Tektronix 4023 User manual

4023
COMPUTER DISPLAY
TERMINAL
SERVICE MANUAL

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077
MANUAL PART NO. 070-1617-00
PRODUCT GROUP 11
COMMITTED TO EXCELLENCE
Please Check for
CHANGE INFORMATION
at the Rear of this Manual
4023
COMPUTER DISPLAY
TERMINAL
SERVICE MANUAL
First Printing JAN 1974
Revised MAY 1981

Copyright © 1974 by Tektronix, Inc., Beaverton, Oregon.
Printed
in the United States of America. All rights reserved.
Contents of this publication may not be reproduced
in any
form without permission of Tektronix, Inc.
This instrument, in whole or in part, may be protected by one
or more
U.S. or foreign patents or patent applications.
Information provided
on request by Tektronix, Inc., P.O. Box
500, Beaverton, Oregon 97077.
TEKTRONIX is a registered trademark of Tektronix, Inc.

4023 Service
TABLE OF CONTENTS
SECTION 1 INSTALLATION AND OPERATION Page
Introduction
1-1
Installation
1-1
General
1-1
Mounting the Terminal
1-1
Circuitry Access
1-1
Selecting Strappable Options 1-1
AC Power Sources and Requirements 1-2
Voltage, Current, and Power Requirements 1-2
AC Power Cord and Grounding Requirements 1-6
Power Cord Color Coding 1-6
Spare Switch Connections 1-8
Spare Indicator Connection 1-8
Rear Panel Connectors 1-8
Control Descriptions 1-8
General 1-8
Display and Power Controls 1-8
Rear Panel Control 1-9
Console Controls and Indicators 1-9
The Keyboard 1-11
Function Pad Controls 1-11
Operating Modes 1-13
General 1-13
Direct Entry
1-13
Buffer Entry 1-13
Enter Key Entry 1-13
Send Key Entry
1-14
Use of Message Separators 1-14
Buffer Form Fill-Out Entry
1-14
Transmitting Form Fill-Out Data Via Enter 1-15
Transmitting Form Fill-Out Data Via Send 1-16
Nul Suppression 1-16
SECTION 2 CHARACTERISTICS
Introduction
2-1
Alphabetic Listing 2-2
Tables 2-7
Accessories 2-7
Code Effect
2-7
Data Coding 2-11
Data Transfer 2-11
Display Specifications 2-12
Editing Specifications 2-13
Environmental Specifications 2-13
Field Attribute Codes 2-14
Physical Specifications 2-14
Power Supply Specifications 2-15
Reset Key Functions
2-15
Strap Options
2-16
Timing Specifications 2-23
SECTION 3 MAINTENANCE
General Information
3-1
Introduction
3-1
Desk Mounting 3-1
Mounting the Terminal on the Optional Pedestal
3-1
Servicing Procedure
3-1
Soldered Options
3-1
Troubleshooting Information 3-2
Troubleshooting Procedure 3-2
Recommended Troubleshooting Equipment
3-2
Disassembly and Assembly 3-3
Access
to the Display Unit Circuitry 3-3
Keyboard Information
3-3
REV. B, DEC. 1974
Circuit Card Information
3-3

4023 Service TABLE OF
CONTENTS (cont)
SECTION 3
MAINTENANCE (Cont)
Page
Rear Assembly Removal 3-3
Monitor Assembly Information
3-4
Monitor Assembly Removal 3-4
CRT Removal 3-5
Monitor (CRT) Installation 3-5
Deflection Amplifier and High Voltage Board 3-5
High Voltage Transformer Removal 3-5
Silicon Grease 3-5
Power Transformer Information
3-5
SECTION 4
PERFORMANCE CHECK/ADJUSTMENT
PERFORMANCE CHECK
4-1
General
4-1
Performance Check Procedure
4-1
ADJUSTMENT
4-9
Introduction
4-9
Equipment Required 4-9
Adjustment Procedure 4-9
Preliminary 4-9
Remove the Terminal Cover 4-9
Detailed Procedure 4-9
SECTION 5 ELECTRICAL PARTS LIST
5-1
SECTION 6
THEORY OF OPERATION
INTRODUCTION
6-1
GENERAL DESCRIPTIONS
6-1
Keyboard
6-1
Timing Card
6-1
Keyboard Interface Card 6-2
Control Card 6-2
Cursor Card 6-3
RAM Card 6-3
Edit Card 6-3
Low Voltage Power Supply
6-3
Display
Circuits
6-4
DETAILED DESCRIPTION 6-4
Keyboard Description 6-4
General 6-4
Coded Character Generation 6-4
Function Pad Operation 6-4
Miscellaneous Functions 6-5
Timing Card 6-5
Timing
6-5
Character Generation 6-7
Retrace Times 6-8
Circuit Functions 6-9
Miscellaneous 6-11
Keyboard Interface Card 6-11
I nputting Keyboard Data 6-11
Control Character Decoders 6-12
Keygate Generator
With Repeat 6-12
TSTROBE and CSTROBE Control
6-12
Move Cursor
Timing
6-12
Move Cursor Gates 6-13
Carriage Return and
Line Feed Circuits 6-13
Clear
Page and Erase Input Circuits 6-13
Page Full Circuit
6-14
Wrap-Around
Circuit
6-14
Miscellaneous Circuits and Operations 6-14
ii ®

