No-Beep Symptoms; Lcd-Related Symptoms; Intermittent Problems - Lenovo ThinkPad X1 Yoga 20LD Hardware Maintenance Manual

No-beep symptoms

Table 3. No-beep symptoms
Symptom or error
No beep, system-status indicator on, LCD blank, and no
POST.
No beep, system-status indicator on, and LCD blank
during POST.
The power-on password prompt appears.
The hard-disk password prompt appears.

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.
Table 4. LCD-related symptoms
Symptom or error
No beep, power-on indicator on, and a blank LCD during
POST.
• LCD backlight not working.
• LCD too dark.
• LCD brightness cannot be adjusted.
• LCD contrast cannot be adjusted.
• LCD screen unreadable.
• Characters missing pixels.
• Screen abnormal.
• Wrong color displayed.
Horizontal or vertical lines displayed on LCD.

Intermittent problems

Intermittent system hang problems can be due to a variety of causes that have nothing to do with a hardware
defect, such as cosmic radiation, electrostatic discharge, or software errors. FRU replacement should be
considered only when a problem recurs.
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Hardware Maintenance Manual
FRU or action, in sequence
1. Ensure that every connector is connected tightly
and correctly.
2. Reseat the memory module.
3. Replace the system board.
Reseat the memory module.
Replace the system board.
A power-on password or a supervisor password is
set. Type the password and press Enter.
A hard-disk password is set. Type the password and
press Enter.
FRU or action, in sequence
Replace the system board.
1. Reseat the LCD connectors.
2. Replace the LCD assembly.
3. Replace the system board.
1. See important note for "LCD-related symptoms."
2. Reseat the LCD connectors.
3. Replace the LCD assembly.
4. Replace the system board.
Replace the LCD assembly.