STAR SJ-48 Service manual
Starjet SJ-48
TECHNICAL MANUAL
[ SECOND EDITION ]
NOTICE
• All rights reserved. Reproduction of any part of this manual in any
form whatsoever, without STAR’s express permission is forbidden.
• The contents of this manual are subject to change without notice.
• All efforts have been made to ensure the accuracy of the contents
of this manual at the time of going to press. However, should any
errors be detected, STAR would greatly appreciate being informed of them.
• The above notwithstanding, STAR can assume no responsibility
for any errors in this manual.
© Copyright 1996 Star Micronics Co.,Ltd.
INTRODUCTION
This manual is an introduction to ink jet printer SJ-48.
It is intended for use as a reference for maintenance procedures.
This manual is prepared for use at a technical level and not for the general user.
• This manual is divided into the following sections:
Chapter 1 General Specifications
Chapter 2 Theory of Operation
Chapter 3 Adjustments
Chapter 4 Parts Replacement
Chapter 5 Precautions and Maintenance
Chapter 6 Troubleshooting
Chapter 7 Parts List
• First edition : Oct.1991
Second edition: Oct.1992
1
2
3
4
5
6
7
GENERAL SPECIFICATIONS
– 2 –
CHAPTER 1
GENERAL SPECIFICATIONS
1. General Specifications..........................................................................................3
2. External Appearance and Composition ..............................................................6
3. DIP Switch Settings...............................................................................................7
4. Parallel Interface....................................................................................................8
4-1. General Specifications ........................................................................................... 8
4-2. Connector Signals .................................................................................................. 8
1
GENERAL SPECIFICATIONS
– 2 –
GENERAL SPECIFICATIONS
1. General Specifications
Printing system Serial Ink Jet Dot-matrix
Printing speed High Quality mode Economy mode
Pica 83 cps 83 cps
Elite 100 cps 100 cps
Semi-condensed 124 cps 124 cps
Condensed pica 142 cps 142 cps
Condensed elite 166 cps 166 cps
Print direction Bi-directional, logic-seeking
Uni-directional, logic-seeking (selectable)
Print head 48 nozzles
Life: 700,000 characters
Line spacing 1/6, 1/8, n/60, n/72, n/180, n/216, n/360
Font styles Roman and H-Gothic
Characters ASCII 96
International 16 sets(*)
IBM special 111
IBM block graphic 50
IBM code page 6 sets (**)
Download 128
* USA, France, Germany, England, Denmark I, Sweden, Italy, Spain I, Japan, Norway, Denmark II, Spain II,
Latin America, Korea, Irish, Legal
** #437 (U.S.A.), #850 (Multi-Lingual), #860 (Portuguese), #861 (Icelandic), #863 (Canadian French), #865 (Nordic)
Number of columns CPI Normal type
Pica 10 80
Elite 12 96
Semi-condensed 15 120
Condensed pica 17 137
Condensed elite 20 160
Proportional Variable
Character matrix High Quality Economy
Pica 48 × 36 24 × 36
Elite 48 × 30 24 × 30
Semi-condensed 32 × 24 16 × 24
Condensed pica 48 × 21 24 × 21
Condensed elite 48 × 18 24 × 18
Proportional 48 × n 24 × n
Bit image dot-matrix. DPI 8-bit 24-bit 48-bit
Normal-density 60 8 × 480 24 × 480 48 × 480
CRT graphics mode I 80 8 × 640 (Not supplied) (Not supplied)
CRT graphics mode II 90 8 × 720 24 × 720 48 × 720
