Zenith Z-171 User manual

585·156-01
Service Guide
Z-171 PC Series
860-14()..j) \
~tNI1!L Idata
systems

The purpose of this page is to make sure that all service bulletins are
entered in this service guide. When a service bulletin is received, mark
the guide and list the information in the record below.
Record of Field Service Bulletins
SERVICE DATE
BULLETIN OF CHANGED PURPOSE OF SERVICE
NUMBER ISSUE
PAGE(S)
BULLETIN
INITIALS
UMITED RIGHTS LEGEND
Contractor is Zenith Data Systems Corporation of Sl Joseph. Michigan 49085. The
entire document is subject to Umited Rights data provisions.
Copyright © 1985 by Zenith Data Systems Corporation
Printed in the United States of America
Zenith Data Systems Corporation
Sl Joseph. Michigan 49085

Contents
. Chapter 1 Introduction and General Information
Related Publications .................................................... 1-1
Ust of Tools and Equipment ........................................... 1-1
Introduction to the Computer ........................................... 1-2
Front View .......................................................... 1-2
Right View .......................................................... 1-3
Left View ........................................................... 1-4
Rear View .......................................................... 1-5
Specifications ........................................................... 1-7
Definition of System Model Numbers ................................... 1-9
Theory of Operation ................................................... 1-10
Chapter 2 Installation
Preparing the Computer for Installation ................................. 2-1
Opening/Closing the Computer ....................................... 2-1
Shoulder Strap Removal . .. ... . .. .. .. .. .. .. .. .. . .. .. .. ... .. .. .. . .. .. 2-2
Installation of Internal Options .......... . ...... . .... .. .. ........ .... 2-2
Connectors .. .. .. ... ... .... ..... .. ...... .. ... ... .. .. .. .. .... . ... . .. .. .. 2-3
Connecting the Peripherals ........................................ 2-10
Final Connections .................................................. 2-11
Before Powering Up the System ................................... 2-13
Chapter 3 Operation
Power Up ............................................................. 3-)
Disk Drives ........................................................... 3-2
Disk Care.......................................................... 3-3
Computer Controls .................................................... 3-4
Keyboard .......................................................... 3-4
Icons ............................................................... 3-6
Alphabetic Keys ..................................................... 3-7
Nonalphabetic Keys .................................. :.............. 3-8
Common Control Keys ............................................. 3-9
Special Function Keys ............................................. 3-10
Control Keys ....................................................... 3-11
Control Key Combinations ......................................... 3-12
Calculator Keyboard Operation ..................................... 3-13
Resetting the Computer............................................... 3-14
Defeating the Autoboot Feature ....................................... 3-14

iv
Contents
Chapter 4 DisassemblylReassembly
Disassembly Procedures
............................................... 4-2
Carry Strap ........................................................ 4-2
Rear Access Panel ................................................. 4-4
Back Cover ........................................................ 4-5
Memory Board .................................................... , 4-7
Main Logic Board .................................................. 4-8
Disk Drive Assembly ............................................... 4-9
DC Power Board .................................................. 4-10
LCD Board ........................................................ 4-11
RGB Video Board ................................................. 4-13
Modem Board..................................................... 4-14
Battery Pack ...................................................... 4-15
Keyboard ......................................................... 4-16
Chapter 5 Configuration
Main Logic Board ............... ;...................................... 5-6
Memory Board . ... .. .. ... ... ... . .. .. .... .... ... .. .. .. .. .. .. ... ... .. . .. 5-7
RGB Video Board ..................................................... 5-9
Disk Drive Configuration ............................................. 5-12
Chapter 6 System Checkout and Troubleshooting
System Checkout Procedure ............................................ 6-1
Troubleshooting Procedure . ... ..... .. .. ... ... .. .. ... .. ... .. .. .. ... .. 6-5
General Power ............ ..... ..... .. .. ... .. . .... .... ... . .. .. .. 6-5
LCD ............................................................ 6-8
Disk Drives ..................................................... 6-8
Real-Time Clock ................................................ 6-10
RGB Video Board ............................................... 6-11
Modem Board .................................................. 6-13
Error Messages.................................................. 6-2
Chapter 7 Parts Ust
Figures
1-1:
1-2:
1-3:
1-4:
1-5:
1-6:
2-1:
2-2:
2-3:
2-4:
Z-170 Computer ............................................... 1-2
Right View .................................................... 1-3
Left View ..................................................... 1-4
Rear View .................................................... 1-5
Model Numbers ............................................... 1-9
Block Diagram ............................................... 1-10
Opening/Closing the Computer ................................. 2-1
Shoulder Strap Removal ................ ... .. .... .... .. .. .. . .. 2-2
Expansion Connector .. . ...... ... .. ... ... .. ... ... ... .. ... . .. .. 2-5
Serial Connector ............................................. 2-6

