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Oki ML420 Series, Maintenance Manual

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Oki ML420 Series Maintenance Manual Download Page 84

42113901TH01  Rev.3

84 /

Oki  Data  CONFIDENTIAL

Item

No.

Specification

Drawing

Adjustment method

Rotation of the push

tractor

4–4–1

To confirm:
The tractor gear shall

rotate smoothly when

the change lever is

set at Friction posi-

tion.

Backlash between

gears

4–4–2

Approx. 0.05 to

0.11 mm

To confirm:
There shall be slight

backlash between

gears to allow smooth

rotation of gears.

(Backlash 0.05 to

0.11 mm)

Change lever (Center friction)

Push tractor

Tractor gear

Slight backlash

Summary of Contents for ML420 Series

Page 1: ...Oki Data CONFIDENTIAL ML420 ML421 Maintenance Manual 080603F PRINTING SOLUTIONS...

Page 2: ...acturers and referred to in this guide will not affect the applicability of the information in it Mention of software products manufactured by other companies does not necessarily constitute endorseme...

Page 3: ...s how to maintain the 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 dest...

Page 4: ...Operation 38 2 2 6 Paper Detection Mechanism 48 2 2 7 Automatic Sheet Feed 50 2 2 8 Paper Park Function 52 3 ASSEMBLY DISASSEMBLY 53 3 1 Precaution for Parts Replacement 53 3 2 Service Tools 54 3 3 D...

Page 5: ...for Printhead and SP LF Motor 100 6 5 Troubleshooting flow chart 102 APPENDIX A PCB LAYOUT 114 APPENDIX B SPARE PARTS LIST 115 APPENDIX C RS 232C SERIAL INTERFACE BOARD OPTION 126 1 GENERAL 126 2 OPER...

Page 6: ...ard Printer Configuration This printer consists of the following assemblies Figure 1 1 Configuration Upper cover Access cover assy Platen knob Sheet guide assy Control board Power supply board Transfo...

Page 7: ...42113901TH01 Rev 3 7 Oki Data CONFIDENTIAL 1 2 Options 1 Cut sheet feeder unit CSF Narrow and wide versions available Dual bin CSF Single bin CSF 2 Pull tractor assy Attachment assy Attachment assy...

Page 8: ...42113901TH01 Rev 3 8 Oki Data CONFIDENTIAL 3 Bottom push tractor unit 4 Roll paper stand Narrow only 5 RS232C Serial interface board...

Page 9: ...Microprocessor and the Peripheral Circuit 1 Microprocessor This processor is a CMOS single chip computer with integrated peripheral device functions and a 16 bit MPU core all OKI original architectur...

Page 10: ...cuit 50 volt 12 volt 5 volt 42V 8V 3 3V 5VS Reset circuit I F IPT Print IPT EEPROM 1Kbits Microproce ssor ADDRESS Serial Serial ROM 4Mbit AD BUS DRAM 4Mbit LSI RESET 5VD POWLEV Fuse 42 V SP LF driver...

Page 11: ...M 2 Program ROM This is a 256 16 bits 4M bit EPROM or MASK ROMwith the control program for the printer stored The MPU executes instructions under this program The program ROM is assigned to the progra...

Page 12: ...8 RAS N VCAS N LCAS N RD N D0 D15 Read WR N D0 D7 Write 16 bit bus Word instruction ALS139 ALS11 T4 Clockout is provided when the original excitation is selected 3 RAM The RAM is CMOS dynamic RAM with...

Page 13: ...and controls the USB interfacee The following shows the USB Controller access operation D0 D7 P02 PSEN MPU USBCS N RD N WRL N A0 A7 USB Controller Clockout A0 A7 D0 D7 Write USBCS N RD N WRL N D0 D7...

Page 14: ...O PE EECS P EECLK P EEDIN P EEDOUT P Address Start code Operation code EEDOUT P EEDIN P EECLK P EECS P D15 D0 D15 D0 D15 0 A0 A5 0 1 1 tCS PRE O PE X 5 EEPROM The EEPROM is a CMOS serial I O type mem...

Page 15: ...SICS N ALE D0 D7 Read RD N D0 D7 Write WRL N Address Address Data Data Clockout is provided when the original excitation is selected 6 LSI This LSI detects and controls the SP motor speeds by monitori...

Page 16: ...itialize 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...

Page 17: ...USY 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...

