IBM 3277 User manual

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Maintenance Library
Display Station Models 1 and 2
Troubleshooting Guide
SY27-2314-5

Preface
The IBM 3270 Information Display System consists of
control units, display stations, printers, and optional
feature devices. This manual contains all the information
required
to maintain IBM 3277 Display Stations and
features such as keyboards, selector-light pen, magnetic
card reader, security keylock, and audible alarm. The
purpose of this manual
is to present maintenance and repair
information rather than theory of operation information.
The titles and form numbers
of the two control unit
Trou bleshooting Guides are listed below under
"Companion Manuals". Both Troubleshooting Guides con-
tain a glossary
of terms that are applicable to control units
and display stations.
Companion Manuals:
• 3271
Control Unit
Models 1 and 2 Troubleshooting
Guide, SY27-2311
•
3272 Control Unit
Models 1 and 2 Troubleshooting
Guide, SY27-2312
•
3275/3277 Display Station Models 1 and 2 Parts
Catalog, S126-0006
This manual
is organized in eight sections. Sections 1
and 2 contain introductory and maintenance background
material. Sections 3, 4, and 5 contain the Symptom Index,
Troubleshooting Diagrams, and repair data. These three
sections contain
all diagnostic procedures and repair infor-
mation necessary to correct a display station malfunction.
Miscellaneous reference data
is included in Section 6.
Section 7 contains location diagrams to aid in identifying
and locating
the display station components referenced in
other sections of this manual. Instructions for installing the
display station are presented
in Section 8.
• IDR-M ID Reader-Motorized Theory-Maintenance-Parts
Catalog, SY26-4188
To successfully use this manual and repair
IBM 3277
display stations, maintenance personnel should have a
level
of training equivalent to the 3270 system basic FE course.
Because the
3277 attaches to both local and remote control
units,
an understanding of the control unit to which the
display station
is attached is also helpful.
Sixth Edition (July, 1975)
The following pUblications may also prove useful:
• An Introduction to the 3270 Information Display
System, GA27-2739
• IBM 3270 Information Display System Component
Description, GA27-2749
This is a major revision of, and obsoletes, SY27-2314-4 with Technical Newsletter
SN31-0146. The TN L incorporated maintenance information about fuses. This infor-
mation is included in Chapters 4, 5, and 7. Several corrections are made to the
Troubleshooting Diagram in Chapter 4. Other technical and editorial corrections are
made
throughout the manual. Significant changes or additions to the text and
illustrations are indicated by a vertical line to the left of the change.
This edition applies to display stations at Board EC level 717946 and earlier. Changes are
periodically made to the information herein; any such changes will be reported in
subsequent revisions
or Technical Newsletters.
Text for this manual has been prepared with the IBM SELECTRIC ®Composer.
A form is provided at the back of this publication for reader's comments. If the form has
been removed, comments may be addressed to: IBM System Communications Division,
Product Publications, Dept. 52L, Neighborhood Road, Kingston, N.Y., 12401
©Copyright International Business Machines Corporation, 1972, 1973, 1974, 1975'
ii

