Radio Shack TRS-80 User manual

Radio /haek
Service
THIS BELONGS TO SHOP #7714
RADIO SHACK COMPUTER CENTER
CHATHAM PLAZA SAVANNAH, GA 314(36
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ILINE PRINTER
Catalog Numbers
26-1150
and
26-1152

NOTE
The purpose of this manual is twofold. It provides the owner with complete
adjustment procedures and it provides Radio Shack Service Personnel with
complete repair procedures.
If you are not technically inclined, do not attempt to repair your Printer. If
you do, you'll void your warranty.

TABLE OF CONTENTS
SECTION PAGE
SECTION 1
INTRODUCTION
1.1 General Description 1-1
1.2 Printer Operation 1-1
1.3 Specifications Summary 1-3
SECTION 2
THEORY OF OPERATION
2.1 Introduction 2-1
2.2 Block Diagram Discussion 2-1
2;3 Initializing the Printer 2-2
2.4 Data Input 2-3
2.5 Character Printing 2-3
2.6 Carriage and Ribbon Movement 2-5
2.7 Paper Motion 2-6
2.8 Power Supplies 2-7
SECTION 3
PRINTER ASSEMBLIES
(REMOVAL/REPLACEMENT AND ADJUSTMENT PROCEDURES)
3.1 Introduction 3_1
3.2 Printer Subassemblies 3_1
3.3 Cover Assemblies 3.5
3.4 Print Head Assembly 3.6
3.5 Video Amplifier Assembly 3.7
3.6 Ribbon Cartridge Assembly 3.9
3.7 Carriage Assembly 3_10
3.8 Drive Motor Assembly 3_1
2
3.9 Platen Drive Assembly 3.13
3.10 Platen Assembly 3_15
3.11 Pinch Roller Assembly (26-1150) 3-17
3.12 Column Scale/Tear Bar Assembly 3_19
3.13 Tractor Drive and Pin Feed Assemblies (26-1 152) 3-20
3.14 Control Panel Assembly 3. 22
3.1 5Primary Voltage Assemblies 3.23
3.16 Electronic Module Assembly 3. 25
3.1 7Logic Board Assembly 3.26
3.18 Hardware Kit 3.28
3.1 9Special Tools 3.28
SECTION 4
MAINTENANCE
4.1 Recommended Tools 4_1
4.2 Preventive Maintenance 4_2
4.3 Troubleshooting Guide 4.3
4.4 Engineering Drawings 4.3
APPENDIX A
PARALLEL INTERFACE SPECIFICATIONS
APPENDIX B
SIGNAL GLOSSARY

LIST OF ILLUSTRATIONS
FIGURE PAGE
1-1 Line Printers 1-1
1-2 Basic Block Diagram 1-1
1-3 Character Printing/Paper Motion 1-2
2-1 Simplified Block Diagram, Electronics 2-1
2-2 Initializing the Printer 2-2
2-3 Data Input 2-3
2-4 Character Printing 2-4
2-5 Carriage and Ribbon Movement 2-5
2-6 Paper Motion 2-6
2-7 +5 VDC Power Supply 2-7
2-8 -12 VDC Power Supply 2-8
2-9 +35 VDC Power Supply 2-8
3-1 Printer Subassemblies 3.
2
3-2 Cover Assemblies 3.4
3-2A Print Head Assembly 3-6
3-3 Penetration Control Adjustment, Print Head Assembly 3-7
3-3A Kit, Video Amplifier Assembly 3-8
3-3B Kit, Ribbon Cartridge Assembly 3.9
3-4 Carriage Assembly, Removal/Replacement 3-10
3-5 RTPand EOP Actuator Arm Adjustments 3-11
3-5A Kit, Drive Motor Assembly, Removal/Replacement 3-12
3-6 Drive Motor Assembly Adjustments 3-13
3-6A Kit, Platen Drive Assembly 3. 14
3-7 Platen Drive Assembly, Adjustments 3_14
3-7A Kit, Platen Assembly 3_1
6
3-8 Platen Assembly Adjustment 3-16
3-8A Kit, Pinch Roller Assembly (26-1150) 3-18
3-8B Column Scale/Tear Bar Assembly 3_19
3-8C Tractor Drive and Pin Feed Assembly (26-1 152) 3-20
3-8D Tractor Drive Timing Belt Tension (26-1 152) 3_22
3-8E Paper Travel Adjustment, Tractor Drive (26-1 152) 3-22
3-8F Control Panel Assembly 3.23
3-8G Kit, Primary Voltage Assembly 3.24
3-8H Electronic Module Assembly 3.25
3-8 1Kit, Logic Board Assembly 3_26
3-9 Deleted
3-10 Deleted
3-1
1
Line Lengths 3.27
3-12 Kit, Special Tools 3_28
4-1 Schematic Diagram, Electronics Board 4.4
4-2 Schematic Diagram, Video Amplifier 4.5
4-3 Wiring Diagram, Printer 4.6
4-4 Wiring Diagram, Primary Voltage 4.7
Assembly Diagram, Electronics Board 4.8
4-5
4-6 Assembly Diagram, Video Amplifier 4.9

