IBM 5256-1 Setup guide

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SY31 -0462-0
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IBM 5256 Printer
Models 1, 2, and 3
SY31-0462-0
Maintenance Information Manual

Preface
This maintenance manual is to be used for servicing the
IBM 5256 Printer. Customer engineers using this r,
manual are assumed to have completed the 5256 Printer
education course.
The maintenance manual is in
two major sections;
maintenance and theory. Maintenance includes
locations, procedures, and diagnostic aids. Theory
includes data flow, functional units, and features.
Setup instructions
for the 5256 Printer are in
Appendix A.
Definition
of terms and abbreviations that are not
common but used in this manual are in the glossary and
abbreviations section.
Related Publications
Related information can be found in the following
manuals:
• IBM 5250 Display Station Reference Card,
GX21-9429
IBM 5251 Display Station Model 11 Maintenance
Analysis Procedures (MAPs), SY31-0571
First Edition (October 1977)
• IBM 5251 Display Station Model 11 Maintenance
Information Manual, SY31-0461
• IBM 5256 Printer Maintenance Analysis Procedures
(MAPs), SY31-0572
• IBM 5251 Display Station Operator's Guide,
GA21-9248
• IBM 5256 Printer Operator's Guide, GA21-9260
• IBM 5256 Printer Setup Procedures, GA21-9290
• IBM 5256 Printer IR Unit and Cause Code Guide,
ZY31-0505
Note: The following pages of the MIM have danger
and caution notices.
If desired, translate these
notices and write your own words on the blank lines
provided on these pages:
1-10 1-46
1-16 1-58
1-24 1-62
1-32 1-63
1-36 1-64
1-37 1-67
1-44 4-23
The information in this manual is sometimes changed. Any changes will be given
in later editions.
Requests
for copies of IBM publications should be made to your IBM
representative or the IBM branch office serving your locality.
A Reader's Comment Form is at the back of this publication. If the form has
been removed. address
your comments to IBM Corporation. Publications.
Department 245. Rochester. Minnesota 55901. Comments become the property
of IBM.
© Copyright International Business Machines Corporation 1977

The IBM 5256 Printer has the following specific
dangers:
• The print head becomes very hot during printing.
Primary power is present at the power supply and the
Power switch.
• High voltage and current are present at the
ferroresonant transformer.
Resistor 1 (in
front under the safety cover) is very hot
while power is on.
vi
Safety