Contents
Section 1.
Maintenance Approach
1-1
5.2.1.7
Model 2 Analog Card Adjustments
5-8
1.1
Introduction
1-1
5.2.2
-12V Regulator Card 5-8
1.1.1
Online/Offline Maintenance
1-1
5.2.3
OFF-PUSH Switch (Model 2 Only) 5-8
1.1.2
Field Replaceable Units (FRU)
1-1 5.3 Removals
5-9
1.1.3
Troubleshooting Aids
1-1 5.3.1 Covers 5-9
1.2
Trouble Analysis
1-1
5.3.2
Power Components
5-10
1.2.1 Obvious Symptoms
1-1
5.3.2.1 Low-Voltage Power Supply A~mbly 5-10
1.2.2
Isolation to a Display Station
1-1
5.3.2.2
-12V Regulator Card 5-10
1.2.3
Offline Symptoms 1-2
5.3.2.3 AC Capacitor 5-10
1.2.4 Formatted Buffer Symptoms
1-2
5.3.2.4
Model 1 Prime Power Box
5-10
1.2.5
Customer-Reported Failures 1-2
5.3.2.5 Model 2 Prime Power Box 5-10
5.3.2.6
Modell Ferro Transformer (50-Hz)
5-10
Section 2. Tools and Diagnostic Programs 2-1
5.3.2.7 Modell Ferro Transformer (50-Hz)
5-10
2.1
Maintenance Tools 2-1
5.3.2.8 Model 2 Ferro Transformer (50-Hz) 5-11
2.1.1
Customer Engineer Tool Kit 2-1
5.3.2.9
Model 2 Ferro Transformer (50-Hz) 5-11
2.1.2 Osci1I0scope
2·1
5.3.2. to
High· Volrage Power Supply
5-11
2.1.3 Logic Probes
2-1
5.3.2.11 Fuses 5-11
2.1.3.1
Description :2 ~
~.3.3 Anaiog Components 5-11
2.1.3.2
Probe Usage 2-1
5.3.3.1 CRT
5-11
2.1.3.3
Probe Checkout 2-1
5.3.3.2 Yoke and Shields 5-13
2.1.3.4
Probe Repair
2-3
5.3.3.3 Modell Analog Card
5-13
2.1.4
Alignment Mask 2-3 5.3.3.4 Model 2 Analog Card 5-13
2.1.5 lOR FE Test Card 2-3
5.3.3.5 Modell Brightness and Contrast Controls 5-13
2.2 Diagnostic Programs 2-3
5.3.3.6 Model 2 Brightness and Contrast Controls 5-13
2.2.1 Test Patterns 2-3
5.3.3.7
Power Control Switch 5-14
2.2.2 Requesting RFT Patterns 2-4
5.3.4 Logic Components
5-14
2.2.2.1 Local Display
Stations
2-8 5.3.4.1
Logic Card 5-14
2.2.2.2 Remote Display Stations
2-8
5.3.4.2 logic Board
5-14
2.2.3
Online Tests (Ol Ts) 2-9
5.3.5 Keyboard Components 5-14
5.3.5.1 Keyboard from Display Station
5-14
Section 3.
Symptom Index
3-1
5.3.5.2
Keyboard Top Cover
5-14
3.1 Symptom I ndex Usage
3-1
5.3.5.3 Keyboard A~mbly from Bottom Pan
5-14
3.2
Developing Symptoms
3-1
5.3.5.4 Audible Feedback Assembly 5-14
5.3.5.5 Keybutton
5-15
Section 4.
Trouble!'hooting Diagrams
4-1
5.3.5.6 Type A Switch Module
5-15
5.3.5.7
Type A Spacebar Assemblies
5-17'
Section 5. Checks,
Adjustments, and Removals
5-1 5.3.5.8
Keybutton Support Modules - Type A
5.1
Checks
5-1
Keyboards Only
5-17
5.1.1 Display
Station Test Using Test 5.3.5.9 Type B Module
5-18
Pattern 1
5-1
5.3.5.10 Type B Spacebar
5-20
5.1.2
Display Station Operational Test 5.3.5.11
Circuit Board and Electronics Assembly -
(without Test Pattern 1) 5-2 Type B Keyboards Only
5·20
5.1.3
Voltage Checks 5-3
5.3.6 Audible Alarm (Optional Feature)
5-20
5.1.3.1
low-Voltage DC Checks 5-3
5.3.7
Security Keylock (Optional Feature)
5-20
5.1.3.2
High·Voltage Check 5-4
5.3.8
Selector Light-Pen (Optional Feature)
5-21
5.1.3.3
Arc-Suppression Check 5-4
5.3.9
Operator Identification Card Reader
5.1.3.4
6.3V AC Check 5-4
(Optional Feature) 5-21
5.1.3.5
High-Voltage Power Supply Check 5·5 5.4 Type B Keyboard Maintenance Aids
5-21
5.1.4
Keyboard Checks 5-5 5.4.1 Cleaning 5-21
5.1.4.1 Voltages 5-5
5.4.2 Liquid Spills
5-21
5.1.4.2
Key Module and Encoding - Type A 5.4.3 Key Modules
5-21
Keyboards Only
" 5-5
5.4.4
Contamination Shields 5-21
5.1.4.3
Output Codes 5-6
5.4.5
Protective Membrane/Shield
5-22
5.1.4.4
Shift Key Modules - Type A Keyboards Only
5-6
5.4.6
Ground Check
5-22
5.1.4.5
Spacebar Assembly Mechanical Checks 5-6 5.4.7
Ground Loop Isolation
5-22
5.2
Adjustm ents 5-6 5.4.8
Crooked or loose Key tops
5-22
5.2.1 Display Image
Adjustments
5-6
5.2.1.1 Brightness 5·7
Section 6.
Reference Data
6-1
5.2.1.2
Contrast
5·7 6.1
Controls
6-1
5.2.1.3
Focus 5·7 6,1.1
External Controls
6-1
5.2.1.4
Yoke
5-7
6.1.2
I ntern:ll Cf'fltrols
6-2
5.2.1.5
Magnetic Centering Rings 5-7
6.2
IndicatC'" 6-2
5.2.1.6
Modell Analog Card Adjustments
5-7 6.2.1
External I nd Icalo. ;,
6-2
Contents
iii

6.2.2
Internal Indicator (SWEEP INDIC)
6-3 Section
7.
Component Locations
7-1
6.2.3
Arc-Suppression Neon 6-3
6.3
Keyboards (Optional Feature) 6-3 Section
8.
Installation Instructions
8-1
8.1
General 8·1
6.3.1 Types
of Keyboards 6-3
8.2
Installation 8·1
6.3.2
EBCDIC Keyboard Codes 6-3
6.4
ASCII Options
6-3 8.2.1
Line Voltage Check 8·1
6.4.1
ASCII Character Generators (Optional
8.2.2
Feature Installation 8·1
Features) 6-3
8.2.3 Prepowe~-On Checks
8·2
6.4.2
ASCII Keyboards (Optional Features) 6-4
8.2.4
Power-On Checks 8-2
6.5
Reference Diagrams
64
8.2.5
Hexadecimal Address Label 8-2
Index
. X-1
Diagrams
1·1
3277 Maintenance Approach
1·2 5·11
Module Removal (Type B) 5-19
2-1
Logic Probes 2·2
5·12 Circuit Board and Electronics Assembly
2·2
Alignment Mask, Model 1 2·3
(Type B)
5·19
2-3
Alignment Mask, Model 2
24
5-13 Base Plate Ground Studs (Type B)
5·19
24
Test Pattern 1 (USA EBCDIC)
2-5
5·14
Spacebar Pivot Removal (Type B) 5-20
2-5 Test Pattern 2 2-6
6·1
External Controls and Indicators
6-1
2-6 Test Pattern 3 2-6 6-2
Typewriter Keyboard 6-5
2·7 Test Pattern 5
(USA EBCDIC) 2·7 6-3
Operator Console Keyboard 6-5
2-8 Character Differences
for ASCII and 6-4 Data
Entry Keyboards 6-6
WTC Languages 2-8 6·5
USA EBCDIC Keyboard Codes (2 Sheets) 6-7
2·9
Test Pattern 10 Numbers
2-8
'
6
•
6 WTC Language Keyboard Codes 6-9
3-1
Test Pattern 1, Model 1 3-7 6-7
ASCII and WTC Language Keyboard Codes 6-9
3·2
Test Pattern 1, Model 2 3-7
6=8
Logic Card Data (2 Sheets)
6-10
3·3
Test Pattern 2 3·7 6·9 Probe Pin Data 6-12
3-4 Test Pattern 3 3-7 6-10 Keyboard Feature Jumpers 6-13
3-5
Yoke Back Too Far on CRT Neck 3-7 6-11
Type A Keyboard Encoding 6-13
3-6
Yoke Tilted
3-7
6·12
Board Layout by Card Function - Without
3-7 Centering Rings
Not Adj usted Properly 3-8 Features (Card Side View) 6-14
3-8 Character
Height Too Small 3-8 6-13 Board
Layout by Card Function - With
3-9
Glow Only on CRT
3-8 Features (Card Side View)
6·15
3·10
Single Horizontal Line on CRT
3-8 6-14 Board
Layout Pin Identification Data
3-11 Model 1 Raster 3-8 (Pin Side
View)
6-16
3-12
Model 2 Raster 3-8
7-1 Model 1 Locations, Front View 7-1
3-13 Cursor
in Every Row 3-9 7-2
Model 1 Locations, Left·Side View 7-2
3-14
Box in Every Character Position 3-9 7-3
Model 1 Locations, Rear View 7-3
3·15
No Horizontal Sync 3-9
17-3.1
Location of +5V and +34V Fuses (Model 1) 7-4
3-16
No I nterrow Spacing 3-9
74 Model 2 Locations, Front View
7·5
3·17
Correct 0 isplay after PO R 3-9 7·5
Model 2 Locations, Right-5ide View
7-6
3-18 Out of Focus Image 3-9 I 7·5.1
Location of +5V and +34V Fuses (Model 2)
7·7
3·19
Yoke Horizontal Return Line Open 3-10 7-6 Model 2 Locations, Left-Side
View
7-8
3-20 Open
in Yoke Horizontal Winding
3·10
7-7
Type A Keyboard Locations 7·9
3·21
1/2 Vertical Yoke Open
3·10
7-8
Type A Keyboard Pin Assembly and Terminal
3·22
Horizontal Yoke Open 3·10
Location 7·10
3-23 Vertical Yoke Open 3-10 7·9
Low-Voltage Printed Circuit Board 7·11
4·1 Display
Station Troubleshooting Di&grams 7-10
Low-Voltage Printed Circuit Board Shield 7-12
(29 Sheets) 4-3 7·11 Model 2 Voltage
Distribution Board 7-12
5-1
OFF-PUSH Switch Adjustment 5-9 7-12
Model 1 Prime Power Box
7·13
5·2
Switch Module Removal (Type A)
5·15
7-13 Brightness and Contrast
Control Terminals 7-13
5-3 Unsoldering Lead Frame Terminals (Type A) 5-15 7-14 High-Voltage Power
Supply
7·14
54 Lead Frame Removal (Type A)
5-15 7-15
Model 1 Arc-Suppression Board 7-14
5-5 Switch Plunger Return Spring Positioning 7-16 Analog Card (2 Sheets) 7-15
(Type A)
5-16 7-17
Type B Keyboard Locations 7-17
5-6
Switch Module Orientation (Type A)
5·16
7-18 Type B Keyboard Assembly 7·18
5-7
Torsion Bar Removal (Type A)
5-17 7-19
Type B Keyboard Assembly Pin and Terminal
5-8 Spacebar Guide
Module Removal (Tyoe A)
&17
Locations 7-19
5-9 Screw Loosening
(Type B)
E-l? 8-1 50-Hz Ferro TB·1 8-1
5-10
Keyboard Assembly Separatio~ (Typ". HI
5~R
f ;,)-1
Data F!ow (Foldout; at back of manual) FO-1
iv