SECTION 1
INTRODUCTION
This Service Manual describes two Line Printers (Catalog Numbers 26-1150 and 26-1152) that are manufactured for Radio
Shack. The manual provides ageneral description of the units, followed by amore detailed theory of operation and spare
parts information enabling field engineering personnel to service these printers. The manual is aimed at subassembly level
maintenance.
For convenience. Operator's Manuals are published separately which describe all operator controls and functions. This Service
Manual is subdivided into the following sections, each with its specific purpose.
SECTION 1-INTRODUCTION, presents the scope and content of the manual and provides the reader with ageneral
description of the printer.
SECTION 2-THEORY OF OPERATION, provides adescription of each functional operation in the printer, based on
asubassembly level.
SECTION 3-PRINTER ASSEMBLIES: REMOVAL/REPLACEMENT/ADJUSTMENT, contains afunctional descrip-
tion, removal/replacement/adjustment and maintenance procedures for each replaceable subassembly in
the printer.
SECTION 4-MAINTENANCE, includes preventive maintenance and troubleshooting procedures, as well as schematic
and wiring diagrams of the printer.
APPENDIX A-PARALLEL INTERFACE SPECIFICATIONS, contains detailed information describing the standard
interface timing signals, connectors and other specifications.
APPENDIX B-SIGNAL GLOSSARY, provides atable of signal names, by mnemonic code, keyed to the Line Printer
Electronics Board Schematic Diagram.
NOTES
The TRS-80 Line Printers are just two of aseries of Line Printers. It is the intent of this manual to provide
information only for the TRS-80 Line Printers. These printers are basically the same; the primary difference is
in the type of paper feed assemblies. The 26-1150 printer has apinch roller assembly and the 26-1152 has a
tractor drive assembly. Where applicable, aprocedure or description pertaining to either paper feed mechanism
will be identified by Catalog Number.
Part Numbers refer to the Manufacturer's Part Number, which may be obtained directly from Radio Shack's
National Parts Department.
Ill

1.1 GENERAL DESCRIPTION (Figure 1-1)
The printers shown in Figure 1-1 are 60 character-per-second, uni-directional impact printers with an effective throughput of
21 to 90 lines per minute at 10 characters per inch; and up to 132 columns of operator variable density (10 to 16.5 characters
per inch). The pinch roller (26-1150) unit prints in 8inch lengths on roll paper up to 9.8 inches (250 mm) wide, while the
tractor drive model (26-1152) prints in 8inch lengths on paper 12.1 inches (307 mm) wide.
PINCH ROLLER
(26-1150)
TRACTOR FEED
(26-1152)
Figure 1-1. LINE PRINTERS
Characters are formed in a5x7 dot matrix. In addition to the standard ASCII, avariety of character sets give great flexibility
in character formation. The printer will accommodate up to 64 characters.
All the electronics, including logic driver circuits and power supplies, are contained on asingle printed circuit board.
1.2 PRINTER OPERATION
The printer contains aline buffer which allows parallel data to be received at rates up to 75,000 characters per second. A
basic block diagram of the printer is shown in Figure 1-2.
CONTROL
PANEL
t
CONTROL
1. PRINT COMMAND
(CROR LAST CHAR.
1
2. PAPER MOVEMENT
(LINE FEED)
3. SPECIAL FUNCTIONS
(MOTOR CONTROLI
HEAD MOTION CONTROL CARRIAGE
ACTIVATOR
SOLENOIDS
DATA PAPER MOTION CONTROL LINE FEED
SOLENOID
INPUT
TIMING
*
LINE
BUFFER CHARACTER
GENERATOR WRITE PRINT
HEAD
PULSES
Figure 1-2. BASIC BLOCK DIAGRAM
Basically, all printer functions can be grouped into one of two categories: (1) character printing, and (2) paper motion.
1-1

