JUKI LK-1900B Series Engineer's Manual
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JUKI LK-1900B Series Engineer's Manual

Computer-controlled high-speed bartacking machine
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Computer-controlled High-speed Bartacking Machine
LK-1900B Series
(LK-1900B, LK-1901B, LK-1902B, LK-1903B, LK-1900BB, LK-1903BB,
LK-1900BN, LK-1901BN, LK-1902BN, LK-1903BN, LK-1900BNB,
LK-1903BNB)
ENGINEER'S MANUAL
40145045
No. E414-03

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Summary of Contents for JUKI LK-1900B Series

  • Page 1 Computer-controlled High-speed Bartacking Machine LK-1900B Series (LK-1900B, LK-1901B, LK-1902B, LK-1903B, LK-1900BB, LK-1903BB, LK-1900BN, LK-1901BN, LK-1902BN, LK-1903BN, LK-1900BNB, LK-1903BNB) ENGINEER’S MANUAL 40145045 No. E414-03...
  • Page 2 PREFACE This Engineer’s Manual is written for the technical personnel who are responsible for the service and maintenance of the machine. The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel factory contains operating instruction in detail. And this manual describes “Standard Adjust- ment”, “Adjustment Procedures”, “Results of Improper Adjustment”, and other important information which are not covered in the Instruction Manual.
  • Page 3 TO ENSURE SAFE USE OF YOUR SEWING MACHINE Adjustment : It means replacement of parts, disassembly, and repair assembly. For the sewing machine, automatic machine and ancillary devices (hereinafter collectively referred to as "machine"), it is inevitable to conduct sewing work near moving parts of the machine. This means that there is always a possibility of unintentionally coming in contact with the moving parts.
  • Page 4 JUKI assumes no responsibility for damages or personal injury or death resulting from the use of the machine for any application other than the intended one.
  • Page 5 1. Be sure to use JUKI genuine table and table stand in order to prevent accident that can result in personal injury or death. If it is inevitable to use a table and table stand which are not JUKI genuine ones, select the table and table stand which are able to support the machine weight and reaction force during operation.
  • Page 6 7. If the machine cannot be normally operated after repair or adjustment, immediately stop operation and contact JUKI or the distributor in your area for repair in order to prevent accident that can result in per- sonal injury or death.
  • Page 7 5. Be sure to use JUKI genuine parts when replacing any of the machine parts. JUKI assumes no responsibility for any accident caused by any part other than JUKI genuine one. In addition, in the event you cannot replace parts within the specified range, immediately stop the re- placement work and ask JUKI or distributor in your area for replacement of the parts.
  • Page 8 Replacement of parts 1. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure to ask an electrical technician of your company or JUKI or distributor in your area for replacement of electrical components. 2. When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident caused by un- familiarity with the machine or electrical-shock accident.
  • Page 9 2. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure to ask an electrical technician of your company or JUKI or distributor in your area for disassembly/as- sembly of electrical components. 3. When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident caused by unfa- miliarity with the machine or electrical-shock accident.
  • Page 10 PRECAUTIONS TO BE TAKEN SO AS TO USE THE LK-1900B SERIES MORE SAFELY 1. To avoid electrical shock hazards, neither open the cover of the electrical box for the mo- tor nor touch the components mounted inside the electrical box.
  • Page 11 21. In order to prevent possible accidents due to a ground fault, the earth cable should be properly grounded. 22. For the control box to be connected to the LK-1900B Series, use the exclusive control box for the LK-1900B Series.
  • Page 12 SAFETY DEVICES AND WARNING LABELS Warning label (Refer to The label gives the min- the warn- imum precautions to be ing label Warning label Thread take-up taken when operating on page i.) against pinching lever cover the sewing machine. This label warns This is a cover that fingers or for preventing...