Page 18: ...met USB Spec Rev 1 1 for normal operation Note Cable is not supplied 3 Table of USB I F signals Contact Signal Name Typical Wiring Number Assignment 1 Vbus Red 2 D White 3 D Green 4 GND Black Shell S...

Page 19: ...Signal Level Input Output Level Parameter Input Levels High driven High floating Low Output Levels Low High driven Output Signal Crossover Voltage Symbol VIH VIHZ VIL OL OH VCRS Min 2 0 2 7 0 0 2 8 1...

Page 20: ...T DT1 DT2 HEAD DRIVE CURRENT Print Data MPU LSI DRIVER HEAD1 N HEAD9 N Print Head A D bus HEAD1 HEAD9 Control Board Print Data 2 1 5 Print Control Print data is transmitted as parallel data HEAD1 HEAD...

Page 21: ...shown below a Voltage compensation See 2 1 8 Alarm Circuit b Temperature compensation See 2 1 8 Alarm Circuit c Pin stroke compensation Head Gap Range 1 2 3 4 5 Print speed 100 90 85 85 80 Drive time...

Page 22: ...he commands sent from the MPU Transmission of SP LF Motor Control Data MPU A B A B B A LF A1 A2 B1 B2 M SLATCH N SDATA N SCLK N LSI MHM2025 SPU SPV SPW SPU Distri butor Driver SPV SPW Decoder Space sp...

Page 23: ...or 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 l...

Page 24: ...vides 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 UTILITY MODE FORWARD PHASE B REVERSE PHASE A...

Page 25: ...h the operation panel control IC A 2 byte 15 bits 1 even parity bit command OPTXD is transmitted to the Operation panel control IC in synchronization with the OPCLK signal The Operation panel control...

Page 26: ...ite instruction for IC reset IC write for LED data etc Read instruction for data read Response check for OK or NG Error notification Instruction for retransmission 1 2 3 4 7 8 5 6 NO YES Note From the...

Page 27: ...ugh the primary coil and making the AC fuse transformer assy open b Overvoltage detection 50V 12V and 5V voltages are monitored at overvoltage alarm circuit turn on the ALM N signal is transmitted to...

Page 28: ...0 Stop DUTY 100 87 30 13 9 5 0 Pass 1 1 1 1 1 1 Characters less than 38ips Mode 1 2 3 4 5 6 7 PrintSpeed 100 85 70 55 40 30 Stop DUTY 100 87 30 13 9 5 0 Pass 1 1 1 1 1 1 Characters more than 38ips Mod...

Page 29: ...tage 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 Mode and print control When the temperature...

Page 30: ...nverter 3 3V 50V Converter 42V The uses of output voltages and signals are described below Voltage signal Use 3 3V USB Controller drive 5V Logic IC LED drive 12V Serial interface line FAN motor drive...

Page 31: ...carriage which moves in parallel with the platen Electrically this unit is connected to the control circuits through the control board Figure 2 2 Arrangement of the Head Pins View from the Tip of the...

Page 32: ...rmature 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...

Page 33: ...TH01 Rev 3 33 Oki Data CONFIDENTIAL 2 When not printing 1 When printing Figure 2 3 Paper Print wire Printhead Platen Wire guide Paper Print wire Thermistor Magnet assembly Spacer Armature assembly Yok...

Page 34: ...g the carriage shaft in parallel with 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 le...

Page 35: ...ear 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 5 the contact which is attached to the under sid...

Page 36: ...IAL Figure 2 5 Range from 5 to 1 Range from 1 to 5 Platen Range Platen Narrows C C W C W Carriage shaft Printhead Printhead Guide rail Adjusting screw Adjusting screw Adjusting gear Idler gear Adjusti...

Page 37: ...e direction feed is used Ink is supplied from an ink tank 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 tr...

Page 38: ...peration 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 De...

Page 39: ...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...

Page 40: ...nge arm Change lever Change gear shaft Rear switch Bottom switch Switch lever Control Power supply Assy Release shaft Figure 2 7 TOP BOTTOM Change lever Tractor gear Change gear REAR Reset spring Plat...

Page 41: ...lerating 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...

Page 42: ...ure 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...

Page 43: ...ull tractor Sheets are fed by these two tractors at the same time To remove slack from the sheets set the sheets according to the following procedure when using the push and pull tractors 1 Set the ch...

Page 44: ...ee 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 thr...

Page 45: ...on 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 tra...

Page 46: ...e 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 t...