v
Contents
2-5: Parallel Connector............................................ 2-7
2-6: RGB Connector .............................................. 2-8
2-7: Rear Panel Connectors ... ' .................................... 2-9
2-8: Power Supply Voltage Selector ............................... 2-12
3-1: Disk Drives....... .... ... ..... .... ... .... .... ...... ..... ... .. 3-2
3-2: Keyboard .................................................... 3-4
3-3: Icon/Function Block .......................................... 3-7
3-4: Alphabetic Keys .............................................. 3-7
3-5: Nonalphabetic Keys........................................... 3-8
3-6: Common Control Keys ....................................... 3-9
3-7: Special Function Keys ....................................... 3-10
3-8: Control Keys .................................... ' ............. 3-11
3-9: Control Key Combinations ................................... 3-12
3-10: Calculator Keypad ........................................... 3-13
4-1: Exploded View ................................................ 4-1
4-2: Carry Strap .................................................. 4-3
4-3: Rear Access Panel ........................................... 4-4
4-4: Back Cover .................................................. 4-6
4-5: Memory Board .... .. .. .... .. .... ... . ... . . .. ..... .. .... ... . . .. 4-7
4-6: Main Logic Board ............................................ 4-8
4-7: Disk Drive Assembly ......................................... 4-9
4-8: DC Power Board ............................................ 4-10
4-9: LCD Board ................................................. 4-12
4-10: RGB Video Board ........................................... 4-13
4-11: Modem Board ............................................... 4-14
4-12: Battery Pack ................................................ 4-15
4-13: Keyboard. ...... .. .. . .. .. ... .... . . .. ... .. .... .... ...... . . . .. 4-17
4-14: Disassembly of the Keyboard ................................ 4-18
5-1: Circuit Board Locations ........................................ 5-1
5-2: Setup Menu ................................................. 5-2
5-3: Main Logic Board Jumper Locations .......................... 5-6
5-4: Memory Board Jumpers ...................................... 5- 7
5-5: RGB Video Board Jumper Locations ......................... 5-10
5-6: Video Test Connection ........................................ 5·11
5-7: Video Waveform ............................................. 5·11
5-8: Disk Drive Configuration .................................... 5·12
6-1: DC Power Board Cable Connections .......................... 6-4
6-2: DC Power Board ............................................. 6-7
6-3: LCD Power Input Waveform .................................. 6-8
6-4: Video Board ................................................ 6·12
6-5: Battery Test ................................................. 6·14

vi
Contents
Tables
2-1:
2-2:
2-3:
2-4:
Bus Expansion Connector Pinout ............................. 2-3
Serial Connector Pinout ...................................... 2-6
. Parallel Connector Pinout..................................... 2-7
RGB Video Connector Pinout ....... .. ......... ............. .. 2-8
3-1: Cross-Reference Table ........................................ 3-5
5-1: Time Zones .................................................. 5-4
5-2: Main Logic Board Jumper Settings ............................ 5-6
5-3: Memory Board Jumper Configuration ......................... 5-8
5-4: Memory Chip Size ........................................... 5-8
5-5: RGB Video Board Jumper Configuration.................. .. . .. 5-9
5-6: Floppy Disk Drive Configuration ............................. 5-12
6-1: Error Messages ............................................... 6-2
7-1: Z-170 Parts List ............................................... 7-1

