Lenovo T420 - Manual (Page 53)

• Lenovo will not provide replacement if the LCD is within specification as we cannot guarantee that any
replacement LCD will have zero pixel defects.
• One 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 blank LCD during
POST. System board.
• LCD backlight not working.
• LCD too dark.
• LCD brightness cannot be adjusted.
• LCD contrast cannot be adjusted. 1. Reseat the LCD connectors.
2. LCD assembly.
3. System board.
• LCD screen unreadable.
• Characters missing pixels.
• Screen abnormal.
• 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.
Chapter 4 . Related service information 47