Star Micronics NX-1500 User manual

DOT MATRIX PRINTER
NX-1500
LC-15
TECHNICAL MANUAL
[FIFTH EDITION]

NOTICE
•Allrightsreserved.Reproductionofanypartofthismanualinany
form whatsoever, without STAR’s express permission is forbid-
den.
•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 in-
formed 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 describes dot matrix printers as shown below.
It is intended for use as a reference for periodic inspections and maintenance procedures.
This manual is prepared for use at a technical level and not for the general user.
Model Destination
NX-1500 MULTI-FONT For American and Asian market
LC-15 MULTI-FONT For European and Pacific market
•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 Maintenance and Lubrication
Chapter 6 Troubleshooting
Chapter 7 Parts List
•First edition : Sep. 1989
Second edition : Apr. 1991
Third edition : Aug. 1993
Fourth edition : Sep. 1995
Fifth edition : Apr. 1996
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CHAPTER 1
GENERAL SPECIFICATIONS
1. General Specifications .........................................................................................3
2. External Appearance and Composition ..............................................................5
3. DIP Switch Settings ..............................................................................................6
4. Parallel Interface ...................................................................................................7
4-1. General Specifications ........................................................................................... 7
4-2. Connector Signals .................................................................................................. 7
5. Serial Interface (option) ........................................................................................8
5-1. General Specifications ........................................................................................... 8
5-2. Connector Signals .................................................................................................. 8
5-3. DIP Switch Settings ................................................................................................ 9
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GENERAL SPECIFICATIONS

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GENERAL SPECIFICATIONS
1. General Specifications
Print system Serial Impact Dot-matrix
Printing speed 150cps (Draft pica)
37.5cps (NLQ pica)
Print direction Bidirectional, logic-seeking
Unidirectional, logic-seeking (selectable)
Print Head 9 pins
Line spacing 1/6, 1/8, n/72, n/216 inches
Paper feed Standard: Friction and push tractor
Option: Pull tractor
Paper feed speed 2.8 inches/second max.
Character set
ASCII 96
Code table (International) 3 sets *1 (For NX-1500 SU, LC-15 SU)/14 sets *2 (Others)
IBM special 111
IBM block graphic 50
Download 255
*1 IBM-Russian, Gost, Code page #866
*2 USA, France, Germany, England, Denmark I, Sweden, Italy, Spain I, Japan, Norway, Denmark II, Spain II, Latin America,
Denmark/Norway
Number of columns CPI Columns
Pica 10 136
Elite 12 163
Condensed pica 17.1 233
Condensed elite 20 272
Proportional Variable
Character dot matrix 9 ×11 (Draft)
18 ×23 (NLQ)
Bit image dot-matrix DPI
8-pin single 60 8 ×816
8-pin double 120 8 ×1632
8-pin high-speed double* 120 8 ×1632
8-pin quadruple 240 8 ×3264
8-pin CRT I 80 8 ×1088
8-pin CRT II 90 8 ×1224
8-pin plotter 72 8 ×976
8-pin double-plotter 144 8 ×1958
9-pin single 60 9 ×816
9-pin double 120 9 ×1632
* It is impossible to print adjacent dots in the modes marked with an asterisk (*).
Paper width
Cut sheet 6" ~ 16.5"
Fanfold(continuous) 4" ~ 16"
Copies Original + 2 copies

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GENERAL SPECIFICATIONS
Maximum buffer size
Without Download 15KB
With Download 1 line
Emulations Epson mode
IBM proprinter mode
Interface Standard: Centronics parallel
Option: RS-232C serial
Ribbon type On-carriage, dedicated
Black
Ribbon life 3 million characters (draft pica)
Dimensions 590(w) ×332(d) ×127(h)mm
23.2(w) ×13.1(d) ×5(h)in
Weight 8.5 kg (18.7 lb)
Power supply 120VAC, 220VAC, 240VAC, 50/60Hz
(varies according to the country of purchase)
Options Automatic sheet feeder
Serial interface board(RS-232C)
Pull tractor feed
Fig. 1-1 External dimensions

