Toshiba Libretto 50CT/70CT Manual

							Libretto 50CT/70CT Maintenance ManualiCopyright
©1998 by Toshiba Corporation.  All rights reserved.  Under the copyright laws, this manual cannot be
reproduced in any form without the prior written permission of Toshiba.  No patent liability is assumed with
respect to the use of the information contained herein.
Toshiba Libretto 50CT/70CT Maintenance Manual
Third edition February 1998
Disclaimer
The information contained in this manual is subject to change without notice.
Toshiba Corporation and Toshiba America Information Systems, Inc., assume no liability for damages
incurred directly or indirectly from errors, omissions, or discrepancies in connection with the furnishing,
performance, or use of this material.
Trademarks
IBM is a registered trademark, and PC/AT, PS/2, OS/2 and VGA are trademarks of IBM Corporation.
MS-DOS and Windows are registered trademarks of Microsoft Corporation.
Intel and Pentium are registered trademarks, and MMX is a trademark of Intel Corporation.
Lotus is a registered trademark of Lotus Development Corporation.
Novell and NetWare are registered trademarks of Novell, Inc.
UNIX is a registered trademark of X/Open Company Ltd.
Sound Blaster and Pro are trademarks of Creative Technology Ltd.
Centronics is a registered trademark of Centronics Data Computer Corporation.
All other properties are trademarks or registered trademarks of their respective holders. 
						

							iiLibretto 50CT/70CT Maintenance ManualPrefaceThis maintenance manual describes how to perform hardware service maintenance for the
Toshiba Personal Computer Libretto 50CT/70CT.
Information on the Libretto 70CT has been incorporated into this manual since its original
release. Information added that is specific to the Libretto 70CT is noted by an asterisk (*).
The procedures described in this manual are intended to help service technicians in the field
isolate and replace faulty Field Replaceable Units (FRUs).SAFETY PRECAUTIONS
Four types of messages are used in this manual to bring important information
to your attention. Each of these messages will be italicized and identified as
shown below.
DANGER:  “Danger” indicates the existence of a hazard that could resultin death or serious injury if the safety instruction is not observed.WARNING:  “Warning” indicates the existence of a hazard that couldresult in bodily injury if the safety instruction is not observed.CAUTION:  “Caution” indicates the existence of a hazard that couldresult in property damage if the safety instruction is not observed.NOTE:  A “Note” contains general information that relates to safemaintenance services.Improper repair of the computer may result in safety hazards. Toshiba requires
service technicians and authorized dealers or service providers to ensure that
the following safety precautions are strictly adhered to.
q Be sure to fasten screws securely with the correct screwdriver. If a screw is
not fully fastened, it could loosen and create a short circuit, which could
cause overheating, smoke, or fire.
q If you replace the battery pack, RTC battery, or backup battery, be sure to
use only the same model battery or an equivalent battery recommended by
Toshiba. Installation of the wrong battery can cause the battery to explode. 
						

							Libretto 50CT/70CT Maintenance ManualiiiThe manual is divided into the following parts:Chapter 1Hardware Overview describes the system unit and each FRU.
Chapter 2Troubleshooting Procedures explains how to diagnose and resolve
FRU problems.
Chapter 3Tests and Diagnostics describes how to perform test and diagnostic
operations for maintenance service.
Chapter 4Replacement Procedures describes the removal and replacement of the
FRUs.
Appendices
The appendices describe the following: 
qHandling the LCD module
 
qBoard layout
 
qPin assignments
 
qKey layout
 
qWiring diagrams
 
qBIOS Rewrite Procedures
qReliability 
						

							ivLibretto 50CT/70CT Maintenance ManualConventionsThis manual uses the following formats to describe, identify, and highlight terms and
operating procedures.Acronyms
On the first appearance, and whenever necessary for clarification, acronyms are enclosed in
parentheses following their definition. For example:
Read Only Memory (ROM)Keys
Keys are used in the text to describe many operations. The keytop symbol as it appears on
the keyboard is printed in boldface 
type.
Key operation
Some operations require you to simultaneously use two or more keys. We identify such
operations by the keytop symbols separated by a plus (+) sign. For example, Ctrl + Pause
(Break)
 means you must hold down Ctrl and at the same time press Pause (Break). If three
keys are used, hold down the first two and at the same time press the third.User input
Text that you are instructed to type in is shown in the boldface type below:
DISKCOPY  A:  B:The display
Text generated by the Libretto 50CT, that displays on the screen, is presented in the typeface
below:Format complete
System transferred 
						

