Toshiba Libretto 50CT User manual

Libretto 50CT/70CT Maintenance Manual i
Copyright
©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.

ii Libretto 50CT/70CT Maintenance Manual
Preface
This 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 result
in death or serious injury if the safety instruction is not observed.
WARNING: “Warning” indicates the existence of a hazard that could
result in bodily injury if the safety instruction is not observed.
CAUTION: “Caution” indicates the existence of a hazard that could
result in property damage if the safety instruction is not observed.
NOTE: A “Note” contains general information that relates to safe
maintenance 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.
qBe 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.
qIf 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 Manual iii
The manual is divided into the following parts:
Chapter 1 Hardware Overview describes the system unit and each FRU.
Chapter 2 Troubleshooting Procedures explains how to diagnose and resolve
FRU problems.
Chapter 3 Tests and Diagnostics describes how to perform test and diagnostic
operations for maintenance service.
Chapter 4 Replacement Procedures describes the removal and replacement of the
FRUs.
Appendices The appendices describe the following:
❑Handling the LCD module
❑Board layout
❑Pin assignments
❑Key layout
❑Wiring diagrams
❑BIOS Rewrite Procedures
❑Reliability

iv Libretto 50CT/70CT Maintenance Manual
Conventions
This 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 Manual v
Table of Contents
Chapter 1 Hardware Overview
1.1 Features..................................................................................................................1-1
1.2 System Unit Block Diagram....................................................................................1-4
1.3 3.5-inch External FDD (Option)..............................................................................1-7
1.4 2.5-inch HDD.........................................................................................................1-8
1.5 Keyboard................................................................................................................1-9
1.6 LCD Panel............................................................................................................1-10
1.7 Power Supply .......................................................................................................1-12
1.8 Batteries ...............................................................................................................1-13
Chapter 2 Troubleshooting Procedures
2.1 Troubleshooting Overview......................................................................................2-1
2.2 Troubleshooting Flowchart.....................................................................................2-2
2.3 Power Supply Troubleshooting...............................................................................2-5
2.4 System Board Troubleshooting.............................................................................2-10
2.5 Floppy Disk Drive (FDD) Troubleshooting...........................................................2-17
2.6 Hard Disk Drive (HDD) Troubleshooting .............................................................2-19
2.7 Keyboard Troubleshooting....................................................................................2-23
2.8 Pointing Device Troubleshooting ..........................................................................2-24
2.9 Display Troubleshooting.......................................................................................2-25
Chapter 3 Tests and Diagnostics
3.1 The Diagnostic Test................................................................................................3-1
3.2 Executing the Diagnostic Test.................................................................................3-3
3.3 Subtest Names........................................................................................................3-7
3.4 System Test............................................................................................................3-9
3.5 Memory Test........................................................................................................3-10
3.6 Keyboard Test ......................................................................................................3-12
3.7 Display Test..........................................................................................................3-14
3.8 Floppy Disk Test...................................................................................................3-17
3.9 Printer Test...........................................................................................................3-20

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

Libretto 50CT/70CT Maintenance Manual vii
4.16 I/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

viii Libretto 50CT/70CT Maintenance Manual

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

Chapter 1
Hardware Overview

1-ii Libretto 50CT/70CT Maintenance Manual

Libretto 50CT/70CT Maintenance Manual 1-iii
Table of Contents
1.1 Features.......................................................................................................................1-1
1.2 System Unit Block Diagram.........................................................................................1-4
1.3 3.5-inch External FDD (Option) ..................................................................................1-7
1.4 2.5-inch HDD..............................................................................................................1-8
1.5 Keyboard.....................................................................................................................1-9
1.6 LCD Panel.................................................................................................................1-10
1.6.1 LCD Module.........................................................................................1-10
1.6.2 FL Inverter Board .................................................................................1-11
1.7 Power Supply............................................................................................................1-12
1.8 Batteries....................................................................................................................1-13
1.8.1 Main Battery Pack.................................................................................1-13
1.8.2 Battery Icon..........................................................................................1-13
1.8.3 Battery Charging Control ......................................................................1-13
1.8.4 RTC battery ..........................................................................................1-14
Figures
Figure 1-1 Front of the computer.......................................................................................1-3
Figure 1-2 System unit configuration.................................................................................1-3
Figure 1-3 System unit block diagram................................................................................1-4
Figure 1-4 3.5-inch FDD ...................................................................................................1-7
Figure 1-5 2.5-inch HDD...................................................................................................1-8
Figure 1-6 Keyboard..........................................................................................................1-9
Figure 1-7 LCD module...................................................................................................1-10
Tables
Table 1-1 FDD specifications.............................................................................................1-7
Table 1-2 HDD specifications............................................................................................1-8
Table 1-3 Keyboard specifications .....................................................................................1-9
Table 1-4 LCD specifications...........................................................................................1-10

