OKI 3320, 3321 Service manual

MICROLINE 3320/3321 PRINTER

Maintenance Manual

All specifications are subject to change without notice.

PREFACE

This maintenance manual describes how to maintain the Microline 3320/3321 printer in the field. This manual is for customer engineers. For further information, refer to the Users Manual for handling or operating the equipment.

iii

1. CONFIGURATION

1.1 Standard Printer Configuration

1.2 Options

2. THEORY OF OPERATION

2.1 Electrical Operation

2.1.1 Summary

2.1.2 Microprocessor and the Peripheral Circuit

2.1.3 Initialization

2.1.4 Parallel Interface Control

2.1.5 Print Control

2.1.6 SP/LF Motor Control

2.1.7 Operation Panel

2.1.8 Alarm Circuit

2.1.9 Power Supply Circuit

2.2 Mechanical Operation

TABLE OF CONTENTS

2.2.1 Printhead Mechanism and Operation

2.2.2 Spacing Operation

2.2.3 Head Gap Adjusting

2.2.4 Ribbon Drive

2.2.5 Paper Feed Operation

2.2.6 Paper Detection Mechanism

2.2.7 Automatic Sheet Feed

2.2.8 Paper Park Function

3. ASSEMBLY/DISASSEMBLY

3.1 Precautions for Parts Replacement

3.2 Service Tools

3.3 Disassembly/Reassembly Procedure

3.3.1 Printhead

3.3.2 Ribbon Protector

3.3.3 Pull-up Roller Assy

3.3.4 Upper Cover Assy, Access Cover Assy and Sheet Guide Assy

3.3.5 Gear Case Assy

3.3.6 PC Connector

3.3.7 Space Motor, Guide Roller Assy

3.3.8 Space Rack

3.3.9 Carriage Cable

3.3.10 Backup Roller Holder Assy

3.3.11 Platen Assy

3.3.12 Driver Board (SDDV)

3.3.13 LF Motor

3.3.14 Operation Panel PCB (LEOP)

3.3.15 Control/Power Supply Board (SDCT)

3.3.16 Transformer Assy

3.3.17 Change Lever and Gears

3.3.18 Carriage Shaft

3.3.19 Paper Pan

3.3.20 Rear Tractor Assy

3.3.21 Rear Pressure Assy

3.3.22 Switch Lever

4. ADJUSTMENT

5. CLEANING AND LUBRICATION

5.1 Cleaning

5.2 Lubrication

6. TROUBLESHOOTING AND REPAIR

6.1 Items to Check Before Repair

6.2 Troubleshooting Table

6.3 Lamp Display

6.4 Connection Circuit Check for Printhead and SP/LF Motor

6.5 Troubleshooting Flow Chart

APPENDIX

A. PCB LAYOUT B. SPARE PARTS LIST C. RS-232C Serial Interface Board (OPTION)

1. CONFIGURATION

1.1. Standard Printer Configuration

This printer consists of the following assemblies:

Sheet guide assy

Platen knob

Access cover assy

Upper cover

Control/Power supply assy

Driver board

Transformer assy

Pull-up roller assy

Operation panel assy

Main chassis assy

Figure 1-1 Configuration

1 – 1

1.2 Options

(1) Cut sheet feeder unit (CSF)

(Narrow and wide versions available)

Dual-bin CSF Single-bin CSF

Attachment assy

(2) Pull-tractor assy

1 – 2

(3) Bottom push tractor unit

(4) Roll paper stand (Narrow only)

(5) Serial I/F

• RS232C

• RS422A

• Current Loop

1 – 3

2. THEORY OF OPERATION

2.1 Electrical Operation

The electrical operation of the printer circuit is described in this section.

2.1.1 Summary Fig. 2-1 shows the block diagram of the printer. The control board is made up of the microprocessors, peripheral circuits, drive circuits, sensors

and interface connectors. The power to the control board is supplied by the power board through the connector cord. The power to other electrical parts is also distributed through the connectors within the control

board.

2.1.2 Microprocessor and the Peripheral Circuit (1) Microprocessor (Q7: 67X640)

This processor is a CMOS single-chip computer with integrated peripheral device functions and a 16 bit MPU core, all OKI original architecture.

The processor has a 20 bit address bus and a 16 bit data bus. It is capable of accessing up to 1M word program memory and 1M bytes of data memory. The following characteristics are also provided:

• Built-in type data memory of 512 bytes

• 8-bit 4-channel A/D converter × 1

• 16-bit automatic reload timer × 2

• 8-bit serial port × 2

• 8-bit parallel port × 3 (bitwise I/O specification available) And others. The function of this microprocessor is to provide a central mechanism for the entire printer

by executing the control program through the LSI and driver circuits.

