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OKI ML184 Maintenance manual

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46 views151 pages

184 TMM

OKI ML184 Maintenance manual

Uploaded by

meimagscanner
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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OKI MICROLINE 184 Turbo MAINTENANCE MANUAL PREFACE This document describes field maintenance procedures for the Microline 184 Turbo. It is intended for field maintenance personnel. CONFIGURATION .... 1 12 INSTALLATION PROCEDURE ...- 24 PRR EEL THEORY OF OPERATION - TABLE OF CONTENTS Standard Printer Configuration Options . . Unpacking .... ig the Packing Box . the Printer Unit Unpacking the Accessories Installation .. Precautions for Installation Removing the Shipping Retainer . Installation of the Accessories . Connecting Cables .. Installing Paper Powering On Electrical Operation .... General Microprocessor and Its Peripherals Circuits . Initialization ... Interface Control Printhead Drive Circuit .. Spacing Drive Circuit ......... Line Feed Circuit Alarm Circuits . Paper End Detection Circuit . Power Supply ... Mechanical Operation .... The Printhead Mechanism and Its Oper: Spacing Mechanism and Operation .. Head-Gap Adjusting Mechanism .........++ bon Feed Mechanism and Operation Paper Feed Mechanism and Operation . Paper-End Detection Mechanism ..... Semi-Automatic Sheet Feed (SASF) Mechanism and Function cA ‘ASSEMBLY/DISASSEMBLY 5 24-1 44 Precautions for Parts Replacement 24-4 42 Maintenance Tools ..... 24-2 43 Disassembly/Reassembly of Procedure 1403 43.1 Print Head .....c000+ 14-5 43.2 Upper Cover . 14-7 43.3 Control Board 24-11 43.4 Transformer Assembly 24-13 43.5 Power Supply Board 4-15 43.6 Operation Board ........ 4-16 43.7 Printer Mechanism ...... 24-17 43.8 LF Motor Assembly . 4-19 43.9 Connection Board .......-. 4-7 43.10 Ribbon Feed-gear Assembly 4-3 43.11 Space Motor Assembly . 24-25 43.12 Space Rack .. : 24-07 43.13 Carriage Cable . 4-29 43.14 Carriage Frame ........ 24-31 43.15 Column Indicator Bar ........ 4-33 43.16 Platen Assembly .. 24-35 43.17 Paper-chute Assembly 14-37 43.18 Bottom Paper Guide Assembly ... 4-38 43.19 Near-end Lever and Bracket .. 4-39 43.20 Bottom Near-end Lever aaa 4-40 43.21 Switch Assembly ......000ceeeseceeseeeeenee 24-41 4322 Pin Tractor Assemblies (R and L\(Optional Tractor Unit) 24-482 ADJUSTMENT ... peer pone 5A Head-Gap Adjustment ......... a 52 Space Rack and Roller-Gap Adjustment .... CLEANING AND LUBRICATION .......--000000008 p00 6-1 64 Cleaning . ees 26-1 62 Lubrication . aaa tienes 6-2 TROUBLESHOOTING AND REPAIR . 27-1 7A Items to Check Before Repair .........++ 27-4 72 Finding the Cause of Error ...........0++ 27-4 7.3 Troubleshooting ... eee 17-6 PCB LAYOUT . CIRCUIT SYMBOLS AND ‘CIRCUIT DIAGRA\ SPARE PARTS LIST . 1. CONFIGURATION 1. CONFIGURATION 1.1. Standard Printer Configuration The standard configuration of the ML184 Turbo is as follows: Paper separator Cover assembly Control board Ribbon cartridge Printer unit Operation parte! SASF switch assembly Figure 1-1. Printer Configuration (1) Tractor unit (consists of Pin tractor assy, acoustic cover, and access cover) @) Roll paper stand @) —Super-speed RS232-C serial interface board (6) Automatic 2. INSTALLATION PROCEDURE 2. INSTALLATION PROCEDURE 2.1 Unpacking 2.1.1 Unpacking the Packing Box () Open the packing box. 2) Remove the printer and the paper separater with the cushioning materials from the packing box. @) Peel the fixing tape off and remove the paper separater. (4) Remove the cushioning material A, B and the cushioning sheet. (5) Peel off the fixing tape off the packaging box and remove the accessories. (©) _ Peel off the fixing tape off the packaging box and remove the user’s manual. Paper separater Cushioning sheet Cusioning material 8 a ‘Accessories Cushioning material A Oe User'smanual Packaging box RS 24.2 a Q) 8) Unpacking the Printer Unit Take out the printer from the plastic bag. Remove the desiccant and the caution sheet along with the fixing tape. Remove the fixing tape from the access cover. Plastic bag Fixing tape \ Caution sheet Printer 2-2 2.1.3 Unpacking the Accessories (1) Take out the AC power cord, the ribbon cassette from the plastic bag. 2) Take out the user’s manual from the plastic bag. 2 Plastic bag Ribbon cassetie AC power cord Plastic bag User's manual 2-3 2.2 Installation (For details, refer to the Setup Guide.) 