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Service Guide ML320/321Turbo
Chapter 0 About This Manual

ML320 Turbo // ML321 Turbo Dot Matrix Printers

Adobe Acrobat printable reference copy of the OKIDATA Service Training Manual. 09/17/97
Note: This Adobe Acrobat version of the Okidata Service Training Manual was built with the pictures rendered at 300 dpi, which is ideal for printing, but does not view on most displays well.

Okidata is a registered trademark, and OkiPage is a trademark of Oki Electric Industry Co., Ltd. HP, LaserJet and PCL5e are trademarks of Hewlett-Packard Co. Adobe and Acrobat are trademarks of Adobe Systems Incorporated. Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

Table of Contents

Page

Service Guide ML320/321Turbo
0 About This Manual Front Cover 1 Configuration 1.1. Standard Printer Configuration 1.2 Options 2 Operation Description ....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 ....2.2.2 Spacing Operation (See Figure 2-4.) ....2.2.3 Head Gap Adjusting (See Figure 2-5.) ....2.2.4 Ribbon Drive (See Figure 2-6.) ....2.2.5 Paper Feed Operation ....2.2.6 Paper Detection Mechanism (See Figure 2-15.) ....2.2.7 Automatic Sheet Feed ....2.2.8 Paper Park Function (Continuous sheet paper) 3 Parts Replacement 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, Access 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) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Table of Contents ....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 Adjustments 4. ADJUSTMENT 5 Periodical Maintenance 5.1 Cleaning 5.2 Lubrication 6 Troubleshooting 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 A Centronics Parallel Interface A. PCB LAYOUT B Parts Listing Parts Listing Figure 11-1 Upper Cover Assy Figure 11-2 Printer General Assy Figure 11-3 Printer Unit Figure 11-4 Carriage Assy Figure 11-5 Option Spare Parts C Software Diagnostics and Adjustments RS-232C SERIAL INTERFACE BOARD 2. OPERATION DESCRIPTION ....2.2.1 Operation at power on ....2.2.2. RS-232C interface 2.3 Communication Procedure Flowchart 3. TROUBLESHOOTING FLOWCHART 3.3 Local Test

Page 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

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Service Guide ML320/321Turbo
Chapter 1 Configuration

1.1. Standard Printer Configuration This printer consists of the following assemblies:

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Service Guide ML320/321Turbo
Chapter 1 Configuration

1.2 Options (1) Cut sheet feeder unit (CSF) Single-bin CSF

(2) Pull-tractor assy

(3) Bottom push tractor unit

(4) Roll paper stand (Narrow only)

(5) Serial I/F - RS-232C

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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 x 1 - 16-bit automatic reload timer x 2 - 8-bit serial port x 2 - 8-bit parallel port 3 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) Program ROM This is a 256 x 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.

(3) RAM (MSM51C464A-80RS) The RAM is CMOS dynamic RAM with (64K x 4-bit) x 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.

(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.

(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.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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.

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

(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 Drive time (e) Print mode compensation

Few < ----- > Many Short < ------ >Long

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

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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 (A, B) 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.

(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.

(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.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.1.7 Operation Panel The clock synchronization OPCLK signal of the LSI is used to input the switch data and output the LED data through the operation panel control LSI (IC1: BU5148S).

A 2-byte (15 bits + 1 even parity bit) command signal (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.

ote: From the illustration above, you can see that the command and the command response are output at the same time. This is because the bit 0 to bit 3 the OPRXD signal are fixed so that the response can be returned before decoding the command.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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 causes the secondary coil (40V) of the transformer to short-circuit, causing an overcurrent to flow through the primary coil and open the AC fuse (transformer assy). (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. (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 m sec. to control and maintain the impact necessary for each printing pin at the fixed value. (b) Print Speed

(3) Head overheat alarm The voltage of the output TSD signal of the thermistors, one of which is in the printhead and the other in the printhead driver, is monitored by the CPU/AD port to control the voltage

- When the temperature is between aC and 119C, the mode switches sequentially to higher level. When the temperature falls below ߰C, the mode switches to lower level. - When the temperature exceeds 119C, printing stops. - When temperature gradient is steep, the higher mode is specified directly.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

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

The uses of output voltages and signals are described below.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2 Mechanical Operation 2.2.1 Printhead Mechanism and Operation (See Figure 2-2 below). The printhead is a spring charged 9-pin driving head using a permanent magnet. It is attached to the carriage, which moves parallel to the platen. Electrically, this unit is connected to the control circuits through the control board.

(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) Printhead Operation (See Figure 2-3 below). (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 attracting 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. (c) After the character has been printed, the armature is magnetically attracted again and the print wires are again concealed under the wire guide.

A thermistor in the printhead prevents burning caused by overheating of the coil during extended continuous bi-directional printing. When the temperature of the coil exceeds a predetermined limit (about 119C) the control circuit detects a thermistor signal. Printing will then be intermittent or stop completely until the coil temperature falls below the limit value.

Figure 2-3

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.2 Spacing Operation (See Figure 2-4 below). The spacing mechanism consists of a carriage shaft mounted in parallel with the platen, and a carriage frame that moves along the shaft. It is driven by a DC motor mounted on the bottom of the carriage frame. Items included in the spacing mechanism are as follows: (a) DC motor with motor gear (b) Carriage frame (stationary yoke and motor driver board included) (c) Carriage shaft (d) Space rack (e) Sensor (f) Encoder disk (1) Spacing operation The carriage frame, on which the printhead and space motor are mounted, moves along the carriage shaft parallel to the platen. When the spacing motor rotates counterclockwise, the driving force is transmitted to the motor gear. As the motor gear rotates, the carriage moves from left to right. Mechanically, it is designed in such a way that for every revolution of the DC motor, the carriage frame moves 0.8 inch (20.32 mm). At the same time the encoder disk rotates together with the motor and passes through the sensor. The position of the carriage frame can be determined by counting the interrupts detected by the sensor. In the same way, the rotation of the space motor can be recognized and controlled by measuring the cycle of interrupts detected by the sensor.

Figure 2-4 Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.3 Head Gap Adjusting (See Figure 2-5 below). The head gap adjusting lever moves back and forth to tilt the carriage frame, altering the gap between the printhead and the platen. The adjusting screw, which is connected to the adjusting gear rotates when the adjusting lever is moved creating a fine gap adjustment. If the adjusting gear is pushed down, the adjusting screw can be turned with a screw driver to change the coarse gap adjustment. When the adjusting lever is set to range 2 - 3, the contact attached to the under side of the carriage cover will connect with the contact of the space motor PC board. The printer will reduce the printing speed automatically to ensure that adequate printing pressure is maintained for multipart paper. Moving the adjusting cam toward the left or right adjusts the guide rail up or down.

Figure 2-5 Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.4 Ribbon Drive (See Figure 2-6 below). The ribbon driver mechanism moves the ribbon in synchronization with the space motor operation. The ribbon drive mechanism consist of the following items: (a) Ribbon drive gear assembly (b) Ribbon gear (space motor) (c) Ribbon cartridge (1) Ribbon cartridge An endless ribbon with a single direction feed is used. Ink is supplied from an ink reservoir, which is built in to the ribbon cartridge. (2) Ribbon feed operation When the space motor is activated, the ribbon gear rotates. The rotation is transmitted via the ribbon drive gear assembly to the drive gear in the ribbon cartridge, thus moving the ribbon. The feed direction of the ribbon is maintained by switching the direction of the gears in the ribbon drive gear assembly. This ensures ribbon movement when bi-directional printing is used.

Figure 2-6 Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.5 Paper Feed Operation Paper is fed by turning the platen and the pin tractor, which is driven by the LF pulse motor. The paper feed mechanism consists of the following: (a) Pulse motor with gears (b) Decelerating gear (c) Platen (d) Tractor feed unit (e) Pressure roller (1) Cut sheet and continuous sheet switching mechanism (See Figure 2-8.) Three different paper paths can be selected and set by the change lever. (a) TOP (for cut sheets) When the cut sheet paper is used in the manual mode or fed by the CSF (option), set the change lever at the position marked TOP. Operation The driving force of the platen gear (R) is transmitted to the idle gear by setting the change lever to the TOP position. However, this causes the idle gear to be disengaged from the change gear, leaving it free. At this time, the pressure rollers (at the rear and the front) are pressed securely to the platen to feed the sheet. At the same time, he cut sheet detection lever turns on the cut sheet detection switch, to confirm to the control board that you are in the cut sheet mode. In the cut sheet mode, the control board automatically feeds the sheet up to the print start position after pausing for the wait time stored in the menu. (b) REAR (Continuous sheet from push tractor) When the change lever is set to REAR position, the change gear is engaged with the idle gear and the tractor gear to transmit the rotation of the platen to the push tractor shaft, and the paper is fed from the push tractor. At the same time, the switch lever turns on the rear switch, to inform the control board that you are in the continuous sheet mode. (c) BOTTOM (Continuous sheet from bottom feeder) (option) When the change lever is set in the BOTTOM position, the rotation of the platen is transmitted to

the drive gear of the bottom tractor feed unit through the idle gear to feed the sheet which set in the bottom tractor feed. At the same time, the switch lever turns on the bottom switch to inform the control board that you are in the continuous sheet mode.

(2) Cut-sheet feeder operation (See Figure 2-9.) The pulse motor used for the paper feed mechanism is mounted on the left of the frame, and the rotation of the motor is transmitted through decelerating gears (LF idle gear, platen gear) to the platen. When using cut-sheet paper, the change lever must be in the TOP position to grab the paper, while disengaging the push tractor. When the change lever is set to the TOP position, the paper is automatically fed in up to the print start position after pausing for the wait time stored in the menu.

(3) Continuous paper feed operation (Rear) (See Figure 2-10.) The force transmitted to the platen turns the tractor gear by means of the platen gear, the idler gear, and the change gear. The rotation of the tractor gear turns the sheet feeder shaft, which moves the pin tractor belt, feeding the paper.

(4) Pull tractor (option) and push tractor operation (See Figure 2-11) This mechanism supports the standard push tractor and an optional pull tractor. It can perform forward and reverse feed by sending paper either to the push tractor (for rear feed) or to the pull tractor (for bottom feed). The rotation of the platen is transmitted to the push tractor and the pull tractor. Paper can be fed to either tractor.

(5) Pull tractor mechanism (option) (See Figure 2-12.) Bottom feed of continuous sheets is possible only when the optional pull tractor unit is installed. The rotation of the platen is transmitted to the idle gear of the pull tractor unit through the platen gear at the left end of the platen. The rotation of the idle gear is transmitted to the drive gear, and paper is fed when the sheet feeder shaft turns the pull tractor.

(6) Bottom push feed operation (Option) (See Figure 2-13.) The bottom push feed of continuous sheet requires the bottom tractor feed unit. When the platen turns, its rotational force is transmitted through the tractor idle gear and the tractor change gear to the tractor drive gear of the bottom push tractor, and paper is fed to the print start position.

(7) Paper clamp mechanism (See Figure 2-14.) When setting the change lever to the BOTTOM , TOP or REAR position, the operation of the front release gear arm changes according to the position of the release cam. At the same time, the position of the cam relative to the front release gear arm changes, opening or closing the pressure roller.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.6 Paper Detection Mechanism (See Figure 2-15 below). (1) Cut sheet detection When the sheet is inserted, point A is pushed backward and the paper near end lever B rotates counterclockwise (CCW). At this time, the rear sensor lever rotates counterclockwise (CCW) and pulls out of the rear and top paper end sensor to detect that the sheet is inserted. The procedure for the paper end is the reverse, that is, detection occurs when the paper end sensor is blocked.

(2) Rear feed detection When the sheet is fed from the push tractor, the point B is pushed to the front side and the paper near end lever A rotates clockwise (CW). At this time, the rear sensor lever rotates counterclockwise (CCW), and pulls out of the rear and top paper end sensor to detect that the sheet is provided. The procedure for the paper end is the reverse, that is, detection occurs when the rear sensor lever interrupts the sensor.

(3) Bottom feed detection When the sheet is fed from the bottom, the point C rotates clockwise (CW). When the bottom sensor lever rotates clockwise (CW), it pulls out of the bottom paper end sensor to detect that the sheet is inserted. The procedure for the paper end is the reverse, that is, detection occurs when the bottom sensor lever interrupts the sensor.

(4) Top line print mechanism (See Figure 2-16.) The top edge of the sheet is protected by the ribbon protector so that it can stop at a position very close to the printhead (0 tear-off position) to start printing at the top of the sheet without causing it to crumple or curl up. Printing starts at the top of the sheet, and continues uni-directionally until the top edge of the sheet gets to the inside of the pull-up roller cover. After that, printing continues bi-directionally.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.7 Automatic Sheet Feed This function is used to feed in the sheet automatically up to the print start position when the cut sheet or the continuous sheet paper is used. Operational procedure (1) When using cut sheet paper: 1) Set the change lever to the TOP position. (See Figure 2-17 below). 2) Insert a sheet of paper between the platen and the paper chute. 3) After the lapse of time selected by the "wait time" item in the menu, the LF motor starts to feed the paper up to the print position. 4) When the default is selected, the paper feeds up to the position 0.35 inches (first dot position) from the top edge of the sheet. However, the 0 tear-off mechanism allows printing at the top edge of the sheet by changing the TOF position.

(2) When using continuos sheet paper

1) Set the change lever either to the rear or the bottom position. (See Figure 2-17 above). 2) Load paper either on the push tractor or on the bottom tractor. 3) Press the "FF/LOAD" button. 4) The LF motor starts to feed the paper up to the print start position. 5) The paper feeds up to the TOF position (Factory default: 0.35 inches from the top). Press the "FF/LOAD" button. When the LF motor completes its operation and the sheet has not been fed in, an alarm condition results.

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Service Guide ML320/321Turbo
Chapter 2 Operation Description

2.2.8 Paper Park Function (Continuous sheet paper) Continuous sheet paper can be backed out automatically by using the "PARK" button on the operation panel. 1) Press the "PARK" button. 2) Reverse LF starts and paper feeds in reverse until paper end occurs or a maximum of 19 inches have been fed. 3) The paper feeds in reverse to leave the paper on the tractor.

The alarm LED lights up when paper end is not detected after 19 inches of reverse feeding. The operator can press the SEL button to turn off the alarm LED, then press the PARK button to continue the park function. This operation is required when the paper to be parked is more than 19 inches long.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3. ASSEMBLY/DISASSEMBLY This section explains the procedures for removing and installing various assemblies and units in the field. Description is mainly limited to the removal procedure; installation should basically be performed in the reverse sequence of the removal procedure.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.1 Precautions for Parts Replacement (1) Remove the AC power cord and the interface cable before disassembling or assembling. (a) Turn off the power switch. Remove the plug of the AC power cord from the outlet. Remove the power cord from the receptacle on the printer. (b) To reconnect the power cord, connect it to the receptacle on the printer first, thenplug it into the outlet.

(2) Do not disassemble the printer as long as it is operating normally. (3) Do not remove unnecessary parts, and limit the extent of disassembly as much as possible. (4) Use the designated service tools. (5) Carry out disassembly in the prescribed sequence; otherwise, damage to the parts may result. (6) It is advisable to temporarily install screws, snap rings and other small parts in their original positions to avoid losing them. (7) Whenever handling the microprocessors, ROM, RAM IC chips and boards, do not use gloves that may cause static electricity. (8) Do not place the printed circuit board directly on the equipment or on the floor. (9) If adjustment is specified in the middle of installation, follow the instructions.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.2 Service Tools Table 3.1 lists the tools necessary for replacing printed circuit boards and parts of units in the field.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3 Disassembly/Reassembly Procedure This section explains the assembly replacement procedures according to the following disassembly system. Parts Layout

How to Change Parts This section explains how to change parts and assemblies appearing in the disassembly diagram below.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.1 Printhead (1) Open the access cover. (2) Pull up and rotate the head clamp 1 to unclamp the printhead 2 as shown in fig. 3.3.1. (3) Disconnect the printhead 2 from PC connector 3 and remove. (4) To install, reverse the removal steps. Notes on installation: (1) Insert the printhead 2 into the PC connector 3 while pushing it against the carriage frame 4. (2) The head clamp 1 must be securely sandwiched between printhead 2 and carriage frame 4 as shown in fig. 3.3.2 below. (3) Be sure to check the gap between platen and printhead (see 4). (4) Be careful not to touch the print head while it is hot. Important: There is a shim on the carriage frame 4, which hangs over the platen side of the frame. Be sure to replace it correctly. Improper positioning of this shim will severely affect the printhead gap.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.2 Ribbon Protector (1) Remove the printhead (see 3.3.1 below). (2) Open the pull-up roller cover 1. (3) Remove the shim on the carriage frame. (4) Loosen the screws holding the carriage assembly to the carriage frame--this allows more play between the printhead and the platen. (5) Raise and remove the ribbon protector 2. (6) To install, follow the removal steps in reverse order. Be sure to replace the shim in exactly the same position as it was before disassembly.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.3 Pull-up Roller Assy (1) Open the access cover 1. (2) Lift up the sheet guide Assy 4 to remove. (3) Tilting the pull-up roller Assy 2 toward the front, remove it from the shaft of platen Assy 3. (4) To install, follow the removal steps in reverse order. Note: Remove the sheet guide Assy 4 before installing or removing the pull-up roller Assy 2.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.4 Upper Cover Assy, Access Cover Assy and Sheet Guide Assy (1) Pull off the platen knob 1. (2) Open the access cover Assy 4 toward the front to remove. (3) Lift up the sheet guide Assy 5 to remove. (4) Turn the change lever 2 toward the bottom position. (5) Insert a flat-blade screwdriver into grooves of frame (5 places for ML 321, 4 places for ML320) and twist to disengage claws of upper cover 3. (6) Raise the front side of upper cover Assy 3 and shift toward the rear to disengage claws of frame (6 places for ML321, 5 places for ML320). (7) Raise the upper cover Assy 3 to remove. (8) To install, follow the removal steps in reverse order. Note on installation: Match the posts A at both sides of the sheet guide 5 with the arrow marks on the upper cover. Push the guide into the cover.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.5 Gear Case Assy (1) Remove the printhead (see 3.3.1 ).

(2) Remove the shim from the carriage frame. (3) Remove the upper cover (see 3.3.4 ).

(4) Move the carriage Assy to right side, remove two screws 1, then remove the carriage Assy. (5) Disengage claws on the gear Assy (4 places). Using a flat-blade screwdriver, push to widen the claw for easy disengagement. (6) Lift up the gear case Assy 3 and release the carriage cable from the cable clamp of the gear case Assy. (7) To install, follow the removal steps in reverse order. Be sure to replace the shim on the carriage frame in exactly the same position as it was before disassembly Notes on installation: (1) To assemble, align the direction of the SP motor axis 4 with the Gear Hole of the Gear Case assy. (2) Be sure to check and adjust the gap between platen and printhead (see 4-1 ).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.6 PC Connector (1) Remove the upper cover (see 3.3.4 (2) Remove the printhead (see 3.3.1 ). ).

(3) Remove the shim from the carriage frame. (4) Remove the gear case Assy (see 3.3.5 ).

(5) Remove the PC connector 1 from the space motor Assy 2. (6) To install, follow the removal steps in reverse order. Be sure to replace the shim on the carriage frame in exactly the same position as it was before disassembly Notes on installation: (1) Do not touch the space motor 2 or terminals of PC connector 1. Also, take care to avoid dust or foreign matter. (2) After installation, check and adjust the gap between platen and printhead (see 4-1 ).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.7 Space Motor, Guide Roller Assy (1) Remove the printhead (see 3.3.1 (2) Remove the upper cover (see 3.3.4 ). ). ). ).

(3) Remove the gear case Assy (see 3.3.5 (4) Remove the PC connector (see 3.3.6

(5) Remove screw 2, then the guide roller Assy 3 from the space motor Assy 1. (6) Push down on the carriage cable and remove it. (7) Remove the two screws 5, from the space motor Assy. (8) Remove the space motor. (9) To install, follow the removal steps in reverse order. Notes on installation: (1) Do not touch the terminals of space motor 1. Also, take care to avoid dust or foreign matter. (2) When installing the guide roller Assy 3, push portions A and B against the space motor 1. (3) When installing the space motor 1, align the face C with carriage frame 4 and push portionD against the frame. (4) After installation, check and adjust the gap between platen and printhead (see 4-1 ).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.8 Space Rack (1) Remove the upper cover (see 3.3.4 (2) Remove the printhead (see 3.3.1 ). ).

(3) Remove the shim from the carriage frame. (4) Remove the gear case Assy (see 3.3.5 (5) Remove the space motor Assy (see 3.3.7 (6) Remove the spring 1. (7) Disengage the claw on left side of space rack 2 from the frame, and remove the space rack 2 in upper direction. (8) To install, follow the removal steps in reverse order. Be sure to replace the shim on the carriage frame in exactly the same position as it was before disassembly Note on installation: After installation, check and adjust the gap between platen and printhead (see 4-1 ). ). ).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.9 Carriage Cable (1) Remove the upper cover (see 3.3.4 (2) Remove the printhead (see 3.3.1 ). ).

(3) Remove the shim from the carriage frame. (4) Remove the gear case Assy (see 3.3.5 (5) Remove the space motor Assy (see 3.3.7 ). ).

(6) Remove the two screws 1, release the driver board 2 and PCB board 9 by lifting clamp 8, and disconnect cable from connector 3, 4, 5, 6. (7) Remove the carriage cable 7 from fasteners on frame. (8) To install, follow the removal steps in reverse order. Be sure to replace the shim on the carriage frame in exactly the same position as it was before disassembly Notes on installation: (1) Take care not to fold the carriage cable 7 during installation. Curve the carriage cable 7 slightly when assembling into the fasteners. (2) Make sure that the paper end lever A will not contact the paper end sensor 10 when installing the driver board.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.10 Backup Roller Holder Assy (1) Remove the upper cover (see 3.3.4). (2) Remove the printhead (see 3.3.1). (3) Remove the carriage Assy (see 3.3.5 (3)). (4) Remove the backup roller spring 2. Disengage claws of roller holder from the carriage frame 1 (2 places), and remove thebackup roller holder assy 3. (6) To install, follow the removal steps in reverse order. Note: Small round hole with metal tip on back of roller holder assy 3 should be facingup when installing.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.11 Platen Assy (1) Remove the printhead (see 3.3.1 (2) Remove the upper cover (see 3.3.1 ). ). ). ).

(3) Remove the pull-up roller Assy (see 3.3.3 (4) Remove the ribbon protector (see 3.3.2

(5) Turn the change lever 1 to the bottom position. (6) Push in the lock levers 2 on both sides to unlock the Assy from the frame, then rotate them upward 90. (7) Remove the platen Assy 4 from the base frame. (8) To install, follow the removal steps in reverse order.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.12 Driver Board (SDDV) (1) Remove the upper cover (see 3.3.4 ).

(2) Remove the two screws 1, and release the driver board 2 by lifting clamp 4. (3) Disconnect all cables from driver board 2. (4) To install, follow the removal steps in reverse order. Note on installation: Insert sensor lever 3 in the sensor as shown when installing the driver board 2.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.13 LF Motor (1) Remove the upper cover (see 3.3.4 (2) Remove the printhead (see 3.3.1 ). ). ). ).

(3) Remove the ribbon protector (see 3.3.2 (4) Remove the pull-up roller Assy (see 3.3.3 (5) Remove the platen Assy (see 3.3.11 (6) Remove the driver board (see 3.3.12 ). ).

(7) Remove the left FG plate 1: lift base at three points to release tabs. (8) Release the lock A to remove the LF motor 2. (9) To install, follow the removal steps in reverse order. Note on installation: Press the LF motor cable with a portion A of the motor plate.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.14 Operation Panel PCB (LEOP) (1) Remove the upper cover (see 3.3.4 ).

(2) Disconnect cable 1 from connector 3 of driver board 2. (3) Disengage claws on both sides from the frame, and remove the operation panel 4. (4) Open claws (8 places) and remove the operation panel PCB 5 from the operation panel 4 . (5) To install, follow the removal steps in reverse order.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.15 Control/Power Supply Board (SDCT) (1) Remove the upper cover (see 3.3.4 ).

(2) Disconnect the two flexible cables 3 from connector 2 on the Control/Power Supply Board 1. (3) Remove cable 5 from connector 4 on the control/power supply board 1. (4) Remove the two screws 6, and remove the control power supply board 1. (5) To install, follow the removal steps in reverse order. Note on installation: To install the control/power supply board, set the change lever to the top position so that the switch lever 7 will not catch on the microswitches 8.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.16 Transformer Assy (1) Remove the upper cover (see 3.3.4 ).

(2) Remove AC inlet 1 and AC switch 2 from the frame guide. (3) Disconnect the cable 3 from the connector 4 on the Control/Power Supply Board 5. (4) Remove a screw 6 and disconnect ground cable 7. (5) Remove two screws 8 and shift the transformer Assy 9 to the left and remove it.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.17 Change Lever and Gears (1) Remove the upper cover (see 3.3.4 ).

(2) Release the reset spring 1 from the tab, remove it, then remove the idle gear 2, the tractor gear 4 and the change gear 5. (3) Push back the protrusion of the change gear shaft 6 gently with a flat blade screw driver to remove the change lever 3. Note: The change lever can be difficult to remove; be careful not to exert too much force with the screwdriver. Make sure the springs do not fly off when you release the change lever from the shaft. (4) To install, reverse the removal procedure. Note on installation: To insert the change lever into the change gear shaft 6, match the flat surface (D cut).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.18 Carriage Shaft (1) Remove the printhead (see 3.3.1 (2) Remove the upper cover (see 3.3.4 (3) Remove the driver board (see 3.3.12 Remove the FG plate (L) 2. ). ). ).

(4) Slide the carriage shaft 1 to the left side (in the direction of the arrow) to remove. (5) To install, reverse the removal procedure. Note on installation: After installation, check and adjust the gap between platen and printhead (see 4-1).

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.19 Paper Pan (1) Remove the printhead (see 3.3.1 ). ). ). ).

(2) Remove the ribbon protector (see 3.3.2 (3) Remove the pull-up roller assy (see 3.3.2 (4) Remove the upper cover assy (see 3.3.4 (5) Remove the platen assy (see 3.3.11 (6) Release claws A . ).

(7) Lift up the paper chute assy 1 and remove. (8) To install, reverse the removal procedure.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.20 Rear Tractor Assy (1) Remove the printhead (see 3.3.1 ). ). )

(2) Remove the ribbon protector (see 3.3.2 (3) Remove the pull-up roller assy (see 3.3.3 (4) Remove the upper cover (see 3.3.4 ).

(5) Remove the reset spring (see 3.3.17 (3) (6) Remove the tractor gear 1.

).

(7) Shift the drive shaft 2 to the right side to remove (in the direction of the arrow). (8) To install, reverse the removal procedure. Note on installation: When the tractor assemblies (L) 3 (R) 4 have been detached from the drive shaft, align the protrusions 5 of the pin tractor wheels in the same direction as before assembly.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.21 Rear Pressure Assy (1) Remove the upper cover (see 3.3.4 ). ).

(2) Remove the change lever and gears (see 3.3.17 (3) Remove the paper pan (see 3.3.19 (4) Remove the rear pressure roller 1. ).

(5) Rotate the release shaft 2 and move it to the left to detach the release shaft 2. Match the main frame rib A with the protrusion B of the release shaft. (6) Remove rear pressure SP assy 3. (7) To install, follow the removal steps in reverse order. Note: (1) When installing the release shaft 2, pay attention to the gear engagement of release shaft 2, change arm lever 6, and change gear shaft 7. (2) On the ML321 Turbo there are 5 rear pressure spring assemblies. Use the two pieces which have larger spring diameter on the right side. Use the three remaining pieces on the left side. (3) Make sure that the release shaft 2 will be on top of the support spring 4. (4) To assemble the release shaft 2, make sure that the protrusion of the switch lever 5 is in the U groove of the release shaft 2.

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Service Guide ML320/321Turbo
Chapter 3 Parts Replacement

3.3.22 Switch Lever (1) Remove the upper cover (see 3.3.4). (2) Remove the change lever and gears (see 3.3.17). (3) Remove the paper pan (see 3.3.19). (4) Remove the rear pressure assy (see 3.3.21). (5) Pull the switch lever toward you and remove it upward. (6) To install, follow the removal steps in reverse order. Note on installation: When installing the switch lever, make sure that the microswitch on the driver board works properly.

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Service Guide ML320/321Turbo
Chapter 4 Adjustments

4. ADJUSTMENT (1) Be sure to carry out these adjustments with the printer mechanism installed on the lower cover. (2) Be sure to carry out these adjustment operations on a level and highly rigid work table (flatness: less than 0.039 inch or 1 mm) so as to minimize adjustment error.

4-1-1 Gap between the platen and the printhead 1) Parallelism adjustment Variation of value at the left, the center and the right shall be less than 0.02 mm. It shall be measured at 3 points: the left end, the center and the right end of the platen.

Adjustment method (1) Gap between the platen and the printhead at the left end and the right end shall be adjusted by rotating the adjust cam. (2) Set the adjust lever at the Range: 1. Press the adjust gear downward (indirection A) to push the adjust gear and the adjust gear out of mesh. (3) Adjust the gap by rotating the adjust screw in direction B or C while the adjust lever and the adjust gear are disengaged. (4) After adjustment, mark the adjust cam position with a red pen. 0.410.03 mm 2) Initial adjustment

Note 1) The head gap shall be measured with the change lever set to rear position. Note 2) The head gap shall be measured positioning the platen gear (R) craw on the top.

Note 3) Move the adjust screw in clockwise direction (in direction B) to measure.

4-1-2 Measure variation of gap when range is changed.

Gap =0 .6 90.05 at the range 5.

Gap between the contact and the monitor. 0.3mm or more

Verify the following. Make sure that the gap between the contact and the motor PCB is 0.3 mm or more. At the time of printing test, make sure that the contact touches the motor PCB and it enters reduced speed mode when the adjust lever is set to range 2 and 4.

4-2 Gap between the platen and the paper pan. 10.5 Verify the following. (1) When the change lever is set at Friction position, the gap between the platen and the paper pan at the rear side shall be 10.5mm. (2) When the change lever is set at Rear or Bottom position, the gap between the platen and the paper pan at the front side shall be 10.5 mm.

4-3 Gap between the platen and the pressure roller

Verify the following. (1) When the change lever is set at Friction position, all the pressure rollers shall be pressed to the platen. (2) When the change lever is set at Rear or Bottom position, the gap between the platen and the pressure roller at the rear side shall be 3mm. The front pressure rollers shall be pressed to the platen.

4-4-1 Rotation of the push tractor Verify: The tractor gear shall rotate smoothly when the change lever is set at Friction position.

4-4-2 Backlash between gears Approx. 0.05 to 0.11 mm

Verify: There shall be slight backlash between gears to allow smooth rotation of gears. (Backlash 0.05 to 0.11 mm) 4-5-1 Ribbon feed Verify: Ribbon shall be fed smoothly when the carriage is moved from side to side.

4-5-2 Running load to spacing mechanism 250g or less without a ribbon cartridge Verify: Make sure that the power is turned off at the time of measurement.

4-6 Engagement of the double gear and the LF motor idle gear of the Platen Assy. Verify: The idle gear of the LF motor and the platen gear (L) and the bias gear of the platen shall be in mesh in such way that the platen gear (L) and the bias gear rotate against each other to pinch the teeth of idle gear. The idle gear stays in mesh with the platen gear (L) and the bias gear and not locked. The bias gear and the platen gear shall b staggered by one tooth as shown in the drawing.

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Service Guide ML320/321Turbo
Chapter 5 Periodical Maintenance

5.1 Cleaning Cautions 1. Be sure to turn OFF the AC POWER switch before cleaning. Remove the AC power cord from the printer. 2. Avoid dust inside the printer mechanism when cleaning. 3. If a lubricated part has been cleaned, be sure to apply lubricating oil to that part after cleaning. (1) Cleaning time After six months or 300 hours of operation, whichever comes first. (2) Cleaning tools Dry cloth (soft cloth such as gauze), vacuum cleaner (3) Places to be cleaned Table 5.1 lists the places to be cleaned.

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Service Guide ML320/321Turbo
Chapter 5 Periodical Maintenance

5.2 Lubrication This printer is designed to be maintenance free and requires no lubrication during normal operation. However it is necessary to apply lubricant if the printer is disassembled, reassembled, cleaned, or if parts have been changed. (1) Cleaning time Remarks: 1) Turn off the power before cleaning. 2) Make sure that paper dust does not fall inside of the machine. - Cleaning period: 6 months of operation or 300 hours of operation, whichever is earlier. - Cleaning points: Carriage shaft and surroundings: Remove paper and ribbon dust. Paper path: Clean stains and dusts. Paper End sensor Remove the dust on the sensor. (2) Lubricant - Pan motor oil (or equivalent): PM - Molicort (or equivalent): EM-30L (3) Amount of lubricant - Medium amount A : Apply three to four drops of oil, or 0.008 inch (0.2 mm) thick grease. - Small amount B : Apply one drop of oil (0.0060.002 g) (4) Areas to Avoid

(5) Lubrication point 1. Ribbon feed gear Assy.

2. Space Rack

3. Platen Assy.

4. Tractor driving mechanism

5. Tractor drive shaft

6. Pressure roller

7. Pull up roller Assy.

8. Main chassis Assy.

9. Carriage Assy.

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Service Guide ML320/321Turbo
Chapter 6 Troubleshooting

6.1 Items to Check Before Repair (1) Check the inspection items specified in the instruction manual. (2) Find out as many details of the problem as possible from the customer. (3) IN the shop, inspect under conditions as close as possible to those at the time the trouble occurred. (4) Proceed with the repair as follows: Check the trouble status according to Table 6.1 for the details of the trouble. Then isolate the problem according to the detailed flowchart. (5) Carry out a thorough test after the repair to check for correct functioning.

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Service Guide ML320/321Turbo
Chapter 6 Troubleshooting

6.2 Troubleshooting Table

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Service Guide ML320/321Turbo
Chapter 6 Troubleshooting

6.3 Lamp Display (1) Printer mode display

(2) Fault alarm display When the printer detects any of the various alarm states, the information is displayed as shown below on the operation panel. The alarm is specified by lamp combination of PRINT QUALITY and CHARACTER PITCH. (See Table 6.3 below for details).

When the printer detects any of the various alarm states, the information is displayed as shown below on the operation panel. The alarm is specified by lamp combination of PRINT QUALITY and CHARACTER

PITCH. (See Table 6.3 below for details.) (3) Fatal Alarm Alarm Category Main Control Alarm Main Control Alarm Main Control Alarm Main Control Alarm Firmware Detection Alarm Alarm MPU internal RAM alarm Program ROM alarm RAM on Control Board alarm EEPROM alarm WDT (Watch Dog Timeout) alarm NMI signal alarm Alar m X X LED Display 10 15 Remarks Read/write error Check sum error No reaction when MPU reads data No reaction when MPU reads data MPU is locked up and it is reset after 65ms. NMI port of MPU is kept low level. FFFF data is detected due to MPU locked up. Read/write error Check sum error Read/write error No reaction from serial I/F board Troubleshooting Replace Control/Power Supply Board Replace ROM or control/Power Supply Board Replace Control/Power Supply Board Replace Control/Power Supply Board Turn the power OFF and ON or replace Control/Power Supply Board Turn the power OFF and ON or replace Control/Power Supply Board Replace ROM or Control/Power Supply Board Replace I/F Board

X

20

X

15, NLQ 17

X

Firmware Detection Alarm

X

17, HSD

Firmware Detection Alarm

BRK instruction alarm MPU internal RAM alarm ROM alarm

X

17, UTL

Serial Interface Alarm Serial Interface Alarm Serial Interface Alarm Serial Interface Alarm

X

10, HSD 15, HSD 20, HSD 12, HSD

X

Replace ROM on I/F board or I/F Board Replace I/F Board

RAM on I/F board alarm I/F not mounted

X

X

Replace I/F Board of Control Board

X = LED Blink (200ms ON, 200ms OFF) All other LED Displays: = LED lights up

Alarm Category Spacing Alarm

Alarm Spacing alarm

Alar m X

LED Display PROP, HSD

Remarks Space IPT is not occurred within in specified timing. Print head does not reach to the home position. Thermister is open, short with 0V or short with +5V. Print Head Gap Signal open

Troubleshooting * Replace space motor. * Replace P.H. cable. * Replace Control/Power Supply Board. * Check the mechanisms if load is too much. * Replace space motor. * Replace P.H. cable. * Replace Control/Power Supply Board. * Check the mechanisms if load is too much. * Check the P.H. Connection. * Replace Print Head. * Replace P.H. cable. * Replace Control/Power Supply Board * Replace P.H. cable. * Replace Space Motor Assy. * Replace Control/Power Supply Board

Spacing Alarm

Print Head homing alarm

X

PROP, UTL

Print Head Alarm

Print Head A/D alarm

X

10, 20

Print Head Alarm

Print Head Gap A/D alarm

X

10, 20, HSD

X = LED Blink (200ms ON, 200ms OFF) All other LED Displays: = LED lights up

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Service Guide ML320/321Turbo
Chapter 6 Troubleshooting

6.4 Connection Circuit Check for Printhead and SP/LF Motor (1) Printhead

(2) Line Feed Motor Resistance of each coil should be about 7.6 Ohms.

(3) Space Motor Resistance of each coil should be about 5 Ohms.

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Service Guide ML320/321Turbo
Chapter 6 Troubleshooting

6.5 Troubleshooting Flow Chart

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Service Guide ML320/321Turbo
Chapter A Centronics Parallel Interface

A. PCB LAYOUT PCB list (1) Circuit board SDCT (Control/Power Supply) (2) Circuit board SDDV (Driver) (3) Circuit board LEOP-3 (Operation Panel)

2

3

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Service Guide ML320/321Turbo
Chapter B Parts Listing

Parts Listing The following Sections give a full parts listing of the product Figure 11-1 Upper Cover Assy Figure 11-2 Printer General Assy Figure 11-3 Printer Unit Figure 11-4 Carriage Assy Figure 11-5 Option Spare Parts Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

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Service Guide ML320/321Turbo
Chapter B Parts Listing

Figure 11-1 Upper Cover Assy

No. 1

Part No. 1PP4128-1186P6 1PP4128-1186P4 1PP4128-1186P2 1PP4128-1231P6 1PP4128-1231P4 1PP4128-1231P2

Description Upper cover (N) Upper cover (N) Upper cover (N) Upper cover (W) Upper cover (W) Upper cover (W)

Qty 1 1 1 1 1 1

Qty Reqd 2 2 2 2 2 2

Remarks For ML320 Turbo For ML320 Turbo For ML320 Turbo For ML321 Turbo For ML321 Turbo For ML321 Turbo

ODA P/N For INT For OEL 53076502 For INT For OEL 53076602

2

1PA4094-7305G10 1PA4094-7308G11

Sheet guide assy (N) Sheet guide assy (W) Access cover assy (N) Access cover assy (W) Acoustic cover (N) Acoustic cover (W)

1 1 1 1 1 1

2 2 2 2 2 2

For ML320 Turbo For ML321 Turbo For ML320 Turbo For ML321 Turbo For ML320 Turbo For ML321 Turbo

51009409 51009510 53076701 53076801 53076901 53077001

3

2PA4128-1237G1 2PA4128-1241G1

4

1PP4128-1188P1 1PP4128-1233P1

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Service Guide ML320/321Turbo
Chapter B Parts Listing

Figure 11-2 Printer General Assy

No

Part No.

Description

Q'ty

Q'ty Req

Remar ks

ODA P/N

1 2

2PP4025-2871P20 4YA4042-1543G301

Platen Knob Control/power supply board (SDCT) Control/power supply board (SDCT) Control/power supply board (SDCT) Driver board (SDDV) Operator panel board (LEOP-3) Operation panel w/frame assy AC cord AC cord AC cord A AC cord for 230V Printhead (9) Fuse 237002 (125V 2A) Fuse 217001 (250V 1A) Transformer assy (ML320 Turbo 120V) Transformer assy (ML320 Turbo 230/240V) Transformer assy (ML321 Turbo 230/240V) PCB plate

1 1

1 9 For ODA/n o ROM For OEL For INT ROM

51902220 55080801

4YA4042-1543G302 4YA4042-1543G303 3 4 5 6 4YA4042-1549G1 4YA4042-1516G3 3PP4044-5360G1 3YS4011-1315P1 3YS4011-1266P1 3YS4011-1329P2 3YS4011-1269P1 7 8 4YA4023-3301G1 4YB4042-1553P1 4YB4042-1552P1

1 1 1 1 1 1 1 1 1 1 1 1

9 9 9 3 2 1 1 1 1 10 10 10

55080701 55081103 50221901

For ODA For OEL For INT

56609701

50114601 For 120V For 230/24 0V 56307301

9

4YB4049-7103P1 4YB4049-7104P1

1 1

2 2

56415301

4YB4049-7104P2

1

2

10

3PB4050-3429P2

1

2

For 230V

ODA, OEL

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Service Guide ML320/321Turbo
Chapter B Parts Listing

Figure 11-3 Printer Unit

No. 1

Part No. 3PA4044-5002G2 53348801

Description Main chassis assy (N) Main chassis assy (W) Bottom paper end lever Pressure spring (F) Pressure spring (F) Roller holder (F)

Q'ty 1 1 1 3