Lenovo ThinkPad T500 Hardware Maintenance Manual - Page 53

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 WSXGA+ 8 10 UXGA, WUXGA, 5 13 13 QXGA Notes: v Lenovo will not provide replacement if the LCD is within specification as we cannot guarantee that any replacement LCD will have zero pixel defects. v A bright dot means a pixel is always on (white or color.) v A dark dot means a pixel is always off (black color.) v 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. 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. Related service information 45