Double-density 120 8 × 960 24 × 960 48 × 960
Triple-density 180(Not supplied) 24 × 1440 48 × 1440
Quadruple-density 240 8 × 1920 (Not supplied) Not supplied)
Hex-density 360(Not supplied) 24 × 2880 48 × 2880
– 3 –
GENERAL SPECIFICATIONS
Paper feed Friction roller feed
Friction flat feed
Paper feed speed 5/6 inches/second max
Paper specifications
Width 7.2" ~ 8.5" (182 ~ 216 mm)
Length 7.2" ~ 14" (182 ~ 356 mm)
Weight 52 ~ 105 g/m
Envelope Commercial 10 only
Maximum buffer size Without Download 28 kB
With Download 4 kB
Emulations Standard mode: Epson LQ-860, NEC 24-wire Graphics command
IBM mode: IBM Proprinter X24E
Interface Centronics parallel
Ink Cartridge
Type Single cartridge ink supply (SC-10)
Ink Color Black only
Ink amount 28 g (0.9 oz)
Dimensions and Weight
Width 310 mm (12.2")
Depth 216.5 mm (8.5")
Height 47.5 mm (1.9")
Weight 1.8 kg (4.0 lb)
AC adapter power supply 120 VAC, 220 VAC, 240 VAC, 50/60 Hz
(varies according to the country of purchase)
Options Battery pack (BP-10)
Automatic Sheet Feeder (SF-10CA)
2
– 4 –
GENERAL SPECIFICATIONS
Fig. 1-1 External Dimensions
– 5 –
GENERAL SPECIFICATIONS
2. External Appearance and Composition
Fig. 1-2 Front View of the Printer
Fig. 1-3 Diagram of Internal Composition
– 6 –
3. DIP Switch Settings
Switch Function ON OFF
1 Emulation Standard IBM
2 RAM usage Buffer Download
3 Auto LF with CR Disabled Enabled
4 Automatic Sheet Feeder Inactive Active
5 Font style Roman H-Gothic
6 Print mode Normal size Quarter size
7
8 International Character Set (See table below)
9or
10 IBM Code Page (See table below)
Character set
(Standard mode)
Character set
Fig. 1-4 DIP Switch Settings
Graphics Italics
(IBM) mode
Set #2 Set #1
GENERAL SPECIFICATIONS
All switches are set ON when the printer leaves the factory.
International Character Set (In the standard italics character set)
Country 8 9 10 Country 8 9 10
U.S.A. ON ON ON Denmark I ON O N OFF
France OFF ON ON Sweden OFF ON OFF
Germany ON OFF ON Italy ON OFF OFF
England OFF OFF ON Spain I OFF OFF OFF
IBM Code Page (Except in the standard italics character set)
Code Page 8 9 10 Code Page 8 9 10
#437 U.S.A. ON ON ON #863 Canadian French ON ON OFF
#850 Multi-Lingual OFF ON ON #865 Nordic OFF ON OFF
#860 Portuguese ON OFF ON (Reserved) ON OFF OFF
#861 Icelandic OFF OFF ON (Reserved) OFF OFF OFF
– 7 –
GENERAL SPECIFICATIONS
4. Parallel Interface
4-1. General Specifications
Item Specifications
Synchronization System Via externally supplied STROBE pulse
I/F Protocol By ACK and BUSY signals
Logic Level Compatible with TTL level
Fig. 1-5 Timing Charts of Parallel Interface
4-2. Connector Signals
Pin No Signal Name Function Description
1 STROBE Goes from high to low (for 0.5µs) when active.
2 DATA1 High when active.
3 DATA2 High when active.
4 DATA3 High when active.
5 DATA4 High when active.
6 DATA5 High when active.
7 DATA6 High when active.
8 DATA7 High when active.
9 DATA8 High when active.
10 ACK 4µs low pulse acknowledges receipt of data.
11 BUSY Low when printer ready to receive data.
12 PAPER END High when paper out.
13 SELECT High when printer is on-line.
14,15 NC Unused.
16 SIGNAL GND Signal ground.
17 CHASSIS GND Chassis ground.
18 NC Unused.
19 ~ 30 GND Twisted pair ground return.
31 RESET When this input signal is low, printer is reset.
32 ERROR Outputs low when printer cannot continue, due to an error.
33 EXT GND External ground.
34 NC Unused.
35 +5V +5V DC output from printer.