Abbreviations
AID
attention identification
KB keyboard
ALD
automated logic diagram
ASCII American
Standard Code for Information
LV low voltage
Interchange
MDT
modified data tag
CE Customer Engineer
CK check NL new line
CNCL cancel
CPU
control processing unit
PA
program access
CRT cathode-ray
tube
PC
printed circuit
CU
control unit
PCBD printed circuit board
CW control word PF program function
POR power
on reset
DEL delete
PS
power supply
DUP duplicate SLT solid logic technology
EBCDIC
extended binary-coded-decimal interchange code
SMS
standard modular system
EC
engineering change SOR start of record
EOF end
of field
TB terminal board
FE
Field Engineering TCU transmission control unit
Ferro ferro-resonant transformer TEST REO test request
FRU field replaceable
unit
TP
test pattern, test point
GLP General Logic Probe
VOM
volt-ohmmeter
HV
high voltage
lOR identification reader
INS MODE insert
mode
I/O
input/output
Abbreviations y

LEGEND
vi
, )
I:
<>
o
v
o 7P
Terminal
Indicates beginning point of a Troubleshooting Diagram.
Action
Indicates a major action. When more than one action is described, bullet symbols appear
to left of each action.
Annotation
Gives descriptive comment or explanatory note.
Decision
Indicates a point in a Troubleshooting Diagram where a branch to alternate data paths
is pOSSible,
Probe
Indicates a point in a Troubleshooting Diagram where a logic pin should be probed with
the loqlc probe. Pin is specified in the symbol. Path to be followed after probing is
determilled by probe result.
Car d Chanqe
IndlCd(~ rhat card or cards specified in symbol should be changed and new ones installed.
()+t Paqe Connector
~f)dH,dtes connection point between different sheets of the Troubleshooting Diagrams.
Uri /)aqe Connector
Indicates connection between two parts of the same sheet or diagram. Arrow leaving
S', '!1t)C)1 points to correspondingly-numbered symbol (line-of·sight).
t\.1 I" II Data Path
Millor Data Path or Control Line
Data Bus
Nlimber of lines on bus is identified in circle.
Data Transfer
Identifies data bits transferred to or from a logic element.
Screwdriver
Adjustment
Switch

