IBM T520I, W520 manual No-beep symptoms, LCD-related symptoms, Intermittent problems

No-beep symptoms

Table 5. No-beep symptoms

Symptom or error	FRU or action, in sequence
No beep, power-on indicator on, LCD blank, and no	1.	Make sure that every connector is connected
POST.		tightly and correctly.
	2.	DIMM
	3.	System board
No beep, power-on indicator on, and LCD blank during	1.	Reseat DIMM.
POST.	2.	System board
The power-on password prompt appears.	A power-on password or a supervisor password is set.
	Type the password and press Enter.
The hard-disk password prompt appears.	A hard-disk 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.

Note:

•This policy applies to all ThinkPad Notebooks purchased on 1 January, 2008 or later.

•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		System board
POST.
• LCD backlight not working		1.	Reseat the LCD connectors.
•	LCD too dark	2.	LCD assembly
• LCD brightness cannot be adjusted.		3.	System board
• LCD contrast cannot be adjusted.
•	LCD screen unreadable	1.	See important note for “LCD-related symptoms.”
•	Characters missing pixels	2.	Reseat all LCD connectors.
•	Screen abnormal	3.	LCD assembly
•	Wrong color displayed	4.	System board
Horizontal or vertical lines displayed on LCD		LCD assembly

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.

Chapter 4. Related service information 43