Page 47: ...42113901TH01 Rev 3 47 Oki Data CONFIDENTIAL Figure 2 13 TOP BOTTOM REAR Change lever Front release gear arm Platen Release cam...

Page 48: ...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...

Page 49: ...bbon 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 The pri...

Page 50: ...ten and the paper shoot 3 After the lapse of time selected by the wait time in the menu the LF motor starts its operation to feed the sheet of paper up to the print position 4 When the default is sele...

Page 51: ...the push tractor or the bottom tractor 3 Press the FF LOAD switch 4 The LF motor starts its operation to feed the paper up to the print start position 5 The paper is fed in up to the TOF position Fact...

Page 52: ...operation panel 1 Press the PARK button on the operation panel 2 Reverse LF is started and paper is fed in reverse until paper end occurs or 19 inches maximum have been fed 3 The paper is fed in rever...

Page 53: ...inlet on the printer first then insert the AC input plug into a receptacle Interface cable Inlet AC cable AC receptacle AC input plug 2 Do not disassemble the printer as long as it is operating normal...

Page 54: ...ield Table 3 1 Service tools 1 No 1 100 Phillips 1 Screws screwdriver 2 6 mm 2 No 2 200 Phillips 1 Screws screwdriver 3 5 mm 3 No 3 100 1 screwdriver 4 Spring hook 1 5 J YX4025 83335 3 1 Head gap adju...

Page 55: ...3 3 Disassembly Reassembly Procedure This section explains the assembly replacement procedures according to the following disas sembly system Parts Layout Operation panel board Control board Power su...

Page 56: ...ss cover and sheet guide 3 3 5 Gear case assy 3 3 6 PC connector 3 3 7 Space motor and guide roller assy 3 3 8 Space rack 3 3 9 Carriage cable 3 3 10 Back up roller holder assy 3 3 11 Platen assy 3 3...

Page 57: ...order 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 surely be sandwiched between printhead 2 and carriag...

Page 58: ...58 Oki Data CONFIDENTIAL 3 3 2 Ribbon Protector 1 Remove the printhead see 3 3 1 2 Open the pull up roller cover 1 3 Raise and remove the ribbon protector 2 4 To install follow the removal steps in th...

Page 59: ...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 from the shaft of platen Assy 3 4 To install follo...

Page 60: ...f upper cover 3 4 Raise the front side of upper cover Assy 3 and shift toward the rear to disengage claws 6 places 5 places for narrow type of frame 5 Raise the upper cover Assy 3 to remove 6 Open the...

Page 61: ...es Using a flat blade screwdriver push to widen the claw for easy disengagement 6 Remove the gear case Assy 3 in upper direction and release the carriage cable from the cable clamp of the gear case As...

Page 62: ...or Assy 2 5 To install follow the removal steps in the reverse order Note 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...

Page 63: ...motor 1 6 To install follow the removal steps in the reverse order Notes on installation 1 Do not touch the terminals of space motor 1 Also take care to avoid dust or foreign matters 2 When installin...

Page 64: ...Assy see 3 3 5 4 Remove the space motor see 3 3 7 5 Remove the spring 1 6 Disengage the claw on left side of space rack 2 from the frame and remove the space rack 2 in upper direction 7 To install fol...

Page 65: ...tor 3 4 5 6 7 Remove carriage cable 7 from fasteners on frame 8 To install follow the removal steps in the reverse order Note on installation 1 Take care not to fold the carriage cable 7 during instal...

Page 66: ...y see 3 3 5 4 Remove the space motor see 3 3 7 5 Remove the backup roller spring 2 Disengage claws 2 places of roller holder from the carriage frame 1 and remove the backup roller holder assy 3 6 To i...

Page 67: ...emove the pull up roller Assy see 3 3 3 4 Remove the upper cover see 3 3 1 1 5 5 Turn the change lever 1 to the bottom position 6 Push in the lock levers 2 on both sides to unlock from the frame then...

Page 68: ...eet 5 by lifting clamp 4 3 Disconnect all cables from Control Board 2 4 To install follow the removal steps in the reverse order Note on installation 1 Insert one sensor lever 3 between sensor when in...

Page 69: ...er Assy see 3 3 3 4 Remove the upper cover see 3 3 4 1 5 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 8 Release the lock A to remove the LF mot...

Page 70: ...3 Disengage claws on both sides from the frame and remove the operation panel 4 4 Open claws 4 places and remove the operation panel Board 5 from the operation panel 4 5 To install follow the removal...

