OKIDATA MICROLINE 320 User manual

Thank You for purchasing this
Factory Service Manual on EBAY
from PCTECHINFO!
Click Here for more Factory Service
Manuals for other Computer and
Printer / Copier Manufacturers
from PCTECHINFO!

All specifications are subject to change without notice.
Service Manual
MICROLINE 320/321
TURBO PRINTER
59273701

OKIDATA and MICROLINE are registered trademarks of Oki Electric Industry Company, Ltd.
OKIDATA est une marque déposée de Oki Electric Indurstry Company, Ltd.
PREFACE
This Service Manual describes how to maintain the Microline 320/321 Turbo printer in the field.
It is intended for service personnel.
Refer to the user documentation for information on handling and operating the printer.

i
TABLE OF CONTENTS
1. CONFIGURATION................................................................................................................. 1-1
1.1 Standard Printer Configuration .................................................................................. 1-1
1.2 Options ....................................................................................................................... 1-2
2. THEORY OF OPERATION................................................................................................... 2-1
2.1 Electrical Operation.................................................................................................... 2-1
2.1.1 Summary ....................................................................................................... 2-1
2.1.2 Microprocessor and the Peripheral Circuit .................................................. 2-1
2.1.3 Initialization.................................................................................................... 2-7
2.1.4 Parallel Interface Control.............................................................................. 2-8
2.1.5 Print Control .................................................................................................. 2-9
2.1.6 SP/LF Motor Control................................................................................... 2-12
2.1.7 Operation Panel .......................................................................................... 2-15
2.1.8 Alarm Circuit ............................................................................................... 2-17
2.1.9 Power Supply Circuit .................................................................................. 2-19
2.2 Mechanical Operation .............................................................................................. 2-20
2.2.1 Printhead Mechanism and Operation ........................................................ 2-20
2.2.2 Spacing Operation ...................................................................................... 2-23
2.2.3 Head Gap Adjusting ................................................................................... 2-25
2.2.4 Ribbon Drive ............................................................................................... 2-27
2.2.5 Paper Feed Operation................................................................................ 2-29
2.2.6 Paper Detection Mechanism ...................................................................... 2-40
2.2.7 Automatic Sheet Feed................................................................................ 2-44
2.2.8 Paper Park Function................................................................................... 2-46
3. ASSEMBLY/DISASSEMBLY ................................................................................................. 3-1
3.1 Precautions for Parts Replacement .......................................................................... 3-1
3.2 Service Tools ............................................................................................................. 3-2
3.3 Disassembly/Reassembly Procedure ........................................................................ 3-3
3.3.1 Printhead ....................................................................................................... 3-5
3.3.2 Ribbon Protector ........................................................................................... 3-6
3.3.3 Pull-up Roller Assy ....................................................................................... 3-7
3.3.4 Upper Cover Assy, Access Cover Assy and Sheet Guide Assy ............... 3-8
3.3.5 Gear Case Assy ........................................................................................... 3-9
3.3.6 PC Connector ............................................................................................. 3-10
3.3.7 Space Motor, Guide Roller Assy ............................................................... 3-11
3.3.8 Space Rack................................................................................................. 3-12

ii
3.3.9 Carriage Cable............................................................................................ 3-13
3.3.10 Backup Roller Holder Assy ........................................................................ 3-14
3.3.11 Platen Assy ................................................................................................. 3-15
3.3.12 Driver Board (SDDV).................................................................................. 3-16
3.3.13 LF Motor...................................................................................................... 3-17
3.3.14 Operation Panel PCB (LEOP).................................................................... 3-18
3.3.15 Control/Power Supply Board (SDCT) ........................................................ 3-19
3.3.16 Transformer Assy........................................................................................ 3-20
3.3.17 Change Lever and Gears........................................................................... 3-21
3.3.18 Carriage Shaft............................................................................................. 3-22
3.3.19 Paper Pan ................................................................................................... 3-23
3.3.20 Rear Tractor Assy ...................................................................................... 3-24
3.3.21 Rear Pressure Assy ................................................................................... 3-25
3.3.22 Switch Lever ............................................................................................... 3-26
4. ADJUSTMENT....................................................................................................................... 4-1
5. CLEANING AND LUBRICATION.......................................................................................... 5-1
5.1 Cleaning ..................................................................................................................... 5-1
5.2 Lubrication .................................................................................................................. 5-3
6. TROUBLESHOOTING AND REPAIR................................................................................... 6-1
6.1 Items to Check Before Repair .................................................................................. 6-1
6.2 Troubleshooting Table ............................................................................................... 6-1
6.3 Lamp Display ............................................................................................................. 6-3
6.4 Connection Circuit Check for Printhead and SP/LF Motor...................................... 6-6
6.5 Troubleshooting Flow Chart....................................................................................... 6-9
APPENDIX
A. PCB LAYOUT ............................................................................................................A-1
B. SPARE PARTS LIST .................................................................................................B-1
C. RS-232C Serial Interface Board (OPTION) ..............................................................C-1
1. General ..................................................................................................................C-1
2. Operation Description ............................................................................................C-2
3. Troubleshooting Flowchart ....................................................................................C-7