2 – 1

12.288

MHz

Vcc-Level

TSD

AUTO-LF

INT

Release-SW

Bottom-Sensor

PE-SENSOR

OPERATION

PANEL

Serial

Rectifier

circuit

40 volt

8 volt

5 volt

Transformer

Reset

circuit

Print-IPT

I/F-IPT

EEPROM

1 Kbits

67 x 640

ADDRESS

ROM

AD-BUS

DRAM

4*64

Kbit*2

LSI

RESET

5VD

Vcc-Level

Fuse

40 V

driver

SP alarm

HD-Alarm

Head

driver

2P Encoder

TSD

Para

-I/F

(opt.)

RS232C

-I/F

Roll paper

Stand

(opt.)

CSF

AC-input

max

16*256 Kbits

Alarm

circuit

Power-off

HD-Alarm

SP-Alarm

Divider

Figure 2-1

2 – 2

(2) Program ROM

This is a 256 × 16 bits (4M bit) [MAX] EPROM with the control program for the printer stored. The MPU executes instructions under this program.

The program ROM is assigned to the program memory area of the MPU and is fetched by the PSEN signal of the MPU.

The following shows the operation of the memory access.

MPU ROM

A0~A17

D0~D15

MPU CLOCK

A0~A17

PG-N

PSEN-N

D0~D15

CSO PSEN

PG-N

Program Program Program

IN IN IN

CE OE

2 – 3

(3) RAM (MSM51C464A-80RS)

The RAM is CMOS dynamic RAM with (64K × 4-bit) × 2 configuration, and used as buffers (such as receiving buffer, printing buffer, DLL buffer and working buffer).

The following shows the examples of the memory access operation.

RAM 1 (Q3)MPU

A0~A7

RAM 2 (Q4)

Clockout*

A0~A7

CS1~CS4

RD

D0~D7 (Read)

P03 CS1

RD

RAS CAS

D0~D3

D4~D7

OE

T1 T2 T3

WRH

WRL

D0~D7 (Write)

8-bit bus, byte instruction

* Clockout is provided when the original excitation is selected.

2 – 4

(4) EEPROM

The EEPROM is a CMOS serial I/O type memory which is capable of electrically erasing and writing 1,024 bits.

The EEPROM contains menu data. The following shows the memory access operation.

MPU EEPROM

EEDIN-P

P24

EECS-P

P27

EEDOUT-P

P25

EECLK-P

P26

PRE = O PE = X

EECS-P

EECLK-P

EEDIN-P

EEDOUT-P

PRE = O PE

EECS-P

EECLK-P

EEDIN-P

Start code

Operation code

Address

A0A5

D15 D0 D15 D0 D15

Read cycle timing (READ)

Address Data

D0D15A0A5

EEDOUT-P

ReadyBus

twp

Write cycle timing (WRITE)

2 – 5

(5) LSI

This LSI detects and controls the SP motor speeds by monitoring the two phase sensor signals obtained from the DC motors and modifying the excitation phases as appropriate.

This LSI is connected in multiplex to the MPU.

MPU

P07 RD

WRL P01

Clockout*

A0~A19

LSICS

ALE

A/D bus

LSI

ALE RDN

WRL LSIC

D0~D15 (Read)

D0~D15 (Write)

WRL

Address

Data

* Clockout is provided when the original excitation is selected.

2 – 6

2.1.3 Initialization This printer is initialized when the power is turned on or when the I-PRIME-N signal is input

from the host side via the parallel interface. For the initialize operation, the RST-N signal is first output from the reset circuit to reset the

MPUs and LSIs. When resetting ends, the program starts and the LSIs are reset by MPU via LSIRST-N. Reset operation by I-PRIME starts program to initialize, but does not reset the MPU.

The program here sets the mode of the LSI including the MPU, checks the memories (ROMs and RAMs), then carries out carriage homing, and determines the LF motor phase.

Finally, the program establishes the interface signals (P-I/F: ACK-P signal sending, and S-I/F: BUSY-N signal off) and lights the SELECT lamp to inform the ready state for receiving to the host side and ends the initialize operation.

Start

MPU RESET

MPU

Initial Setting

Internal RAM

CHECK

Serial

I/F

I/F BUSY OFF

ROM CHECK

LSI RESET

External RAM

CHECK

LSI Initial Setting

and I/F Busy ON

RAM Clear

Carriage Homing

LF Motor Phase

Initialization

Parallel

I/F

I/F ACK Send

End

2 – 7

2.1.4 Parallel Interface Control The parallel data input from the host to the interfaced LSI is latched to its internal register at

the falling edge of the STROBE-N signal. At the same time, the LSI sets the BUSY signal to the high level to inform the host that the

data is being processed, and outputs the RXD signal to inform the MPU of data reception. The data is read upon receiving the RD-N signal from the MPU.