1.2.1 CHARACTER PRINTING (Figure 1-3)
Line Printer characters are printed by selectively activating the seven print wires aligned in avertical column in the print
head. As the print head moves across the paper, the appropriate print wires are momentarily activated driving them against
the ribbon, paper and platen to form the specified dot pattern.
The print commands to the seven print wires are developed by the read-only-memory (ROM). Avariety of character sets is
obtainable simply by changing the ROM. Each character within aROM is addressed by a7-bit character code and each
column within acharacter is specified by timing signals internal to the printer.
As shown in Figure 1-3, the print head and ribbon cartridge are attached to the carriage assembly. By activating either of the
two carriage solenoids, the carriage attaches to acontinuously rotating band. Activating the forward carriage solenoid attaches
the carriage to the upper half of the band and moves the print head in the forward (left to right) direction. Activating the
reverse carriage solenoid, attaches the carriage to the lower half of the band and moves the head in the reverse direction.
PRINT HEAO
PLATEN
KNOB
-DRIVE MOTOR
Figure 1-3. CHARACTER PRINTING/PAPER MOTION
1.2.2 PAPER MOTION
Paper can be moved manually by pushing in and rotating the platen knob, or automatically by performing aline feed opera-
tion.
As shown in Figure 1-3, power from the drive motor is applied via aline feed clutch to the platen and forms handling mech-
anism (pinch roller or tractor) drive gears. Paper is advanced one line by momentarily activating the paper motion solenoid in
the line feed clutch, allowing the drive gears to turn and advance the paper by one line.
1.2.3 SPECIAL FUNCTIONS
In addition to printable character codes, the printer also recognizes four special control codes-. Refer to subsection 2.4.2 for
these control codes and the printer action performed upon receiving these codes.
1-2

1.3 SPECIFICATIONS SUMMARY
DATA INPUT
Data Format 7bit ASCII parallel
Input Code 64 character ASCII
Data Rate Up to 75,000 characters per second
Buffer One-line character buffer (up to 132 characters)
Input Gating Data Strobe is normally gated with acknowledge of previous
character.
PRINTING
Printing Method Impact, character-by-character, unidirectional
Dot Matrix 5x7
Print Format 10 to 16.5 characters per inch (operator adjustable)
Print Rate 60 characters per second at 10 cps
100 characters per second at 16.5 cps
Number of Copies
26-1 150 Prints original and one carbon copy
261 152 Prints original and up to four carbon copies
Character Set Standard 64 character ASCII. Optional 5x7, 64 character sets
available
PAPER ADVANCE
Vertical Format 6lines per inch
Paper Entry Rear Paper Feed
Auto Line Feed Automatic line feed on carriage return. Disable by option
Paper Feed
26-1150 9.8 inches (250 mm) wide paper
26"1152 12.1 inches (307 mm) maximum width
10.2 inches (259 mm) maximum print width
CONTROLS/INDICATORS
Switches Print and Power
Indicators Power
Manual Controls Forms Thickness, Paper Advance, Print Density
PHYSICAL/ENVIRONMENTAL/ELECTRICAL
Height 8inches (203 mm)
DePth 19.5 inches (495 mm)
Width 19.8 inches (503 mm)
Weight 45 lbs (20 kg)
Temperature
Operating 40° to 100°F (4.4° to 37.7°C)
Storage _40° to 140°F (-40° to 60°C)
Humidity
Perating 20% to 90% (No condensation)
Storage5% to 90% (No condensation)
Input Voltage 60 Hz, 120 VAC
1-3