2.2.1 Precautions for Installation When installing the printer, observe the following precautions: a @ 8 Do not install the printer in the following places: a) Place exposed to direct sunlight b) Place with great fluctuations in temperature ©) Place exposed to outdoor wind ¢) Dusty place e) Near a door f) Too near an air conditioner 8) Place subject to heavy vibrations Adjust the temperature and humidity of the installation site as follows: Temperature: 41°F to 104°F (5°C to 40°C) Humidity: 20%RH to 90%RH To install the printer and printing paper, observe the following procedure: a) Adjust the height of the desk on which to place the printer to 30 inches (75 cm) as a standard. (See to it that the desk surface is horizontal and smooth and that the rubber protectors on the bottom of the desk legs are level.) b) Set the printing paper on the floor below the printer so that it may be fed into the printer without skewing from the feeding path by more than 2 inches (5 cm). —— 2 inches (5 cm) or less c) Align the rear section of the printer with the rear edge of the desk. Keep a distance of 24 inches (60 cm) or more between the rear section of the printer unit and the wall to provide a space for printed paper being fed out. d) Keep a distance of 4 to 6 inches (10 to 15 cm) or more between the unprinted paper fed into the printer and the printed paper fed out of the printer. If the paper going in one direction interferes with the paper going the other way, they may jam inside the printer. 24 inches (60 cm) or more Wall 30 inches (75 cm) 4 to 6 inches (10 to 15 em) 2.2.2 Removing the Shipping Retainer Remove the shipping retainer that secures the printhead. Shipping retainer 2.2.3. Installation of the accessories (1) Ribbon cartridge @ Remove the wrapper of the ribbon cartridge. Ribbon cartridge @ Before setting, turn the take-up knob to tighten the ribbon. @ Push the rear of the cartridge down first. Make sure it snaps into the boss. Important: Do not peel off the plastic film on the top of the cartridge. It is a part of the cartridge. @ Lower the front of the cartridge over the printhead. © Grasp the cartridge on both sides, making sure the take-up knob revolves in the direction of the arrow icon. Note: When passing the ribbon between the printhead and the platen, make sure that the ribbon is not twisted or bent and that the left/right arms of the cartridge fit correctly. Inserting the Ribbon Cartridge [a side view] Front of the cartridge Platen Ribbon Ribbon Protector \ \ —_ J x x ° (incorrect) (incorrect) (Correct) (2) Paper separator Install the paper separator by placing its hooks in the slots provided in the upper cover. Upper cover 2.2.4 Connecting Cables (1) Connect the interface cable to the printer. If your interface has a pressure connection terminal for grounding, connect the terminal in the chassis ground connector by using a suitable screw. Interface cable Pressure connection ‘terminal for grounding Screw 2) Connect the AC cable to the printer. AC cable f 2.2.5 Installing Paper Install printing paper on the printer for the test run. 2.2.6 Powering On (1) Turn on the POWER switch on the right side of the printer unit. Q) Confirm that the POWER LED is on and that the printhead returns to its home (left most) position. @) If the printer unit shows no abnormality after it is powered on, proceed to the next step (4) for test printing. “a Test printing a) After confirming that the POWER switch is off, turn it on wi FEED and SELECT switch. le pressing the LINE b) Confirm that the printer unit prints out the test pattern as shown in the figure below. ©) Press the SELECT switch to end the printing test. d) Confirm that the SELECT lamp is on, indicating that the printer unit is ready to receive printing data from the host computer. vase’ ()74,>,/0123456789: S506" ()74,5./0123456789+ penp7engc~ ss57eaaco S36" 701234567091; <=>7eABCOE #526" ()7*,+./0123456789: ; <->? CABCOLE S34" ()'4,5, 101234567894 <=>? PABCDETG 3G" () 7,5, /0123456789) ; <=>? OABCDETGH ete =>? eaBCOEFGHI *()t4,2, 70123456789, , <=>7 @ABCOEFGNIS [)te, 5, 70123856799+; <=>? @ABCDEFGHIIK }ter2, 701234562894; <=>? @ABCOEECHTIEL 7)01238567891 ; <=>? @ABCOEFGHIIKLM 4 152)91234567896; <=>? enscoEFcHIIKLHN 70123456789, ; <=>? OABCOEFEMIIKLHNO 70123456789; | <->? @ADCOETGIIKLHNOP 10123456789: ; <=>? ADCOEFGHIIKLMNOFO 70123456709, ; <=>? CABCOEFCMZIKLMNOPOR 0123456709, ; <=>? @ABCOETGHZIKLUNOPORS 123456783, 23456789) 7eABCOETCH }t+12) 701234567894; <=>7 @ABCOETGH 0,5, 70123456789: <->7 EABCOETGHTT 2234567691; =? @ABCDETGNTIK 701234567890; <9>7 @ABCDEFGHIIKL 117 70123456789, ; <=>? @ABCOEFGHIIKLM {y0123456789, ; <=>? @ABCDEFGHTIKLIN 179123456789. ; <=>? ABCOEFGHTIKLMNO 1701238567891 ; <=>7 @ABCDEFCHTIKLMNOP 70123456789, , <=>? @ABCDLEGHIIKLHNOPO 0123456789: ; <=>? CABCDEFGIITJRLMNOPOR 123456789, ; ? @ABCOEEGHITKLMNOPORS: 23456789, ; <=>7 @ABCOEEGHIIKLUNOPORST 3456789, ; <=>? @ARCDEECHIIKLMNOPORSTU ‘ 1 456789, ; <=>? @ABCOLFGHIIKLMNOPORSTUV 36789; ; <=>? @ABCOEECHTIKLMNOPORSTUVH 6789, ; <=>? @ABCDEFGHIIKLMNOPORSTUVHX 389s ; <=>? ABCOEFONIIKLUNOPORSTUVHXY 03; | <->? OABCOEFCHIIKLMNOPQRSTUVHXYZ =94 ; <=>7 @ABCOEFGHTIKLHNOPQRSTUVHXY2( 3. THEORY OF OPERATION 3. THEORY OF OPERATION 3.1. Electrical Operation This section describes the operation of the printer circuits. 3.1.1. General ‘The electrical section of the printer consists of the components shown in figure 1. In addition to the microprocessor, the control board also contains a DC power circuit, drive circuits, a paper-end sensor, and an interface connector. ‘The power supply connects with the control circuit board via a cable, and other electrical parts connect via the connection board. BAD a @ ) @) Microprocessor and Its Peripheral Circuits Microprocessor (Q12: 80C154) ‘The microprocessor is the nucleus of the control circuit, and its peripheral circuits operate under control of this microprocessor. The 1/O ports of the control lines. foprocessor are connected with the address bus, data bus, and Program ROM (Q8) The program ROM stores the control program for the printer. The microprocessor operates under control of this program. RAM (Q13) The RAM stores data such as received print data. LSI (MsM6990) ‘The MSM6990 is an external interface and motor control LSI. It has the following functions: A: External interface controller (@) Parallel interface function The parallel interface function mode is selected when the level of the mode selection signal (ISEL) is high. In this mode, IFD1 to 8 are used as an input port; the parallel data received through the interface connectors is latched in synchronization with the strobe signal (STB) and is sent to the CPU in synchronization with the RD signal. In this mode, the MSM6990 also sends BUSY, ACK, PE and SELECT signals to the inter- face connector in synchronization with the WR signal. (b) Address decoder The address decoder decodes the address signal (A12 to A15), and sends out the RAM (Q13) chip select signal © RAM SEL). (©) Parallel port function This function is used to load the DIP switch data. B: Motor controller dd) e) (0) ® Space speed control function This function accelerates and decelerates the space motor in accordance with com- mands from the microprocessor and controls the space motor speed in each printing mode. Dot timing generation function This function generates the dot-on timing signal (PD, synchronized with the printing speed in accordance with output signals (PHASE A, B) of the encoder on the space motor, and sends this timing information to the microprocessor. VO ports ‘The MSM6990 has a 12-bit output port and a 10-bit input port. It outputs control signals in accordance with the commands input from the microprocessor. The input port is also used to read information from the operation panel switches, etc. ‘Address latch ‘The address latch latches the low-order 8 bits of the address (A0 to A7). These bits are used as an address for read/write operations with peripheral devices. 