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GENERAL SPECIFICATIONS
2. External Appearance and Composition
Fig. 1-2 Front View of the Printer
Fig. 1-3 Diagram of Internal Composition

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GENERAL SPECIFICATIONS
3. DIP Switch Settings
3-1. For NX-1500 SU, LC-15 SU
Switch Function ON OFF
1-1 Page length 11 inches 12 inches
1-2 Auto CR Yes No
1-3 Character Set Gost Other (See 2-4)
1-4 Auto sheet feeder Inactive Active
1-5 Paper-out detector Enabled Disabled
1-6 Emulation mode Standard IBM
1-7 Character set Set #1 Set #2
1-8 Auto LF No Yes
2-1 Usage of RAM Buffer Download
2-2 Italic OFF ON
2-3 ESC 4/ESC 5 (*1) Italic MSB
2-4 IBM code page IBM-Russian #866
*1 The switch 2-3 is valid only in the standard emulation mode.
3-2. Others
Switch Function ON OFF
1-1 Page length 11 inches 12 inches
1-2 Auto CR Yes No
1-3 Printing area A type B type
1-4 Auto sheet feeder Inactive Active
1-5 Paper-out detector Enabled Disabled
1-6 Printer mode Standard IBM
Character set (Standard mode) Italics Graphics
Character set (IBM mode) Set #2 Set #1
1-8 Auto LF No Yes
2-1 Usage of RAM Buffer Download
2-2
2-3 International character set
2-4
International character sets:
Country 2-2 2-3 2-4 Country 2-2 2-3 2-4
U.S.A. ON ON ON Denmark I (*2) ON ON 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
*2 Denmark/Norway when switch 1-6 is OFF and switch 1-7 is ON.
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GENERAL SPECIFICATIONS
4. Parallel Interface
4-1. General Specifications
Item Specifications
Synchronization System Via externally supplied STROBE pulses
I/F Protocol By ACK and BUSY signals
Logic Level Compatible with TTL level
Fig. 1-4 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 DATA0 High when active
3 DATA1 High when active
4 DATA2 High when active
5 DATA3 High when active
6 DATA4 High when active
7 DATA5 High when active
8 DATA6 High when active
9 DATA7 High when active
10 ACK 9µs low pulse acknowledges receipt of data
11 BUSY Low when printer ready to receive data.
12 PAPER High when paper out. Can be disabled with Memory Switch setting.
13 SELECT High when printer is on-line
14,15 NC Unused
16 SIGNAL GND Signal ground
17 CHASSIS GND Chassis ground (isolated from signal ground)
18 +5V +5V DC output from printer
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
34,35 NC Unused
36 SELECT IN Always high

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GENERAL SPECIFICATIONS
5. Serial Interface (option)
5-1. General Specifications
Item Specifications
Interface RS-232C level
Synchronization System Asynchronous
Baud rate 150-19,200 bit per second (BPS) [selectable]
150, 300, 600, 1200, 2400, 4800, 9600, 19200BPS
Word length
Start bit: 1 bit
Data bit: 7 or 8 bits (selectable)
Parity bit: Odd, Even or None (selectable)
Stop bit: More then 1 bit length
Signal polarity
Mark: Logic “1” (–3V to –15V)
Space: Logic “0” (+3V to +15V)
Handshaking DTR
XON/XOFF
ETX/ACK
Data buffer 8KB (standard)
5-2. Connector Signal and Functional Descriptions
Pin No. Signal name Direction Function
1 GND — Printer’s chassis ground.
2 TXD OUT This pin carries data from the printer.
3 RXD IN This pin carries data to the printer.
4 RTS OUT Always space.
This pin is Space when the computer is ready to send data.
This printer does not check this pin.
6 NC Unused.
7 GND — Signal ground.
8-10 NC Unused.
This printer turns this pin Space when it is ready to receive data.
This line carries the same signal as pin 20.
12 NC Unused.
13 GND — Signal ground.
14-19 NC Unused.
20 DTR OUT The printer turns this pin Space when it is ready to receive data.
21-25 NC Unused.
5 CTS —
11 RCH OUT