SECTION 2
THEORY OF OPERATION
2.1 INTRODUCTION
This section contains adescription of each major function performed by the Line Printer electronics. This section is organ-
ized as follows:
2.2 Block Diagram Discussion
2.3 Initializing the Printer
2.4 Data Input
2.5 Character Printing
2.6 Carriage and Ribbon Movement
2.7 Paper Motion
2.8 Power Supplies
Each function is discussed at asubassembly level, supplemented with block diagrams showing signal flow between major
subassemblies and the connector/pin locations of each signal. Figure 2-1 is asimplified block diagram of the overall printer
electronics.
"1
1
1ELECTRONICS BOARD
1
POWER
DRIVERS 1
1>MEMORY
(RAMI
f
>CHARACTER
GENERATOR
(ROM)
K\
INTERFACE
CONNECTOR 1
1
DATA 1-DATA 7>>CG1-CG7 >PRINT HEAD
'LV/*- jVSOLbNUtUS
ADDRESS TIMING
INPUT
CONTROL
LOGIC
LINES
DATA INPUT (OATA l-DATA 71 —
^
LF orCR
1
1
1
1
1
1
DATA STROBE ADDRESS
COUNTER
STROUT PRINT
CONTROL
LOGIC
HEAD MOTION \CIP.CIR 1T
1
1
1
i
1
1
I
DSTA y
PRINT
ACKNOWLEDGE.BUSY
COMMAND ITIMING
INPUTS LINE FEED
SITY
PMSOL 1T0
1
1
i
'
i
1
1
OCSILLATOR 5DEN
L
CONTROL
PANEL MARGIN
INDICATOR'S
Figure 2-1. SIMPLIFIED BLOCK DIAGRAM, ELECTRONICS
NOTE
THE NOTATION (N) AFTER ASIGNAL MNEMONIC IS USED TO INDICATE THE "NOT" OR INVERSE
FUNCTION OF THE SIGNAL. FOR EXAMPLE: CIP (N) IS THE NOT FUNCTION OF THE CIP SIGNAL. THE (N)
NOTATION IS EQUIVALENT TO THE BAR APPEARING OVER ASIGNAL AS SHOWN ON THE SCHEMATIC.
2.2 BLOCK DIAGRAM DISCUSSION (Figure 2-1)
The unit is aunidirectional printer, whose print head moves to the right when printing and left when returning the carriage.
The seven print wires in the print head are selectively activated to form the dot matrix pattern for the specified character.
The print commands to the seven print wires are developed by the character generator which consists of aread-only-
memory (ROM). Attached to the carriage assembly are the print head and ribbon cartridge. By activating either the forward
or reverse carriage solenoid the carriage attaches to acontinuously rotating fibre band. The forward solenoid is activated
during the print cycle and the reverse solenoid is activated to return the carriage. Paper is advanced one line by momentarily
activating the paper drive solenoid in the line feed clutch unit.
The Line Printer electronics is contained on one printed circuit board. As shown in Figure 2-1, printable data goes from left
to right across the diagram to the print head, with control of this data coming from the input control logic and the print
control logic. When the printer is first turned on, the printer logic is initialized and the printer is not print enabled. To receive
data, the printer must then be enabled by depressing the PRINT rocker switch on the operator's panel.
2-1

