Lenovo ThinkPad T40, Hardware Maintenance Manual

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LCD-related symptoms
Important
The TFT LCD for the notebook computer contains
many thin-film transistors (TFTs). The presence of 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.
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 means a pixel is always on
(white or color.) A dark dot means a 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 .
Symptom-to-FRU index
64
T40/T40p, T41/T41p, T42/T42p
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