1.1 INTRODUCTION
Maintenance of IBM 3277 Display Stations (including
repair and adjustment
of Model 1 and Model 2 units) and of
attached features is described in this manual. Features that
can be attached to a 3277 include keyboards, a selector
light-pen, and an operator identification card reader.
The objective of display station maintenance is to return
the failing
unit to customer service as quickly as possible.
This manual guides the Customer Engineer through
procedures
that enable him to adjust or replace a
malfunctioning component.
1.1.1 Online/Offline Maintenance
Display Station maintenance and testing can be performed
online
and/or offline. It is better, however, to service the
unit offline when possible because it eliminates the
possibility of interaction with other units of the display
system. Unnecessary delays
in normal customer infor-
mation processing are thereby avoided. The maintenance
approach described
in this manual is structured to perform
offline analysis first to resolve reported troubles.
1.1.2 Field Replaceable Units (FRU)
Component replacement
is limited to certain field-
replaceable units (FRU). When the trouble is isolated to an
FRU
the unit should be replaced immediately rather than
repaired. The FRU parts replacement philosophy is
practical because functionally packaged logic and densely
packed components are used throughout
the display
station.
1.1.3 Troubleshooting Aids
Several tools are available
to the Customer Engineer to
simplify trouble analysis. The following paragraphs describe
these aids.
1.1.3.1 Symptom Index
The Symptom Index (Section 3) lists (by category)
malfunctions
that may be encountered on display stations.
The categories include such areas as display malfunctions,
power malfunctions, keyboard malfunctions, etc. In each
category, subcategories specify unique trouble areas. The
subcategories direct the Customer Engineer to an entry in
the Troubleshooting Diagrams (Section 4), which contain
step-by-step isolation procedures. In some cases, the
Symptom Index points directly
to a replaceable unit
causing the problem.
Section 1. Maintenance Approach
1.1.3.2 Troubleshooting Diagrams
The Customer Engineer is directed to Troubleshooting
Diagrams from
the Symptom Index. The diagrams detail
procedures
to isolate a failing F RU or an out-of-tolerance
adjustment.
The diagrams call out specific checks and
observations that shou Id be made during the diagnostic
procedure.
The logic probe test device is used in many of
the diagrammed procedures.
1. 1.3.3 Diagnostic Programs
Two types of diagnostic programs may be available to the
Customer Engineer. Diagnostic program aids are described
in Section 2 of this manual.
1.1.3.4 Customer Engineer Tool Kit
Special tools are not required to maintain 3277 Display
Stations. The basic Customer Engineer
tool kit, the IBM
volt-ohmmeter, and the logic probe can successfully isolate
most display station problems. An oscilloscope may be
required in some instances when the basic tools fail to
resolve a problem.
1.2 TROUBLE ANALVSIS
The sequence in which display station trouble analysis is
performed is important in minimizing machine down-time.
Diagram
1-1 shows the five-step procedure that should be
used
to isolate display station failures. The main points of
the display station maintenance approach are summarized
below.
1.2.1 Obvious Symptoms
Obvious symptoms are those
that do not require any
operator or Customer Engineer action
to bep>me evident.
Failures
that could cause obvious symptoms to occur
include display image quality and positioning, mechanical
problems, and component breakage. These failures should
be remedied by going directly to the Symptom Index or to
the appropriate adjustment or removal procedure in Section
5.
Use the first entry that matches the failure.
1.2.2 Isolation
to a Display Station
If an obvious symptom does not exist on a display station,
the cause
of the failure must be isolated between the
control unit and the display station. Sheet 1 of the
Troubleshooting Diagrams describes the procedure for
isolating the cause
of a failure to either the control unit,
connecting coaxial cable,
or display station.
Maintenance Approach 1-1

r--- ....... ---or--------...---------..,
I.
2,
3.
4.
,Obvious symptoms include:
'
focus,
tilt, centering,
physicol damage, etc.
Find failure in
~_.Ylie.s ____ .. ~ Symptom Index.
.J' (Use first entry
that matches failure.)
• _____ .. ~ Use Troubleshooting
Diagram,
Sheet 1.
... _____ .. ~ Use keyboard check
po (Paragraph 3.2).
Yes Find
failure in
Symptom
Index.
(Use first entry
that matches foil ure.)
.. _____ .. ~Use Test Pattern 1
,.. (Paragraph 5. 1• 1).
Yes Find
failure in
Symptom Index.
(Use first entry
that matches failure.)
Find failure in
Symptom Index .
f
,-' I
L ,':,>01- persis ...
• -----.~ (Use first entry
that matches failure.)
a>.·.: ·n 1·1. 3277 Malfltenance Approach
'·2
1.2.3 Offline Symptoms
Once it is determined that the display station is the cause of
a failure, an offline symptom should be developed. A quick
offline
test of the display station is described in paragraph
3.2.
That test should expose a repairable symptom. Stop
the test as soon as a symptom becomes evident, and match
the symptom with one listed in the Symptom Index. Use
the first entry that matches the failure. The Symptom
Index tells what corrective action should be taken.
1.2.4 Formatted Buffer Symptoms
If an offline symptom does not become evident, the entire
display station, including features, must be tested with
the
buffer formatted. The procedure described in paragraph
5.1.1 should be used with Test Pattern 1
to develop a
symptom. Stop the test as soon as a symptom becomes
evident, and match it
in the Symptom Index. Use the first
entry that matches the failure. The Symptom Index tells
what corrective action should be taken.
1.2.5 Customer-Reported Failures
It may be necessary to work with a customer-reported
failure if a
symptom cannot be developed offline or with
Test Pattern 1 using the procedures described
in the
preceding paragraphs. Try to duplicate the conditions that
existed when the customer failure occurred. Match the
duplicated symptom in the Symptom Index and perform
the corrective action indicated. Use the first entry that
matches the failure. If the originally reported failure cannot
be duplicated, it must be assumed that it was an operator
error or an intermittent failure that has failed to reappear.