If the printer is print enabled and not busy, the input data is loaded into the printer by the data strobe from the input device.
The printer responds with an acknowledge pulse to acknowledge reception of the data. Printable data, after being inverted
by the input gating, is loaded into the Random Access Memory (RAM), consisting of two 4-bit by 256 maximum character
memories. The address counter generates the seven address inputs for the RAM.
Printable data will continue to be loaded until the memory is filled or acarriage return control code is received by the printer.
In either case, the printer goes busy and starts the print cycle by activating the forward carriage solenoid (CIP). This attaches
the carriage to the rotating band, moving the carriage from left to right across the page. The address counter is clocked
(STROUT (N)) to address the appropriate location in memory for the character to be printed. The character is translated by
the character generator (ROM), which generates the impulse signals to drive the head solenoids.
At the end of the printed line, the forward solenoid is deactivated and the reverse solenoid (CIR (N)) is activated to return the
carriage to the left margin. The printer remains busy until the end of the print cycle. Also at the end of the line, the paper
drive solenoid is momentarily activated, causing the paper to advance by one line.
When the carriage has returned to the left margin, the reverse solenoid is deactivated, the busy signal goes away, the
acknowledge signal is generated, and the next line of data is taken in.
The left margin indicator (RTPSW) signals the logic when the carriage reaches the extreme left margin of the printer. As
the carriage moves, the oscillator (ME1) provides the control for print timing.
2.3 INITIALIZING THE PRINTER (Figure 2-2)
Before the printer can accept data, it must be power primed, paper loaded and print enabled. The power prime operation
initializes the printer logic to aready state. The print enable operation, resets the busy line to the interface connector and
makes the printer ready to receive data.
2.3.1 POWER PRIME
The power prime signal (PWRPRM (N)) is generated when the power switch is turned on. The (PWRPRM (N)) signal gen-
erates the (EOPPRM (N)) signal which clears the print control logic.
2.3.2 PRINT ENABLE
Before the printer can receive data, it must be enabled. This can be done by depressing the PRINT switch on the operator's
panel.
2.3.3 PAPER EMPTY
With paper loaded in the printer and the printer is power primed and print enabled the printer can receive data. If paper is
not loaded in the printer or a paper empty condition exists in the printer, the paper empty switch opens, causing aBUSY
signal to the input device. Apaper empty condition is detected in the printer by the paper empty switch located in the path
of the paper. ri
ELECTRONICS BOARD
rCONTROL PANEL
ItEL^/3~SELRET
3
PRINT O-
SWITCH
L.
PAPER EMPTY SWITCH
I
P003 JCKJ3
-Q-CD
INPUT
CONTROL
LOGIC
PRINT
CONTROL
LOGIC
-ED—cm
I
I
I
I
L_.
C5
20ufd
0V- ^
CR4 Jp
IN4002J&
j,ME13
L5V-
R26
4.7K< R27
4.7K<
J
Figure 2-2. INITIALIZING THE PRINTER
2-2

2.4 DATA INPUT (Figure 2-3)
Inputs to the printer consist of seven standard parallel data lines (DATA 1-DATA 7) and an active low data strobe (DSTA
(N)) The seven data lines represent the 7-bit USASCII code (refer to the operator's manual). The data strobe is used to
synchronize the input data with the printer electronics.
In response to received data, the printer generates an active low acknowledge (ACK(N)) pulse to acknowledge reception
of acharacter. If the received character caused the printer to perform some function such as paper movement character
printing, etc., the printer responds with aBUSY signal and does not acknowledge until termination of the busy condition.
2.4.1 DATA INPUT TIMING
In general, the data transfer sequence consists of the input device placing the appropriate code on the data lines to the
printer and then generating adata strobe pulse. The printer responds with an acknowledge pulse, or if the received data
caused abusy condition, the printer first activates the busy line for the duration of the busy condition and then responds
with an acknowledge pulse.
Refer to Appendix Afor the timing involved in transferring data, which does not cause abusy condition, and the timing
involved in receiving any character, which causes abusy condition in the printer.
2.4.2 FUNCTION DECODER
In addition to monitoring the input data for the first printable character, the function decoder monitors the data for the four
special control codes used in the printer. Line Feed/Carriage Return and Top of Form. The data lines are decoded and if one
of these control codes is detected, the following action occurs:
FUNCTION
Line Feed/Carriage Return
Top of Form
INPUT
DEVICE
,DATA 1-DATA 7
DSTA
ACK
rPENOTSEL
CONTROL CODES
(DECIMAL)
10or 13
11 or 12
|ELECTRONICS BOARD
I
HJ
10
12
DATA 1-DATA
;
ywPUT
GATIMG
PRINTER ACTION
Advances the paper one line and returns the print head
to its home position.
Advances the paper to top of the next page (as defined
by BASIC. See LEVEL II, BASIC Reference Manual
page 10/3).
PRINTABLE DATA
DATA LINES )FUNCTION
DECODER
LOGIC
L_.
CONTROL
CODES
sz.
MEMORY
(RAMI
1
.J
Figure 2-3. DATA INPUT
2.5 CHARACTER PRINTING (Figure 2-4)
When the memory is full (CARRY (N)) or acarriage return code (DCCR(N)) is detected in the input data, the print command
(CIP) is generated causing the print head to move left to right across the page. The address counter is set to count up then
clocked to select via the eight address lines, the appropriate character location in the RAM. The read/write (R/W(N)) input
to the RAM is held high during the print cycle. Conversely, the R/W(N) input is pulsed low during the data input cycle The
/-bit character code, specifying the character, is sent to the ROM.
As the print head moves across the page, the timing inputs generated by ME7 and ME8. are used by the ROM to register
the column of dots in the printed character.
The ROM, in response to the character code and timing signals, generates seven logic signals (CG1-CG7) which are
amplified and sent to the seven solenoids in the print head. There the signals activate the solenoids driving the print wires
which form the appropriate dot pattern for the addressed character and column.
The standard character line length is 132 characters. The end user has the option of varying the line length by adding
jumper wires and making cuts on the printed circuit board. Refer to Section 3.17 Electronic Board Assembly for the pro
cedure on changing the line length.
2-3