®
TABLE OF CONTENTS (cont)
SECTION 6 THEORY OF OPERATION (Cont)
Control Card
General Circuitry Information
Miscellaneous Circuits and Operation
Explanation of Transmission Control
Cursor Card
General
Register Description
Cursor Register Operation
Display Register Operation
Edit Effects on the Registers
Cursor Addressing and Reading
Miscellaneous Circuits
Summary of Register Operations
Random Access Memory (RAM) Card
Introduction
Operation of Major Circuits
Sense Amps
Miscellaneous Circuits
Edit Card
Introduction
Edit Circuits
RolI·Up Circuitry
Read Cursor Position
Cursor Positioning
Character Decoding Circuit
Bit 8 and Bit 9
Set
Tab/Backtab Circuits
Display Circuits
General
Vertical
Horizontal
Video
Brightness
Focus
Power Supply
+15·Volt Supply
-12 and -5·Volt Supplies
+5·Volt Supply
WIRING AND SIGNAL INFORMATION
Wiring
How
to Use the Wiring Information
Wire Lists
Minibus Signal Listing and Descriptions
DIAGRAMS
SECTION 7 MECHANICAL PARTS LIST
CHANGE INFORMATION
Page
6·14
6·14
6·15
6·16
6·20
6·20
6·20
6·20
6·20
6·21
6·23
6·24
6·24
6·26
6·26
6·26
6·27
6·27
6·28
6·28
6·28
6·29
6·29
6·30
6·30
6·30
6·30
6·31
6·31
6·31
6·31
6·32
6·32
6·32
6·33
6·33
6·33
6·33
6·34
6·34
6·34
6·35
6·44
7·1
4023 Service
iii

4023 Service Fig. 1·
1.4023 Computer DisPlay Terminal .
®

Section 1-4023 Service
INSTALLATION
AND OPERATION
This manual is a part of the following set of documents
which describe the 4023 Refreshed Computer Display
Terminal:
4023 USERS MANUAL, Tektronix Part No.
070-1621-00.
Contents-An explanation of how to operate and pro-
gram the 4023.
4023 SERVICE MANUAL, Tektronix Part No.
070-1617-00.
Contents-A comprehensive explanation of the 4023. It
includes operation, characteristics, servicing, adjustment,
circuit description, and parts lists.
Optional items used with the Terminal are explained in
separate manuals.
INTRODUCTION
The 4023 Computer Display Terminal interfaces be-
tween man and computer by permitting inputs through an
integral keyboard and providing a display of computer
output data. In addition, the Terminal can relay data
bi-directionally between peripheral devices and a computer.
An Interface Unit must be installed in the Terminal and
connected to the computer-either directly or through a
modem (modulator-demodulator)-to permit information
interchange. The Terminal has the ability to have copies
made of its display, via a Hard Copy Unit.
INSTALLATION
GENERAL
Installation consists of desk-mounting the Terminal,
selecting the proper operating voltage and fuse size, setting
the desired strap options, and connecting the Terminal to
the computer. These steps are discussed in the following
paragraphs.
MOUNTING THE TERMINAL
Desk-Mounting consists of simply setting the Terminal
on a desk or other surface. The air vents on the bottom and
sides should be kept free of obstructions to permit air flow
through the unit.
A dimensional drawing is provided in Fig. 1-2 as an
installation aid.
REV. S, Dl:C. 1974
CIRCUITRY ACCESS
The display unit cover must be removed to permit access
to the Motherboard into which the Terminal Control cards,
interface cards,
and optional accessory cards are installed.
Removing the display unit cover opens a line voltage safety
interlock switch, which automatically cuts power when the
cover is removed. The switch actuator (located, in the top,
left-rear corner) can be pulled up to permit Terminal
operation with the display unit cover removed.
I WARNING I
Dangerous voltages exist in the display unit area when
the line cord
is connected. Servicing should be done
only
by qualified technicians.
SELECTING STRAPPABLE OPTIONS
Strappable options are movable wire straps located on
circuit cards inside the display unit, Figs. 1-3 and 1-4 show
the strap option locations. These straps provide options for
the operator and programmer and can be set at the user site
by qualified technical personnel. The circuit cards (seven of
them) plug into the Motherboard. See Fig. 1-5 for card
locations on the Motherboard.
1. Do not remove or install circuit cards while the
Terminal power
is on.
2. The cards must be installed in the order shown in
Fig. 1-5; otherwise, heat is not dissipated properly.
The positions of the straps are dependent upon com-
puter and program requirements, and in some cases, upon
user preference. The location and description of the
movable strap options for the Keyboard Interface, Control,
Timing, and Basic Data Communications I nterface cards are
shown in Figs. 1-3 and 1-4. Information on cut-strap
options can be found in Section 2 of this manual. The
Optional Data Communications Interface (021-0112-00) is
to be installed in P8. The Standard Data Communications
Interface (021-0111-00) is installed in P9. Detailed strap-
pable option information for these two interfaces can be
found in their respective manuals.
1-1