3.1.3 Initialization ‘The printer is initialized when the power is turned on or when the parallel interface signal I-PRIME is received from the host computer. Initialization is started by resetting Q12 (microprocessor) and Q4 (interface LSI) with the RST OUT signal output from the reset circuit (Q7 pin 13). A program then starts and sets microprocessor(Q12) and LSI (Q4) modes, checks memory (ROM and RAM), initializes the RAM, and moves the carriage to home. Next, the program establishes the inter- face signals (output ACK and BUSY signals), turns on the SELECT indicator, and informs the host ‘computer that the printer is ready to receive data, thus completing the initialization. 314 a Interface Control Parallel interface ‘The data from the interface is input through the connector (CN1), and the interface LSI (Q4: ‘MS6990) latches this input data in synchronization with the STB signal. The BUSY signal is on while processing this data. After processing, the BUSY signal is turned off and an ACK signal is sent to request the next data. ‘The BUSY signal is also sent to stop data sending when the receive buffer is full. omatee | bd COS susy J aK TTT mT 3.1.5. Print Head Drive Circuit ‘This circuit drives the head magnets corresponding to the HEAD DATA to 9 signals in syn- chronization with the HEAD-ON signal, thus making the print head print characters. When the HEAD-ON signal goes high, the RC integrator (R548 and C5) determines the head drive time. This integrator adjusts the printing pressure automatically to compensate for varia- tions in the drive voltage (+30 V). “That is, the integrator increases the drive time if the drive voltage drops and decreases the drive time if the drive voltage rises. HEADI to 9 x x x HEAD-ON n n n are THresHown | a Leven oven oRIVE ors 3.1.6 Spacing Drive Circuit a Space motor control The motor control LSI (Q4: MSM6990) outputs the space motor phase signals (SPU, SPV, and SPW) in accordance with the spacing command from the microprocessor. At the same time, it outputs the overdrive signal (SPD-A). The SPD-A signal is a fixed-period pulse signal whose pulse width is controllable by program. It is used to control the motor drive time. ‘The SP ON/OFF signal is output during acceleration and deceleration, which requires a large amount of torques. The motor driver (MTDV) drives the space motor in accordance with these signals. Pins 9 and 11 of the MTDV are for the overvoltage and overcurrent protective circuits respectively. SPU sP-v SPW Sus eo —————— ae coos LFLSU SLM sp oNorr | ‘Overdrive current waveform | Slit encoder PHASE-A and PHASE-B signals are generated by the photosensor and circular slit when the space motor rotates. ‘The motor control LSI (Q4: MSM6990) frequency divides these edge pulse signals in accord- ance with the print pitch and outputs the IPT signal to provide dot-on timing and carriage position detection timing. SPU SPV sew PHASE-A 1 l l J l mses Lf LPLIELIDLSI LS er(i0cPD) Tea IPT(12CPI) Lz J — 1PT(17.ACP1) Lae] 3.1.7. Line Feed Circuit ‘The line feed motor is locked at +8 V when it is not turning. accordance with the LF During line feed, the line feed motor is driven by the +30 V level apple OVD signal. mL LFovD LF. 92 uF & 3.1.8 Alarm Circuits a @ Drive circuit error alarm This circuit protects the print head drive circuit, space motor drive circuit, line feed motor drive circuit, and peripheral circuits by blowing a fuse when an error occurs. ‘The circuit monitors the drive time using the HDALM, SPALM, and LFALM signals interlocked with the overdrive signal of each drive circuit. If the drive time of any drive circuit exceeds the specified time, the drive circuit fault alarm circuit outputs an ALM signal (high) to turn on the SCR. This short-circuits the secondary coil (30 V) of the transformer, resulting in an overcurrent in the primary coil, and blows the AC fuse. Head overheat alarm circuit In order to protect the head coils, this circuit monitors the head temperature using the thermistor built into the print head. If printing is performed continuously for an extended period, the print head gets hot. When the head temperature reaches a certain value (approximately 100 degrees C), a head overheat alarm is detected. When this alarm is detected, printing stops temporarily to wait for the head to cool. When the head temperature drops below the alarm detection temperature, printing resumes. Alarm detection is performed as follows: When the temperature in the print head rises, the resistance of the thermistor decreases, and the potential of the comparator (Q7) negative input decreases to invert the comparator out- put, causing the HEAD TEMP signal to be output to the motor control LSI. 3.1.9 Paper End Detection Circuit ‘When the paper runs out, the photosensor (PE) on the control board turns off, and as a result, the PAPER END signal goes to 0. This signal is fed to pin 55 of the motor control LSI (Q4), stopping the printing operation and lighting the ALARM indicator. 