This section describes the tools and programmed diagnostic
aids used
to maintain 3277 Display Stations. A compre-
hensive description of the logic probe is included because
proper
use of this tool is essential to successful display
station maintenance.
2.1 MAINTENANCE TOOLS
2.1.1 Customer Engineer Tool Kit
The Customer Engineer tool kit contains all basic tools
necessary to maintain IBM 3277 Display Stations. The
standard
IBM volt-ohmmeter (VOM) is adequate for all
voltage measurements. The meter's input impedance of
20,000 ohms per volt causes an erroneous reading when
checking
the 400V dc power supply. This effect is noted
when a check
of that power supply is called out. When
using
the VOM, all dc voltage measurements should be
referenced to dc return rather than to frame ground. DC
return and frame ground are at different levels when the
display station is not connected to a control unit.
2.1.2 Oscilloscope
In some cases of trouble analysis, it may be necessary to use
an oscilloscope. The Tektronix * model 453 oscilloscope, or
equivalent, should be used when an oscilloscope is required.
However, the logic probe
is recommended for use,
whenever possible, rather than an oscilloscope.
2.1.3 Logic Probes
Either of two styles of logic probes can be used to probe
signal levels
while using the Troubleshooting Diagrams or
FE ALDs. The older-style probe (PN453652) is described
completely in the following paragraphs and shown in
Diagram
2·1 A. The newer General Logic Probe (G LP) is
shown in Diagram 2-18. An available GLP Kit (PN 453212)
includes the GLP, standard accessories, and the General
Logic Probe Manual, SY27-0113. The manual describes the
features
of the GLP, the functions and limitations of each
feature, and acheckout procedure. (That information is not
duplicated here, so the user is referred to SY27-0113.)
A probe should be obtained from Mechanicsburg by all
Customer Engineers
who service 3270 units. Normal tool-
ordering procedures should be used to obtain the probe.
*Trademark of Tektronix, Inc.
Section 2. Tools and Diagnostic Programs
2. 1.3. 1 Description
The logic probe (Diagram
2-1 A) is a self-contained device
consisting
of an anodized aluminum tube with a red and
green indicator incorporated near the probe end. A cable
containing
two wires and SL T-type push-on terminals leads
from the sealed top end of the probe. A plastic head with a
threaded stud
is at the probe end of the device. Red and
green indicators tell the state
of the net being probed. The
three signal states
that can be distinguished are: (1) a solid
plus level, (2) a solid minus level, and (3) a pulse or the
presence of pulses. The two wires with the SL T-type
push-on connectors are attached to pins on the back of the
logic board being probed. They carry the operating voltage
(+5V dc and ground) for the probe. An oscilloscope probe
tip screws on the threaded stud at the tip of the probe. This
carries the
input signals to the indicators.
2.1.3.2 Probe Usage
To use the logic probe, a probe tip must be attached to the
threaded stud.
An SL T probe tip (PN 453163, or
equivalent) should be used. The two wires at the top of the
probe are attached to the back of the logic board being
probed. The
leads are clearly labeled: GND and +6V.
Connect the GND lead to any D08 pin, and connect the
+6V lead to any D03 pin (+5V dc). The leads are connected
to the board by pushing the connector at the end of each
lead onto the designated pin. When the last wire is
connected, the red indicator should light.
Connect the oscilloscope probe
tip to the pin designated
in the Troubleshooting Diagrams
or as determined in logic.
The
following conditions can be observed by the logic
probe:
1. Red indication
a. Probe not attached to a pin (floating condition), or
b. Plus signal on the net being probed.
2. Green indication -Ground (negative) signal on the net
being probed.
3. Red and green indication - A pulsing signal (alternately
plus and ground) is present on the net being probed.
This
condition can appear either as the red and the green
indicator pulsing on
and off, or as both indicators
seemingly on at the
same time (depending on the
frequency
of the pulsing signal). Single pulses can also be
seen.
2.1.3.3 Probe Checkout
Note: This checkout procedure applies
to the Older-style
logic probe (PN 453652). G LP checkout is described in
General Logic Probe Manual, SY27-0113, which accom-
panies the GLP.
Tools and Diagnostic Programs 2-1

Threaded Tip
Red Green
A. Older Style Probe
61
I11I1
I
J:
U
0
t=
~
.-
.....
...J N «
..J
~
0 ...J
:>
~
~
Z
~
en
J:
~
U
W
.....
Tip
Z
~
Q.
8
:>
~
~
0)
0)
B. IBM General Logic Probe
Diagram 2·1. Logic Probes
2-2
I 1II1 I
~I
I IIII I
Q.
w Z > 0 >
:> z
~
w
~
Z
~
0 0
.....
Z 0 « +
(!)
.,
<:J
Cable
Connect to any
003 pin
Push-Qn
Connectors
~@
@
.....
+
«
<:J
w
III
0
II:
Q.
u
e,:)
0
..J
..J
ct
II:
w
Z
W
e,:)
Z
.xl
.....
Cable

Power must be applied to the 3277 during this procedure.
1. Attach probe tip to probe. Use SLT probe tip PN
453163 or similar.
2. Connect probe GN 0 lead wire to any 008 pin.
3. Connect probe +6V lead wire
to any 003 pin. Probe's
red indicator should light as soon as this wire
is attached.
4. Touch probe
tip to any 003 pin. Probe's red indicator
should remain lighted.
5. Touch probe tip to any 008 pin. Probe's green indicator
should light and remain lighted
as long as probe is on
008 pin.
6. Remove probe tip from
008 pin. Probe's red indicator
should light again.
2.1.3.4 Probe Repair
The logic probe is not field-repairable. If trouble is
experienced during probe checkout, check for the following
conditions:
1. Power is applied to the 3277.
2. Probe leads are on proper source pins.
3. Proper pins are being probed.
If the above conditions are met and the probe fails to
operate correctly, obtain a new probe before trouble-
shooting the display station.
2.1.4 Alignment Mask
Alignment masks are provided for both display station
models. The mask is used during all display image adjust-
ments. Diagram 2-2 illustrates the Model 1 alignment mask
(PN 2577899), and Diagram 2-3 illustrates the Model 2
alignment mask
(PN 2565170). The mask is constructed of
thin, clear plastic. Horizontal and vertical lines printed on
the mask serve as boundaries when the display image
adjustments described
in Section 5 are being performed.
Each line
is identified by an arrow and a letter designation.
The mask
is centered against the CRT, and the tabs on
each edge are tucked under
the CRT bezel to keep the mask
~=== [±] =====
H
Diagram 2-2. Alignment Mask. Model 1
in position while adjusting the display image. When the
mask is not being used, it should be stored in or near the
display station.
2.1.5 lOR FE Test Card
This tool
(PN 2143816) is a magnetically encoded, plastic
test card which conforms to American Banking Association
specifications
in respect to size, format, and coding. A
37-character
test message is encoded on the magnetic stripe
on
the back of the card. A start-of-record (SOR) character
precedes
the message, and an end-of-card character and a
check character follow
the message. The SOR character
initiates
the read operation but is not transferred to the
display station. The card is used to check the performanct~
of the operator identification card reader. Two test cards
are shipped with each card reader.
2.2 DIAGNOSTIC PROGRAMS
Diagnostic programs provide test patterns and interactive
tests to
al ign and exercise 3277 Model 1 and Model 2
Display
Stations on both local and remote control units.
The programs reside
in the host CPU program and can be
called in by the display station when they are required. The
two diagnostic programs that apply to 3277's are Requests
for Test (RFT) and Online Tests (OLT).
Some systems may
not include OLTs since this is optional to the customer.
Most systems will have RFTs.
The following paragraphs
describe
the test patterns and the methods for calling them
in to the display station when RFTs or OL Ts are available.
2.2.1 Test Patterns
Six test patterns are included in RFTs and OLTs. Four
patterns are used to troubleshoot and align 3277 Display
Stations. Model 1 display stations use patterns 1, 2, and 5;
Model 2 display
stations use patterns 1, 3, and 5. (patterns
4 and 6 are used by printers and are
not described here.)
EBCDIC, ASCII, and World Trade Corporation display
stations use these patterns. EBCDIC test patterns are shown
in Diagrams 2-4 through 2-7. Some characters will differ
from those shown for
patterns 1 and 5 if the display station
uses the ASCII code or a WTC language. The differences for
those patterns are summarized in Diagram 2-8.
2.2.1. 1 Test Pattern 1 (Diagram 2-4)
Test Pattern 1 is a functional test that thoroughly checks
the display station. All available characters are displayed.
The pattern contains
protected data fields, numeric fields,
high-intensity fields, nondisplay fields, and selector-pen-
detectable fields. The field marked "NON DISPLAY" in
Diagram 2-4 is not displayed on the screen but is included
in the illustration to show that a programmed nondisplay
field
is in the display buffer. The audible alarm feature is
also tested by this pattern.
Tools and Diagnostic Programs 2-3