CE SAFETY PRACTICES
All Customer Engineers are expected to take every safety
precaution possible and observe the following safety prac·
tices while maintaining IBM equipment:
1. You should not work alone under hazardous conditions
or around equipment with dangerous voltage. Always
advise
your manager if you MUST work alone.
2. Remove all
power, ac and dc, when removing or assem·
bling major components, working in immediate areas of
power suppiies, performing mechanical inspection of pow-
er supplies, or installing changes in machine circuitry.
3. After turning off wall box power switch, lock it in the
Off position or tag it with a "Do Not Operate" tag, Form
229-1266. Pu II power supply cord whenever possible.
4. When it is absolutely necessary to work on equipment
having exposed operating mechanical parts or exposed
live electrical circuitry anywhere in the machine, observe
the fol.lowing precautions:
a. Another person familiar with power off controls must
be in immediate vicinity.
b. Do not wear rings, wrist watches, chains, bracelets, or
metal cuff links.
c. Use
only insulated pliers and screwdrivers.
d. Keep one hand in pocket.
e. When using test instruments, be certain that controls
are set correctly and that insulated probes of proper
capacity are used.
f. Avoid
contacting ground potential (melal floor strips,'
machine frames, etc.). Use suitable rubber mats, pur-
chased locally if necessary.
5. Wear
safety glasses when:
a. Using a hammer to drive pins, riveting, staking, etc.
b.
Power or hand drilling, reaming, grinding, etc.
c. Using spring hooks, attaching springs.
d. Soldering, wire
cutting, removing steel bands.
e. Cleaning parts with solvents, sprays, cleaners, chemi-
cals, etc.
f. Performing any other work that may be hazardous to
your eyes. REMEMBER -THEY ARE YOUR EYES.
6.
Follow special safety instructions when performing special-
ized tasks such as handling cathode ray tubes and extremely
high volta'ges. These instructions are outlined in CEMs
and the safety portion of the maintenance manuals.
7.
Do not use solvents, chemicals, greases, or oils that have
not been approved by IBM.
8. Avoid using tools or test equipment that have not been ap-
proved by IBM.
9. Replace worn or broken tools and test equipment.
10. Lift by standing or pushing up with stronger leg muscles -
this
takes strain off back muscles. Do not lift any equip-
ment or parts weighing over 60 pounds.
11. After maintenance, restore all safety devices, such as guards,
shields, signs,
and grounding wires. -
12. Each Customer Engineer is responsible to be certain that
no action on his part renders products unsafe or exposes
customer personnel to hazards.
13. Place
removed machine covers in a safe out-of-the-way
place
where no one can trip over them.
14. Ensure that all machine covers are in place before returning
machine to customer.
15. Always place CE tool kit away from walk areas where no
one can trip over it; for example, under desk or table.
16. Avoid touching moving mechanical parts when lubricating,
checking for
play, etc.
17. When using stroboscope, do not touch ANYTHING -it
may
be moving.
18. Avoid wearing loose clothing that may be caught in mao
chinery. Shirt sleeves must be left buttoned or rolled above
the elbow.
19. Ties must be tucked in shirt or have a tie clasp (preferably
nonconductive) approximately 3 inches from end. Tie
chains are
not recommended.
20. Before starting equipment, make certain fellow CEs and
customer personnel are not in a hazardous position.
21. Maintain good housekeeping in area of machine while per·
forming and after completing maintenance.
Knowing safety rules is not enough.
An unsafe act will inevitably lead to an accident.
Use good judgment· eliminate unsafe acts.
ARTIFICIAL RESPIRATION
General Considerations
1. Start Immediately - Seconds Count
Do not move victim unless absolutely necessary to remove
from danger. Do
not wait or look for help or stop to
loosen clothing, warm the victim, or apply stimulants.
2. Check Mouth for Obstructions
Remove foreign objects. Pull tongue forward.
3. Loosen Clothing -Keep Victim Warm
Take care of these items after victim is breathing by him-
self or when help is available.
4. Remain in Position
After victim revives, be ready to resume respiration if
necessary.
5. Call a Doctor
Have someone summon medical aid.
6.
Don't Give Up
Continue without interruption until victim is breathing
without help or is certainly dead.
Rescue Breathing for Adults
1. Place victim on his back immediately.
2. Clear throat of water, food, or foreign matter.
3. Tilt head back to open air passage.
4. Lift jaw
up to keep tongue out of air passage.
5. Pinch nostrils to prevent air leakage when you blow.
6. Blow until you see chest rise.
7.
Remove your lips and allow lungs to empty.
8. Listen for snoring and gurglings -signs of throat obstruc-
tion.
9. Repeat mouth to mouth breathing 10-20 times a minute.
Continue rescue breathing until victim breathes for himself.
Thumb and
finger positions Final
mouth~to
mouth position
CE Safety Practices 5256 MIM vii