3.1.10 Power Supply The power supply consists of a power transformer, power supply board, and a DC power supply circuit. ‘The input AC voltage is transformed into 7.6 VAC, 24 VAC, and 10 VAC by the power transformer, and these AC voltages are further converted to +8 VDC, +5 VDC, and +30 VDC by the DC power supply Circuit and supplied to each circuit. (1) Power supply board The power supply board contains the power switch, AC fuse, and the AC noise filter. @) Power transformer If the power transformer temperature rises abnormally, the built-in temperature fuse of the transformer blows to prevent any adverse effect on other components. 3.2 Mechanical Operation 3.24 The print head is spring-loaded, uti ‘The Printhead Mechanism and Its Operation (see figure 3) i a permanent magnet, and can be easily removed oF i stalled. The print head is mounted on a carriage that runs parallel to the platen and is connected with the control circuit via the head board. ‘The print head consists of: a (@) Wire guide (b) Print wires (©) Armature assembly (@) Yoke (e) Springs (® Spacer (@) Magnet assembly (h) Thermistor (i) Printed-circuit board Print head operation ‘When the print head is in the non-printing state, each armature is attracted by the permanent magnet, and the springs holding the armatures are compressed by the thickness of the spac- et. The print wires, which are fastened to the individual armatures, are therefore held re- tracted within the wire guide. ‘When signals corresponding to a character to be printed are detected by the control circuit, currents flow through the corresponding coils to nullify the magnetic flux generated by the permanent magnet between the armatures corresponding to those coils and the permanent magnet pole. As a result, those armatures are driven toward the platen by the force of the armature springs, and the print wires fastened to those armatures eject from the tip of the wire guide and strike the paper through the ribbon to print dots on the paper. After the character is printed, the magnetic flux of the permanent magnet attracts the arma- tures again so that the print wires retract into the wire guide. ‘The print head has a built-in thermistor to prevent the coils from overheating and burning due to continuous bi-directional printing over a long period. If the coil temperature exceeds the limit (approximately 100 degrees C), the control circuit detects the thermistor signal and stops the printing operation until the coil temperature drops below the limit. ‘Armature assembly ‘Thermistor = ‘Magnet coll Figure 3 3.2.2. Spacing Mechanism and Operation (see figure 4) ‘The spacing operation is performed by driving the carriage frame, which is guided by the carriage shaft mounted parallel to the platen, with the DC motor mounted on the bottom of the carriage frame. The space mechanism consists of: a (@) DC motor with motor gear (b) Carriage frame (including stator yoke and motor board) (0 Carriage shaft (@) Space rack (@) Slit sensor (Slit disk Spacing operation The carriage, with the print head and space motor mounted on it, moves parallel to the platen along the carriage shaft. As the space motor rotates counterclockwise, the motor gear is driven rightward along the space rack, and as a result, the carriage is also driven rightward. The spacing mechanism is so designed that the carriage frame moves 0.8 inch (20.56 mm) when the space motor rotates once. ‘The motor also rotates the slit disk, and the slit passes through the slit sensor. The position of the carriage frame can be obtained by counting the number of slits detected by the slit sensor. Carriage shaft SMES KE Figure 4 3.2.3. Head-Gap Adjusting Mechanism (see figure 5) ‘The head-gap adjusting mechanism adjusts the gap between the platen and print head by changing the tilt angle of the carriage frame with the adjusting lever. When the adjusting lever is operated, the adjusting screw, which is interlocked with the lever via a ‘gear, rotates to change the tilt angle of the carriage frame around the carriage shaft. ‘The print head, mounted vertically opposite the adjusting screw on the carriage frame, moves toward or away from the platen with change in the carriage frame tilt angle. 