Chapter 1
Introduction and General Infonnation
This service guide is intended to aid the service technician in the installa-
tion and repair of a Z-170 Computer. This guide provides information
to service the computer to the circuit board or subassembly level only.
The abbreviated installation procedure contained in this guide provides
basic information on installing this computer. If further information is
required, refer to the other publications listed below.
Basic operating instructions are also provided to aid the service technician
who is not familiar with this computer model.
Related Publications
595-3532
595-3440
585-174
Z-170 PC Portable Computer Owner's Manual
Z-170 Series Technical Reference Manual
Z-170 Schematics and Parts list
Options and peripheral equipment for this computer have separate manu-
als which are not listed here.
List ofTools and Equipment
The tools and equipment required to service the computer include:
1 flat-blade screwdriver
1 #2 phillips-head screwdriver
1 oscilloscope
1 VOM (volt-ohm meter) or a DVM (digital voltmeter)

Page 1-2
Introduction and General Information
Introduction to the Computer
The computer is equipped with a built-in LCD (liquid crystal display),
built-in keyboard, and two floppy disk drives. The available options include
expansion up to 640K of user memory, an internal modem, a RGB video
board and battery pack.
Figure I-I: Z-170 Computer
FrontView
The following components are illustrated in Figure 1-1.
• Keyboard -The keyboard has 77 keys for data entry and control
functions. The lower portion consists of 63 keys and forms a typewri-
ter-type keyboard. The upper portion consists of the 10 user function
keys and 4 unique icon keys.

Page 1-3
Introduction and General Information
• Screen - The screen is a 25-line electroluminescent LCD that is
compatible with the IBM PC color graphics adapter in text and
graphics mode.
Right View
The disk drives are illustrated in Figure 1-2.
• Disk drives - The computer has one or two floppy disk drives
installed. The front of the drive may differ slightly from that illustrated
in the figure.
• Disk access indicators - The indicator light acknowledges when
the disk drive has been selected.
DISK ACCESS
INDICATORS
Figure 1-2: Right View
®
c::::J
®
DRIVE B

Page 1-4
Introduction and General Information
Left View
The following components are illustrated in Figure 1-3.
• Backlight dial - Adjusts the intensity of light behind the screen.
This dial is also used as a contrast control to improve the visibility
of the display.
• On/off switch - Use this switch to turn the computer on and off.
• AC adapter connector ;;- Used for AC operation. Plug the external
AC adapter connector into this jack.
• Battery compartment - The optional battery pack is stored inside
this compartment.
BACK LIGHT
DIAL \'
AC ADAPTER
CONNECTOR
-- - '"
ON/OFF ~ ill
BATTERY PACK
COMPARTMENT
Figure 1-3: Left View

Rear View
Page 1-5
Introduction and General Information
The following connectors are illustrated in Figure 1-4. For a more detailed
description of the connectors and their pinouts, refer to Chapter 2, "Installa-
tion."
• Parallel connector - Parallel Centronics-type output for a parallel
printer or other peripheral.
• Serial connector - RS-232C OTE input/output for a printer, modem,
or other serial peripheral or communication device.
• Bus expansion connector - Bus signals for use with an expansion
chassis.
• Phone/modem connector -Input/output for a phone or external
modem.
RGB COMPOSITE
\ VIDEO OUT
~",../
~(@j
EXPANSION PORT
Figure 1-4: Rear View

Page 1-6
Introduction and General Information
• Composite video connector - Composite video output for an exter-
nal monochrome video monitor. This connector is supplied with
the optional video board.
• RGB video connector - Red, green, blue, and intensity output for
an external RGB (color) monitor. This connector is also supplied
with the optional video board.

Page 1-7
Introduction and General Information
Specifications
CPU
Processor .................. .
Type ....................... .
Clock speed ................ .
Memory
Display ....................... .
Sound ........................ .
InpuVOutput
Serial I/O .................. .
Parallel I/O ................ .
Video ...................... .
Expansion ................... ..
Modem ....................... .
Disk drives ................... .
80C88 CMOS I6-bit processor.
I6-bit internal.
4.77 MHz.
4K non-volatile RAM; 256K dy-
namic RAM expandable to 640K
80 x 25 character (640 x 200
pixel) LCD display. Compatible
with the IBM PC color graphics
adapter In text and graphics
modes.
8 ohm, 2-inch speaker.
Asynchronous serial RS-232C
(OB-25 connector) port -1 start
bit; 7- or 8-bit word length; 1 or
2 stop bits; selectable baud rates
of 110, 150,300,600, 1200,2400,
4800, or 9600; RD, ers, DSR,
CD signals recognized; TO, RTS,
DTR signals controlled; full- or
half-duplex operation.
Centronics-compatible
parallel
output port (OB-25 connector).
Composite video signal (RCA
phono jack) and RGB color video
signals (9-pin D-type connector).
Bus interface to optional expan-
sion chassis.
RJ-ll modular connector.
5.25-inch double-sided, oll.e-
third height double-density