Installation and Operation-4023 Service
•
Fig. 1·2. Physical Dimensions.
AC Power Sources and Requirements
Thi s Te rminal is intended to be operated from a
sing le phase , earth , referenced power source having
one current carrying conductor (neutral) at ground
(earth) potential . Operation from power sources
where both curre nt- carrying conductors are live
with respect to earth (such as phase-to-plyase on a
multiphase system, or across the leg s of a 117-234
si ngl e phase three-wire system) is not recommend -
ed because on ly the line conductor has overcurrent
(fuse) protection within the instrument.
1-2
This Terminal is designed tooperate from either a 110
or 220 volt nominal line voltage source that 'has a
frequency of 48 to 440 Hz. In addition , any of three voltage
ranges for 100 Vac or four voltage ranges for 220 Vac may
be selected. Voltage,
current and power requirements are
listed below .
VOLTAGE, CURRENT, AND POWER REQUIREMENTS
VOLTAGE
FREQUENCY
LINE FUSE
INPUT POWER
RANGE
(slo blow)
100,115, 48Hz
2A
120
or
220 W Max
200,220, 440Hz 1.25A -,
230, 240
REV . B, DEC. 1974

BUF-position with BUFFER
selection perm its a keyboard
CR to also generate a linefeed.
IN position permits either a
keyboard or computer gen·
erated CR to generate a
simultaneous linefeed.
OUT position inhibits simulta-
neous linefeeds with CR,
regardless of CR origin.
0--. EOL LF GEN
I
n-I~J
I
LOCAL OUT I
I
O-_J
LOCAL enables line feeds to
be generated in LOCAL
when transmitting from the
Terminal buffer to an aux-
iliary device. Line feeds are
not transmitted to the com-
puter is on line_
IN enables linefeeds to be
generated by transmit circuits
when operating in LOCAL or
ON LINE with BUFFER
selected.
OUT prevents linefeeds from
being generated at end of a
line.
Ln o:t M N
~ ~ ~ ~ ~
iii iii iii iii iii
ciqqciq
A. Keyboard I nterface Card.
B. Control Card.
MESSAGE END
The Message End character is
the last character sent in a
buffer or Read Cursor trans-
mission.
The standard END
character is strapped to be
CR.
Installation and Operation-4023 Service
LF DOES CR
td:~:~
LF position performs a line-
feed only upon receipt of a
linefeed
command.
LF/CR position causes a
simultaneous carriage return
function upon receipt of a
linefeed
command.
IN causes wrap-around when
moving cursor past 80th
character position. OUT dis-
ables wrap-around
OUT is used when 4023 does
not require a prompt char-
acter for data transmission
from buffer a line at a time.
IN is used when 4023 is to
receive a prompt character for
data transmission from buffer.
Fig. 1-3A & B. Options on the Keyboard I nterface and Control cards that can be selected by strap placement.
® 1-3