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Service Hints & Tips

Document ID: MIGR-47NJQH

This document is provided to IBM and our Business Partners to help sell and/or service IBM products. It is not to be distributed beyond that audience or used for any other purpose.

TP 570 - LCD / intermittent / undetermined symptoms

Applicable to: World-Wide

The following information is intended for IBM Dealers and Authorized Servicers only. Customers attempting to follow any of the procedures below may void their warranty.

LCD-related symptoms
Important
The TFT LCD for the notebook computer contains over 2,359,000 thin-film transistors (TFTs). A small number of missing, discolored, or lighted dots (on all the time) is characteristic of TFT LCD technology, but excessive pixel problems can cause viewing concerns. The LCD should be replaced if the number of missing, discolored, or lighted dots in any background is 8 or more.

Symptom / error	FRU / action in sequence
No beep, power-on indicator on, and a blank LCD during POST.	1. System board
o LCD backlight not working. o LCD too dark. o LCD brightness cannot be adjusted. o LCD contrast cannot be adjusted.	1. Reseat the LCD connectors. 2. LCD assembly 3. System board
o LCD screen unreadable. o Characters missing pels. o Screen abnormal. o Wrong color displayed.	1. See important note for LCD-related symptoms. 2. Reseat all LCD connectors. 3. LCD assembly 4. System board
LCD has extra horizontal or vertical lines displayed.	1. LCD assembly

Intermittent problems
Intermittent system hang problems can be caused by a variety of reasons 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 recurring problem exists.

When analyzing an intermittent problem, do the following:

1. Run the diagnostic test for the system board in loop mode at least 10 times.
2. If no error is detected, do not replace any FRUs.
3. If any error is detected, replace the FRU shown by the FRU code. Rerun the test to verify that no more errors exist.

Undetermined problems
You are here because the diagnostic tests did not identify which adapter or device failed, installed devices are incorrect, a short circuit is suspected, or the system is inoperative. Follow these procedures to isolate the failing FRU (do not isolate nondefective FRUs).

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 systems
checkout on page 37 of the HMM):
1. Power off the computer.
2. Visually check them for damage. If any problems are found, replace the FRU.
3. Remove or disconnect all of the following devices:
a. Non-IBM devices
b. Devices attached to the port replicator
c. Printer, mouse, and other external devices
d. Battery pack
e. Hard disk drive
f. External diskette drive
g. DIMM
h. CD-ROM and diskette drive in the UltraslimBay
i. PC Cards

4. Power on the computer.
5. Determine if the problem has changed.
6. If the problem does not recur, reconnect the removed devices one at a time until you find the failing FRU.
7. If the problem remains, replace the following FRUs one at a time. Do not replace a nondefective FRU:
a. System board
b. LCD assembly

	Search Keywords
	Document Category	Error Messages
	Date Created	07-05-99
	Last Updated	07-05-99
	Revision Date	08-05-2000
	Brand	IBM ThinkPad
	Product Family	ThinkPad 570
	Machine Type	All
	Model	All
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