Page 71: ...pply Board 1 4 Remove two screws 6 and remove the Power Supply Board 1 5 To install follow the removal steps in the reverse order Remark on assembly 1 To mount the Power Supply Board set the change le...

Page 72: ...see 3 3 4 1 5 2 Remove AC inlet 1 and AC switch 2 from the frame guide 3 Disconnect the cable 3 from the connector 4 on the Power Supply Board 5 4 Remove a screw 6 and disconnect ground cable 7 5 Remo...

Page 73: ...e idle gear 2 the tractor gear 4 and the change gear 5 3 Push back the protrusion of the Change Gear Shaft 6 with a flatblade screw driver to remove the change lever 3 4 To perform mounting follow the...

Page 74: ...3 3 4 1 5 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 perform mounting follow the reverse pr...

Page 75: ...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 1 5 5 Remove the platen assy see 3 3 11 6 Release claws A 7 Lift up the pap...

Page 76: ...3 3 4 1 5 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 perform mounting follow the rever...

Page 77: ...ure SP assy 3 7 To install follow the removal step in the reverse order Note 1 At mounting release shaft 2 pay attention to the gear engagement of release shaft 2 change arm lever 6 change gear shaft...

Page 78: ...ange 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 ste...

Page 79: ...T 1 Be sure to carry out this adjustment with the printer mechanism mounted on the lower cover 2 Be sure to carry out this adjustment operation on a level and highly rigid work table flatness less tha...

Page 80: ...he right end shall be adjusted by rota ting the adjust cam 2 Set the adjust lever at the Range 1 Press the adjust gear downward in direction A to push the adjust gear and the adjust gear out of mesh 3...

Page 81: ...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 Measure variation of gap when range is chan...

Page 82: ...tor 0 3mm or more Confirm followings Make sure that the gap between the con tact 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 i...

Page 83: ...n 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 pla ten and the pre...

Page 84: ...firm The tractor gear shall rotate smoothly when the change lever is set at Friction posi tion Backlash between gears 4 4 2 Approx 0 05 to 0 11 mm To confirm There shall be slight backlash between gea...

Page 85: ...To confirm Ribbon shall be fed smoothly when the carriage is moved from side to side Running load to spac ing mechanism 4 5 2 To confirm Make sure that the power is turned off at the time of measure...

Page 86: ...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...

Page 87: ...aned be sure to apply lubricating oil to that portion after cleaning 1 Cleaning time When the equipment operating time has reached six months or 300 hours whichever comes first 2 Cleaning tools Dry cl...

Page 88: ...d 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...

Page 89: ...ibbon feed gear Assy 2 Space rack Drive gear shaft upper and lower PM B 0 006 0 002g Idle gear shaft upper and lower PM B 0 006 0 002g Planetary gear shaft upper and lower EM 30L A Space rack Rack upp...

Page 90: ...42113901TH01 Rev 3 90 Oki Data CONFIDENTIAL 3 Platen Assy Bias gear Platen gear L Grease the contact face of platen gear L and bias gear PM B...

Page 91: ...e of FG spring and drive shaft end EM 30L A Drive shaft bearing portion EM 30L A Drive shaft bearing portion EM 30L A Change lever Tractor gear bearing portion EM 30L A Change arm Idle gear teeth EM 3...

Page 92: ...EM 30L A Contact portion of support spring and shaft EM 30L A Sliding portion of release shaft and rear roller holder EM 30L A Release shaft Front pressure roller Controller holder Sliding portion of...

Page 93: ...901TH01 Rev 3 93 Oki Data CONFIDENTIAL 7 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 3...

Page 94: ...94 Oki Data CONFIDENTIAL 8 Main chassis Assy Grease portion Grease portion at rib N 9 portions EM 30L A Grease portion N 3 portions rear side EM 30L A 9 Carriage Assy NK2 10 SUS Bearing portion of gui...

Page 95: ...Troubleshooting Flowchart No Surmise of Trouble Power is not supplied No spacing operation 1 2 Power Supply Board Control Board Transformer Assy Space Motor Carriage Cable Printhead Homing does not e...

Page 96: ...EL key Print Head thermal alarm OFF BLINK 1 Print head temperature exceeds 119 C Wait until it is cooled Replace P H or Control Board Space motor thermal alarm OFF BLINK 1 Temperature of space motor e...

