No-Beep Symptoms; Lcd-Related Symptoms; Intermittent Problems - Lenovo ThinkPad T540p Hardware Maintenance Manual

No-beep symptoms

Table 5. No-beep symptoms
Symptom or error
No beep, power-on indicator on, LCD blank, and no
POST.
No beep, power-on 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 6. 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.
When analyzing an intermittent problem, do the following:
1. Run the diagnostic test for the system board in loop mode at least 10 times.
FRU or action, in sequence
1. Ensure that every connector is connected tightly
and correctly.
2. Reseat memory module.
3. Replace the system board.
1. Reseat memory module.
2. 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 all LCD connectors.
3. Replace the LCD assembly.
4. Replace the system board.
Replace the LCD assembly.
Chapter 4
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Related service information
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