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2-4

2.6 CARRIAGE AND RIBBON MOVEMENT (Figure 2-5)
Mounted on the carriage are the print head, ribbon cartridge and forward/reverse carriage solenoids. The carriage moves
from left to right during the print operation and from right to left when returning to the start position. The ribbon is auto-
matically advanced, during the forward and reverse movement of the carriage, making full use of the ribbon. All carriage
movement is aresult of the drive signals from the electronics board, causing the forward and reverse solenoids to seize
the band.
2.6.1 LEFT AND RIGHT MARGIN INDICATORS
Located on the left side of the printer, is alight emitting diode (LED) and phototransistor device which indicates if the print
head is in the start position. If the carriage is sitting at the left margin, the carriage arm extends into the slot in the device,
preventing the LED from energizing the phototransistor. This generates alow ready to print (RTP) signal to the print control
logic. When the carriage is to the right of the indicator, the arm is out of the slot, permitting light to energize the photo-
transistor and thus make RTPSW(N) high. Therefore, the RTPSW(N) is low when the carriage arm is in the indicator and
high when the arm is out of the indicator.
The right margin indicator, located on the right side of the printer, is aLED and phototransistor device identical to the left
margin indicator. When the carriage reaches the end of travel at the extreme right margin, the end of print (EOPSW) signal
is generated, which in turn generates EOPSW(N) and is sent to the print control logic. The EOPSW(N) signal is low when the
carriage arm is in the indicator and high when the carriage arm is out of the indicator.
2.6.2 CARRIAGE DRIVE
The carriage is moved by the drive motor, rotating fibre band and forward/reverse solenoids. The drive motor rotates at a
constant speed rotating the fibre band clockwise. If the forward solenoid (CIP (N)), is energized, the solenoid seizes the top
half of the band moving the carriage to the right. Energizing the reverse solenoid, (CIR (N)), attaches the carriage to the
bottom half of the band, moving the carriage to the left.
2.6.3 CARRIAGE DRIVE SIGNALS
The signals for energizing the forward/reverse solenoids are generated by flipflop ME3. When the printer is ready to print
the received line of data, the flip flop activates the forward drive signal CIP (N). The signal is amplified by the power driver,
the output of which activates the forward solenoid. The forward solenoid remains active until acarriage return code is
detected in the data at the end of aline or until the buffer full condition occurs at the end of afull line of data. Either of these
two conditions causes the flip flop to deactivate the forward solenoid and activate the reverse solenoid signal CIR(N) to return
the carriage to the left margin.CIR (N) is deactivated when the RTP switch is reached.
2.6.4 RIBBON DRIVE
The mobius loop ribbon is advanced during the forward and reverse movement of the carriage. The ribbon drive shaft
rotates clockwise feeding the ribbon out of the back of the cartridge, around to the front of the print head and then back into
the front of the cartridge. Movement of the ribbon drive shaft is the result of the two one-way slip clutches, one for forward
movement and one for reverse movement. Two ribbon drive wires, upper and lower, are attached to the left and right sides
of the printer and looped one-half turn around the upper and lower clutch. The drive wires are arranged such that when
the carriage moves to the right, the top pulley is engaged and when moving to the left, the bottom pulley is engaged.
II5VAC
FROM
TRANSFORMER
—-0-0—HZh-0-
Figure 2-5. CARRIAGE AND RIBBON MOVEMENT
2-5