Page 97: ...rite error No reaction when MPU reads data MPU is locked up and it ios 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 Re...

Page 98: ...ace P H cable Replace Control Board Check the mechanisms if load is too much Check the P H connection Replace Print Head Replace P H cable Replace Control Board Print head does not reach to the home p...

Page 99: ...42113901TH01 Rev 3 99 Oki Data CONFIDENTIAL Switch AC connector Power Supply Board Transformer Centro connector Space motor LF motor FAN motor Print head Control Board Operation Panel Board...

Page 100: ...nnection Circuit Check for Printhead and SP LF Motor 1 Printhead Signal Connector pin number CN1 1 1 2 2 3 4 4 6 5 8 6 7 8 9 10 11 9 12 7 13 5 14 3 15 Thermistor 5K at 25 C HEAD1 HEAD2 HEAD4 HEAD6 HEA...

Page 101: ...coil should be about 10 4 Signal Connector pin number LF1 LF2 LF3 LF4 CN4 LF motor 1 2 3 4 3 Space Motor Resistance of each coil should be about 22 4 Signal Connector pin number SP U SP V SP W SPA SPB...

Page 102: ...F1 on the Power Supply Board blown No Yes Replace fuse with same type and rating Remedied No Yes End Does DC 50V out No Yes Remove Printhead Turn power off then on Remedied No Yes End Replace carriage...

Page 103: ...ki Data CONFIDENTIAL Pin No 20 19 18 17 16 15 14 13 12 11 10 9 8 7 4 3 1 Signal 50V 0V 5V 0V 12V 8V No Yes Replace Control Board Replace Transformer assy Remedied No Yes End Replace Power Supply Board...

Page 104: ...inks Is carriage assembly binding or jammed No Yes 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 R...

Page 105: ...the mechanism Space rack ribbon feed assembly back up roller carriage frame support protector and ribbon protector Remedied No Yes End Replace Space motor assy Replace Space motor assy Remedied No Ye...

Page 106: ...narrow 3 pcs wide 5 pcs mounted properly or not Tension of all of front pressure rollers is properly Make sure of the fitting position of change gear shaft change arm shaft and release shaft are corre...

Page 107: ...Smearing missing dots Does ALARM LED blink and display alarm No Yes See Tables 6 2 and 6 3 for troubleshooting information Replace Printhead Remedied No Yes End Replace Control Board Remedied No Yes...

Page 108: ...NTIAL 6 Faint or dark print Is the print head gap set properly Yes No Adjust the printhead gap see section 5 Remedied No Yes End Replace Printhead Remedied No Yes End Replace Control Board Remedied No...

Page 109: ...he ribbon cartridge Move carriage to left and right Does the ribbon drive shaft rotate No Yes Change Ribbon cartridge Remove Ribbon feed mechanism Move carriage to left and right Does the ribbon drive...

Page 110: ...Replace Platen assembly Is the LF motor idle gear broken No Yes Replace the LF motor assembly or LF idle gear Is the platen gear R idle gear or change gear broken No Yes Replace the gear Set change l...

Page 111: ...ONFIDENTIAL 9 Malfunction of switch on operation panel Is the CN1 of Operation panel connected to the CN3 on the Control Board Yes No Connect the cable properly Replace Operation panel board Remedied...

Page 112: ...rint sup press Ineffective when the function is not required Is the I F RS232C No Yes To step 10 2 Does the SEL LED light up Yes No Press SEL key Remedied No Yes Does the printer receive data properly...

Page 113: ...oubleshooting Make sure of the parameters for RS232C in the menu are correct Baud rate Bit length Parity Protocol Busy signal and its polarity Remedied No Yes End Are 12V and 8V supplied on Control Bo...

Page 114: ...4 Oki Data CONFIDENTIAL Appendix A PCB LAYOUT PCB list 1 Circuit board TPW Power Supply Board 2 Circuit board NNS Control Board 3 Circuit board LEOP Operation Panel Board 1 2 3 CN3 CN1 CN2 CN4 CN1 CN3...

Page 115: ...ber 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...

Page 116: ...009409 Sheet Gude Assy N 1 2 ML420 Beige 40165004 Sheet Gude Assy N 1 2 ML420 Black 51009510 Sheet Gude Assy W 1 2 ML421 Beige 41772403 Sheet Gude Assy W 1 2 ML421 Black 3 42115401 Access Cover Assy N...