SAFETY ............................•..... vi
GLOSSARY OF TERMS AND ABBREVIATIONS ......... xiii
LEGEND
................................. xvi
USING THE IBM 5256 MAINTENANCE INFORMATION
MANUAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . xvii
Glossary of Terms and Abbreviations ....
Maintenance. . . . . . . ... " ..
Wiring Diagram ....... .
Diagnostic Aids
....... .
Preventive Maintenance
.. .
Tools and Test Equipment.
Theory .......... .
Features
....
Appendix A .
Index ..... .
MAINTENANCE .............. .
SEQUENCE-AFFECTED PROCEDURES.
LOCATIONS ........... " ..... .
100 Front and Right Side Locations ....
xvii
xvii
xvii
xvii
xvii
xvii
xvii
...... xviii
.. xviii
.......... xviii
..•........ 1-1
... 1-1
.1-2
.1-2
101 Front and Left Side Locations. . . . . . . . . . . . . . .. .1-3
102 Back Locations ........................... 1-4
103 Printer Mechanism Bottom Locations (Print Mechanism
in Service Position) . . . . . . . . . . . . . . . . . . .
.1-5
104 Printer Mechanism Base Locations. . . . . . . . . . . .1-6
105 Power Supply Board A1 Locations and Jumpers. . . . . .1-7
106 Planar Board Bl Locations and Jumpers. . . . • . . . . .1-8
107 Power Adapter Board Cl Locations. . . . . .. 1-9
108 Cabling Locations and Station Protector ........... 1-10
Motor Cables (EC2 to TPBl and TPB2) .. 1-10
COVER . . . . . . . . . . . ............... 1-12
110 Printer Covers . . . . . . . . . . . . . . . . 1-12
Adjustment . . . . . . . . . . . . . . . . . . . . . . 1-12
Top Cover Removal and Replacement. . . . . . .1-12
Back Cover Removal and Replacement ............. 1-12
Front Cover Removal and Replacement ............ 1-12
111 Control Panel and
AC Cable Assembly ............ 1-13
Control Panel Removal and Replacement ........... 1-13
AC Cable Assembly Removal and Replacement ........ 1-13
SERVICE POSITIONS ........................ 1-14
115 Separating the Printer From the Power Supply Board A1
For Service Positions. . . . . . . . . . . . . . . . . . . . 1-14
116 Moving the Power Supply for Printer Servicing ..... " .. 1-16
PART NUMBERS. . . . . . . . . . . . . . . . . . . . . . . 1-16
117 Boards, Card, Interposers, and Jumpers. . . . 1-16
FORMS MOVING PARTS. . . . . . . . . .1-17
120 Platen and Paper Deflector ................... 1-17
Removal and Replacement .................... 1-17
121 Platen Latches (Release Eccentrics and Springs)
....... 1-18
Adjustment .......... " . . . . . . . . . . . . . 1-18
122 Platen Gears and Bushing. . . . . . . . . . . . 1-18
Removal, Replacement, and Adjustment. . . 1-18
123 Platen Pressure Rolls
............. .
Adjustment ......... .
124 Platen Gear Backlash (Play) ... .
Adjustment ............. .
125 Forms Motor Gear Backlash (Play)
Adjustment . . . . . . . . . .
126 Forms Motor and Emitter .
Removal and Replacement ..
Disassembly ......... .
Assembly ........... .
127 Forms Feed Emitter Disk ..
Adjustment ......... .
128 Forms Motor to Emitter Timing ..
Service Check.
Adjustment . .
129 A-Frame ...
Service Check.
Alignment ...
130 End-of-Forms Switch ..
Service Check ...... .
Adjustment ..... ' .. .
Removal and Replacement. . . .
131
Forms Tractor Unit .... .
Removal and Replacement ..... .
Disassembly and Assembly ..... .
Left
Tractor Acljustment ...... .
132 Forms Tractor Unit Chain Cover ..
Service Check .............. .
viii
Contents
· . 1-19
· ... 1-19
· ... 1-20
· ... 1-20
· ... 1-21
· ... 1-21
· ... 1-23
· . 1-23
.1-24
· .1-24
· ... 1-25
· ... 1-25
· . 1-26
· ... 1-26
· . 1-27
· ... 1-29
· •...... 1-29
· ... 1-29
· ....... 1-30
· ....... 1-30
· ....... 1-30
· ....... 1-30
.
..... 1-32
· ....... 1-32
· ... 1-32
· ... 1-33
· ... 1-33
· ... 1-33
Adjustment . . . . . . . . . . . . . . . . . . . . . . . ... 1-33
133 Forms
Tractor Unit Chain ................... 1-35
Removal and Replacement .................... 1-35
134 Forms Guide Rack Static Eliminator Replacement. . . 1-35
PRINTER EMITTER. . . . . . . . . . . . . . . . . . . . . . . 1-36
140 Print Emitter Board to Pickup and Amplifier Card . ·
.1-36
Service Check ...................... . · . 1-36
Adjustment . . . . . . . . . . . . . . . . . . . . . . . . · . 1-36
Printer
Emitter Pickup and Amplifier Removal and
Replacement ............................ 1-37
141 Print
Emitter Board. . . . . . . . . . . 1-38
Removal and Replacement. . . . . . . . 1-38
142 Print Emitter Hold Down Bracket. .. 1-38
Adjustment ..
143 Left Margin ..
Service Check.
Adjustment ..
CARRIER .....
150 Carrier Main and Support Shafts ..
Service Check .......... .
Adjustment ............. .
151 Carrier
Support Shaft ....... .
Removal and Replacement. .
152 Carrier and Main
Shaft ...
Removal and Replacement ..
153 Belt Tensioner Assembly ..
Removal and Replacement .
154 Carrier Motor and Pulley ..
Removal and Replacement ..
· . 1-38
. 1-38
· .1-38
· . 1-38
.1-40
· .1-40
· .1-40
· .1-40
· . 1-41
· . 1-41
· . 1-41
· . 1-41
· . 1-42
· ... 1-42
· ... 1-43
· •.. 1-43
· .1-43 155 Carrier Leaf Spring and Bearing
Removal and Replacement ....
. . . . . . . . . . . . . . . . 1-43