36 NC Unused.
– 8 –
CHAPTER 2
THEORY OF OPERATION
1. Block Diagram .....................................................................................................11
2. Mechanism...........................................................................................................12
2-1. Overview................................................................................................................ 12
2-2. Ink Cartridge.......................................................................................................... 13
2-2-1. Ink Jet Mechanism ......................................................................................... 13
2-2-2. Ink Cartridge Structure .................................................................................. 13
2-2-3. Ink Jet Head Unit Structure ........................................................................... 14
2-3. Purge Unit.............................................................................................................. 17
2-3-1. Purge Unit Functions..................................................................................... 17
2-3-2. Purge Unit Structure ...................................................................................... 17
2-4. Carriage Section ................................................................................................... 19
2-4-1. Carriage Section Functions .......................................................................... 19
2-4-2. Carriage Section Structure............................................................................ 19
2-5. Paper Feed Section .............................................................................................. 22
2
2-5-1. 3-way Paper Feed Section ............................................................................. 22
2-5-2. Paper End Detection Section ........................................................................ 22
3. Logic Board .........................................................................................................24
3-1. Logic Board Functions......................................................................................... 24
3-2. Control Section Block Diagram........................................................................... 26
3-3. Control Section Components .............................................................................. 27
3-4. Power Supply Section Block Diagram................................................................ 28
3-5. Power Supply Section Components ................................................................... 29
4. Auto Sheet Feeder...............................................................................................31
4-1. Gear Train.............................................................................................................. 31
4-2. Spring Clutch ........................................................................................................ 31
THEORY OF OPERATION
– 10 –
1. Block Diagram
The block diagram of this printer is shown in Figure 2-1.
THEORY OF OPERATION
Fig. 2-1 Block Diagram
– 11 –
THEORY OF OPERATION
2. Mechanisms
2-1. Overview
This section explains the outline of the printer mechanism. The following sections explain each details.
a) Ink cartridge
The ink cartridge contains the 64-nozzle ink jet head with resolution of 360 DPI and ink tank.
b) Purge unit
The purge unit, drive by the carriage motor, maintains the ink jet nozzles of the ink cartridge to keep the best
printing quality.
c) Carriage part
The carriage, driven by the carriage motor, moves horizontally to the print paper with logical seeking. The carriage
motor drives either the purge unit or the carriage.
Printing signals are transmitted from the logic board to the ink cartridge on the carriage through the ribbon cable.
d) Paper feed part
The paper feed parts, driven by the paper feed motor, rotates the feed roller and moves the print paper vertically.
When the printer is placed horizontally, paper can be fed from the top of the printer. When the printer is placed
vertically, paper can be inserted from the bottom slot of the printer for flat feeding and can be fed from the optional
auto sheet feeder. Since the printer has no paper feed knob for manual feeding, paper is always fed using control
buttons.
Fig. 2-2 Internal View
– 12 –
THEORY OF OPERATION
2-2. Ink Cartridge
2-2-1. Ink Jet Printing Mechanism
The ink jet printing system prints characters and graphics by firing ink
drops at the paper from thin nozzles. Heating the ink in these nozzles
produces bubbles that quickly expand and eject the ink. The heat is
generated by applying electrical pulses to the heating elements built into
each nozzle. Each pulse serves a two-fold purpose.
(1) The electrical pulse first generates heat that vaporizes the ink almost
instantly.
The resulting bubble generates a pressure wave that ejects an ink drop
from the nozzle.
(2) A vacuum is then produced as the bubble contracts after the pulse
ends.
This draws fresh ink into the nozzle.
2-2-2. Ink Cartridge Structure
a) Side cover
This plastic cover has been adhered to the cartridge body to prevent leakage of ink from the ink sponge.
b) Ink sponge
The ink sponge contains about 20 grams of black ink for printing about 450 pages of regular office paper (ordinary
paper).
c) Cartridge body
The plastic cartridge body holds the ink sponge and ink jet head unit.
d) Ink jet head unit
The ink jet head unit loads ink to the 64 ink jet nozzles from the tip of the joint pipe that contacts with the ink sponge.
Printing signals are transmitted from the signal contacts.
e) Head cover
The plastic head cover protects the ink jet head unit.