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GENERAL SPECIFICATIONS
5-3. DIP Switch Settings
Switch ON OFF
1 8 data bits 7 data bits
2 No parity Parity checked
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5 Odd parity Even parity
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7 Data transfer rate — see table below
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All switches are set ON when the printer leaves the factory.
Protocol Switch 3 Switch 4
DTR mode ON ON
XON/XOFF mode ON OFF
ETX/ACK mode OFF ON
Baud rate Switch 6 Switch 7 Switch 8
150 OFF OFF OFF
300 OFF OFF ON
600 OFF ON OFF
1200 OFF ON ON
2400 ON OFF OFF
4800 ON OFF ON
9600 ON ON OFF
19200 ON ON ON
Handshaking protocols — see table below

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GENERAL SPECIFICATIONS

CHAPTER 2
THEORY OF OPERATION
1. Block Diagram ..................................................................................................... 13
2. Main Logic Board ................................................................................................ 14
2-1. Data Input Operation............................................................................................. 14
2-1-1. Parallel Interface ............................................................................................... 14
2-1-2. Serial Interface .................................................................................................. 15
2-2. General Flow Chart ............................................................................................... 18
2-2-1. Editing ............................................................................................................... 19
2-2-2. Print Head Driving Circuit ................................................................................ 19
2-2-3. Print Head Temperature Detection Circuit......................................................19
2-2-4. Carriage Motor Driving Circuit......................................................................... 20
2-2-5. Carriage Motor Speed Control......................................................................... 21
2-2-6. Paper Feed Motor Driving Circuit .................................................................... 21
2-3. Reset Circuit.......................................................................................................... 23
2-4. Reset by +5V Line Voltage Detection ..................................................................24
2-5. Protection Circuit .................................................................................................. 24
3. Power Supply Unit .............................................................................................. 24
4. Mechanisms......................................................................................................... 25
4-1. Print Head Mechanism.......................................................................................... 25
4-2. Print Head Carrying Mechanism .......................................................................... 25
4-3. Ink Ribbon Feed Mechanism................................................................................ 26
4-4. Paper Feed Mechanism ........................................................................................ 27
4-5. Detectors ............................................................................................................... 28
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THEORY OF OPERATION

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THEORY OF OPERATION
1. Block Diagram
The block diagram of this printer is shown in Fig. 2-1.
Fig. 2-1 Block Diagram
(1) Main Logic Board
This board receives data from the host computer and stores it in the RAM in the order of arrival. The CPU on this
board reads the data from the RAM, and edits it according to the program stored in the ROM.
When the editing is completed, various drive signals from the CPU are sent to the printer mechanism to perform
printing.
<Explanation>
1 CPU M50734SP
•Controls this printer.
2 EPROM 27512×1 64K-bytes, 27256×1 32K-bytes
•Contains the program which executes control of the printer.
3 RAM 32K-bytes
•Used as stack area, work area and data buffer of the CPU.
4 Parallel interface
5 Gate array (custom IC)
•Inputs or outputs several signals.
6 Driver
•The data edited by the CPU and gate array are sent to the printer mechanism after conversion to the signal
for the print head drive, carriage motor drive and paper feed motor drive respectively.
(2) Control Panel Board
This panel circuit is for manual operation of the printer.
(3) Printer Mechanism
The printer mechanism consists of a print head, carriage motor, paper feed motor and detectors.
(4) Power Supply Unit
AC power is converted to 25.5VDC and 5VDC.