2.7 PAPER MOTION (Figure 2-6)
There are two methods of moving paper through the printer: 1) manually, by pushing in and rotating the platen knob in a
clockwise direction and 2) remotely, by adecoded line feed function, which causes the paper to move one line.
The decoded line feed function causes the paper to advance by activating the paper movement solenoid in the line feed clutch
unit. When energized, the solenoid allows the line feed clutch unit to rotate, driving the platen and paper feed mechanism.
For each single line feed operation, the solenoid is energized 11milliseconds.
2.7.1 LINE FEED/CARRIAGE RETURN
Aline feed/carriage return is generated by the following conditions:
1. Receiving aline feed/carriage return code (decimal 10 or 13).
2. The auto line feed function is enabled when ajumper wire is installed between E1 and E2 on the electronics board. To dis-
able the auto line feed function, ajumper wire is installed between E1and E3.
During aline feed/carriage return operation, the line feed solenoid is activated via the power driver (PMSOL(N)). Also the
printer goes BUSY and cannot receive any input data for the duration of the line feed/carriage return operation.
NOTE
FOR THE 26-1150 LINE PRINTER,
SEE FIGURE 3-1 AND ITS NOTE.
INPUT DEVICE
INPUT
CONTROL
LOGIC
PSSOL -O-t?]4IHI} HI
lCI P(NOTE I) I
NOTE I: CIP WILL NOT CAUSE PMSOL IF CUT
AUTO LINE FEED OPTION IS INSTALLED
Figure 2-6. PAPER MOTION
2-6

2.8 POWER SUPPLIES
The standard power input to the printer is 115VAC, 60 Hz. For the 230VAC, 50 Hz option, adifferent drive motor assembly
is used.
The power input is applied through acircuit breaker (S1) at the rear of the printer and then through aline filter to the multi-
tap transformer (T1). From the transformer the main power goes to the logic board.
The secondary windings of the transformer develop the following voltages:
VOLTAGE
12VAC
35VAC
27.5VAC
WINDING
11-12
13-14-15
16-17
The 12VAC and 35VAC voltages are used as inputs to the +5VDC and -1 2VDC power supplies on the electronics board,
where they are rectified, filtered and regulated. The 27.5VAC is used to generate the +35VDC unregulated output.
2.8.1 +5V REGULATOR (Figure 2-7)
The 12VAC output from the secondary winding of the transformer is rectified by the full-wave diode bridge located on the
electronics board and filtered by C2 located in the cavity. The unregulated, filtered 15VDC output of the bridge rectifier is
fused and supplied to the power driver circuits. The 15VDC is also applied to the +5V regulator circuits which provide a
regulated 5VDC output.
12 J002 P002
T'11 vAc m__rg
TO CIRCUITS
+15 VDC +5 VDC
~l
TO
TAPE READER,
CONTROL PANEL,
LEFT MARGIN
INDICATOR
Figure 2-7. +5 VDC POWER SUPPLY
2-7

2.8.2 -12VDC REGULATOR (Figure 2-8)
The voltage generated by the 35VAC center-tapped secondary winding of the transformer is used as input to the -1 2VDC
regulator. This input is rectified, filtered, and then regulated to maintain aconstant -12VDC output.
17 5J002 P002
T'13 VAC
35
VAC Fov
15 17.5
VAC
ELECTRONICS BOARD
HALF WAVE
DIODE
RECTIFIER
FUSE
12V
REGULATOR
-12VDC
TO
CIRCUITS
±OV
Figure 2-8. -12 VDC POWER SUPPLY
2.8.3 +35VDC POWER SUPPLY (Figure 2-9)
The 27.5VAC output from the transformer is rectified by afull-wave diode bridge and filtered by C1 to generate the +35VDC
unregulated voltage applied through fuse 5ASB to the driver circuits and paper motion solenoid.
J002ITJ
+C1
*—\/W—*•
I
R1
ICAVITY
-±OV
T,27.5 J002 P002
16 VAC
27.5
VAC
17 RET. 10 10
-P002- 4
FULL WAVE
DIODE
BRIDGE
RECTIFIER
TO
CIRCUITS
+35 VDC
1
FUSE
5ASB
•+OV
ELECTRONICS BOARD
•1005 T„
0TO
PAPER
MOTION
SOLENOID
Figure 2-9. +35 VDC POWER SUPPLY
2-8