1-iv Libretto 50CT/70CT Maintenance Manual
Table 1-5 FL inverter board specifications .......................................................................1-11
Table 1-6 Power supply board output rating....................................................................1-12
Table 1-7 Battery specifications.......................................................................................1-13
Table 1-8 Time required for quick charge........................................................................1-14
Table 1-9 RTC battery charging/data preservation time....................................................1-14

1Hardware Overview 1.1 Features
Libretto 50CT/70CT Maintenance Manual 1-1
1
1.1 Features
The Libretto 50CT/70CT uses Toshiba’s advanced Large Scale Integration (LSI) and
Complementary Metal-Oxide Semiconductor (CMOS) technology extensively to provide
compact size, minimum weight, low power usage, and high reliability. The following features
and benefits are incorporated:
❑Microprocessor
The Libretto 50CT has a 64-bit microprocessor, Intel Pentium processor running at a
clock speed of 75MHz.
∗The Libretto 70CT has a 64-bit microprocessor, Intel Pentium processor with MMX
technology running at a clock speed of 120MHz.
qMemory
Standard 16MB of Extend Data Out (EDO) DRAM.
qHard Disk Drive (HDD)
The Libretto 50CT has a 2.5-inch HDD with a capacity of 815MB.
∗The Libretto 70CT has a 2.5-inch HDD with a capacity of 1.58GB.
qDisplay
A 6.1-inch, Thin Film Transistor (TFT) color Liquid Crystal Display (LCD), that
enables a display of up to 16M colors at a resolution of 640 x 480 pixels.
A video controller and 1MB of VRAM enable an external monitor to display 16M
colors at a resolution of 1280 x 1024 pixels.
qKeyboard
An easy-to-use 80/82-key keyboard provides: a numeric keypad overlay for fast
numeric data entry and cursor/page control; two keys that have special functions in
Microsoft Windows 95; and software that supports a 101- or 102-key enhanced
keyboard.
qBatteries
Two batteries: a Lithium-Ion main battery pack and RTC battery that backs up the
Real Time Clock and CMOS memory.
qExpansion
An optional 8 or 16MB memory kit can be installed in the memory slot.

1.1 Features 1Hardware Overview
1-2 Libretto 50CT/70CT Maintenance Manual
qParallel port
A Centronics compatible parallel port on the I/O adapter enables connection of a
printer or other parallel device and supports the Extended Capabilities Port (ECP)
conforming to IEEE-1284.
qSerial port
A standard, 9-pin, serial port only on the I/O adapter enables connection of such serial
devices as a serial printer, mouse, or modem. A Universal Asynchronous
Receiver/Transmitter (UART) is 16550A equivalent.
qExternal monitor port
The port is available only on the I/O adapter and enables connection of an external
SVGA compatible monitor.
qPC card slot
A PC card slot accommodates one 5mm card (Type II). The slot supports PCMCIA
Release 2.01 cards and an optional external FDD.
qDocking interface port
A 132-pin, docking interface port enables connection of the I/O port adapter or an
optional Enhanced Port Replicator.
The Enhanced Port Replicator has one additional PC card slot that accommodates a
10.5mm card (Type III) and duplicates the ports available on the I/O adapter, in
addition to the connection of the PS/2 compatible mouse and keyboard.
qAccuPoint
The pointer control stick, located on the right of the display panel, provides
convenient control of the cursor without requiring desk space for a mouse.
qInfrared port
An Infrared Data Association (IrDA) 1.0 standard infrared port, which enables
cableless 115.2Kbps data transfer.
qSound system
A Sound Blaster Pro compatible, 16-bit sound system enables the computer to play
back sound. The sound system is equipped with a built-in speaker and stereo
headphone jack.
qExternal Floppy Disk Drive (FDD) (Option)
A 3.5-inch external FDD is connected to the PC card slot and accommodates both
2HD (1.44MB) and 2DD (720KB) disks.