Page 1-8
Introduction and General Information
Keyboard ..................... .
Power requirements ........... .
External AC adapter
Input
voltage ............... .
Frequency
.................. .
Current .................... .
Output voltage .............. .
Environment
Operating .................. .
Storage ..................... .
Humidity ................... .
D· .
ImenSlons ................... .
Weight
With 2 drives ............. ..
With battery ................ .
With internal modem ....... .
floppy disk drives, 360K format-
ted capacity each drive,
48 tpi, 9 sectors/track. Write-
protection recognized. Operating
system: MS-DOS (PC-DOS com-
patible) version 1.25 and higher.
63-key QWERTY arrangement
with 4 cursor control keys. Also
included are the 10 touch control
function keys and 4 icon keys.
+ 12.8 VDC at 2.5 amperes (32
watts).
115 VAC (95-130 VAC); 220 VAC
(190-260 VAC); jumper selecta-
ble.
60 Hz (48-62 Hz); 50 Hz (48-62
Hz).
4 amperes maximum continu-
ous (full load, 115 VAC).
+ 12.8 VDC.
50-90 degrees Fahrenheit (10-
32 degrees Celsius).
- 40 through + 125 degrees
Fahrenheit
(- 40 through + 51
degrees Celsius).
20-80% relative humidity (non-
condensing).
9.5" x 13.0" x 6.0" (24.l cm
x 33.0 cm x 15.2 cm) with key-
board closed. 13.4" deep (34.0
cm) with keyboard open.
14.4lbs. (6.54 kg).
16.0 Ibs. (7.26 kg).
14.7Ibs. (6.67 kg).

Page 1-9
Introduction and General Information
Definition of System Model Numbers
The Z-170 is a member of the Z-100 PC series of computers. The full
model number designates the configuration of the computer. An example
of the full model number is listed in Figure 1-5 and each portion of the
number is defined.
Drive type
F = Floppy disk drives
W = Winchester/rigid
disk drives
Selling organization
H =
Heath Company
Z = Zenith Data Systems
Any other letter indicates
sale by a non-Zenith subsidiary
or company.
\
CRT type (built-in)
A =
Amber
G = Green
L = Liquid crystal display
Number of floppy disk drives
o= No drives
1 = One floppy disk drive installed
2 = Two floppy disk drives installed
ZFL-171-21
-\
Series type It User memory size
11 = Low-Profile Z-100 (non-PC) 2 = 128K
12 = All-in-One Z-100 (non-PC) 3 = 192K
13 = Z-130 Portable Series 4 = 256K
14 = Z-140 Desktop Series 5 = 320K
15 = Z-150 Desktop Series
16 = Z-160 Desktop Series
17 = Z-170 Portable Series
Floppy disk drive type/Clock speed
o= Full height, 5 MHz
1 = Half height, 5 MHz
1 = Third height, 5 MHz (Z-170 Series)
8 = Half height, 8 MHz
Figure 1-5: Model Numbers

Page 1-10
Introduction and General Information
Theory ofOperation
The following section describes the internal boards and other major com-
ponents of the computer system. A brief description of the function of
each main circuit is provided. Refer to Figure 1-6 for the system block
diagram.
POWER
SUPPLY
I
POWER
DISTRIBUTION
BOARD
I
~ LCD I
SERIAL, DISPLAY
PARALLEL,
f.-
110 MEMORY
AND EXPANSION INTERFACE OPTIONAL
CONNECTORS
I---
VIDEO
BOARD
CPU
I
DISK I
-------
DRIVE A I
OPTIONAL:
FLOPPY DISK KEYBOARD
LM~~I':<:,R_I
CONTROLLER PROCESSOR
DISK
HKEYBOARDI
DRIVE B
I
MEMORY
Figure 1-6: Block Diagram
Main logic board - The heart of the computer. It contains the circuitry
required for operation of the computer except for the memory, LCD driver,
and
power supply. The functional areas of the main board are described
in the following paragraphs.
CPU - An 80C88 microprocessor that performs the logic functions
of the computer and controls the operation of all other sections of
the computer.

