OKI 4w Troubleshooting Manual

OKIPAGE4w LED Page Printer

Troubleshooting Manual with Component Parts List

(ODA/OEL/INT)

1997.12.10 Rev. 2

All specifications are subject to change without notice.

CONTENTS

1. OUTLINE..................................................................................................... 1

2. TOOLS........................................................................................................ 1

3. CIRCUIT DESCRIPTION............................................................................ 2

4. TROUBLESHOOTING.............................................................................. 21

5. CIRCUIT DIAGRAM.................................................................................. 27

6. COMPONENT PARTS LIST

1. OUTLINE

This manual has been written to provide guidance for troubleshooting of the OKIPAGE4w Printer (primarily for its printed circuit boards), on an assumption that the reader is knowledgeable of the printer. Read the maintenance manual for this printer P/N M-521426 if necessary.

Note:

1. High voltage power supply board and power supply unit containing a high voltage power supply is dangerous. From the viewpoint of the safety standards, the local repairing of a defective board is not allowed. Thus, the objects to be locally repaired as a result of troubleshooting are switches and fuses.

2. TOOLS

For troubleshooting the printer, the tools listed below may be needed in addition to general maintenance tools.

Oscilloscope Frequency response 100 MHz or higher Soldering iron A slender tip type, 15-20 watts Ectension code kit P/N : 40105501

Tool Remarks

- 1 -

3. CIRCUIT DESCRIPTION

3.1 Outline

The circuit of OKIPAGE4w consists of a main control board, a high voltage power supply board and a power supply unit. The block diagram is shown in Fig. 3-1. The main control board controls the reception and transmission of data with a host I/f and processes command analysis, bit image development, raster buffer read. It also controls the engine and high voltage outputs.

(1) Reception and transmission control

The main control board has one parallel I/F port which is compliant to the IEEE 1284 specification. An interface task stores all data received from the host into a receive buffer first, and returns the printer status upon request of the host.

(2) Command analysis processing

The OKIPAGE4w printer has the following emulation mode.

Hiper-W: OKI original

An edit task fetches data from the receive buffer, analizes commands, and sets I/O registers.

(3) Raster data processing

The decompression circuit in the CPU expands the compressed data and stores the data into the raster buffer.

(4) Raster data transfer

The LED head control circuit in the CPU sends the data stored in the raster buffer to the LED head.

(5) High voltage control

The high voltage control circuit in the CPU.

The high voltage power supply board generates high voltage outputs, and have sensors, LED for display. The power supply unit generates +24VDC output, +5DC output.

- 2 -

I/F

Parallel

LS07

Main motor

Electromagnetic

Driver

clutch

Manual feed sensor

Paper sensor

Outlet sensor

Toner sensor

Cover open switch

LED

Thermistor

EP cartridge

power

HIgh voltage

Heater

(Halogen lamp)

AC

(120 V/230 V)

supply

<High-voltage Power Supply Board>

Switching

AC output ON/OFF

power supply

I/F

Parallel

D0 ~ D7

EPROM

(64 KByte)

A8 ~ A15

A0 ~ A7

latch

Address

AD0 ~ AD7

LED head LED head

Main motor

Electromagnetic

clutch

LED

D0 ~ D3

Sensors

D-RAM

(128 KByte)

A0 ~ A10

TEMP

power

High-voltage

TR-ISEN

TR-VSEN

Driver

HEAT ON

High-voltage power I/F

LED

Driver

+5V

0VL

0VP

+24V

HEAT ON



10MHz

CPU

(MSM65917)

EEPROM

I/F

Parallel

LED head

clutch

Main motor

Electromagnetic

Sensors

Figure 3-1 OKIPAGE4w Block Diagram

- 3 -

TEMP

TR-VSEN

TR-ISEN

Reset

circuit

0VL

3.2 CPU and Memory

(1) CPU (MSM65917)

CPU core nX-8 CPU clock 10 MHz Data bus width External 8 bits, Internal 8 bits

(2) Program ROM

ROM capacity 64k-bytes (512-kbit EPROM) ROM type 512 kbits (64k x 8 bits) Access time 150 nsec

When mask ROM in the CPU is valid, the EPROM is not mounted. (3) Resident RAM

RAM capacity 128k bytes (256k x 4 bits D-RAM one piece) RAM type 1M bits (256k x 4 bits) Access time 70 ns

The block diagram of CPU and memory circuit is shown in Fig. 3-2.