1Hardware Overview 1.1 Features
Libretto 50CT/70CT Maintenance Manual 1-3
The front of the computer is shown in Figure 1-1.
Figure 1-1 Front of the computer
The system unit configuration is shown in Figure 1-2.
Figure 1-2 System unit configuration

1.2 System Unit Block Diagram 1Hardware Overview
1-4 Libretto 50CT/70CT Maintenance Manual
1.2 System Unit Block Diagram
Figure 1-3 is a block diagram of the system unit.
Figure 1-3 System unit block diagram

1Hardware Overview 1.2 System Unit Block Diagram
Libretto 50CT/70CT Maintenance Manual 1-5
The system unit is composed of the following major components:
qMicroprocessor
Libretto 50CT: Intel 75 MHz Pentium processor operates at 2.9/3.3 volts and
incorporates the math co-processor and 16 KB cache memory.
∗Libretto 70CT: Intel 120 MHz Pentium processor with MMX technology operates
at 2.9/3.3 volts and incorporates the math co-processor and 16 KB cache memory.
qStandard RAM
•16 MB, eight 1M x 16-bit EDO DRAM chips
•3.3 volt operation
•No parity bit
•Access time 70 ns
•Data transfer is 64-bit width
qBIOS ROM (Flash EEPROM)
•256 KB, one 256K x 8-bit chip
−64 KB are used for system BIOS
−40 KB are used for VGA BIOS
−152 KB are reserved
•Access time 120 ns
•Data transfer is 8-bit width
qExpansion memory
One expansion memory slot is available for 8 and 16 MB memory kits, which consist
of 1M x 16-bit EDO DRAM chips.
•3.3 volt operation
•No parity bit
•Access time 70 ns
•Data transfer is 64-bit width
qVideo Controller
Chips & Technologies F65550 is used. The video controller integrates an LCD/CRT
graphics controller, RAMDAC, and clock synthesizers.
qVideo RAM
•1 MB, two 256K x 16-bit DRAM chips
•3.3 volt operation
•Access time 50 ns

1.2 System Unit Block Diagram 1Hardware Overview
1-6 Libretto 50CT/70CT Maintenance Manual
qSystem Controller Gate Array
This gate array has the following functions:
•Two PICs:82C59 equivalent
•Two UARTs:16550A equivalent (one SIO is used for SIR)
•One PIT:82C54 equivalent
•One RTC:T9934 equivalent
•Two DMACs:82C37 equivalent
•I/O port decode
•SIO port control
•Parallel (ECP) port control
•Speaker control
•Power supply microprocessor interface
•PnP support
•CPU control
−SMI control
−Clock speed control
•Memory control
−64-bit memory bus control
•Video local bus control
−64 to 32-bit, 32 to 64-bit data bus interface
•Address latch control
−Address conversion
−Address latch
•Hibernation control
•Ring wake up control
•PC card control
−Memory card control
−I/O card control
•BIOS-ROM interface
•Infrared port control
•Sound control
qKeyboard Controller (KBC)
This KBC includes: the keyboard scan controller and keyboard interface controller;
and controls: the internal keyboard, external keyboard, IPS and PS/2 mouse.

1Hardware Overview 1.2 System Unit Block Diagram
Libretto 50CT/70CT Maintenance Manual 1-7
qInternal Pointing Stick Controller (IPSC)
Provides simultaneous control of both an AccuPoint and a PS/2 mouse.
qSound Controller
The Libretto 50CT uses one OPL3-SA2 that incorporates: OPL3 FM synthesizer,
Digital Analog Converter (DAC), and MPU401 MIDI interface.
∗The Libretto 70CT uses one OPL3-SA3 that incorporates: OPL3 FM synthesizer,
Digital Analog Converter (DAC), and MPU401 MIDI interface.