t'
B 11
H
r-
-1.
N
-----.
9 -
--
.........
0 M
J K
'-
--
480 CHAR
L
E G
F
1920 CHAR 2565170
'-
Diagram 2-3. Alignment Mask, Model 2
Paragraph 5.1.1 describes the comprehensive checkout
procedure
that uses Test Pattern 1. This pattern is also used
during
the execution of several Troubleshooting Diagrams.
2.2.1.2 Test Pattern 2 (Diagram 2-5)
Test Pattern 2 is used to align the Modell display image as
described in paragraph 5.2.1. All data is protected and
displayed in normal intensity. The audible alarm (if
installed) sounds when this pattern appears on the screen.
22.1.3 Test Pattern 3 (Diagram 2-6)
Test Pattern 3 is used to align the Model 2 image as
described in paragraph 5.2.1. All data is protected and
displayed in normal intensity. The audible alarm (if
installed) sounds when this pattern appears on the screen.
22.1.4 Test Pattern 5 (Diagram 2-7)
Test Pattern 5 loads the display station buffer with all
available uppercase and lowercase character codes. The
2-4
./
audible alarm (if installed) sounds when this pattern
appears
on the screen.
2.2.2 Requesting RFT Patterns
RFT patterns can be requested for
3277 Display Stations
attached
to a local control unit (3272) or to a remote
control unit (3271). Patterns can be requested from one
display station to be displayed on another. To display
patterns, the controlling CPU must be operating under as
BTAM (Operating System Basic Telecommunications
Access Method)
or DOS BTAM (Disc Operating System
Basic Telecommunications Access Method), and the appli-
cation program must be set up to accept test requests. The
system programmer can verify that the requirements to
request RFT patterns are met. The eight test patterns (four
EBCDIC and four ASCII) that can be requested by RFTs
and their identification numbers are listed
in Diagram 2-9.

ABCDEFGHIJKLMNOPQRSTUVWXYZ NON DISPLAY
COpy
ABOVE IN THIS LINE INSERT CK
I Q#$%¢ & ~: ( ) _ + ! ; f t <>? -= I; I / 01 234 56 789 ~ • - A
COpy ABOVE IN THIS LINE
?SEL
PEN TEST > SEL
PEN TEST ADR-6G48
(Model 1 Patternl
(Model 2 Pattern)
Notes: 1.
AOR -ctppears only when patter') Ie; called "' Irr"n ()L fEP
2. NON OISPLA Y Ie; not displayed
3. Use Olawam 2-8 to determlnP unique chilrilctp.r rr>p!.I(.;elr.~nts wiWIl A~";CII vr lllTe 1.1!)(ludges .lrE' u~ed
Diagram 2-4. Test Pattern 1 (USA EBCDIC)
ToOls and Diagnostic Programs 2·5

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
c
H H
H H
H H
H H
,H 0 00 H
H DO H
H
TEST PATTERN FOR 3275-1/3277-1 H
H ALIGNMENT H
H * UNPROTECTED AREA * H
H 0 ADR-6040 H
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
Note' AOR
appears only when pattern IS called In from OL TEP
Diagram 2·5. Test Pattern 2
Not£! AOR
dpf..H.'ars (HliV when pattern IS c<Jlled 111 from OL TEP
Diagram 2·6. Test Pattern 3
2·6

ABCD~FGHI~«+I&JKLMNOPQR!);~
STU VWxYZ ~u _ > ? : ~ ~ , =', . $ *-/, G1234 56789
ABCDEFGHIJKLMNOPQRSTUVWXYZG123456789
ABCDEFGHIJKLMNOPQRSTUVWXYZ8123456789
&-/ &-/
<;:.«+1 !$*);-, ,% >?:n0'="
<;:.«+1 !$*)j-' ,~t=>?:#Qt="
I"J/L CHECK55555
EOfVl CHECK99
(Model 1 Pattern)
Note: I Jse DlagrnJn 28 to deterrninf' unique Lhdrdcter repldU'n1t'nts ,,,,,'twn A:,\:: I l' \", T ~ 1,!fHjlJd<WS drt' lJSPU,
Diagram 27. fest Pattern 5 (USA EBCDIC)
Tools dnd Diagnostic Programs 2-7