PRINT HEAD ...
160 Print Head . .
Service
Check.
Adjustment . . . . . . . . . . . .
· .1-44
· .1-44
· .1-44
· .1-44
Removal and Replacement. . . • . . . . . . . . . . 1-44
161 Print Head Forms Guide
.................... 1-45
Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . 1-45
Removal
and Replacement. . . . . . . . . . . . . . . . 1-45
162 Print Head Cable (EC1). . . . . . . . . . ....... 1-46
Removal. . • . . . . • . . . • . . . . . . . ......... 1-46
Replacement. . . . . . . . . . • . . . . . . . . . . . . . . . . . 1-47
163 Oil Felt Service. . . . . . . • • • . . . . . ........• 1-48
164 Print Head Ribbon Lifter ..••..........••..•• 1-48
Removal and Replacement
...•..........•....• 1-48
165 Print Head Ribbon Shield ...........••.....•• 1-49
Service Check ..........••••..•.•......•• 1-49
Removal, Replacement, and
Adjustment .•••.•••...• 1-49
166 Copy Control Dial .........•.•.•...•••.••. 1-51
Removal
and Replacement .....••...•..•....•. 1-51
167 Print Head Retract Ramp. . . . . . . . . ....... 1·51
Adjustment. . . . .. . . . . . . • . . . . ..... 1·51
RIBBON DRIVE
.................•......... 1·52
170 Ribbon Drive ........................... 1-52
Removal and Replacement. . . . . . . . .
... 1-52
171 Ribbon Drive
Clutches. . . . . . . . . 1-52
Removal and Replacement. . . . . . 1-52
172 Ribbon Drive Shaft. . . . . . . . . . . . . 1-52
Removal and Replacement. . • . . . . . 1-52
173 Ribbon Drive Lines. . . . . • . . . . . . . 1-52
Removal and Replacement. . . . • . . . . . . . . . . . . . 1-52
174 Ribbon Feed Rolls. . . . . . . • . . . . . . . . . ..... 1-54
Service Check
.......... .
...... 1-54
Adjustment . . . . . . . . . . . . ...... 1-54
Removal and Replacement. . . . . . . . . . . . 1-54
175 Ribbon Drive Gears . . . • . . . . . • . . . . . . . . . . . . . 1-54
Removal and Replacement
..•••....•••.•...... 1-54
176 Ribbon Box and Cover ..•.......•••. ~ ...... 1-54
Removal and Replacement. . . . . . . . . . . • . . . . . . . . 1-54
177 Ribbon Changing .......•......•.•....... 1-55
. POWER AND ELECTRONICS •.•.•.••••••....... 1-57
180 Power Supply .••..•.•.....• _ •••....•... 1-57
Removal and Replacement. . • • . . . . . . . • • • • . _ . . . 1-57
Ripple Level Check ....••••.•..•..... _ . __ • _1-57
181 Power
Transformer .••..••..........•..... 1-58
Removal and Replacement __ • . . • . • • • . • . . . . •••• 1-58
182 Fans ...................•........•.•• 1-60
Fan B1 Removal and Replacement ........•...••• 1-60
Fan B2 Removal and Replacement ................ 1-60
183 TB2 and Line Filter ....................... 1-60
TB2 Removal and Replacement ................. 1-60
Line Filter Removal and Replacement. ~ ........... 1-60
184 Power Adapter Board C1 and Capacitor Assembly ..... 1-62
Capacitor Service Check. . . . . . . . . . ......... 1-62
Removal and Replacement. . . . . . . . . . . ....... 1-62
185 AC Capacitor (C12) and Capacitor C3 .......... 1-63
C12 Removal and Replacement ................. 1-63
C3 Removal and Replacement. . . . . . .. . ....... 1-63
186 Power Supply Board A1 and Cable .......... 1-64
Removal and Replacement ..................... 1-64
187 Transistor (Q1). ......................... 1-65
Service
Check. . . . . . . . . . . . ......... 1-65
Removal and Replacement. . -. .
188 Planar Board B1 ...... .
Removal and Replacement. .
189 Printer Wiring Diagram ...
· ......... 1-65
· ......... 1-67
· ......... 1-67
.
........... 1-68
DIAGNOSTIC AIDS.
· ... 1-70
190 Power on Diagnostic .............. . ·
... 1-70
191 Offline Tests .... . ·
... 1-74
Print Test (PRT04) ........... . .
........... 1-74
Carrier Motor (PRT05) ......... . · . 1·75
Forms Motor (PRT06) ..
......... 1-75
Alignment (PRT07). ...
Print Character Set (PRT08). ..
Print Receive Buffers (PRT09) .
Left Margin Recognition (PRT10) .
Printer Characteristics Display (PRT11) ....
Data Storage (PRT12) ......... .
Address Switches (PRT13).
...... .
Set Transparent Mode (PRT14) .. .
Print WireslTab (PRT15).
192 Online Tests ............ .
Online Tests Overview
....... .
Matrix Printer Verification
Test (Online Exerciser) •.
Matrix Printer Verification Test Printout ....••.
Matrix Printer Verification Test (Online Exerciser)
· . 1-75
· . 1-76
· ... 1-77
· ... 1-77
· . 1-77
· . 1-78
· .1-78
· . 1-78
· . 1-79
· .1-80
· . 1·81
·
.1-82
· .1-86
Printout in Transparent Mode (Partial) . . . . . . . . . . 1.87
Fierd Definition
of Error History Table (Sample Printout) . 1-88
193 Error Codes, Lights, Switches, and Test Points. . • . 1-89
Error Codes and Descriptions . . . . . . . . . . . . . . 1-89
Lights. . . . • . . . . . • . . . . . • . . . . . . . . . . . 1-90
Control Panel Switches. . . . . . . . . . . . . . . . .. 1-93
Test Points. . . . . . . . . . . • . . . . . . . . . . . . . 1-93
195 Print Quality and Registration Problems ........•.. 1·94
Print Quality Problem Examples ................ 1-94
Registration Problem Examples •................ 1-95
196 Probe, Probing Information, and Interposer Check ..... 1-96
Probe Setup and Accessories. . . . . . . . . . . . . . . . . . . 1-96
Probe Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-96
Probe Test .............•............... 1-96
Probe Light Conditions ..•.......•.....•..... 1-96
Probing EC1, EC2, and C1A1 .................. 1-96
Continuity Check for Interposers ................ 1-97
Removing Wire From Plugs P2, P3, P4, and P5 ......•. 1-97
PREVENTIVE MAINTENANCE •••••••.•.•.•...••• 2·1
TOOLS AND TEST EQUIPMENT ••••••....••..•••• 3-1
General Logic Probe ........................ 3-1
Standard CE Tool Kit . . . . . . . . . . . .......... 3-1
Metric Tool Kit ........................... 3-1
Contents 5256 MIM ix