Fig. 2-3 Exploded View of Ink Cartridge
– 13 –
THEORY OF OPERATION
2-2-3. Ink Jet Head Unit Structure
a) Ink jet nozzles
The ink in the ink sponge pass through the meshed ink filter to remove dust, and is flowed to the ink jet nozzles
through the joint pipe. When the head drive current flows through the heater plate of a nozzle, the ink boils and
bubbles are produced, forming into one large bubble. The head drive current is cut off before a drop of ink is ejected
from the nozzle, but bubbling is grown because of the remaining heat on the heater, and the drop of ink is ejected
from the nozzle at about 12 m/s. After ejected the drop of ink, the nozzle is refilled with ink.
The ink jet head is formed on the silicon plate based on semiconductor technology.
The heater and its electrical wiring are formed on the plate.
A plastic cover with face plate and 64 nozzles is bonded to the plate.
Fig. 2-4 Ink Jet Nozzles
– 14 –
THEORY OF OPERATION
b) Nozzle arrangement
The 64 ink jet nozzles are arranged in a line at intervals of 1/360 inch. The upper 60 nozzles are used for actual
printing. The 64 heater plates are controlled by the matrix structure of the 8 COM signal circuits and 8 SEG signal
circuits.
Fig. 2-5 Nozzle Arrangement
c) Printing signals
The COM signal connects circuits COM1 to COM8 to the head drive power supply (VH) in order so that the 64
nozzles are ready to print in units of 8 nozzles.
The SEG signal connects the SEG circuit (SEG1 to SEG8) nozzles to be used for printing to the ground while the
COM signal is connected to the head drive power supply, and applies the heater voltage to the heater plate.
Fig. 2-6 Printing Signals
– 15 –
THEORY OF OPERATION
d) Heater voltage
One of four heater voltage levels that determine the ink jet speed is selected to correct any manufacturing variations
in the ink jet head units. The heater voltage ID is indicated by the PCB pattern of the contact points of the ink jet
head unit, and is used to switch the heater voltage output of the printer heater drive voltage supply circuit.
Fig. 2-7 Heater Drive Voltage ID
– 16 –
THEORY OF OPERATION
2-3. Purge Unit
2-3-1. Purge Unit Functions
a) Capping function
When printing does not take place for more than five seconds or when the printer goes offline, the capping function
pushes the rubber cap of the purge unit against the face plate (nozzle part) of the ink cartridge to prevent the ink from
drying up or leaking.
b) Cleaning function
To maintain high quality printing with the ink cartridge, the cleaning function is performed for about 12 seconds
when the “Head cleaning buttons” are pressed until the beeper sounds at the state of the power being on or the printer
being online. For cleaning, a wiping operation takes place to wipe off paper fiber and ink remaining on the face plate
of the ink cartridge, and a pumping operation takes place to suck about 0.1cc of ink from the capped ink cartridge
and fill the nozzles with fresh ink.
2-3-2. Purge Unit Structure
a) Purge unit control gear
The purge unit control gear is driven by the clutch gear of the lead screw, which is driven by the carriage motor.
This gear functions as a cam that drives the purge unit rubber wiper, cap, and pump, and controls the overall
movement of the purge unit operations.
b) Wiper arm unit
The wiper arm has a rubber wiper and a maintenance jet absorber. The rubber wiper wipes off the face plate of the
ink cartridge from top to bottom every 60 seconds during cleaning, before starting printing, and during printing.
The maintenance jet absorber absorbs the ejected ink from the nozzles as a test to stabilize the nozzles when the
power is switched on, before starting printing and every 12 seconds while printing. The stains on the rubber wiper
and the ink in the maintenance jet absorber are mopped up by the ink absorber when the wiper arm goes down.
c) Cap unit
The cap arm with its rubber cap advances and caps the ink cartridge when the wiper arm goes down. The rubber
cap connects to the ink pump and sucks ink from the ink cartridge during cleaning.
d) Pump unit
The pipe-shaped pump unit sucks ink through the rubber cap and runs it to the waste ink absorber in the paper feed
roller.