							Libretto 50CT/70CT Maintenance ManualvTable of ContentsChapter 1Hardware Overview
1.1Features..................................................................................................................1-1
1.2System Unit Block Diagram....................................................................................1-4
1.33.5-inch External FDD (Option)..............................................................................1-7
1.42.5-inch HDD.........................................................................................................1-8
1.5Keyboard................................................................................................................1-9
1.6LCD Panel............................................................................................................1-10
1.7Power Supply.......................................................................................................1-12
1.8Batteries...............................................................................................................1-13
Chapter 2Troubleshooting Procedures
2.1Troubleshooting Overview......................................................................................2-1
2.2Troubleshooting Flowchart.....................................................................................2-2
2.3Power Supply Troubleshooting...............................................................................2-5
2.4System Board Troubleshooting.............................................................................2-10
2.5Floppy Disk Drive (FDD) Troubleshooting...........................................................2-17
2.6Hard Disk Drive (HDD) Troubleshooting.............................................................2-19
2.7Keyboard Troubleshooting....................................................................................2-23
2.8Pointing Device Troubleshooting..........................................................................2-24
2.9Display Troubleshooting.......................................................................................2-25
Chapter 3Tests and Diagnostics
3.1The Diagnostic Test................................................................................................3-1
3.2Executing the Diagnostic Test.................................................................................3-3
3.3Subtest Names........................................................................................................3-7
3.4System Test............................................................................................................3-9
3.5Memory Test........................................................................................................3-10
3.6Keyboard Test......................................................................................................3-12
3.7Display Test..........................................................................................................3-14
3.8Floppy Disk Test...................................................................................................3-17
3.9Printer Test...........................................................................................................3-20 
						

							viLibretto 50CT/70CT Maintenance Manual3.10Async Test............................................................................................................3-22
3.11Hard Disk Test.....................................................................................................3-24
3.12Real Timer Test....................................................................................................3-27
3.13NDP Test..............................................................................................................3-29
3.14Expansion Test.....................................................................................................3-30
3.15Sound Test...........................................................................................................3-31
3.16Error Codes and Error Status Names....................................................................3-32
3.17Hard Disk Test Detail Status.................................................................................3-35
3.18Hard Disk Format.................................................................................................3-37
3.19Head Cleaning......................................................................................................3-41
3.20Log Utilities..........................................................................................................3-42
3.21Running Test........................................................................................................3-44
3.22Floppy Disk Drive Utilities....................................................................................3-45
3.23System Configuration............................................................................................3-49
3.24SETUP.................................................................................................................3-50
Chapter 4Replacement Procedures
4.1Overview................................................................................................................4-1
4.2Battery Pack...........................................................................................................4-6
4.3Optional PC Card....................................................................................................4-8
4.4Hard Disk Drive (HDD)........................................................................................4-10
4.5Optional Memory Module.....................................................................................4-12
4.6Keyboard..............................................................................................................4-14
4.7Display Assembly..................................................................................................4-16
4.8RTC Battery.........................................................................................................4-19
4.9System Board.......................................................................................................4-20
4.10Display Mask........................................................................................................4-21
4.11FL Inverter Board.................................................................................................4-23
4.12LCD Module........................................................................................................4-25
4.13Power Switch Board.............................................................................................4-27
4.14AccuPoint Board..................................................................................................4-29
4.15LCD Flexible Cable...............................................................................................4-31 
						

							Libretto 50CT/70CT Maintenance Manualvii4.16I/O Adapter Board................................................................................................4-33
Appendices
Appendix A  Handling the LCD Module............................................................................A-1
Appendix B  Board Layout................................................................................................B-1
Appendix C  Pin Assignments............................................................................................C-1
Appendix D  Key Layouts.................................................................................................D-1
Appendix E  Wiring Diagrams...........................................................................................E-1
Appendix F  BIOS Rewrite Procedures...............................................................................F-1
Appendix G  Reliability......................................................................................................G-1 
						

							viiiLibretto 50CT/70CT Maintenance Manual 
						

							TOSHIBA
Toshiba America Information Systems, Inc.
Computer Systems Division
9740 Irvine Boulevard
Irvine, CA  92618 
						

							Chapter 1Hardware Overview