Page 117: ...42113901TH01 Rev 3 117 Oki Data CONFIDENTIAL Figure B 2 Printer General Assy 6 9 7 1 2 3 11 10 4 5 8...

Page 118: ...9 4 55081107 Op Panel Board LEOP 1 3 5 42116101 Operation Panel 1 2 Beige 42116405 Operation Panel 1 2 Black 6 56609701 AC Cord 1 1 120V 41888902 AC Cord 1 1 230V 7 41923901 Printhead 9 1 10 8 4212470...

Page 119: ...42113901TH01 Rev 3 119 Oki Data CONFIDENTIAL Figure B 3 Printer Unit A A B B 29 30 23 7 6 15 20 11 19 12 27 25 26 24 28 1 31 21 10 9 2 17 14 33 34 35 32 8 37 18 42 22 13 5 4 3 16 14 41 40 36 38 39...

Page 120: ...2 ML421 7 53349201 Paper Pan Plate N 1 2 ML420 53349301 Paper Pan Plate W 1 2 ML421 8 42256301 Leaf Spring N 1 2 ML420 42256201 Leaf Spring W 1 2 ML421 9 50809301 Paper End Lever 1 1 10 40775901 Sens...

Page 121: ...ML420 Beige 42044703 Pull Up Roller Assy N 1 2 ML420 Black 42045701 Pull Up Roller Assy W 1 2 ML421 Beige 42045704 Pull Up Roller Assy W 1 2 ML421 Black 31 40355101 Gear Idle LF Motor 9 Pin 1 4 32 53...

Page 122: ...42113901TH01 Rev 3 122 Oki Data CONFIDENTIAL Figure B 4 Carriage Assy 12 9 8 6 14 4 10 7 11 13 3 1...

Page 123: ...e Roller Assy 1 2 5 6 42103601 Space Motor Assy 1 4 7 42252703 Head Cable 23 1 5 ML420 42252701 Head Cable 23 1 5 ML421 8 56731301 15 Pin Connector 1 2 9 42348103 Gear Case Assy 1 3 10 50702901 Head C...

Page 124: ...42113901TH01 Rev 3 124 Oki Data CONFIDENTIAL Figure B 5 Option Spare Parts Pull Tractor Bottom Tractor I F Board 3 2 1 4 5 6 7...

Page 125: ...1 Tractor Cover Assy N 1 3 ML420 53077301 Tractor Cover Assy W 1 3 ML421 4 51902301 Bottom Push Stand L 1 2 Beige 42451601 Bottom Push Stand L 1 2 Black 5 51902302 Bottom Push Stand R 1 2 Beige 424516...

Page 126: ...up to 19 200 bits per second Two protocols are available printer Ready Busy and X ON X OFF modes 2 OPERATION DESCRIPTION 2 1 Element Description 1 80C51 with MASK ROM An eight bit microprocessor cont...

Page 127: ...re C 1 2 2 1 Operation at power on After power is turned on an RST OUT signal is sent from the printer control board to reset the printer When the reset is canceled the 80C51 CPU performs initializati...

Page 128: ...character in buffer Is the printer in DESELECT state or is the paper low No No Yes Yes No DSR High Yes Store 40 H in buffer Yes Yes No Yes Is remaining buffer space 256 Yes No Turn on the SSD signal...

Page 129: ...r Is the printer in DESELECT state or is the paper low No No Yes Yes No DSR High Yes Store 40 H in buffer Yes Yes No Yes Is remaining buffer space 256 Yes No Printer busy No Output one character to pr...

Page 130: ...perform the printers self test and thoroughly test the printers functionality If the trouble is reproducible proceed to the troubleshooting section 3 2 Troubleshooting 1 The data is not received using...

Page 131: ...WR Figure C 6 ST bit SP bit 5V 0V 5V 0V RxD SSD No Replace the Q3 Yes Are T1 SELECT and INTO BUSY signals low level No Check Q3 on the Control Board Yes Are 9V and 9V input to Q1 No Replace defective...

Page 132: ...in Figure C 7 No Replace the Q2 Yes Are WR and BUS signals of Q3 pin 3 as specified in Figure C 8 No Replace the Q3 Yes Is the level of a BUS signals at Q7 pins 2 9 the same as that of DB0 7 when WR s...

Page 133: ...ed on below 1 The program revision using two numerical characters is printed 2 LOOP TEST is printed 3 Memory is checked for the message buffer 4 Prints OK is printed if the memory check is OK and BAD...

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