– 17 –
THEORY OF OPERATION
Fig. 2-8 Purge Unit
– 18 –
THEORY OF OPERATION
2-4. Carriage Section
2-4-1. Carriage Section Functions
a) Ink cartridge mounting function
The carriage fixes the ink cartridge mechanically and connects the electrical circuits to the logic board.
b) Carriage drive function
The carriage is moved horizontally over the print paper by the carriage motor.
c) Head gap adjustment function
The gap between the head and print paper can be adjusted with the head gap dial to suit the paper thickness.
d) Purge unit drive function
The carriage motor returns the carriage to its home position and drives the purge unit.
2-4-2. Carriage Section Structure
a) Ink cartridge mounting section
The hook that is moved with the hooking lever fixes the ink cartridge on the carriage. When the ink cartridge is fixed
on the carriage, the contact portion of the ribbon cable connects with the contact portion of the ink jet head unit to
transfer printing signals from the logic board.
b) Carriage drive section
The DC stepping carriage motor rotates the lead screw via the drive belt. The carriage moves horizontally over the
print paper driven by lead pin, which engages in the groove of the lead screw. For the carriage position, the
photocoupler home position sensor under the carriage detects the photointerrupter (part of the guide shaft holder)
at the left of the carriage guide shaft, and logical seeking takes place using a stepping pulse transmitted to the
carriage motor.
c) Head gap adjustment function
The eccentric carriage guide shaft can be adjusted with the head gap dial on the bottom of the printer to match the
head gap to the print paper thickness. The head gap is about 0.04 inch (1 mm) when the dial is turned fully in the
direction of the cut sheet mark and about 0.075 inch (1.9 mm) when turned fully in the direction of the envelope
mark. When the optional auto sheet feeder is used, set the dial to the middle point between the cut sheet mark and
envelope mark where the dial clicks.
d) Purge unit drive section
When the lead pin enters the left margin groove, the carriage pushes the clutch gear of the lead screw to the purge
unit, and transmits the carriage motor power to the purge unit control gear.
– 19 –
THEORY OF OPERATION
Fig. 2-9 Carriage
– 20 –
THEORY OF OPERATION
Fig. 2-10 Purge Unit Drive Section
– 21 –
THEORY OF OPERATION
2-5. Paper Feed Section
2-5-1. 3-way Paper Feed Section
The 3-way paper feed section is driven by the DC stepping paper feed motor. In roller-wind feeding, print paper is inserted
from the top rear of the printer, and fed around the paper feed roller. In flat feeding, print paper is inserted from the paper
slot in the bottom part of the printer, and fed by the paper feed roller and pressure roller. In ASF feeding, when the optional
auto sheet feeder is fitted to the printer, automatic paper feed and manual flat feed can be done.
2-5-2. Paper End Detection Section
The leaf switch paper end sensor at the lower left of the feed roller detects print paper.
Fig. 2-11 Paper Feed Section
– 22 –
THEORY OF OPERATION
Fig. 2-12 3-way Paper Feed
– 23 –
THEORY OF OPERATION
3. Logic Board
The logic board converts data from the interface to printing signals or printer operational signals
3-1. Logic Board Functions
The logic board, consisting of a control section and a power supply section, provides the following functions;
a) Printer control
The control section logically controls printer operations with the paper feed motor and carriage motor according
to the printer state monitored with a paper sensor and a home position sensor.
b) Interface control
The control section converts data from the computer via a parallel interface to print data and printer control
commands.
c) Head control
The control section converts print data to print signals for the ink cartridge and controls printing.
d) Power control
The control section controls the power supply circuit according to signals from the control buttons, power switch
and outputs from the power supply circuit.
e) Switch detection
The control section detects the states of the control buttons and function selectors.
f) Indicator control
The control section displays the printer operating states with indicator lamps.
g) Power supply
The power supply section makes various DC voltages for the printer from the Ni-Cd battery pack and AC adapter.
h) Battery charger
When the power is switched on with an AC adapter connected to the printer and the
until the beeper sounds, the Ni-Cd battery pack is charged by power supply section.
ON LINE
button is held down
– 24 –
THEORY OF OPERATION
Fig. 2-13 Block Diagram of Logic Board
– 25 –
THEORY OF OPERATION
3-2. Control Section Block Diagram
Fig. 2-14 Control Section Block Diagram
– 26 –
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