3-18 Figure 5 3.2.4 Ribbon Feed Mechanism and Operation (see figure 6) ‘The ribbon feed mechanism feeds the ribbon in synchronization with the spacing operation. The mechanism is driven by the space motor. The ribbon feed mechanism consists of: a @ (a) Ribbon feed gear assembly (©) Ribbon gear (space motor) (©) Ribbon cartridge Ribbon cartridge A one-way-feed endless ribbon is used. Ink is replenished by the built-in ink tank in the ribbon cartridge so that clear printing is always assured. Ribbon feed operation ‘As the space motor rotates, the ribbon gear on the space motor shaft rotates to drive the drive gear in the ribbon cartridge via the ribbon feed gear assembly, thus feeding the ribbon. In bi-directional printing, the ribbon gear rotational direction reverses every time the carriage movement reverses. In this case, the gears in the ribbon feed gear assembly switch the rota- tional direction so as to feed the ribbon in a fixed direction. 3.2.5 Paper Feed Mechanism and Operation Paper feed is performed by rotating the platen and pin tractors, which are driven by the LF pulse motor. ‘The paper feed mechanism consists of: a (@) Pulse motor with gear (&) Reduction gear (c) Platen (@) Tractor feed ui (©) Pressure roller Paper feed operation (see figure 7) The paper feed pulse motor is mounted on the left side frame. Its rotation is transmitted to the platen through the reduction gear. Platen rotation is also transmitted through the idle gear to the tractor feed unit. The paper feed mechanism is so designed that when the pulse motor rotates 48 steps (360 degrees), paper is fed 0.17 inch (4.32 mm). ‘Tractor feed (option) @ Paper clamp mechanism (see figure 8) When the release lever is set to open, the release link moves backward, and the front and rear release links rotate counterclockwise. At the same time, the interlocked release shaft also rotates counterclockwise so that a gap is made between the pressure rollers and platen, allowing insertion of paper. ‘When the release lever is set to close, the release link moves forward, and the front and rear release links rotate clockwise. At the same time, the interlocked release shaft also rotates clockwise so that the pressure rollers are pushed against the platen by the front and rear pressure levers, allowing paper to be fed. 3.2.6 Paper-End Detection Mechanism (see figure 9) a @ Rear paper feed When paper is present in the printer, the paper prevents the near-end lever from falling into the groove of the paper-chute, and the paper-end sensor is on. When the printer runs out of paper, the near-end lever falls into the groove of the paper chute so that the rear part of the near- end lever turns off the paper-end sensor, and thus paper-end is detected. Paper-end is detected when the end of the remaining paper is approx- imately 1 inch (25.4 mm) from the printing position. Bottom paper feed ‘When paper is present in the printer, the paper prevents the bottom near-end lever from falling into the hole in the bottom paper guide. That is, the wedge on the bottom near-end lever pushes down the projection of the near-end lever, and the paper-end sensor is on. When the printer runs out of paper, the tip of the bottom near- end lever falls into the hole in the bottom paper guide so that the rear part of the near-end lever turns off the paper-end sensor, and thus paper-end is detected. Paper-end is detected when the end of the remaining paper is approximately 1 inch (25.4 mm) from the printing position. 