  • Page 13: Table Of Contents

    CONTENTS 1. S pecifications ..........................1 2. C onfiguration ..........................5 (1) N ames of main unit ............................... 5 (2) N ames and explanation of switches on the operation panel ................... 6 3. S tandard adjustment value ......................8 (1) M ain shaft connection/disconnection ........................8 (2) R emoval of the main shaft motor and coupling ...................... 10 (3) Crank connecting rod connection/disconnection ....................... 12 (4) C rank balancer positioning ............................
  • Page 14 6. Check program ..........................84 (1) Starting the Check program ............................84 (2) Input signal check ..............................85 (3) X/Y motor origin adjustment ............................86 (4) Continuous operation ..............................87 (5) Main motor rpm check ............................... 88 (6) Output check ................................88 (7) Work clamp foot/thread trimming motor origin adjustment ...................

  • Page 15: Specifications

    18 Lubricating oil JUKI NEW Defrix oil No.2 (equivalent to ISO VG32) (Lubrication system) 19 Grease 1. Penetration No. 2 lithium grease, 2. Templex N3, 3. JUKI Grease A (Caution) 2. 20 Memory medium Memory of MAIN board (80 Kbyte) 21 Number of stitches that can be Max.
  • Page 16 18 Lubricating oil JUKI NEW Defrix oil No.2 (equivalent to ISO VG32) (Lubrication system) 19 Grease 1. Penetration No. 2 lithium grease, 2. Templex N3, 3. JUKI Grease A (Caution) 2. 20 Memory medium Memory of MAIN board (80 Kbyte) 21 Number of stitches that can be Max.
  • Page 17 18 Lubricating oil JUKI NEW Defrix oil No.2 (equivalent to ISO VG32) (Lubrication system) 19 Grease 1. Penetration No. 2 lithium grease, 2. Templex N3, 3. JUKI Grease A (Caution) 2. 20 Memory medium Memory of MAIN board (80 Kbyte) 21 Number of stitches that can be Max.
  • Page 18 18 Lubricating oil JUKI NEW Defrix oil No.2 (equivalent to ISO VG32) (Lubrication system) 19 Grease 1. Penetration No. 2 lithium grease, 2. Templex N3, 3. JUKI Grease A (Caution) 2. 20 Memory medium Memory of MAIN board (80 Kbyte) 21 Number of stitches that can be Max.

  • Page 19: Configuration

    2 . Configuration ( 1) Names of main unit ❸ ❶ ❹ ❷ ❺ ❾ ❼ ❻ ❽ ❶ Sewing machine head ❷ Work clamp foot ❸ Thread stand ❹ Operation panel ❺ Power switch ❻ Control box ❼ Pedal switch ❽ Power switch (EU Type) ❾...

  • Page 20: N Ames And Explanation Of Switches On The Operation Panel

    ( 2) Names and explanation of switches on the operation panel 2-1 Standard Application ❻ ❼ ❶ ❾ ❽ ❷ ❸ ❹ ❺ NAME FUNCTION NAME FUNCTION ❽ EDIT key This key is used to display the ❶ LCD display Various data such as pattern edit screen, to select the item or No., shape, etc.
  • Page 21 2-2 NFC Application ❽ ❻ ❼ ❶ ⓯ ❾ ❷ ❸ ❹ ❺ NAME FUNCTION NAME FUNCTION ❶ LCD display Various data such as pattern ❽ EDIT key This key is used to display No., shape, etc. are dis- the edit screen, to select the item or to display the detail played.

  • Page 22: Standard Adjustment Value

    3. Standard adjustment value (1) Main shaft connection/disconnection WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling 1. Loosen the setscrew ❷ of the main shaft counterbalance ❶ through the screwdriver hole A, then re- move the taper screw ❸...
  • Page 23 Procedures of assembling 1. Insert the crank rod  , balancer  , hand pulley gear A  , bobbin winder driver wheel  , and the main shaft counterbalance ❶ in the main shaft ❼ in this order, and mount the assembly on the frame. 2. Insert the taper screw ❸ in the taper hole of the main shaft, and tighten it. Then, tighten the setscrew ❷ to fix the main shaft counterbalance ❶ . 3. Lightly press the main shaft counterbalance ❶ in the direction of the arrow D and also the middle metal  in the direction of the arrow E. Then, tighten the two setscrews ❺...