Hex Code/Graphic
Language 4A 5A 5B 78 7C
7F 4F SF
-USA EBCDIC t ! $ # @ " I
-.,
USA ASCII-A [ ) $ # @
..
I
--,
USA ASCII-B r ) $ # fit " I
~
Austrian/German
0 U U A
ii A I
-.,
Danish/Norwegian
{lS
l 1 4- 0 4- I
--,
Finnish/Swedish 0 1 1 A 0 A I
-.,
A
cr
-0' I
.....,
Portuguese C
~
A
Spanish
~
! p+ N • N t
-.,
United Kingdom $ !
t. # @ " I
-.,
-Belgian, French, and Italian languages use t"p USA eecotC character set.
Diagram 2-8. Character Differences for ASCII and WTC L.nguages
Test Pattern
10 Number
EBCDIC ASCII
1
23
29
2 (Model 1)
24
30
3 (MocIe121
25 31
5
27
33
Diagram 2-9 Test Pattern 10 Numbers
2.2.2. 1 Local Display Stations
1. Position the cursor at the top left (character position 0)
of an unformatted screen. (One way to accomplish this
is to press the CLEAR key and then press the RESET
key.)
2. From the keyboard, enter the RFT request message in
the following format:
XXYYNCUU
where:
XX The number of the test pattern desired. Use
EBCDIC column of Diagram 2-9.
YY Any number from 01 to 99. This number
specifies the number of times the pattern
will be repeated.
N The number 3. This identifies the request as
com ing from a display station attached to a
3272
Control Unit.
CUU The three-digit hexadecimal number of the
channel (C) and the display station (UU)
address
to which the pattern is to be sent.
A/phabetic characters in the hexadecimal
number must be entered
in uppercase.
3. Press TEST REQ key. INPUT INHIBITED indicator
should come on.
4. The desired pattern should appear within 15 seconds. If
INPUT INHIBITED indicator stays on and the pattern
does not appear, proceed as follows:
2-8
a. Repeat the request while ensuring that steps 1-3 are
performed correctly.
b. Check that the operating system and the BTAM
application program are still executing.
c. Check that the STAM application program is set up
for online test requests. (The customer's _tern
programmer can provide this information.)
2.2.2.2 RemoteDisplayStations
1. Position the cursor at the top left (character position 0)
of an unformatted screen. (One way to accomplish this
is to press the CLEAR key and then press the RESET
key.)
2. From the keyboard, enter the RFT request message in
the following format:
XXYYNMMDD
where:
XX The number of the test pattern desired. Use
appropriate column of .Diagram 2·9.
YY Any number from Ol to 99. This number
specifies the number of times the pattern
witt be repeated.
N :; The number 4. This identifies the request ~s
MMOD
coming from a display station attached to a
3271 Control Unit.
The selection address characters of the
control unit (MM) and the display station
tOO) to which the pattern is to be sent.
(The release level of the operating system
bemg used determines what characters will
be
entered. Check with the customer pro·
grammer for this information.!

3. Press TEST REQ key. INPUT INHIBITED indicator
should come on.
4. The desired pattern shoUld appear within 15 seconds. If
iNPUT INHIBITED indicator slays on and the pattern
does not appear, proceed as follows:
a. Repeat the request while ensuring that steps 1-3 are
performed correctiy.
b. Check
that the operating system and the BTAM
application program are stili executing.
c. Check
that the BTAM application program is set up
for online test reQuests. (The customer's system
programmer can provide this information.)
2.2.3 Online Tests (OL Ts)
Online tests may be available, at the customer's option, to
aid in maintaining 3277 Display Stations. Detailed descrip-
tions and instructions
for using OLTs are contained in the
diagnostic program binder that is shipped with each control
unit. Control unit ML TGs also contain this information.
Most OLT routines apply
to control units. The following
three routines apply
to display stations:
1. KEY -This routine handles manually generated inter-
rupts from
the keyboard, selector light-pen, and program
function keyboard. The results
of the interrupts are
presented on
the display station screen, informing the
CE of the success or failure of the interrupt operation.
Th is routine also reads back data entered from the
keyboard to check lowercase character codes.
2. MAG -This routine tests the operator identification card
reader and identification cards.
3. PAT -This routine displays
the test patterns described in
paragraph 2.2.1. The 'test patterns appear in sequence on
the CRT after they are initially called in. An explanatory
message containing instructions
for running the test
pattern sequence precedes Test Pattern 1.
Tools and Diagnostic Programs 2-9

3.1 SYMPTOM INDEX USAGE
The Symptom Index lists trouble symptoms that could be
encountered on
3277 Display Stations and features. Illus-
trations that show both correct and incorrect display
images are also
contained in this section. Use the Symptom
Index and illustrations as the first step in a systematic
method of resolving display station problems. The index is
divided into six major categories:
1. Display malfunctions.
2. Keyboard malfunctions.
3. Selector light-pen malfunctions.
4. Power malfunctions.
5. CPU error indications.
6. Operator identification card reader malfunctions.
Some categories are divided into subcategories, making it
easier
to relate the trouble experienced to the correct item
in the index. Beginning with 1A 1, the first item that most
closely describes the display station trouble should
be used.
Categories and specific items are identified by a one-, two-,
or three-letter/number code (e.g., 1A1, 2G, or
4) in the left
column
of the index. The code specifies the entry point
into
the Troubleshooting Diagrams in Section 4.
The right column of the
Symptom Index specifies action
to take
to remedy the display station problem. That
column directs the Customer Engineer to a section trouble-
shooting diagram sheet or specifies a logic card (or cards) to
change. When more than one card is listed, isolate the
failing card by card swapping from among those specified.
Change the failing card and return
the others to stock. The
right column may also specify an adjustment procedure
in
Section 5.
Diagrams 3-1 through 3-24 show both
correct and some
incorrect display images.
The symptom Iist refers to these
illustrations
to aid in identifying display station symptoms.
As an aid
to rapid repair, diagrams that show incorrect
display images also specify
the repair action.
Section 3. SYmptom Index
3.2 DEVELOPING SYMPTOMS
Display station malfunctions should be isolated offline
unless
the trouble occurs only when operating online
through
the control unit to the host CPU. Failures of this
type are listed in Category 5 (CPU Error Indications).
Display station operations
that require a formatted buffer
for failure
symptoms to become evident are:
1. Selector light-pen operations.
2. Display intensity
control (high intensity and non-
display).
3. Protected and numeric field operations.
4. Tab operations.
5. Erase input and erase field operations.
Test Pattern 1 contains fields that test these operations.
The
test pattern may be loaded from the system as an RFT
or OLT. Symptoms that require a formatted buffer are
marked with an asterisk
(*) in the Symptom Index.
Offline symptoms should be developed by performing
the following tl..'5t sequence after the I/O signal cable is
removed.
1. Turn power on. (Always begin from a power-on reset
condition.)
2. Test cursor move keys --+,
t, ..t., +-, ~ , ~, +-' •
3. Test CLEAR key.
4. Enter four
or five characters.
5. Press Tab
(~) key.
6. Press Backspace (+-) four times.
7. Enter four characters.
8. Press Backspace (+-) four times.
9. Press
INS MODE.
10. Enter
four or five characters.
11. Test DEL key.
Stop the test sequence and go to the Symptom Index
when the first failure occurs.
Symptom Index 3-1