THEORY ••••••••.•••••••••.••••••••••••• 4-1
INTRODUCTION ................ '. . . . ..... .4-1
Printer Operation Overview and Data Flow ............ .4-2
System Configuration
Cable Adapter. . . . . . . . .
Frame Concept
....... .
Transmission Sequences
.. .
Commands. . . . . .
~ . . . .
Poll Response Frames ..
Read Status Response Frame ..... .
Printer SCS Formatting Control Characters ..... .
Set Graphic Error Action Summary ..•.....
Set Horizontal Format Summary ..
Set Vertical Format Summary ....
Interface ........... .
Poll for Status. . . . . . . . .
Write Data
...
Data Transfer .
Microprocessing Unit
...
Read/Write Storage. .
Internal Processing Queues ..
Control Panel and CE Lights .....
Sense Latches. . . . . . . . . . . . .... .
Print Emitter Control and Print Timings ... .
Power and Signal Distribution ..... .
Power On and Power Off Timings ... .
Print Timings ........ .
Printer to Adapter Interface.
Functional Parts ..
Motors .. .
Print Head .. .
Carrier· .............•.......
Print Emiiter and Print Emitter Pickup .. .
Ribbon Drive . . . . .
.. . ..... .
Forms Feed
....... .
.4-5
.4-6
.4-6
.4-7
.4-8
· . .4-9
· .4-10
· .4-11
· .4-12
· .4-12
· .4-13
· .4-13·
· .4-13
· .4-13
• .4-14
· .4-15
· .4-15
· .4-15
· .4-17
· .4-17
· .4-18
· .4-20
· .4-20
. ... 4-19
· . 4~22
· .4-23
· .4-23
· .4-25
· .4-33
· .4-34
• .4-36
· .4-37
Forms Tractor Unit ... . . ............... 4-41
FEATURES .•••.•••••.••••••..•••.•••..•.• 5-1
Cable Thru. . . .5-1
Audible Alarm .............................. 5-2
APPENDIXA. SETTING UP THE IBM 5256 PRINTER .••. A-1
SECTION 1. Standalone Checkout. . . . . . . . . . . . . . . . . A-2
CABLE THRU FEATURE ...................... A-7
SECTION 2. CONNECTING TO THE SYSTEM. . A-8
PROBLEM CHECK LIST ...................... A-11
x