  • Page 24: Removal Of The Main Shaft Motor And Coupling

    (2) Removal of the main shaft motor and coupling WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling 1. Removal of the main shaft motor together with coupling Loosen the two setscrews ❺...
  • Page 25 Procedures of assembling 1. Mounting of the main shaft motor together with the coupling 1) Tighten the four motor setscrews ❹ . Then, tighten the two setscrews ❺ on the main shaft side of the coupling ❷ . 2) The cords of the main shaft motor ❸ should be positioned in the lateral direction. 2. Incorporation of the coupling in the main shaft motor 1) Provide a clearance of 0.5 mm between the coupling ❷...

  • Page 26: Crank Connecting Rod Connection/Disconnection

    (3) Crank connecting rod connection/disconnection WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling 1. Remove the two setscrews ❶ and four setscrews  . Then take out the lengthwise feed motor ❷ and the crosswise feed motor mounting plate ❸...
  • Page 27 Procedures of assembling 1. Mount the main shaft ❼ according to "3.-(1) Main shaft connection/disconnection." Assemble the crank rod unit  . 2. Mount the frame while the oscillator  and the oscillator arm  is passed through the oscillator shaft ❻ . 3.

  • Page 28: Crank Balancer Positioning

    (4) Crank balancer positioning WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment [Rotating direction] When the needle bar ❸ lowers and the clearance between the needle bar connecting ❹ and the needle bar bushing, lower ❺...
  • Page 29 Adjustment procedures Results of Improper adjustment If the main shaft eccentric cam ❽ is not fixed, this adjustment If the angle for fixing the crank should be carried out after defining its position and fixing it. balancer ❻ is inadequate, vibra- 1. Loosen the two setscrews ❼ of the crank balancer ❻ . tion of sewing machine operation 2. Using the two setscrews ❷ , remove the crank rod cover ❶ . will be intensified.

  • Page 30: Oscillator Gear Positioning

    (6) Oscillator gear positioning WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment 1. When the oscillator is lightly swung by a finger in the direction of the arrow, the oscillator ❷ is fixed in the center position of swinging. No. 2 screw No. 1 screw B: 8.5 to 9.0 mm (7) Adjustment of hook oil amount WARNING :...
  • Page 31 Adjustment procedures Results of Improper adjustment 1. Loosen the two setscrews ❺ and increase the backlash of the If the position for fixing the oscil- lower shaft gear ❸ . lator ❷ is inadequate, this can (Caution) If the lower shaft gear ❸ has insufficient backlash, also be a cause of the frictional the oscillator ❷...

  • Page 32: Shuttle Connection/Disconnection And Oil Wick Piping

    (8) Shuttle connection/disconnection and oil wick piping WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling 1. Loosen the four setscrews ❶ . 2.
  • Page 33 Procedures of assembling 1. Pass the two lubrication pipes ❻ and the oil drain pipe ❼ through the frame, and mount the shuttle  . 2. Hold the lubrication pipe ❻ with the lubrication pipe holder plate  and fix it with the setscrew ❶ . At that time, make sure not to let the lubrication pipe ❻ come in contact with the thread trimmer connec- tor rod.

  • Page 34: 10) H Ook Adjustment

    (10) Hook adjustment WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment For DP × 17 For DP × 5 0.05 to 0.1 mm –...
  • Page 35 Adjustment procedures Results of Improper adjustment 1. Turn the pulley by hand. When needle bar ❶ has gone up, adjust so that lower marker line ❷ engraved on the needle bar aligns with the bottom end of the needle bar bushing lower ❸ . 2. Loosen setscrew ❹ in the driver ❾ . Open inner hook pressers ❺...