SYMPTOM INDEX
Symptom
Note: Bad or mIssing green wire grounds on display stations or control units can cause
failures ranging from intermittent to catastrophic. Verify proper grounding by using ground
checker
PN 9900453.
1. DISPLAY MALFUNCTIONS
A. No Display:
1. No visible light or glow on CRT. (Device Check not indicated; no cursor,
characters,
or indicators displayed.)
2.
Glow only on CRT (Diag 3-9)
B. Intensity and Focus:
1. One
horizontal line on CRT (Diag 3-10) ................ .
2.
Modell -Full raster on screen (Diag 3-11) OR
Model 2 - 24 rows of nine scan lines with space between each row (one row of
ten scan lines) (Diag 3-12) .................. .
3. Block displayed
in every character position; cursor normal (Diag 3-14).
a. INPUT INHIBITED lighted ................ .
b.
INPUT INHIBITED not lighted .............. .
I 4. Display too dim or too bright (No control of intensity), or dim and blurred (no
I
effect usi ng display focus control).
5. Characters out of focus (Diag 3-18)
*6. Dual-intensity problems
or characters displayed that should not
7. Display erratic (e.g., display flashes, characters move, more than one cursor)
8. Screen
full of lines ............. .
9. Retrace unblanked
............. .
10. Random data on screen. INPUT INHIBITED lighted
11. Cursor on
left side in all rows . . . . . . . . .
12. One
dot at character location zero cursor position
C. Display Position and Size:
1.
Horizontal size too large or too small (vertical normal) OR
Vertical size too large or too small (horizontal normal, Diag 3-8)
2. Both horizontal and vertical size too large or too small
Diagram Sheet or
Direct Action Repair
Sheet 2
Sheet 4
Sheet 4
Sheet 5
Change card J2.
Change card K2.
Sheet 5
Sheet 5
Sheet 6
Sheet 6
Sheet 6
Change cards H2, J2, K2.
Change card H
2.
Change card H2.
Change card J2.
Adjust analog card. If out
of range of adjustment,
change analog card and
card J2.
If less than 1" in either
direction, adjust analog
card.
If more than 1", or
if display size erratic,
change HV power
supply.
3.
No space between rows of characters (Model 2 only) (Diag 3-16) . . . . . .. Sheet 7
• Requ ires a formatted buffer.
3-2

SYMPTOM INDEX (Cont)
Symptom
1. DISPLAY MALFUNCTIONS (Cont)
C. Display Position and Size: (Cont)
4. Rows of characters not evenly spaced
5. Display
not centered (Diag 3-7)
6. Display tilted (Diag 3-6) . . .
D. Dlaracters:
1. No characters displayed, but cursor displayed. (See Symptom 2B4 if keyboard
Diagram Sheet or
Direct Action Repair
Change analog card
See centering procedure
(5.2.1.5).
See yoke adjustment
procedure (5.2.1.4)
problem only.) . . . . . . . . . . . . . . . . . . . . . . . . . .
.. Sheet 7
2. 0 isplay
out of sync. (Characters may be recognizable but are moving, and more
than one cursor
is seen. INPUT INHIBITED not lighted.) (Diag 3-15) Sheet 6
3. Character(s)
not formed correctly wherever displayed on screen Change card K2.
4. Screen full of quote marks (no Device Check) . . . . . . . . Change cards A2, K2.
a. Quote mark
in location 0 and cursor in location 1 after POR Replug connector inside
5. Wrong character displayed from program, keyboard,
or POR:
a. Without Device Check
b. With Device Check . . . . . . . . . . . . . . . . .
6. Data displayed that should not ............ .
7. Screen full
of one character with or without INPUT INHIBITED lighted
8. Screen slowly fills with character of last keyboard key pressed. INPUT
INHIBITED
not lighted
9. Attribute characters displayed
E. Cursor:
1. No cursor on screen, but rest of display normal (no Device Check) ..... .
2.
No cursor with INPUT INHIBITED lighted. Cursor cannot be returned to screen
by Power On Reset or CLEAR key .................. .
3. Cursor appears normally. INPUT INHIBITED lighted
........... .
4. Cursor under all
or most character positions, and Device Check indicated (INPUT
INHIBITED lighted) (Diag 3-13)
................... .
5. Cursor under all character positions, but Device Check not indicated (Diag 3-13) .
6. Cursor
not positioned correctly under a character; may be in character area
7. Cursor too long or too short . . . . . . . . . . . . . . . . . . . .
8.
No cursor, and INPUT INHIBITED not on. Partial cursor appears as each
character enters until
80 characters in row appear with partial cursor under each
character. Occurs on one row at a time . . . . . . . . . . . . . . . . . .
9. Screen slowly fills with cursors . . . . . . . . . . . . . . . . . . . . .
10. Cursor appears in three or four rows equally spaced on left side of display after
PORe Characters mayor may not enter and appear at cursor location. Display
may blink
............................. .
11.
No cursor on screen after PORe Characters may enter, but only first scan 1ine of
each row displays as character enters. (INPUT INHIBITED not lighted)
keyboard.
Change card K2.
Sheet 7
Sheet 8
Sheet 8
Change card A2.
Sheet 8
Change card K2.
Sheet 9
Sheet 9
Sheet 10
Change card K2.
Change card K2.
Change card K2.
Change card J2.
Change cards A2, C2, H2.
Sheet 10
Change card
J2.
Symtom Index 3-3