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THEORY OF OPERATION
2. Main Logic Board
2-1. Data Input Operation
2-1-1. Parallel Interface
Communications between the host computer and this printer are facilitated via parallel connectors. This section explains
the handshake of this interface.
The data input circuit of this interface is shown in Fig. 2-2.
Fig. 2-2 Data Input Circuit with Parallel Interface
The following is an explanation of this handshake.
(1) When the BUSY signal is LOW (Ready), the host computer outputs 8-bit data 1 through 8 to the connector CN1.
Pin 1 carries the STROBE pulse signal from the host computer to the printer.
This signal is normally held HIGH by the host computer. When the host computer has data ready for the printer,
it sets this signal to LOW for at least 0.5 µS.
(2) The gate array of the main logic board reads data 1 through 8 at the time of STROBE signal fall, and then turns the
BUSY and RDF0 (in the device U1) signals to low.
(3) WhentheBUSYsignal of thegatearrayissettoLOW, the BUSYsignalofconnectorCN1will be turnedtoHIGH,
notifying the host computer that data cannot be accepted.
(4) The CPU is informed via the D0 data line that the RDF0 signal is LOW. The CPU then, set the RD signal to LOW
and read the data.
(5) Upon completion of the data reading, the CPU notifies the host computer of the data receivable state by setting the
BUSY signal of connector CN1 and the ACK signal to LOW for a certain period of time.
This concludes the explanation of the parallel interface handshake. The following chart shows the timing chart of
the handshake.

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THEORY OF OPERATION
Fig. 2-3 Timing Chart of Parallel Interface
2-1-2. Serial Interface (option)
When the serial interface is used, an optional Serial Interface Board is required to be installed. The board will change the
voltage level (RS-232C <-------> TTL) and the data transfer method (Serial <-------> parallel).
Fig. 2-4 Serial Interface

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THEORY OF OPERATION
IC4 is a dual RS-232C driver/receiver which includes a capacitive voltage generator to supply RS-232C voltage levels
from a single 5V supply.
Datafromthehostcomputerissentfrom RXD via IC4 and is input to the MPU. Serial data input to theMPUisconverted
into parallel data, and output to the main logic board. Conversely, parallel data received by the MPU is converted there
into serial data, and output to the TXD terminal via IC4.
The CTS terminal is hardware-connected, not software- connected. (This signal is not checked.)
This printer employs 3 different transfer methods, which can be selected using the dip switches. (Refer to Chapter 1, 5-
3 Setting Dip Switches)
(1) DTR method
The DTR signal is considered a BUSY signal at the handshake, and when the data buffer capacity is 256 bytes or
less, the DTR signal is given a marked status, meaning it cannot receive data.
Whenthecapacityof thedatabufferincreasesto512 bytes ormoreduringprinting,the DTR signalisgivenaspace
status, which indicates that it can receive data.
(2) XON/XOFF method
When a handshake is carried out with the host computer, the XON/XOFF method makes use of ASCII codes (DC1)
and(DC3).(DC1andDC3are calledXON andXOFF,respectively.)Whentheprinterbuffer isfull,DC3(ASCIIcode
19)isoutputtotheTXDterminal,andthecomputerreceivesarequesttostopdatatransfer.TheprinteroutputsDC3
until it (the computer) stops data transfer. During printing, when the buffer full status is cancelled and data can be
received, DC1 (ASCII code 17) is output to the TXD terminal. When DC1 is output from the printer, the computer
follows the data format, and begins data transfer. Data transfer will continue until DC3 is output again.
(3) ETX/ACK method
The data block is configured as shown below, but the initial STX code is not necessary. When an STX code is sent
from the host computer, that 1 byte is ignored. When the ETX code is received, that 1 byte is not regarded as data,
anACKorNACKcodeissentto the TXD terminal, and the host computer is informed that data reception has been
completed.
Data block form:
STX DATA (8 KB or less) ETX
Fig. 2-5 Data Format