When the data processing ends, the BUSY signal is set to off and the ACK-N signal in sent to request the next data. When reception is impossible because the buffer is full, the BUSY signal is sent to request stopping of data transmission.

MPU LSI

CN1

Receive Data

Data 1 to 8

STROBE

BUSY ACK

RXD

A/D bus

RXD

P16 NRXD

500ns max.

2~8µs

NBSY

ACK NSTB

BUSY

ACK-N STB-N

2 – 8

2.1.5 Print Control Print data is transmitted as parallel data (HEAD1~HEAD9) from LSI to print head. LSI generates

print timing and drive time.

Control/Power Supply Board

MPU LSI

DT1

A/D bus

Driver Board

Print Data

HEAD1-N~ HEAD9-N

DRIVER

HEAD DRIVE TIMING CHART

Print Data

HEAD1~ HEAD9

Print Head

DT2

HEAD DRIVE CURRENT

2 – 9

Print Compensation Control The print compensation can be made as shown below: (a) Voltage compensation (See 2.1.8 “Alarm Circuit.”) (b) Temperature compensation (See 2.1.8 “Alarm Circuit.”) (c) Pin stroke compensation

Platen

Print Head

Pin 1, 2

As shown in the drawing left, the stroke length up to the platen is different for each pin.

3~6

8, 9

Pin coil current

Pin 1, 2,  8, 9

Pin 3~6

Time

(d) Simultaneous Compensation of the number of impact pins

The MPU is provided with the compensation table for each pin to make necessary compensation.

Number of impact pins Few Many Drive time Short Long

2 – 10

(e) Print mode compensation

According to the thickness of the printing medium, the print mode is compensated as shown in the table below:

Head Gap Range 1 2 3 4 5 Print speed 100% 95% 85% 85% 80% Drive time Short Long

(Drive time lengthens at each step.)

2 – 11

2.1.6 SP/LF Motor Control (1) Space motor control

The SP motor driver (HA13412) drives the three-phase brushless motor based on the phase signal (SPU, SPV and SPW) and the speed instruction data from the LSI. The MPU can identify the current speed of the space motor by measuring through the LSI the pulse length of the output (øA, øB) of the slit encoder included in the space motor.

By comparing the target speed for each print mode with the actual current speed to change the speed instruction data, the motor speed is accelerated or decelerated to maintain the specified speed for each print mode.

SPU

SPV

SPW

SP truth table

HALL AMP INPUT OUTPUT

SPU SPV SPW U V W

H H L OPEN L H H L L L OPEN H H L H L H OPEN

L L H OPEN H L L H H H OPEN L L H L H L OPEN

2 – 12

(2) Encoder disk

In the operation of the spacing motor, the PHASE-A and PHASE-B signals are generated when the encoder disk interrupts the photo sensor.

The LSI divides these edge pulse signals in accordance with the print pitch, and sends the IPT signal to provide dot-on timing and carriage position detection timing.

SPU SPV

SPW

PHASE-A

PHASE-B

1/720"

IPT 10 CPI

IPT 12 CPI

IPT 15 CPI

IPT 17 CPI

IPT 20 CPI

• UTILITY MODE

1/120"

1/144"

1/180"

1/206"

1/240"

2 – 13

(3) LF motor control

The LF motor driver (MTD2005F) drives the LF motor in two-phase or 1-2 phase bipolar, based on the phase changeover data and the output current data from the LSI.

The data from the LSI is processed by a specific register contained in the LF motor driver to measure the overdrive time and to change the phase.

PHASE-A

PHASE-B

[FORWARD]

[REVERSE]

2 – 14

2.1.7 Operation Panel The clock synchronization OPCLK of LSI is used to input the switch data and output the LED

data through the operation panel control LSI (IC1: BU5148S).

LSI

OPTD

OPCK

NPA2

OPRD

OPTXD

77

OPCLK

78

OPCLR-N

80

OPRXD

79

Command

and Data 

latch

LED driver

+5V

Switch

controller

A 2-byte (15 bits + 1 even parity bit) command (OPTXD) is transmitted to the LSI (BU5148S) in synchronization with the OPCLK signal. The LSI decodes this command and when it is found to be legal, returns a 2-byte command response back to the LSI which includes data on Switch information, LED status, receive command ACK/NAK and 1 odd parity bit.

Any transmission errors found cause the command to be reissued after the transmission of the OPCLR-N signal.

