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...

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...

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...

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...

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...

viLibretto 50CT/70CT Maintenance Manual3.10Async Test............................................................................................................3-22
3.11Hard Disk Test.....................................................................................................3-24
3.12Real Timer Test....................................................................................................3-27
3.13NDP...

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...

viiiLibretto 50CT/70CT Maintenance Manual 

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

Chapter 1Hardware Overview