3.1 INTRODUCTION
This section describes the function, removal/replacement, adjustment and preventive maintenance procedures of the printer
assemblies in the Line Printers. This section is aimed at subassembly level.
The section is organized as follows:
Subsection: 3.2 Printer Subassemblies
3.3 Cover Assemblies
3.4 Print Head Assembly
3.5 Video Amplifier Assembly
3.6 Ribbon Cartridge Assembly
3.7 Carriage Assembly
3.8 Drive Motor Assembly
3.9 Platen Drive Assembly
3.10 Platen Assembly
3.11 Pinch Roller Assembly (26-1150)
3.12 Tear Bar Assembly
3.13 Tractor Drive and Pin Feed Assemblies (26-1 152)
3.14 Control Panel Assembly
3.15 Primary Voltage
3.16 Electronic Module Assembly
3.17 Logic Board Assembly
3.18 Hardware Kit
3.19 Special Tools
3.2 PRINTER SUBASSEMBLIES (Figure 3-1
)
Figure 3-1 illustrates and lists the major subassemblies used in the printers. Following this overall diagram is abrief functional
description, removal/replacement/adjustment and preventive maintenance procedures for each individual assembly.;
NOTE
THE MAJORITY OF THESE SUBASSEMBLIES ARE PACKAGED IN KIT FORM. THE KIT CONTAINS THE
SUBASSEMBLY AND NECESSARY HARDWARE TO MOUNT THE SUBASSEMBLY. IF NOT PACKAGED
IN KIT FORM JUST THE SUBASSEMBLY IS ILLUSTRATED AND LISTED.
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LIST OF MATERIALS
PRINTER SUBASSEMBLIES
REFERENCE
ASSEMBLY PART NUMBER
1535139001-5070
2535146001-2001
3535143001-2001
4535645001-5070
5535136001-2070
6535644001-5070
7535137001-2070
863780126-2002
9535067001-2070
10 535068001-2070
11 62001136-5002
12 63779120-6001
13 63700289-6001
14 63780155-6001
15A 63780152-6001
15B 63780152-6002
16 63700643-6003
17 63780154-6001
18 535220001-6001
19 535121001-5001
20 63780153-6001
21 535502001-5001
22 535501001-5001
23 63779115-5001
24A 63703115-6001
24B 63703115-6002
25 63779103-5001
26 63779119-6001
27 63780141-6001
28 63701194-6001
DESCRIPTION
Cover, Front
Decorator Plate
Cover, Top Clear
Cover, Left
Cover, Left, Tractor Drive (26-1152)
Cover, Right
Cover, Right, Tractor Drive (26-1152)
Cover. Electronic Module
Cover, Left, Pinch Roller (26-1 150)
Cover, Right, Pinch Roller (26-1 150)
Print Head Assembly
Kit, Video Amplifier Assembly
Kit, Ribbon Cartridge Assembly
Kit, Carriage Assembly
Kit, Drive Motor Assembly, 60Hz
Kit, Drive Motor Assembly, 50 Hz
Kit, Platen Drive Assembly
Kit, Platen Assembly
Kit, Pinch Roller Assembly (26-1150)
Column ScaleATear Bar Assembly, 10 CPI
Kit, Tractor Drive Assembly (26-1 152)
Pin Feed Assembly, Left (26-1 152)
Pin Feed Assembly, Right (26-1 152)
Control Panel Assembly
Kit, Primary Voltage (100V -120V)
Kit, Primary Voltage (200V -240V)
Electronic Module Assembly
Kit, Logic Board Assembly
Kit, Hardware
Kit, Special Tools
O.TY
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