  • Page 36: 11) T Hread Trimmer Cam Position Adjustment And Connection/Disconnection

    (11) Thread trimmer cam position adjustment and connection/disconnection WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling 1. Loosen the two setscrews ❷ of the thread trimmer cam (cam hereafter) ❶ . 2.
  • Page 37 Procedures of assembling 1. Apply a proper amount of grease (JUKI Grease A) to the grooved cam block of the cam ❶ , the periph- eral cam block, and the rollers of the work clamp foot lifter link ❽ and the thread trimmer link ❾ . Refer to "10.-(4) Parts to which grease is applied". 2. While the cam ❶ is being inserted in the shaft of the work clamp foot lifting motor ❻ , mount the assem- bly on the sewing machine frame and tighten the four setscrews ❺...

  • Page 38: 13) A Djustment Of The Height Of The Work Clamp Foot

    (13) Adjustment of the height of the work clamp foot WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches. Standard adjustment Max.
  • Page 39 Adjustment procedures Results of Improper adjustment 1. With the machine in stop mode, remove six setscrews ❶ of the top cover, and take off top cover ❷ . 2. Apply L-shaped wrench ❸ to socket bolt ❺ of clamp ❹ , and loosen the socket bolt. 3. Push down L-shaped wrench ❸ to increase the lift of the work clamp hoot, or pull it up to decrease the lift.

  • Page 40: 15) A Djustment Of The Moving Knife And Counter Knife Position

    (15) Adjustment of the moving knife and counter knife position WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Counter knife position : The clearance between the counter knife ❺ and the needle hole guide ❻ is 0.5 mm. Moving knife position : Before thread trimmer operation (standby state), the distance from the throat plate ❹...
  • Page 41 Adjustment procedures Results of Improper adjustment 1. Counter knife position If the clearance is less than 0.5 Loosen the counter knife setscrew ❶ to adjust the position. mm, thread may be cut by the 2. Moving knife position counter knife ❺ blade when the Loosen the screw ❷ to adjust the position. thread is pulled with the moving knife ❽...

  • Page 42: 17) I Nclination Of The Blade Point Of The Counter Knife

    (17) Inclination of the blade point of the counter knife WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment To cut the two threads (needle thread and, bobbin thread) uniformly, the blade face of the counter knife ❶ is made to have an inclination of 0.2 mm. ❶...
  • Page 43 Adjustment procedures Results of Improper adjustment 1. If the thread on Side B cannot be cut, grind Side C. If the thread When less than 0.2 mm: on Side C cannot be cut, grind Side B. Thread on Side C cannot be (Caution) When grinding the side, make the angle more acuter cut.

  • Page 44: 19) S Econd Thread Tension Connection/Disconnection

    (19) Second thread tension connection/disconnection WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling/assembling 1. Loosen the setscrew ❷ . 2. Remove the two setscrew ❹ . 3. Move the AT link unit (front) ❸...
  • Page 45 Cautions for disassembly and reassembly 1. When pulling out the second thread tension ❶ , confirm that the pin block ❺ of the AT link unit (front) ❸ has been displaced from the hole of the thread tension releasing pin ❻ . If this action is taken forcedly with the pin block ❺ left connected, this can be a cause of breaking the second thread tension ❶ . 2.

  • Page 46: 20) A T Unit Connection/Disconnection

    (20) AT unit connection/disconnection WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling/assembling 1. Remove the setscrew ❷ of the AT link unit (front) ❶ and take out the second thread tension ❸ . (Refer to "3.-(19) Second thread tension connection/disconnection".) 2.
  • Page 47 Cautions for disassembly and reassembly 1. When incorporating the AT solenoid unit  , the solenoid cable  should be laid beside the AT sole- noid. If this solenoid cable  is positioned in the vicinity of the AT link unit (rear) ❹ , this will be a cause of AT solenoid malfunction. 2. The center-to-center distance is 358 mm between the AT joint block ❽ of the AT connector rod  . In cases of disassembly and reassembly of the AT joint block ❽ , the center-to-center distance must be secured correctly. In addition, the parallelism of the two front and rear joint block ❽ must also be se- cured, without fail. If the correct distance and parallelism are lost, this can be a cause of AT malfunction and normal sewing tension cannot be obtained. 3. Upon the completion of all reassembly work, confirm that there is a close contact between the thrust collar  and the AT solenoid unit  . If any clearance is perceived, loosen the two setscrews ❾...