Page 1-11
Introduction and General Information
Control signals and timing - Responsible for generating the signals
and clock pulses that are required for proper coordination of the com-
puter.
Disk drive control - Composed of both digital and analog sections
which are responsible for encoding and decoding all information to
and from the floppy disk drives and for controlling the operation of
the drives themselves.
InpuVoutput circuits - Provides for the interfacing between the CPU
and external peripherals.
Keyboard proc~ssor - Uses an 80C39 microcontroller to perform the
keyboard scan functions and acknowledge interrupts to the CPU.
DC power board -Distributes the power supply voltages to the LCD
assembly, disk drives, main logic board, and the RGB video board.
LCD decoder/driver board -Generates an 80-column by 25-line display
of the information written to it by the main logic board. This board also
generates both the IBM compatible low-resolution and the high-resolution
graphics on the LCD.
High-resolution video logic board- Produces both composite and RGB
high-resolution outputs which are available at the back panel video con-
nectors of the computer for connection to an external composite or RGB
monitor. This optional card is plugged into the main logic board.
System RAM card -Contains the system RAM. This memory is used
to store all programs and data that are in process. It can be configured
with 64-kilobit and/or 256-kilobit memory devices providing several si2es
of system memory ranging from 128K to 640K.
Disk drives - Used to access the information stored on the floppy disk.

Chapter 2
Installation
This chapter discusses the basic installation of the computer. For the pur-
poses of this discussion, installation is defined as connecting the computer
to power and peripherals in preparation for use.
Preparing the Computer for
Installation
Opening/Closing the Computer
Refer to Figure 2-1 for the location of the keyboard latches. To open
the computer, press down on the front edges of the latches and slide
the latches toward the back of the computer. Gently swing the keyboard
down into the horizontal position. To close the computer, swing the key-
board up. Hold it in the closed position and slide the latches towards
the front of the computer until they lock into place.
Figure 2-1: Opening/Closingthe Computer

Page 2-2
Installation
ShoulderStrap Removal
Removal of the shoulder strap is recommended for ease in connecting
the peripherals. To remove the strap, pull up on the latch on each side
of the case as shown in Figure 2-2. Slide the latching assembly down
to unhook the strap and set it aside. To reinstall the strap, pull up on
the latch and insert the hooked portion into the opening on the side
of the computer.
1. LIFT UP
Figure 2-2: ShoulderStrap Removal
Installation ofInternal Options
Anumber of options may be installed inside the computer. These include:
a modem board, RGB video board, and additional memory. The instruc-
tions for installing them are covered in related publications (see Chapter
1).

Connectors
Page 2-3
Installation
The connectors are illustrated in Figure 2-7. These connectors are used
to allow communication between the computer and various external de-
vices. The pinout of each connector is listed in Table 2-1 through Table
2-5.
Bus expansion connector - This port provides the necessary data, address,
and control signals for use with an expansion chassis.
Table 2-1: Bus Expansion ConnectorPinout
PIN NUMBER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
SIGNAL NAME
NC
D7
D6
D5
D4
D3
D2
Dl
DO
I/OCHRDY
AEN
A19
A18
A17
A16
A15
A14
A13
A12
All
A10
A9
A8
DESCRIPTION
No connection.
Data bit 7.
Data bit 6.
Data bitS.
Data bit 4.
Data bit 3.
Data bit 2.
Data bit 1.
Data bit O.
Input/output channel ready. Used by
slower I/O devices to ensure data is not
lost during read and write operations. May
be held low (not ready) up to 10 clock cy-
cles (210 ns).
Address enable. Assigns control of lead
and
write operations to DMA controller.
Address bit 19.
Address bit 18.
Address bit 17.
Address bit 16.
Address bit 15.
Address bit 14.
Address bit 13.
Address bit 12.
Address bit 11.
Address bit 10.
Address bit 9.
Address bit 8.