- 4 -

CPU IC 6

ALE

RDN

ROCS

DA10

DWR

CAS

AD00 to AD07

LS373

IC3

A08 to A15

DD00 to DD03

DA00 to DA09

A00 to A07

IC2 

EPROM

(64k x 8 bits)

IC11

DRAM

(256k x 4 bits)

RAS0 RAS1 RAS2

Main Control Board

Figure 3-2 Block Diagram of CPU & Memory in OKIPAGE4w

- 5 -

3.3 Reset Control

When power is turned on, RST-N signal is generated by IC5.

+5V+5V

+5V

Power ON

IC5

Power OFF

CPU

RSTN

RST-N

- 6 -

3.4 EEPROM Control

The BR93LC46A on the main control board is an electrical erasable/programmable ROM of 64bit x 16-bit configuration. Data input to and output from the ROM are bidirectionally transferred in units of 16 bits through I/O port (EEPRMDT-P) in serial transmission synchronized with a clock signal from the CPU.

The EEPROM operates in the following instruction modes.

Instruction Start bit Operation Address Data

Read (READ) 1 10 A5 to A0 Write Enabled (WEN) 1 00 11XXXX Write (WRITE) 1 01 A5 to A0 D15 to D0

CPU

EEPRMDT-P

EEPRMCS-P

EEPRMCLK-P

code

DI DO

EEPROM

IC4

Write All Address (WRAL) 1 00 01XXXX D15 to D0 Write Disabled (WDS) 1 00 00XXXX Erase 1 11 A5 to A0 Chip Erasable (ERAL) 1 00 10XXXX

Write cycle timing (WRITE)

Min. 450 ns

1 2 4 9 10 25

10 1

HIGH-Z

A5 A4 A1 A0 D15

D14

D1 D0

Max. 10 ms

Read cycle timing (READ)

110

A5 A4 A1 A0

910

25 26

STATUS

Max. 500 ns

BUSY READY

HIGH-Z

D15 D14 D1 D00 D15 D14

- 7 -

3.5 Parallel Interface

Parallel data is received from a host system via parallel interface which is compliant to the IEEE1284 specification.

CPU

65 to 68, 71 to 74

PDATA1-P to PDATA8-P

PSTB-N

BUSY-P

ACK-N

PE-P

SEL-P

FAULT-N

IPRIME-N

SELIN-N

AUTOFD-N

IC7

2 to 9

CN4

DATA8-P

to

DATA1-P

STB-N

BUSY-P

ACK-N

PE-P

SEL-P

FAULT-N

IPRIME-N

SELIN-N

AUTOFEED-N

+5V



+5V

Compatible mode The CPU sets a BUSY-P signal to ON at the same time when it reads the parallel data (PDATA1P to PDATA 8-P) from the parallel port at the fall of PSTB-N signal. Furthermore, it makes the store processing of received data into a receive buffer terminate within a certain fixed time and outputs an ACK-N signal, setting the BUSY-P signal to OFF.

PARALLEL DATA (DATA BITs 1 to 8)

0.5 µs min.

DATA STROBE

0.5 µs min.

0.5 µs max.

BUSY

0 min.

ACKNOWLEDGE

0.5 µs to 10 µs

0.5 µs min.

0 min.

- 8 -

3.6 LED Lamp Control

There is an LED lamp on the high voltage power supply board which is connected to and controled by the CPU on the main control board.

The light from the LED lamp can be seen on the Lens Cover through the LED Lens.

CN1

main control board high voltage power supply board

CPU

LED-P

CN1

- 9 -

3.7 LED Head Control

When a paper form is made to arrive at the data write position on print start, the sending of data to the LED head starts as synchronized with the page synchronous signal/line synchronous signal (CPU internal signal).

