Lenovo 21BX001LGE, Hardware Maintenance Manual

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Table 4. No-beep symptoms (continued)
Symptom or error FRU or action, in sequence
No beep, power indicator on, LCD blank, and LED
indicators on Esc, F1 and F4 blink sequentially during
POST. BIOS is performing memory retraining. Do not press the
power button to interrupt this process. Wait a few minutes
until the logo screen is displayed.
The power-on password prompt appears. A power-on password or a supervisor password is set.
Type the password and press Enter.
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.
If the LCD you are servicing has two or less visible defective pixels, it should not be considered faulty.
However, if the LCD has three or more visible defective pixels, it will be deemed as defective by Lenovo and
it should be replaced.
Notes:
• This policy applies to all ThinkPad Notebooks purchased on 1 January, 2008 or later.
• Lenovo will not provide warranty replacement if the LCD is within specifications because we cannot
guarantee that any replacement LCD will have zero pixel defects.
• One pixel consists of R, G, B sub-pixels.
LCD Self Test
When you turn on the computer and the LCD goes black, run LCD Self Test to help you determine whether
the LCD functions normally.
To run LCD Self Test:
1. Ensure that the computer is connected to ac power. Then, press the power button for about seven
seconds to turn off the computer.
2. Press Fn, left Ctrl, and the power button at the same time. If the computer displays five solid colors in
sequence across the entire screen, it indicates that the LCD functions normally.
3. The test lasts for about 20 seconds and then exits automatically. You also can press the power button to
exit the test.
Table 5. LCD-related symptoms
Symptom or error FRU or action, in sequence
No beep, power-on indicator on, and a blank LCD during
POST. 1. Run LCD Self Test .
2. Replace the 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. Replace the LCD assembly.
3. Replace the 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. Replace the LCD assembly.
4. Replace the system board.
Horizontal or vertical lines displayed on LCD. Replace the LCD assembly .
Chapter 4
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Related service information
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