  • Page 48: 21) P Osition Of The Mechanical Origin

    (21) Position of the mechanical origin WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment A : 147mm (LK-1900B, 1902B, 1900BN, 1902BN) : 146mm (LK-1901B, 1903B, 1901BN, 1903BN) B : 61mm (LK-1900B, 1902B, 1900BN, 1902BN) : 62mm (LK-1901B, 1903B, 1901BN, 1903BN) C : 74mm (LK-1900B, 1902B, 1900BN, 1902BN)
  • Page 49 Adjustment procedures Results of Improper adjustment 1. The position of the mechanical origin is shown in the illustration The maximum area cannot be at left. secured. 2. In the horizontal direction, the needle hole center ❶ <center of the horizontal feed fulcrum shaft ❷ > and the center of the verti- cal feed fulcrum shaft ❸ are aligned on a straight line. 3. Adjustments should be carried out according to "3.-(22) Adjust- ment of the Y origin" and "3.-(23) Adjustment of the X origin".

  • Page 50: 23) A Djustment Of The X Origin

    (23) Adjustment of the X origin WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches. Standard adjustment ❻...
  • Page 51 Adjustment procedures Results of Improper adjustment 1. Select the check program 02. Refer to "6.-(3) X/Y motor origin adjustment". 2. Adjust the origin to be the dimensions that were described in "3.- (21) Position of the mechanical origin" by the operation panel. Adjustment procedures Results of Improper adjustment 1. Loosen the screw ❶ to adjust the clearance between the wiper If Distance A is too small, the ❷ and the needle so that this clearance attains 1.5 mm or more. work clamp foot may tread on 2.

  • Page 52: ( 25) A Djustment Of The Wiper Spring (Lk-1903B, 1903Bn)

    (25) Adjustment of the wiper spring (LK-1903B, 1903BN) WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment (26) Adjustment of the position of the X feed motor and the Y feed motor (Adjustment of the backlash of the driving gear) WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the...
  • Page 53 Adjustment procedures Results of Improper adjustment After thread cutting, the wiper spring ❶ is used to hold the needle thread with the aid of the wiper ❷ . Adjust the wiper spring ❶ and fix it with the setscrew ❸ so that the intensity of the spring force be- comes 20 to 30g (somewhat stronger than that of the bobbin thread that is protruded from the bobbin case).

  • Page 54: 27) I Nstalling The Feed Plate Support Plate

    (27) Installing the feed plate support plate WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Machine (28) Installation of the feeder bar rear cover WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine.
  • Page 55 Adjustment procedures Results of Improper adjustment 1. Loosen the Y feed arm ❹ setscrew ❶ . The feeding load becomes too 2. Push the Y feed shaft ❸ in the direction of the arrow A ⇒ . much and this can be a cause of 3.

  • Page 56: 29) A Djustment Of The Bobbin Winder Driving Wheel Position

    (29) Adjustment of the bobbin winder driving wheel position WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment The distance is 10 mm between the measuring plane B of the bobbin winder driving wheel ❶ and the cover mounting plane A of the sewing machine frame ❸...
  • Page 57 Adjustment procedures Results of Improper adjustment 1. Adjust the position of the bobbin winder driving wheel ❶ and fix it If the distance of 10 mm is in- with two setscrews ❷ . sufficient, rubber ring wear may occur in the bobbin winder unit. In addition, the bearing life may be reduced in the bobbin winder unit.