Glossary,
Seq.
Affected, 0
Locations
Remove, Replace,
Adjust Wiring Diagram,
Diagnostic Aids
Preventive
Maintenance,
Tools
and
Test Equipment
PM, Tools
o
Theory,
Features
Appendix,
Index
xi

xii
This page is intentionally left blank.

This list includes words and abbreviations used in the
MAPs
as well as those used in this manual.
A-frame: The part of the printer that supports the
platen and pressure rolls.
ALU: Arithmetic and logic unit.
amp: Amplifier.
amplifier (amp and AR): A device used to increase the
size
of a signal.
AR: Amplifier.
AR-DF: Differential amplifier.
AR-MD: Amplifier for driving magnets.
ASCII: American National Standard Code for
Information Interchange.
backiash: Gear play.
belt tensioner: The part that gives tension to the drive
belt.
blows, blown (fuse): Open or opens.
buffer: A small special storage device.
C: capacitor.
carrier: The part of the printer that carries the print
head and ribbon box.
CE: Customer engineer.
chk: Check.
com: The common connection on a switch.
compression spring: A spring that is pressed into a
small space so
that it can supply force.
CR: Diode.
crooked: Skewed; not straight; sloping.
Glossary, Seq.
Affected, Loc,;
Glossary of Tenns and Abbreviations
deflector: A part that moves something away.
detenting: Locking.
dr: Drive.
EBCDIC: Extended binary coded decimal interchange
code.
EC: Engineering change.
emitter: A device that generates pulses of electricity.
EOM: End of message.
EOQ: End of queue.
E1, E2, E3: Print emitter pulses.
FB
(fuse): A fuse that opens the circuit with no delay.
FF:
Form-feed switch.
FL: Latch (flip latch).
frame: A 16-bit group that carries information.
FRU: Field replaceable unit.
GLP: General logic probe.
gnd: Ground.
10: Identification.
interposer: A small connector with pins on both sides
(see reference 196).
IRS: Interchange record separator.
J: Jack.
LF: Line feed switch.
line turnaround: See the System Theory Maintenance
Diagrams manual.
MAPs: Maintenance analysis procedures.
MHz: Megahertz.
Glossary of Terms and Abbreviations 5256 MIM xiii