2 – 15

8

6

7

3 1

Command (second)

Command response (second)

Note

Command (first)

Command response (first)

bit0 bit7

1 2 3 2

OPTXD

OPCLK

OPRXD

1

OPCLR-N

2

Reset

within

3

BU5148S

4

NO

7

Error notification

8

Instruction for

retransmission

the bit 0 to bit 3 of OPRXD are fixed so that the response can be returned before decoding the command.

YES

for OK or NG

Response check

Note: From the illustration above, you can see that the command and the command response are output at the same time. This is because

5

6

Power ON

reset

Write instruction for LSI

etc.

LSI write for LED data,

data read

Read instruction for

2 – 16

2.1.8 Alarm Circuit (1) Head drive time alarm circuit

This circuit monitors the drive time using the HDALM signal interlocked with the overdrive signal of each drive circuit.

If the drive time of any drive circuit exceeds the specified time, the drive fault alarm circuit sends an ALARM-N signal to turn on the SCR (SO).

This cause the secondary coil (40V) of the transformer to be short-circuited, causing an overcurrent to flow through the primary coil and making the AC fuse (transformer assy) open.

(2) Alarm processing when DC power is low.

+ 40V is converted into the POWLEV signal (0V to +5V) by R28 and R29 and input into the A/D port of the MPU to control the drive time and the print speed (pass number) of the head.

+40V

R28

POWLEV

R29

(a) Head drive time

The head drive time is lengthened to compensate for the amount of voltage drop by monitoring the POWLEV signal once every 500 µ sec. to control and maintain the impact necessary for each printing pin at the fixed value.

(b) Print speed

Voltage, +40V Pass number Print speed

38V or more 1 Pass 100%

25V to 37V 1 Pass 100~30%

25V or less 1 Pass 30%

2 – 17

(3) Head overheat alarm

The voltage of the output TSD signal of the thermistors, one of which is contained in the print head and the other in the print head driver, is monitored by the CPU/AD port to control the voltage

Temp

Mode and print control

Mode Speed Pass Direction

1 100% 1 Bi 2 85% 1 Bi 3 70% 1 Bi 4 55% 1 Bi 5 40% 1 Bi

Stop

119°C

Mode up

α°C ß°C

Mode down

6 30% 1 Bi 1.5 Sec Stop

(7) Stop

• When the temperature is between α°C and 119°C, the mode switches sequentially to higher level. When the temperature falls below ß°C, the mode switches to lower level.

• When the temperature exceeds 119°C, printing will stop.

• When temperature gradient is steep, higher mode shall be specified directly.

2 – 18

2.1.9 Power Supply Circuit This power supply circuit supplies the +5VDC, +8VDC, +40VDC, 10VAC.

Control Board

Fuse

Noise

filter

circuit

Transformer

The uses of output voltages and signals are described below.

Voltage/signal Use

+5V Logic IC/LED drive voltage +8V Serial interface line voltage and SP motor driver

+ 40V Printhead, LF motor drive voltage, SP motor drive voltage

AC 10V Option board

Rectifier

Regulation

Circuit

+40V

+8V

+5V

AC10V

2 – 19

2.2 Mechanical Operation

2.2.1 Printhead Mechanism and Operation (See Figure 2-2.) The printhead is a spring charged 9-pin driving head using a permanent magnet. It is attached

to the carriage, which moves in parallel with the platen. Electrically, this unit is connected to the control circuits through the control board.

Figure 2-2 Arrangement of the head pins

View from the tip of the printhead

(1) The printhead configuration:

The printhead is composed of the following parts: (a) Wire guide (b) Spring assembly (Wire, Armature, Spring, Yoke, Spacer) (c) Magnet assembly (Magnet, core, coil, Yoke) (d) Printed circuit board (e) Fin

2 – 20

(2) Operation of printhead (See Figure 2-3.)

(a) When the printhead is idle, the armature is attracted by a permanent magnet and

the spring fixing the armature is compressed. The print wires fixed to each armature are thus concealed under the wire guide.

(b) When a signal for a character to be printed is detected, a current flows through the

coil. When the coil is activated, the magnetic flux (caused by the permanent magnet between the armature and the core) is canceled to eliminate the attraction force. The armature is driven in the direction of the platen by the force of the armature spring. The print wire fixed to the armature protrudes from the tip of the wire guide, strikes the paper through the ribbon and prints a dot on the paper.

and the print wires are again concealed under the wire guide. A thermistor in the printhead prevents burning caused by over-heating of the coil

during extended continuous bi-directional printing. When the temperature of the coil exceeds a pre-determined limit (about 119°C) the control circuit detects a thermistor signal. Printing will then be intermittent or stop completely until the coil temperature falls below the limit value.

2 – 21

+ 195 hidden pages

OKI 3320, 3321 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual