Oki ML490 Maintenance Manual
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Oki ML490 Maintenance Manual

Oki ML490 Maintenance Manual

Maintenance manual
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See also: User Manual , Setup Manual
ML490/491 PRINTER
Maintenance Manual
ODA
1 / 135
42114101
Rev.1

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Summary of Contents for Oki ML490

  • Page 1 ML490/491 PRINTER Maintenance Manual 1 / 135 42114101 Rev.1...
  • Page 2 42114101 Rev.1...
  • Page 3 PREFACE This maintenance manual describes how to maintain the ML490/491 printer in the field. This manual is for customer engineers. For further information, refer to the Users Manual for handling or operating the equipment. The relation between the destination point and the model name of this printer is as follows.

  • Page 4: Table Of Contents

    Contents 1. CONFIGURATION ....................6 Standard Printer Configuration .................... 6 Options ..........................7 2. THEORY OF OPERATION ..................9 Electrical Operation ......................9 2.1.1 Summary ......................... 9 2.1.2 Microprocessor and the peripheral circuit ............... 9 2.1.3 Initialization ......................16 2.1.4 Interface Control ....................17 2.1.5 Print Control ......................
  • Page 5 3.3.20 Rear Tractor Assy ....................77 3.3.21 Rear Pressure Assy ....................78 3.3.22 Switch Lever ......................79 4. ADJUSTMENT ....................80 5. CLEANING AND LUBRICATION ...............88 Cleaning ..........................88 Lubrication ......................... 89 6. TROUBLESHOOTING AND REPAIR ..............97 Items to Check Before Repair .................... 97 Troubleshooting Table .......................

  • Page 6: Configuration

    CONFIGURATION Standard Printer Configuration This printer consists of the following assemblies: Platen knob Sheet guide assy Access cover assy Upper cover Transformer assy Pull-up roller assy Power supply board Control board Operation panel assy Main chassis assy Figure 1-1 Configuration 42114101 Rev.1...

  • Page 7: Options

    Options Cut sheet feeder unit (CSF) (Narrow and wide versions available) Dual-bin CSF Single-bin CSF Attachment assy Attachment assy Pull-tractor assy 42114101 Rev.1...
  • Page 8 Bottom push tractor unit Roll paper stand (Narrow only) RS232C Serial interface board 42114101 Rev.1...

  • Page 9: Theory Of Operation

    Microprocessor 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.
  • Page 10 10 / 42114101 Rev.1...
  • Page 11 Program ROM This is a 512K 16 bits (8M bit) [MAX 16M bit] OTPROM or MASK ROM 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-N signal of the MPU.
  • Page 12 The RAM is CMOS dynamic RAM with 256K 16-bit (4M bit), 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. A0~A8 RAS-N CAS-N UCAS-N UCAS ALS139 WRH-N...
  • Page 13 USB Controller The USB Controller detects and controls the USB interfacee. The following shows the USB Controller access operation. USB Controller A0~A7 D0~D7 USBCS-N RD-N WRL-N PSEN Clockout * A0~A7 USBCS-N RD-N D0~D7 (Read) WRL-N D0~D7 (Write) * Clockout is provided when the original excitation is selected. 13 / 42114101 Rev.1...
  • Page 14 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. EEPROM EEDIN-P EECS-P EEDOUT-P EECLK-P PRE = O PE = X EECS-P EECLK-P...
  • Page 15 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. A/D bus RD-N WRL-N LSICS-N LSIC...

  • Page 16: Initialization

    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.

  • Page 17: Interface Control

    2.1.4 Interface Control Parallel Interface 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.
  • Page 18 Universal Serial Bus (USB) Universal Serial Bus Specification Revision 1.0 compliance. Connector • Printer Side : “B” Receptacle (Upstream Input to the USB Device) • Cable Side : Series “B” Plug Cable • Cable Length : Approx 1.8m (A cable must be met USB Spec Rev 1.1 for normal operation) Note: Cable is not supplied.
  • Page 19 Signal Level • Input / Output Level Parameter Symbol Min. Max. Units Input Levels : High (driven) High (floating) Output Levels : High (driven) Output Signal Crossover Voltage 19 / 42114101 Rev.1...

  • Page 20: Print Control

    2.1.5 Print Control Print data is transmitted as parallel data (HEAD1~HEAD24) from LSI to print head. LSI generates print timing and drive time. Control Board A/D bus DRIVER Print Head Print Data Print Data HEAD1-N~ HEAD1~ HEAD9-N HEAD9 HEAD DRIVE TIMING CHART HEAD DRIVE CURRENT 20 /...
  • Page 21 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.”) Pin stroke compensation Platen Print Head Pin 1~4 As shown in the drawing left, the stroke length up to the platen is different for each pin.

  • Page 22: Sp/Lf Motor Control

    2.1.6 SP/LF Motor Control The MPU transmits serially the SP motor data and the LF motor control data too the SP/LF motor driver, according to the commands sent from the MPU. MHM2025 SP Motor SPM U SPM V Distri- Driver butor SPM W A/ B...
  • Page 23 Space Motor Control The SP motor driver (MHM2025) drives the three-phase brushless motor based on the phase signal (SPU, SPV and SPW) from the LSI and the speed instruction data from the MPU. 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.
  • Page 24 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. PHASE-A PHASE-B 1/720"...

  • Page 25: Operation Panel

    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 IC. Operation panel control IC OPTXD OPTD OPCLK OPCK Command LED driver and Data OPCLR-N NPA2 latch...
  • Page 26 5 or 8 bit0 bit7 OPTXD Command (first) Command (second) Power ON OPCLK bit0 bit7 OPRXD Write instruction for IC reset Command response (first) Command response (second) Note OPCLR-N IC write for LED data, etc. Reset Read instruction for within IC data read Response check for OK or NG...

  • Page 27: Alarm Circuit

    2.1.8 Alarm Circuit AC Fuse open alarm (a) 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 ALM-N signal to turn on the Thyristor.
  • Page 28 Overheat alarm (a) Head overheat alarm The voltage of the output HTEMP signal of the thermistors, one of which is contained in the print head and the other in the SP/LF driver, is monitored by the A/D port of the MPU to control the voltage. Temp Stop 132 C...
  • Page 29 (b) SP Motor overheat alarm The voltage of the output SPTEMP signal of the thermistors, one of which is contained in the SP Motor, is monitored by the A/D port of the MPU to control the voltage. Temp Stop 105 C 95 C Mode and print control Mode...

  • Page 30: Power Supply Circuit

    2.1.9 Power Supply Circuit This power supply circuit supplies the +3.3VDC, +5VDC, +12VDC, +42VDC, +50VDC and -8VDC. Power supply board Noise Rectifier +50V filter AC Fuse circuit Trans- Rectifier former +12V Converter Regulation Circuit Converter +3.3V +50V Converter +42V Control board The uses of output voltages and signals are described below.

  • Page 31: Mechanical Operation

    Mechanical Operation 2.2.1 Printhead mechanism and operation (See Figure 2-2.) The printhead is a spring charged 24-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.
  • Page 32 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.
  • Page 33 Paper Print wire Printhead Platen When printing Paper Armature assembly Print wire Thermistor Wire guide Yoke Spacer Magnet assembly When not printing Paper Figure 2-3 33 / 42114101 Rev.1...

  • Page 34: Spacing Operation (See Figure 2-4.)

    2.2.2 Spacing operation (See Figure 2-4.) 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.

  • Page 35: Head Gap Adjusting (See Figure 2-5.)

    2.2.3 Head gap adjusting (See Figure 2-5.) 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.
  • Page 36 Platen Range Carriage shaft Printhead Adjusting lever Adjusting screw Idler gear Adjusting gear Range from Narrows Printhead Adjusting screw Adjusting cam C.C.W. Platen Guide rail Widens Range from C.W. Figure 2-5 36 / 42114101 Rev.1...

  • Page 37: Ribbon Drive (See Figure 2-6.)

    2.2.4 Ribbon drive (See Figure 2-6.) 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) Ribbon cartridge Ribbon cartridge An endless ribbon with a single direction feed is used.
  • Page 38 Ribbon cartridge Drive gear Ink tank Figure 2-6 38 / 42114101 Rev.1...

  • Page 39: Paper Feed Operation

    2.2.5 Paper feed operation Feeding of the paper is performed by turning the platen and the pin tractor, which is driven by the LF pulse motor. Item of the paper feed mechanism are as follows: (a) Pulse motor with gears (b) Decelerating gear Platen (d) Tractor feed unit...
  • Page 40 Cut sheet and continuous sheet switching mechanism (See Figure 2-7.) Three different paper paths can be selected and set by the change lever. TOP (for cut sheet) When the cut sheet is used in the manual mode or fed by the CSF (option), set the change lever at the position marked TOP.
  • Page 41 Control Power supply Assy Bottom switch Switch lever Change gear shaft Rear switch Change lever Release shaft Change arm Platen BOTTOM REAR Change lever Tractor gear Change gear Platen gear (R) Reset spring Idle gear (Bottom tractor unit) Figure 2-7 41 / 42114101 Rev.1...
  • Page 42 Cut-sheet feeder operation (See Figure 2-8.) 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.
  • Page 43 Continuous paper feed operation (Rear) (See Figure 2-9.) The force transmitted to the platen, rotates the tractor gear through platen gear, the idler gear and the change gear. The rotation of the tractor gear makes the pin tractor belt rotate through a sheet feeder shaft, feeding the continuous paper.
  • Page 44 Push and pull tractor mechanism (Option) (See Figure 2-10). This mechanism consist of an optional pull tractor and a standard push tractor mechanism. This mechanism can perform forward and reverse feed by setting continuous sheets to the push tractor and pull tractor. The rotation of the platen is transmitted to the push tractor and the pull tractor.
  • Page 45 Pull tractor mechanism (option) (See Figure 2-11.) Bottom feed of continuous sheets is possible only when an 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.
  • Page 46 Bottom push feed operation (Option) (See Figure 2-12.) The bottom push feed of the continuous sheet is possible only when the bottom tractor feed unit is installed. When the platen rotates, the rotational force of the platen is transmitted through the tractor idle gear and the tractor change gear to the tractor drive gear of the bottom push tractor, and the sheet of paper is fed in to the print start position.
  • Page 47 Paper clamp mechanism (See Figure 2-13.) 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. And at the same time, the position of the cam installed to the front release gear shaft changes, and the open and close of the pressure roller.
  • Page 48 Change lever Release cam Platen Change arm BOTTOM REAR Figure 2-13 48 / 42114101 Rev.1...

  • Page 49: Paper Detection Mechanism (See Figure 2-14.)

    2.2.6 Paper detection mechanism (See Figure 2-14.) Cut sheet detection When the cut sheet is inserted, the point A is pushed backward and the paper near end lever B rotates counter clockwise (CCW). At this time, the rear sensor lever rotates counterclockwise (CCW), the rear sensor lever and pulls out of the rear and top paper end sensor to detect that the sheet is provided.
  • Page 50 Top line print mechanism (See Figure 2-15). The front edge of the sheet is protected by the ribbon protector so that it can stop at a position just near to the print head (0 tear off position) to start printing at the front end of the sheet, without causing the sheet to crumple or curl up.

  • Page 51: Automatic Sheet Feed

    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 is used. [Operational procedure] When using the cut sheet Set the change lever to the TOP position. (See Figure 2-13.) Insert a sheet of paper between the platen and the paper shoot.
  • Page 52 When using the continouos paper Set the change lever either to the rear side or the bottom side position. (See Figure 2-13.) Set a sheet of paper either to the push tractor. Press the “FF/LOAD” switch. The LF motor starts its operation to feed the paper up to the print start position. The paper is fed in up to the TOF position (Factory default: 0.85 inches from the top).

  • Page 53: Paper Park Function (Continuous Paper)

    2.2.8 Paper park function (continuous paper) Continuous sheets which have been inserted can be reversed automatically by using the “PARK” button on the operation panel. Press the “PARK” button on the operation panel. Reverse LF is started and paper is fed in reverse until paper end occurs or 19 inches maximum have been fed.

  • Page 54: Assembly/Disassembly

    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. Precaution for Parts Replacement Remove the AC cable and the interface cable before disassembling or assembling.

  • Page 55: Service Tools

    Service Tools Table 3.1 lists the tools necessary for replacing printed circuit boards and parts of units in the field. Table 3.1 Service tools Service Tool Q’ty Remarks No. 1-100 Phillips Screws screwdriver 2.6 mm No. 2-200 Phillips Screws screwdriver 3-5 mm No.

  • Page 56: Disassembly/Reassembly Procedure

    Disassembly/Reassembly Procedure This section explains the assembly replacement procedures according to the following disassembly system. [Parts Layout] Upper cover assy Transformer assy Printhead Control/Power supply board Driver board Operation panel board Printer unit Figure 3-1 Printer unit 56 / 42114101 Rev.1...
  • Page 57 [How to Change Parts] This section explains how to change parts and assemblies appearing in the disassembly diagram below. 3.3.1 Printhead Printer unit 3.3.2 Ribbon protector 3.3.3 Pull-up roller assy 3.3.4 Upper cover, access cover and sheet guide 3.3.5 Gear case assy 3.3.6 PC connector 3.3.7...

  • Page 58: Printhead

    3.3.1 Printhead Open the access over. Pull up and rotate the head clamp to unclamp the printhead as shown Figure 3-2. Disconnect the printhead from PC connector To install, follow the removal steps in the reverse order. Notes on installation: (1) Insert the printhead into the PC connector while pushing it against the carriage...

  • Page 59: Ribbon Protector

    3.3.2 Ribbon Protector Remove the printhead (see 3.3.1). Open the pull-up roller cover Raise and remove the ribbon protector To install, follow the removal steps in the reverse order. 59 / 42114101 Rev.1...

  • Page 60: Pull-Up Roller Assy

    3.3.3 Pull-up Roller Assy Open the access cover Lift up the sheet guide Assy to remove. Note: Please do after always remaining the sheet guide Assy when the pull-up roller Assy is installed and removed. Tilting the pull-up roller Assy toward the front, remove from the shaft of platen Assy To install, follow the removal steps in the reverse order.

  • Page 61: Upper Cover Assy, Access Cover Assy And Sheet Guide Assy

    3.3.4 Upper Cover Assy, Access Cover Assy and Sheet Guide Assy Pull off the platen knob Turn the change lever toward the bottom position. Insert a flat-blade screwdriver into grooves (5 places) (4 places for narrow type) of frame and twist to disengage claws of upper cover Raise the front side of upper cover Assy and shift toward the rear to disengage claws (6 places) (5 places for narrow type) of frame.

  • Page 62: Gear Case Assy

    3.3.5 Gear Case Assy Remove the printhead (see 3.31). Remove the upper cover (see 3.3.4 (1) – (5)). Move the carriage Assy to right hand side, remove two screws , then the space motor Disconnect a carriage cable. Disengage claws (4 places). Using a flat-blade screwdriver, push to widen the claw for easy disengagement.

  • Page 63: Pc Connector

    3.3.6 PC Connector Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the gear case Assy (see 3.3.5). Remove the PC connector from the space motor Assy To install, follow the removal steps in the reverse order. Note on installation: (1) Do not touch the space motor or terminals of PC connector...

  • Page 64: Space Motor, Guide Roller Assy

    3.3.7 Space Motor, Guide Roller Assy Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the gear case Assy (see 3.3.5). Remove the PC connector (see 3.3.6). Remove screw , then the guide roller Assy from the space motor To install, follow the removal steps in the reverse order.

  • Page 65: Space Rack

    3.3.8 Space Rack Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the gear case Assy (see 3.3.5). Remove the space motor (see 3.3.7). Remove the spring Disengage the claw on left side of space rack from the frame, and remove the space rack in upper direction.

  • Page 66: Carriage Cable

    3.3.9 Carriage Cable Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the gear case Assy (see 3.3.5). Remove the space motor (see 3.3.7). Remove the space rack (3.3.8). Remove two screws , release the Control Board and PCB sheet by lifting clamp , and disconnect cable from connector...

  • Page 67: Backup Roller Holder Assy

    3.3.10 Backup Roller Holder Assy Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the gear case Assy (see 3.3.5). Remove the space motor (see 3.3.7). Remove the backup roller spring Disengage claws (2 places) of roller holder from the carriage frame , and remove the backup roller holder assy To install, follow the removal steps in the reverse order.

  • Page 68: Platen Assy

    3.3.11 Platen Assy Remove the printhead (see 3.3.1). Remove the ribbon protector (see 3.3.2). Remove the pull-up roller Assy (see 3.3.3). Remove the upper cover (see 3.3.1 (1) – (5)). Turn the change lever to the bottom position. Push in the lock levers on both sides to unlock from the frame, then rotate them upward by 90 .

  • Page 69: Control Board (Tfs)

    3.3.12 Control Board (TFS) Remove the upper cover (see 3.3.4 (1) – (5)). Remove two screws , and release the Control Board and PCB sheet by lifting clamp Disconnect all cables from Control Board To install, follow the removal steps in the reverse order. Note on installation: (1) Insert one sensor lever between sensor when installing the Control Board...

  • Page 70: Lf Motor

    3.3.13 LF Motor Remove the printhead (see 3.3.1). Remove the ribbon protector (see 3.3.2). Remove the pull-up roller Assy (see 3.3.3). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the platen Assy (see 3.3.11). Remove the driver board (see 3.3.12). Remove the left FG plate Release the lock A to remove the LF motor To install, follow the removal steps in the reverse order.

  • Page 71: Operation Panel Board (Leop)

    3.3.14 Operation Panel Board (LEOP) Remove the upper cover (see 3.3.4 (1) – (5)). Disconnect the cable from connector of Control Board Disengage claws on both sides from the frame, and remove the operation panel Open claws (4 places) and remove the operation panel Board from the operation panel To install, follow the removal steps in the reverse order.

  • Page 72: Power Supply Board (Tpw)

    3.3.15 Power Supply Board (TPW) Remove the upper cover (see 3.3.4 (1) – (5)). Disconnect two flexible cable from the connector the Power Supply Board Remove the cable from the connector on the Power Supply Board Remove two screws , and remove the Power Supply Board To install, follow the removal steps in the reverse order.

  • Page 73: Transformer Assy

    3.3.16 Transformer Assy Remove the upper cover (see 3.3.4 (1) – (5)). Remove AC inlet and AC switch from the frame guide. Disconnect the cable from the connector on the Power Supply Board Remove a screw and disconnect ground cable Remove two screws and shift the transformer Assy to the left and remove it.

  • Page 74: Change Lever And Gears

    3.3.17 Change Lever and Gears Remove the upper cover (see 3.3.4 (1) – (5)). Remove the reset spring , then remove the idle gear , the tractor gear and the change gear Push back the protrusion of the Change Gear Shaft with a flatblade screw driver to remove the change lever To perform mounting, follow the reverse procedure of removal.

  • Page 75: Carriage Shaft

    3.3.18 Carriage Shaft Remove the printhead (see 3.3.1). Remove the upper cover (see 3.3.4 (1) – (5)). Remove the driver board (see 3.3.12). Remove the FG plate (L) Slide the carriage shaft to the left side (in the direction of the arrow) to remove. To perform mounting, follow the reverse procedure of removal.

  • Page 76: Paper Pan

    3.3.19 Paper Pan Remove the printhead (see 3.3.1). Remove the ribbon protector (see 3.3.2). Remove the pull-up roller assy (see 3.3.2). Remove the upper cover assy (see 3.3.4 (1) – (5)). Remove the platen assy (see 3.3.11). Release claws Lift up the paper chute assy and remove.

  • Page 77: Rear Tractor Assy

    3.3.20 Rear Tractor Assy Remove the printhead (see 3.3.1). Remove the ribbon protector (see 3.3.2). Remove the pull-up roller assy (see 3.3.3) Remove the upper cover (see 3.3.4 (1) – (5)). Remove the reset spring (see 3.3.17 (3)) Remove the tractor gear Shift the drive shaft to the right side to remove (in the direction of the arrow).

  • Page 78: Rear Pressure Assy

    3.3.21 Rear Pressure Assy Remove the upper cover (see 3.3.4 (1) – (5)). Remove the change lever and gears (see 3.3.17). Remove the paper pan (see 3.3.19). Remove the rear pressure roller Rotate the release shaft and move it to the left to detach the release shaft Match the Main Frame Rib A with the protrusion B of the Release Shaft.

  • Page 79: Switch Lever

    3.3.22 Switch Lever Remove the upper cover (see 3.3.4 (1) – (5)). Remove the Control/Power Supply Board. (see 3.3.15). Remove the change lever and gears (see 3.3.17). Remove the paper pan (see 3.3.19). Remove the rear pressure assy (see 3.3.21). Pull the Switch Lever toward you and remove it upward.

  • Page 80: Adjustment

    ADJUSTMENT Be sure to carry out this adjustment with the printer mechanism mounted on the lower cover. Be sure to carry out this adjustment operation on a level and highly rigid work table (flatness: less than 0.039 inch or 1 mm) so as to minimize adjustment error. 80 / 42114101 Rev.1...
  • Page 81 Item Specification Drawing Adjustment method 4–1–1 Gap between the plat- It shall be measured en and the print head at 3 points: the left end, the center and 1) Parallelism the right end of the justment Variation of platen. value at the left, the center Adjustment method and the right...
  • Page 82 Item Specification Drawing Adjustment method Note 1) The head gap shall be measured with the Adjust lever change lever set to rear position. Note 2) The head gap shall be measured positioning Adjust gear the platen gear (R) craw on the top. Adjust Note 3) spring...
  • Page 83 Item Specification Drawing Adjustment method Gap between the con- 0.3mm or more Confirm followings. tact and the monitor Make sure that the Adjust lever gap between the con- tact and the motor PCB is 0.3 mm or more. 0.3mm or more Contact Motor PCB...
  • Page 84 Item Specification Drawing Adjustment method 4–2 between 1 0.5 Confirm followings. platen and the paper (1) When the change lever is set at Friction position, the gap between Change lever the platen and the paper pan at the rear side shall be Bottom Rear 1 0.5mm.
  • Page 85 Item Specification Drawing Adjustment method 4–4–1 Rotation of the push To confirm: tractor The tractor gear shall rotate smoothly when the change lever is set at Friction posi- tion. Change lever (Center friction) Push tractor Tractor gear Slight backlash Approx. 0.05 to To confirm: 4–4–2 Backlash between...
  • Page 86 Item Specification Drawing Adjustment method 4–5–1 Ribbon feed To confirm: Ribbon shall be fed smoothly when the carriage is moved from side to side. Ribbon feeding 4–5–2 Running load to spac- 250g or less To confirm: ing mechanism without a rib- Make sure that the Ribbon bon cartridge...
  • Page 87 Item Specification Drawing Adjustment method 4–6 Engagement of the To confirm: double gear and the LF The idle gear of the motor idle gear of the LF motor and the Platen Assy. Platen gear (L) platen gear (L) and LF Motor the bias gear of the idle gear platen shall be in...

  • Page 88: Cleaning And Lubrication

    CLEANING AND LUBRICATION Cleaning [Cautions] Be sure to turn OFF the AC POWER switch before cleaning. Remove the AC Power cord from the printer. Avoid dust inside the printer mechanism when cleaning. If a lubricated part has been cleaned, be sure to apply lubricating oil to that portion after cleaning.

  • Page 89: Lubrication

    Lubrication This printer is designed to be maintenance free and requires no lubrication during normal operation. However it is necessary to apply lubricant in case the printer is disassembled, reassembled, cleaned or parts have been changed. Cleaning time Remarks: 1) Turn off the power before cleaning. 2) Make sure that paper dust will not fall inside of the machine.
  • Page 90 Lubrication point Ribbon feed gear Assy. Drive gear shaft (upper and lower) Planetary gear shaft PM-B (0.006 0.002g) (upper and lower) EM-30L-A Idle gear shaft (upper and lower) PM-B (0.006 0.002g) Space rack Space rack Rack upper side Approx. 35 (greasing range) EM-30L-A 90 / 42114101...
  • Page 91 Platen Assy. Bias gear Grease the contact face of platen gear (L) and bias gear PM-B Platen gear (L) 91 / 42114101 Rev.1...
  • Page 92 Tractor driving mechanism Change lever Tractor gear bearing portion EM-30L-A Surface of idle gear's teeth (Circumference) EM-30L-A Reset spring Gear bearing portion EM-30L-A Sliding surface of change lever and gear Sliding surface of EM-30L-A reset spring and gear EM-30L-A Tractor drive shaft Sliding surface of FG spring and drive shaft end EM-30L-A Drive shaft bearing portion...
  • Page 93 Pressure roller Change arm lever Release shaft Support spring Contact portion of support Front pressure roller spring and shaft EM-30L-A Contact portion of rear holder and shaft EM-30L-A Roller holder Sliding portion of rear roller holder and Sliding portion of release shaft cam surface (release release shaft and rear shaft plane portion)
  • Page 94 Pull up roller Assy. Pull-up roller frame Pull-up roller shaft All bearing portions of pull-up roller shaft and pull-up roller frame EM-30L-B Gear and post EM-30L-A 94 / 42114101 Rev.1...
  • Page 95 Main chassis Assy. Grease portion (N: 3 portions, W: 5 portions) rear side EM-30L-A Grease portion at rib (N: 9 portions W: 13 portions) EM-30L-A Grease portion 95 / 42114101 Rev.1...
  • Page 96 Carriage Assy. NK2-10-SUS Bearing portion of guide roller EM-30L-B 96 / 42114101 Rev.1...

  • Page 97: Troubleshooting And Repair

    TROUBLESHOOTING AND REPAIR Items to Check Before Repair Check the inspection items specified in the instruction manual. Find out as many details of the trouble as possible from the customer. Inspect in the conditions as close as possible to those at the time the trouble occurred. Proceed with the repair as follows: Check the trouble status according to Table 6.1 for the details of the trouble.

  • Page 98: Lamp Display

    Lamp Display Printer mode display Table 6.2 LED CONDITION ALARM TROUBLE ALARM CONTENTS CATEGORY SHOOTING ALARM MENU 10CPI 15CPI From, cut sheet or bottom Paper end alarm Set New paper. paper end Change lever is set to TOP Set the lever to specified Paper change BLINK position while paper is...
  • Page 99 99 / 42114101 Rev.1...
  • Page 100 100 / 42114101 Rev.1...
  • Page 101 Operation Panel Board Centro-connector Control Board AC connector Switch Transformer Print head LF motor Power Supply Board Space motor FAN motor 101 / 42114101 Rev.1...

  • Page 102: Connection Circuit Check For Printhead And Sp/Lf Motor

    Connection Circuit Check for Printhead and SP/LF Motor Printhead Signal Connector pin number N.C. HD11 +50V +50V HD17 HD19 HD21 HD22 HD20 HD18 +50V +50V HD12 HD10 HTEMP N.C. HD13 HD15 +50V +50V HD23 HD24 +50V +50V HD16 HD14 Thermistor (5k at 25 C) N.C.
  • Page 103 Line Feed Motor Resistance of each coil should be about 10.4 . Signal Connector pin number motor Space Motor Resistance of each coil should be about 22.4 . Signal Connector pin number SP-U SP-V Motor SP-W Photo sensor Thermistor SPTEMP at 25 C) 18, 22 103 /...

  • Page 104: Troubleshooting Flow Chart

    Troubleshooting flow chart Power is not supplied. Is the AC cable connected correctly? Connect the AC cable correctly. Is fuse F1 on the transformer assy/or F1 on the Power Supply Board blown? Replace fuse (with same type and rating). Remedied? Does DC + 50V out? Remove Print Head.
  • Page 105 No Yes Replace Control Board. Control Board Replace Transformer Assy. Remedied? No Yes Replace Power Supply Board. Pin No. 19 18 17 16 15 14 13 12 11 10 8 7 4 Signal +50V +12V -8V (0V) (0V) 105 / 42114101 Rev.1...
  • Page 106 No spacing operation (The alarm LED Blinks) Is carriage assembly binding or jammed? Check around space motor to repair the mechanism of space rack, back up roller, ribbon feed mechanism, and carriage frame etc. Replace space motor assy. Remedied? Replace Control Board Remedied? Replace carriage cable.
  • Page 107 Homing does not end normally Check around space motor to repair the mechanism. (Space rack, ribbon feed assembly back up roller, carriage frame, support protector and ribbon protector.) Remedied? Replace space motor assy. Replace space motor assy. Remedied? Replace carriage cable Remedied? Replace Control Board Remedied?
  • Page 108 Paper jam while paper insertion Jam 1 Check the ribbon protector. Check the pull up roller cover is closed properly. Pull up roller cover Platen Ribon Protector Paper Jam 2 (wrinkled paper) Check around pressure roller mechanism. • Front pressure springs are narrow: 3 pcs; wide: 5 pcs) mounted properly or not. •...
  • Page 109 Smearing/Missing Dots Does ALARM LED blink and display alarm? See Tables 6.2 and 6.3 for troubleshooting information. Replace print Head. Remedied? Replace Control Board Remedied? Replace carriage cable or space motor assembly. 109 / 42114101 Rev.1...
  • Page 110 Faint or dark print Is the print head gap set properly? Adjust the print head gap (see section 5) Remedied? Replace print Head. Remedied? Replace Control Board Remedied? Replace ribbon feed mechanism 110 / 42114101 Rev.1...
  • Page 111 Ribbon feed trouble Remove the ribbon cartridge. Move carriage to left and right. Does the ribbon drive shaft rotate? Change ribbon cartridge. Remove ribbon feed mechanism. Move carriage to left and right. Does the ribbon drive shaft rotate? Replace ribbon feed mechanism Replace space motor assy.
  • Page 112 Line feed trouble Turn the power off, and rotate the platen manually. Does the platen rotate smoothly? Is the platen gear (L) broken? Replace platen assembly Is the LF motor idle gear broken? Replace the LF motor assembly or LF idle gear. Is the platen gear (R), idle gear or change gear broken? Replace the gear.
  • Page 113 Malfunction of switch on operation panel Is the CN1 of operation panel connected to the CN3 on the Control Board? Connect the cable properly. Replace operation Panel Board Remedied? Replace Control Board 113 / 42114101 Rev.1...
  • Page 114 Data receiving failure Is the SEL LED blinking? Printer went into the print suppress mode. Wait until printer to receives DC1 code, or change the menu item “Print suppress-Ineffective” when the function is not required. Is the I/F RS232C? To step 10-2 Does the SEL LED light up? Press SEL key.
  • Page 115 10-2 (RS232C I/F) Printer I/F pin assignment. Is the correct cable used? 2 pin, 3 pin, 11 pin, 20 pin, Change I/F cable 6 pin. Is ALARM LED blinking? See tables 6.2 and 6.3 for the troubleshooting. Make sure of the parameters for RS232C in the menu are correct. Baud rate Bit length Parity...

  • Page 116: Appendix Apcb Layout

    Appendix A PCB LAYOUT PCB list Circuit board TPW (Power Supply Board) Circuit board TFS (Control Board) Circuit board LEOP (Operation Panel Board) 116 / 42114101 Rev.1...

  • Page 117: Appendix Bspare Parts List

    Appendix B SPARE PARTS LIST Quantity per year: Indicates the recommended number of each part that should be ordered for routine maintenance for one year for 500 units of printers and assuming that the printers are operated for 2 hours/day of 600 hours/year. The following codes are used to indicate the number of printers for which maintenance parts are ordered.
  • Page 118 Table B-1 Upper Cover Assy Q'ty Part No. Description Q'ty Remarks Required 42040801 Upper cover (N) For ML490 42040901 Upper cover (W) For ML491 51009409 Sheet guide assy (N) For ML490 51009510 Sheet guide assy (W) For ML491 42115401 Access cover assy (N)
  • Page 119 Figure B-2 Printer General Assy 119 / 42114101 Rev.1...
  • Page 120 Table B-2 Printer General Assy Q'ty Part No. Description Q'ty Remarks Required 51902220 Platen Knob 42024002 Power supply board (TPW) 42020002 Control board (TFS) 55081109 Operator panel board (LEOP) 42116101 Operation panel AC cord for 120V AC cord for 230V AC cord for 230V 42124201 Print head (24)
  • Page 121 Figure B-3 Printer Unit 121 / 42114101 Rev.1...
  • Page 122 Table B-3 Printer Unit (1/2) Q'ty Part No. Description Q'ty Remarks Required 42114901 Main chassis assy (N) For ML490 42115001 Main chassis assy (W) For ML491 50809201 Bottom paper end lever 50931301 Pressure spring (F) For ML490 For ML491 53349001...
  • Page 123 Table B-3 Printer Unit (2/2) Q'ty Part No. Description Q'ty Remarks Required 51022201 Guide rail plate (N) For ML490 51022301 Guide rail plate (W) For ML491 51238601 Adjust cam 51114201 Carriage shaft (N) For ML490 51114202 Carriage shaft (W) For ML491...
  • Page 124 Figure B-4 Carriage Assy 124 / 42114101 Rev.1...
  • Page 125 53349801 Carriage frame set 53343201 Back up roller holder assy 40493301 Guide roller holder assy 42104201 Space motor assy (24) 42252704 Head cable (23) ML490 42252702 ML491 42252801 Head cable (20) ML490 42252802 ML491 PC connector (36/40) 51238801 Gear case assy...
  • Page 126 [Pull-Tractor] [Bottom-Tractor] [I/F Board] Figure B-5 Option Spare Parts 126 / 42114101 Rev.1...
  • Page 127 Required 50098001 Pull and bottom tractor assy (L) 50097901 Pull and bottom tractor assy (R) 53077201 Tractor cover assy (N) For ML490 53077301 Tractor cover assy (W) For ML491 51902301 Bottom push stand (L) 51902302 Bottom push stand (R) 50098701...

  • Page 128: Appendix Crs-232C Serial Interface Board (Option)

    Appendix C RS-232C SERIAL INTERFACE BOARD (OPTION) GENERAL This section describes the operation of the RS-232C Serial Interface board installed in the Printer as an option using a start-stop synchronization and serial communications circuit. This serial interface board is capable of transmitting and receiving simultaneously at speeds up to 19,200 bits per second.

  • Page 129: Circuit Description

    Circuit Description A block diagram is shown in Figure C-1. 80C51 75188 75189 ADR latch IF WR DB0 to DB9 LS245 64Kbit 64Kbit Serial data +5 VD +9 V control line +12VDC ±9 V power –9 V Bus line supply circuit -8VDC +5 V Control line...

  • Page 130: Communication Procedure Flowchart

    Communication Procedure Flowchart 2.3.1 Mode a Ready/Busy Received one character? Is DSR valid? DSR High? Buffer overflow? Parity error Error? No error Store the received Store 40 H in buffer. character in buffer. Is the printer in DESELECT state or is the paper low? Is remaining buffer space ≤...

  • Page 131: Mode B

    2.3.2 Mode b X-ON, X-OFF Received one character? Is DSR valid? DSR High? Buffer overflow? Parity error Error? No error Store the received Store 40 H in buffer. character in buffer. Is the printer in DESELECT state or is the paper low? Is remaining buffer space <...

  • Page 132: Troubleshooting Flowchart

    TROUBLESHOOTING FLOWCHART Before Repairing a Fault Before servicing the printer, ask the customer in what situation the trouble occurred and record the response. Before starting troubleshooting, operate the printer in the same situation as that at the time of trouble occurrence to see if the same trouble occurs again. If not, perform the printers self test and thoroughly test the printers functionality.
  • Page 133 Yes Are ALE, PSEN, RD, WR, signals as specified in Figure C-6? 542ns 180ns PSEN 271ns 542ns RD/WR Figure C-6 Replace the Q3. Yes Are (T1) SELECT and (INTO) BUSY signals low level? Check Q3 on the Control Board. Yes Are +9V and -9V input to Q1? Replace defective component in +9/–9 volt control circuit.
  • Page 134 In receiving by serial interface, printing data is omitted or printing operation is not performed. Are RxD and SSD of Q3 as specified in Figure C-7? Replace the Q2. Yes Are, WR, and BUS signals of Q3 pin 3 as specified in Figure C-8? 542ns Q3-3 Figure C-8...

  • Page 135: Local Test

    Local Test 3.3.1 Circuit test mode 3.3.1.1 Setting Diagnostic test (set by menu) Test connector Connect the test connector shown in Figure C-9 to the interface connector Equivalent to Cannon DB-25P Figure C-9 Test Connector Connection Diagram 3.3.1.2 Function After the settings outlined in Section 3.3.1.1 are completed and power is turned on, the serial interface checks the message buffer memory and interface driver/receiver circuit.

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