Lcd-Related Symptoms; Intermittent Problems - Lenovo ThinkPad 13 Hardware Maintenance Manual

The symptom-to-FRU index in this section lists symptoms and errors and their possible causes. The most
likely cause is listed first, in boldface type.
Note: Do the FRU replacement or other actions in the sequence shown in the column headed "FRU or
action, in sequence." If replacing a FRU does not solve the problem, put the original part back in the
computer. Do not replace a nondefective FRU.
This index can also help you determine, during regular servicing, what FRUs are likely to need to be
replaced next.
A numeric error is displayed for each error detected in POST or system operation. In the displays, n can
be any number.
If no numeric code is displayed, check the narrative descriptions of symptoms. If the symptom is not
described there, go to "Intermittent problems" on page 20.
Note: For a device not supported by diagnostic codes in the ThinkPad notebook computers, see the
manual for that device.

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 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 1. LCD-related symptoms
Symptom or error
No beep, system-status 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:
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ThinkPad 13 Hardware Maintenance Manual
FRU or action, in sequence
System board
1. Reseat the LCD connectors.
2. LCD assembly
3. System board
1. See important note for "LCD-related symptoms."
2. Reseat all LCD connectors.
3. LCD assembly
4. System board
LCD assembly