Lenovo 33472YU, S230U manual LCD-related symptoms, Intermittent problems, Undetermined problems

Table 5. Beep symptoms (continued)

Problem	Solution
Five short beeps	The system board has a problem. Have the computer
	serviced.
Five short beeps, pause, five short beeps, and pause	Continue to boot immediately when the error was
	detected.

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 notebook computers 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.

Undetermined problems

If the diagnostic tests did not identify the device that has failed, if wrong devices are installed, or if the system simply is not operating, follow these procedures to isolate the failing FRU (do not isolate FRUs that have no defects).

Verify that all attached devices are supported by the computer.

Verify that the power supply being used at the time of the failure is operating correctly. (See “Power system checkout” on page 28)

Chapter 4. Related service information 39