Lenovo SL500c, SL400c manual LCD-related symptoms

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 as follows:

Table 5. Minimum quantity of defective pixels required for LCD replacement on June 2006 or later manufactured ThinkPad

LCD resolution	Bright dots	Dark dots	Bright and dark dots
XGA, WXGA	5	6	6
WXGA+, SXGA+,	5	8	10
WSXGA+
UXGA, WUXGA,	5	13	13
QXGA

Notes:

vLenovo will not provide replacement if the LCD is within specification as we cannot guarantee that any replacement LCD will have zero pixel defects.

vA bright dot means a pixel is always on (white or color.)

vA dark dot means a pixel is always off (black color.)

vOne pixel consists of R, G, B sub-pixels.

Table 6. LCD-related symptoms

Symptom or error		FRU or action, in sequence
No beep, power-on indicator on, and a		System board.
blank LCD during POST.
v LCD backlight not working.		1.	Reseat the LCD connectors.
v	LCD too dark.	2.	LCD assembly.
v LCD brightness cannot be adjusted.		3.	System board.
v LCD contrast cannot be adjusted.
v	LCD screen unreadable.	1.	See important note for “LCD-related
v	Characters missing pixels.		symptoms.”
v	Screen abnormal.	2.	Reseat all LCD connectors.
v	Wrong color displayed.	3.	LCD assembly.
		4.	System board.
Horizontal or vertical lines displayed on		LCD assembly.
LCD.

46ThinkPad SL400, SL400c, SL500, and SL500c Hardware Maintenance Manual