Bit image data developed on the raster buffer in the CPU are DMA-transferred to the register of a video interface controller (CPU built-in) and then sent to the shift register of the LED head in a serial transmission synchronized with the VCLK-P signal by the VD0-P signal.

When 1-dot line data (2560 bits) is completely shifted, it is latched by means of the VLD-P signal, causing LEDs to be driven by the VSTB1-N through VSTB4-N signals in different timing for each signal.

Some of LED heads have 2496 dots rather than 2560 dots. The controls regarding the number of dots are adjusted to the LED head installed when the printer is shipped from the factory.

Main control board

CPU

CN6 CN1

LED Head

VCLK-P

VD0-P

VLD-P

VSTB 1-N VSTB 2-N VSTB 3-N VSTB 4-N

+5V

92 93

94 95

Chip 40

64 bit shift REG

LATCH

Bit 2560

Chip 1

1 to 640 bits

641 to 1280 1281 to 1920 1921 to 2560

Bit 1

- 10 -

Page  synchronous  signal*

Line  synchronous  signal*

VDT-P

3.33 msec

VCLK-P

VDT-P

VCLK-P

VDT-P

VLD-P

VSTB1-N

VSTB2-N

VSTB3-N

VSTB4-N

* CPU internal signal

8 bits

0.2 µs

2560 bits

- 11 -

3.8 Motor and clutch control

The electromagnetic clutch is driven by a control signal from the CPU and the drive circuit shown below. The main motor is driven by the control signals from the CPU and the driver IC.

CPU

DMP1 DMP2

DMP3

0V 0V

+5V

96 97 98

+5V

IC10

27 18

ENA A

To Out3, 4Logic

DECAY

PHASE A PHASE B

CN7

GATE CIRCUIT

Main Motor

+24V OPEN

37 1 1412 24

Out2 Out3

Out1

SW1 SW3

Out4Vmm A Vmm B

ALARM

120

140

ENA B

GATE CIRCUIT

Signal of 

DECACY

+5V

+5V +24V

RMON

(1) Main motor

+5V

BRUNK

SW4SW2



Current

Sensor

OSC

Vref A Vref B

Vs A Vs BRs A Rs BLG A PG LG B

23 22 28 15 10 21 20TAB5

CN8

Electromagnetic clutch

0VP

SW4SW2

Current

Sensor

DMON-P

DMPH1-P

DMPH2-P

Rotation

T0 T1 T2 T3

Forward rotation

Reverse rotationStop

Operation at normal speed: T0 to T3 = 1.515 ms

- 12 -

(2) Motor drive control

Time T0 to T3 determines the motor speed, while the phase different direction between phase signals DMPH1-P and DMPH2-P determines the rotation direction. DMON-P signal control a motor coil current. According to the polarity of the phase signal, the coil current flow as follows:

1) +24V → SW1 → motor coil → SW4 → resistor → earth, or,

2) +24V → SW3 → motor coil → SW2 → resistor → earth The drop voltage across the resistor is input to comparator, where it is compared with a

reference voltage. If an overcurrent flows, a limiter operates to maintain it within a certain fixed current.

(3) Electromagnetic clutch control

Mechanical operation mode is switched by the combination of the clutch status and the direction of motor rotation.



clutch status



off



off

 

on



on



rotation direction



Forward



Reverse

 

Forward



Reverse



operation mode



cleaning



Hopping from manual

feed slot



illegal operation



Hopping from tray

- 13 -

3.9 Fuser Temperature Control

The temperature change in a heat controller is converted into the electric potential TEMP corresponding to the change in the resistance value of a thermistor, and the resultant potential is fed back to the control circuit. The CPU performs ON/OFF control of the HEATON-P signal to keep the heat roller temperature constant in accordance with the state at which the thermistor voltage (TEMP) is read into directly by the AD converter of the CPU. THCHK-N signal is fixed to “0”. When the paper thickness is set on the menu of the host, the temperature is adjusted to the targeted thickness accordingly.

Main Control Board

CPU

TEMP

AI4

(A/D)

THCHK-N

HEATON-P

High voltage power  supply board

IC20

+5V +5V

IC20

+5V

Ther- mistor

HEATON-N

Heater

Thermostat

Heat Roller

+5V

ACIN

Power supply unit

- 14 -

Flowchart of Thermistor Circuit Check

START

HEATER OFF

Short check timer(t16)set

Time-out ?