1 – 1
1. CONFIGURATION
1.1. Standard Printer Configuration
This printer consists of the following assemblies:
Figure 1-1 Configuration
Sheet guide assy Platen knob
Access cover
assy
Upper cover
Control/Power supply assy
Traansformer assy
Pull-up roller assy
Operation panel assy
Main chassis assy
Driver board

1 – 2
1.2 Options
(1) Cut sheet feeder unit (CSF)
Attachment assy
(2) Pull-tractor assy
Single-bin CSF

1 – 3
(3) Bottom push tractor unit
(5) Serial I/F
• RS-232C
(4) Roll paper stand (Narrow only)

2 – 1
2. THEORY OF OPERATION
2.1 Electrical Operation
This section describes the electrical operation of the printer circuit.
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 – 2
12.288
MHz
4
Vcc-Level TSD AUTO-LF
AI
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
LF
driver
SP
driver
SP alarm
HD-Alarm
Head driver
2P Encoder
M M
SP
LF
TSD
Para
-I/F
(opt.)
RS232C
-I/F
Roll paper
Stand
(opt.)
CSF
AC-input
1M
max
4M
16*256 Kbits
Alarm circuit
Power-off HD-Alarm
SP-Alarm
Divider
Figure 2-1

2 – 3
(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 CLOCK
A0~A17
PG-N
PSEN-N
D0~D15
Program Program Program
IN IN IN
CSO
PSEN
CE
OE
PG-N
D0~D15
A0~A17
MPU ROM

2 – 4
A0~A7 RAM 1 (Q3)MPU
P03
CS1
RD OE
D4~D7
D0~D3
RAS
CAS
RAM 2 (Q4)
T1 T2 T3
Clockout*
A0~A7
CS1~CS4
RD
D0~D7
(Read)
WRH
WRL
D0~D7
(Write)
8-bit bus, b
y
te instruction
* Clockout is provided when the original excitation is selected.
(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 examples of the memory access operation.

2 – 5
MPU EEPROM
EEDIN-P
EECS-P
EEDOUT-P
EECLK-P
P24
P27
P25
P26
D1
CS
DO
SK
,
,
,
,
,
,
,























ReadyBus
twp
D0D15A0A5
11 0
Start
code Operation
code Address Data
tCS
PRE = O
PE
EECS-P
EECLK-P
EEDIN-P
EEDOUT-P
Address
Start
code
Operation
code
EEDOUT-P
EEDIN-P
EECLK-P
EECS-P
D15 D0 D15 D0 D15
0
A0A5
0
11
tCS
PRE = O
PE = X
Read cycle timing (READ)
Write cycle timing (WRITE)
(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.

2 – 6
P07
MPU A/D bus LSI
RD
WRL
P01
ALE
RDN
WRL
LSIC
Clockout*
A0~A19
LSICS
ALE
D0~D15
(Read)
RD
D0~D15
(Write)
WRL
Address
Address
Data
Data
* Clockout is provided when the original
excitation is selected.
(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.

2 – 7
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 the program to initialize, but does not reset the
MPU.
The program 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. When the ready state is set, the host is informed
that the printer is ready to receive data.
End
I/F BUSY OFF
Serial
I/F
I/F ACK Send
Parallel
I/F
LF Motor Phase
Initialization
Carriage Homing
RAM Clear
LSI Initial Setting
and I/F Busy ON
External RAM
CHECK
LSI RESET
ROM CHECK
Internal RAM
CHECK
MPU
Initial Setting
MPU RESET
Start

2 – 8
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 stop data transmission.
A/D bus
MPU LSI
NBSY
ACK
NSTB
RXD
P16 NRXD
Receive Data
CN1
BUSY
ACK-N
STB-N
Data
1 to 8
STROBE
BUSY
ACK
RXD
2~8µs
500ns max.

2 – 9
2.1.5 Print Control
Print data is transmitted as parallel data (HEAD1~HEAD9) from the LSI to the print head. The
LSI generates the print timing and drive time.
HEAD DRIVE TIMING CHART
DT1
DT2
HEAD
DRIVE CURRENT
Print Data
MPU LSI
DRIVER
HEAD1-N~
HEAD9-N
Print Data Print Head
Control/Power Supply Board
A/D bus
HEAD1~
HEAD9
Driver Board

2 – 10
(d) Simultaneous Compensation of the number of impact pins
The MPU is provided with the compensation table for each pin to compensate as
necessary.
Number of impact pins Few Many
Drive time Short Long
Print Head
Time
Pin 3~6
Pin 1, 2,
8, 9
Pin coil
current
Pin 1, 2
3~6
8, 9
Platen
Print Compensation Control
The print compensation methods are shown below:
(a) Voltage compensation (See 2.1.8 “Alarm Circuit.”)
(b) Temperature compensation (See 2.1.8 “Alarm Circuit.”)
(c) Pin stroke compensation
As shown in the drawing left, the stroke length
up to the platen is different for each pin.

2 – 11
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.)
(e) Print mode compensation
According to the thickness of the printing medium, the print mode is compensated
as shown in the table below:

2 – 12
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 increased or decreased to maintain the
specified speed for each print mode.
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
SPU
SPV
SPW