microprocessor: Microprocessing unit.
MIM: Maintenance information manual.
mini-MAPs: MAPs 0500 through 0516.
miscellaneous MAP: A MAP that guides you in replacing
parts sequentially when all other
MAPs have failed to
locate the problem.
MPU: Microprocessing unit.
Multi: A switch setting on the general logic probe.
N: Not (inverter).
N/C: Normally closed point of a switch.
N/O: Normally open point of a switch.
osc: Oscillator.
P: Plug
pickup: A device that senses electrical pulses.
planar: The electronic board that contains the MPU,
character generator, cable adapter, control storage,
control panel adapter, printer adapter, data storage, and
the offline tests.
poll, polled, polling: To question a station to determine
if it is ready to send or to receive data.
POR: Power on reset.
power on transition bit: A bit sent to the controller to
indicate that power is on in the printer.
pressure rolls: Rubber rollers that press paper against
the platen
of the printer.
prt: Print.
pulsing: A distinct change between the on and off
conditions of the lights on the general logic probe.
pwr: Power.
Q: A symbol for transistor.
r: Reset.
reg: Register.
xiv
reinstall: Put back the part that was removed.
remove: Take a part off the printer.
replace,
replaced: Put a new part back in place of one
that was removed.
retract ramp: The metal blade that moves the print
head away
from the platen when the carrier is moved as
far as possible to the left in the printer.
ribbon drive lines: The material that is wrapped around
the ribbon drive clutches to drive them when the carrier
is moved.
s: Set
S8 (fuse): A fuse that opens the circuit after a delay.
SCS: SNA character string.
SOLC: Synchronous data link control.
serv: Service voltage or ground.
short: Shorted or grounded circuit.
sideframe: A plate on each side of the printer
mechanism.
SL T:. Solid logic technology.
SNA: System network architecture.
solid: A continuous failure or indication.
SP: Stop.
ST: Start.
static eliminator: A printer part (reference 100 II> that
attaches to the forms rack. The static eliminator
removes electrical
c~arges that build up when the forms
move through the printer.
stepper motor: A motor that moves in regular steps.
synchronization:
Two or more events occurring at the
same time.
stuck: Unable to move.
TO: Time delay.
TP: Test point.

TPB: Taper pin block.
tractor chains: The parts on the tractor that protrude
through the forms.
transition: Changing from active to inactive or from
inactive to active.
twinaxial: A cable made of two twisted wires inside a
shield.
Vac: Volts alternating current.
Vdc: Volts direct current.
Glossary, Seq.
Affected, Loc ..
Glossary of Terms and Abbreviations 5256 MIM xv

Legend
o
(--)
Decision Block
Information Block
Note Block
On-Page Connector
Off-Page Connector
Start
or End
of Flowchart
Display Screen
xvi

Using the IBM 5256 Maintenance InfonnationManual
The information in this manual is to be used as
reference material when diagnosing machine failures.
The maintenance information manual contains
maintenance procedures, diagnostic aids, theory, and
high level logics.
An appendix gives general information
that is not directly associated with the maintenance of
the 5256 Printer (information such as setup procedures).
This manual is engineering change controlled and
will be
revised
as needed to give you the latest information
possible for diagnosing problems.
The format for page numbering is X-YVY.Z. X is the
section number, YYY is the page number, and Z
(although
not n.ormally used) is for expansion when it is
not practical to give new numbers to all pages.
Reference methods used in the maintenance information
manual are:
MAP 3-digit reference numbers
-Page-to-page
On-page
MAP 3-digit reference numbers are assigned to location
drawings and maintenance procedures to reference from
the MAPs. For example, 127 indicates the forms feed
emitter disk adjustment.
Page-to-page references in a
section are
to the specific page containing the
information. For example,
see page 4-15. On-page
references are: this page, see below, ·etc. For figures
with named or numbered parts, the reference is to the
specific number
or name of the part.
Glossary of Terms and Abbreviations
This section contains definitions of terms and
abbreviations
that are not common, but are used in the
MIM and MAPs.
Glossary, Seq.
Affected, Loc
..
Maintenance
This section contains location drawings and maintenance
procedures
for repairing or installing FRUs that the
MAPs diagnosed as failing. The location drawings are
of 2 types: a reference drawing showing the major
functional units, and detail location drawings showing
the FRUs in a functional unit. Maintenance procedures
are service checks, removals, replacements, and
adjustments. All procedures have
3-digit reference
numbers assigned
to reference from the MAPs.
Wiring Diagram
A wiring figure shows point-to-point wiring between
the individual electrical FRUs in the printer.
Diagnostic Aids
This section contains diagnostic program descriptions,
how to use them, and what is available when they are in
control. To aid in diagnosing machine failures in greater
detail, a list if error conditions is included in this section.'
Preventive Maintenance
Parts needing regular service are described in this
section.
Tools and Test Equipment
The tools needed to service the printer are described in
this section.
Theory
The theory section contains descriptions of the
functional units and features. These descriptions are
preceded by a
view of the system that gives you a
general idea of the complete operation and where each
function or feature
fits in.
Using the MIM 5256 MIM xvii