Short error TEMP ?

Thermistor error check

timer (t2) set

Thermistor disconnection

check timer (t35) set

Heater On

Temperature > Tn

Yes

Tn...T0 =

T2 = T4 =

Thermistor short error

End

Light Medium Heavy

To constant

temperature control

Thermistor

error check timer (t2)

within time

Yes

Thermistor

disconnection check timer

(t35) within time

Yes

t2 = t16 = t35 =

90 sec

520 msec

10 sec

Time-out

A/D value changed?

Yes

- 15 -

Fuser error

End

Thermistor disconnection 

error

End

Temperature

Controlled

Temperature

HEATER ON

OFF

Time

Temperature table

THCHK-N

O Z

Heater control mode Normal operation Not used

T 135˚C: 140˚C: 150˚C: 155˚C: 155˚C:

Paper Thickness light medium light medium medium heavy heavy

- 16 -

3.10 Sensor Control

The CPU supervises the state of each sensor every 40 ms.

Main Control Board High Voltage Power Supply Board

CN1 CN1

+5V

CPU

Sensor  signal

OFF

+5V

TNRSNS-N

PSIN-N

PSOUT-N

WRSNS-N

TransparentShield

PS1

PS2

PS3

PS4

- 17 -

3.11 Cover Open

When the cover is opened, a cover open microswitch is opened. This makes a CVOPN-N signal low, thereby the CPU detects that cover is open. Furthermore, opening the cover stops applying a +5V power to the high voltage power supply part, resulting in stopping all high voltage outputs.

CN1 CN1

Main Control Board

CVOPN-N

CPU

+5V

Cover close Cover open

CVOPN-N

Cover  Open Microswitch

+5V

High Voltage Power Supply Board

High

Voltage

Power

Supply

+5V

Part

High 

voltage 

output

- 18 -

3.12 Power Supply Part

(1) Power supply unit

An AC power from an inlet is input to Switching Reg. part .AC power is converted to a +24 VDC output and +5 VDC output.

ACIN

F1 F2L

FG N

Filter

Circuit

Power supply unit

+24V +5V 0V

HEATER

Switching Reg. Part

CONTROLER

HEATON-N

to AC output

Fuse Ratings

AC Input

Fuse

F1 F2

230 V

250 V 6.3 A 250 V 2 A

120 V

125 V 10 A 250 V 2 A

(2) High voltage power supply board

The +5 VDC power supplied to the high voltage power supply part via the cover open microswitch as source voltage. The high voltage power supply part supplies necessary voltage for electro-photography print to output terminals CH, DB, SB, TR, and CB according to a control signal from the CPU. The table on the next page shows the relationship between control signals and high voltage outputs.

CN1

MainControl Board High Voltage Power Supply Board

TR1PWM-P

55

TR2PWM-P

59

CHPWM-P

56

SDB1-P

53

CPU

52 54  45

SDB2-P DBPWM-P

CVOPN-N

+5V

CN1

High Voltage

Power Supply

Part

CH DB SB TR CB

Cover Open Microswitch

- 19 -

Control Signals and High Voltage Outputs

Control signal name Level Function

TR1PWM-P 

TR2PWM-P  CHPWM-P

SDB1-P

SDB2-P

DBPWM-P

H/L (PWM) L H/L(PWM) L H/L(PWM) L H   L H   L H/L(PWM) L 

Makes the part put out a power to TR. 

+3 to 5 µA +0.5 to 4 KV

 Makes the part put out a -750V power to TR.  Makes the part put out a -1.35 KV power to CH.  Makes the part put out the following power:  

+450V or 0V power to SB  +300V power to DB

  Makes the part put out the following power:  

-450V power to SB

-300V power to DB +400V power to CB

 Makes the part put out the power to SB, DB, CB.

- 20 -

+ 49 hidden pages

OKI 4w Troubleshooting Manual

Specifications and Main Features

Frequently Asked Questions

User Manual