or more bright dots, 16 or more dark
dots, or a total of 16 or more bright and dark
dots.
Note: A bright dot is a white or colored pixel that is
always on. A dark dot is a pixel that is always
off and shows as black.
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.
Symptom-to-FRU index
54 ThinkPad A20m/p, A21m/p, A22m/p
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