3-26 Bottom near-end lever Paper (rear paper feed) Bottom near-end lever Paper {bottom paper feed) Figure 9 3-27 3.2.7 Semi-Automatic Sheet Feed (SASF) Mechanism and Function 1. Rear-feed type semi-automatic sheet feed (SASF) ML184 Turbo This mechanism has the function of automatically determining the position to start print the paper insertd after the paper-end indication has be made on the preceding paper, while printing is made in the single sheet mode. Operation procedures are as described below: (1) _ Inserta paper from behind the platen when the paper-end indication has been made. (2) Throw the column indicator lever toward you to set it to the OPEN position, then the SASF switch is turned on. 3) _Line-feed operation is started and the paper is fed until the paper-end indication disappears. (4) Subsequently the paper is fed by approx. 1.8 inches. (5) When restoring the column indicator lever to the original position, the paper is further fed by approx. 0.3 inch. Asthe result, the first line of printing is set to the position approx. 1 inch below the paper top. Column ingicator ever Column indicator lever ‘OPEN CLOSE SASF 5 t 5 Paper detection y x Line Feed TIE ed Feed until the paper-end indication disappears 3-28 2. Semi-automatic sheet feed (SASF) used together with Sheet Insert Guide (SIG) ML184 Turbo. This mechanism has a function to automatically determine the position to start printing on the paper inserted while printing is made in the single-sheet mode. Operation procedures are as described below. a) (2) 8) (4) Insert a paper from the front side along the SIG until reach the roller when the paper- end indication has been made. (The paper-end indication disappears when the paper is detected.) Throw the column indicator lever toward you to set it to the OPEN position, then the SASF switch is turned on. inches. Line-feed operation is started and the paper is fed by approx. 1. When restoring the column indicator lever to the original position, the paper is further fed by approx. 0.3 inch As the result the first line of printing is set to the position approx. 1 inch below the paper top. Column indicator lever Column indicator lever ‘OPEN CLOSE SASF y ee ° Paper detection PE A Ue \ Le poprox 02neh eed Approx. 1.1-inch feed 3-29 4, ASSEMBLY/DISASSEMBLY 4. ASSEMBLY/DISASSEMBLY 4.1. Precautions for Parts Replacement (1) Besure to remove the AC cord and interface cable before disassembly or reassembly: (a) Turn off the AC power switch, remove the AC input plug on the AC cord from the. AC receptacle, then remove the AC cord from the inlet on the printer side. {b) To reconnect the AC cord, first connect it to the inlet on the printer side, then connect the AC input plug to the AC receptacle. —— AC Receptacle a AC Input plug Intet Interface cable ee fe 2) Do not disassemble the printer as long as itis in good operating condition. G) Be careful not to remove parts unless necessary. Disassembly should be kept to a minimum. (4) Use only the specified maintenance tools. (5) _ Disassemble the printer in the specified order. Otherwise, parts may be damaged. (6) During disassembly temporarily attach small parts, such as screws and collars, in their original places so as not to lose them. 7) ICs such as the microprocessor, ROM, and RAM units are easily damaged by static electricity. Do not wear gloves that are apt to produce static electricity when handling printed-circuit boards. (8) Do not place the printed-circuit boards directly on the printer or the floor. 4.2. Maintenance Tools The tools table 4-1 are necessary for replacing printed-circuit boards and parts in the field. Different tools may be necessary for other maintenance procedure. Table 4-1 Maintenance Tools No. Too! Quantity Purpose a or 1 |2-t02.6-mm screws 2 Phillips screwehiver 1 |3-to 5mm screws 3. | Screwdriver No. 3-100 1 4 [Cutters No. SH 1 5_|Round Pliers No. 1 1 6 [Tension gauge 1 [Bog 7_ [Metal rod 1___|for head gap adjustment 6 |Volt-ohm-milliammeter 1 1 |() for head gap adjustment 9. | Thickness gauge set 1 |@) for adjusting gap between space rack and roller 4.3 Disassembly/Reassembly of Procedure This section explains the assembly replacement procedures according to the following disassembly system. ° Zo De [Parts Layout]

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