Features
The features section describes the operation of features
for the printer.
Appendix A.
Appendix A contains the setup procedures.
Index
The index is a detailed list of all material in the
maintenance information manual.
xviii

Sequence-Affected Procedures
Following is a list of sequence-affected procedures.
Enter each list at any point, but perform all indicated
operations from the entry point to the end of that list.
126 Forms Motor and Emitter Disassembly
125 Forms Motor Gear Bac~lash (Play) plus
127 Forms Feed Emitter Disk Adjustment
128 Forms Motor to Emitter Timing
124 Platen Gear Backlash (Play)
End
121 Platen Latches (Release Eccentrics and Springs)
Adjustment or
129 A-Frame Alignment (see next list also)
124 Platen Gear Backlash (Play)
End
123 Platen Pressure Rolls Adjustment or
129 A-frame Alignment (see preceding list also)
130 End-Of-Forms Switch Adjustment
Glossary, Seq.
Affected, Lac ..
End
Maintenance
140 Print Emitter Board and Print Emitter Board
to Pickup and Amplifier Card Removal and
Replacement or
141 Print Emitter Board Removal and Replacement or
152 Carrier and Main Shaft Removal and Replacement
151 Carrier Support Shaft Removal and Replacement or
162 Print Head Cable Removal and Replacement or
140 Print Emitter Board and Print Emitter Board to
Pickup and Amplifier Card Adjustment
143 Left Margin Adjustment
End
164 Print Head Ribbon Lifter Removal and
Replacement or
166 Copy Control Dial Removal and Replacement or
160 Print Head Removal and Replacement
160 Print Head Adjustment
End
Maintenance 5256 MIM 1-1

1-2
Locations
100 FRONT
AND RIGHT SIDE LOCATIONS
II Static Eliminator
III
Oscillator, J3
II
Forms Tractor Unit Rack
II
Fine Adjustment Mounting Screw
II
Rollers
IE
Print Emitter Support
..
Right Tractor Release Knobs
1&
Carrier Motor and Pulley
II
Address Switches
II
Safety Lable
II
Cable Connectors
III
Safety Cover
II
Audible Alarm
'm
Guide (ribbon box)
II
Paper-Advance Knob
II
Print Head Retract Lever'
B Forms Tractor Drive Gear
fI1
Paper-Advance Knob
m TPB2 fIl Ribbon-Advance Knob
III
TPB1
'til
Ribbon Release Lever (in operate position)
III
Horizontal Fine Adjustment Knob m Left Tractor
II
P3

101
FRONT AND LEFT SIDE LOCATIONS
..
End-of- Forms Switch
II
Platen-Release Lever (Latch) (2)
D
A-Frame
II
Power Supply
II
Platen
II
Print Head Forms Guide
II
Planar Board
II
Paper Release Lever
II
Platen Gears
m Idler Gear
III
Ribbon Box
IE
Print Head Cover
III Control Panel
End-of-Forms
Switch
COMO
N/O
N/C
III
IE
m
II
lID
III
m
II
til
til
fI
m
m
Copy Control Dial
Connector
EC3 (under the cover)
Oil Felt
Carrier
Ribbon Drive Lines
(2)
Print Emitter Board Assembly
Hold
Down Bracket
Retract Ramp
Drive Belt
Carrier Main Shaft
Platen Pressure Rolls
Connector J 1
Connector
P1
-----m
~----im
Top
802 002
~ EC3
100,101
Glossary, Seq.
Affected, Loc ..
Maintenance 5256 MIM 1-3