  • Page 58: ( 31) A Djustment Of The Shuttle Upper Spring Position ( Except For Lk-1900B-Bs, 1900B-Bf, 1903B-Bs, 1900Bn-Bs, 1900Bn-Bf And 1903Bn-Bs)

    (31) Adjustment of the shuttle upper spring position (Except for LK-1900B-BS, 1900B-BF, 1903B-BS, 1900BN-BS, 1900BN-BF and 1903BN-BS) WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling For the right and left positions, the needle center is made to coincide with the center of the groove width C.
  • Page 59 Adjustment procedures Results of Improper adjustment 1. Remove the feed bracket, feed plate, and the throat plate. Make If there is a front and rear dis- adjustments with the screw ❶ . placement or a right and left dis- placement, needle thread biting (Caution) The right and left positions can also change during may occur into the hook.

  • Page 60: 33) S Hape Of The Inner Hook Presser

    (33) Shape of the inner hook presser WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment If wear seems to be too much around the pointed tip of the inner hook, release the inner hook presser ❶...
  • Page 61 Adjustment procedures Results of Improper adjustment 1. If the dimensions of 0.3 x 8 mm are not secured, retouching is required with the aid of an oil stone. Dimension A Part No. Name of part Remarks (mm) 14103253 Inner hook presser A Conforming to Specifications F and M as standard 14103352 Inner hook presser B Conforming to Specifications S as standard 14103659...

  • Page 62: 35) N Eedle Thread Clamp Device Connection/Disconnection

    (35) Needle thread clamp device connection/disconnection WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches. Procedures of disassembling 1.
  • Page 63 Procedures of assembling and adjustment procedures 1. Push the needle thread clamp device ❸ in the direction of A and fix it with the three (LK-1900BB, 1903BB, 1900BNB, 1903BNB : four) setscrews ❷ . Tighten the hinge screw ❶ . 2.

  • Page 64: 36) A Djustment Of The Needle Thread Clamp Reference Position

    (36) Adjustment of the needle thread clamp reference position WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches. Standard adjustment When the needle thread clamp release plate ❹...
  • Page 65 Adjustment procedures Results of Improper adjustment 1. Attain the check program 07. [LK-1900BB, 1900BNB] 2. Tread on the pedal for needle thread clamp ❸ origin retrieval. If a clearance A between the needle thread clamp release 3. Press EDIT key ❽...

  • Page 66: 37) A Djustment Of The Needle Thread Clamp Notch

    (37) Adjustment of the needle thread clamp notch WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment 1. Needle thread clamp notch R position 2.
  • Page 67 Adjustment procedures Results of Improper adjustment 1. Needle thread clamp notch R adjustment If the distance is too long between the needle 1) Loosen the two setscrews ❶ . thread clamp ❹ and the needle thread clamp base 2) Push the needle thread clamp link (asm.) ❷ ❺...

  • Page 68: Assembling The Shorter Thread Remaining Unit

    (38) Assembling the shorter thread remaining unit WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Procedures of disassembling ❶ ❷ ❸ ❼ ❺ ❻ ❽ [Table 1] Part No.
  • Page 69 Adjustment procedures Results of Improper adjustment [Counter knife] The position of the moving knife 1. Fix the counter knife ❹ to the throat plate ❻ with two setscrews ❼ is decided by a countersink ❺ . screw, but when the moving (Caution) Make sure that the hole of counter ❹...

  • Page 70: 40) A Ssembling The Suction Pipe

    (40) Assembling the suction pipe WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches. Standard adjustment ❸ Waiting (initial) position of cylinder ❷...
  • Page 71 Adjustment procedures Results of Improper adjustment 1. Move the suction cylinder ❶ to most advanced position. (If the air When the position of the suction is supplied, lock the solenoid valve hook manually in most ad- pipe ❹ is inappropriate, suction vanced position.) of an end thread after operat- 2.

  • Page 72: ( 41) A Djustment Of The Shuttle Upper Spring Position (Lk-1903B-Bs, 1900B-Bs, 1900B-Bf, 1903Bn-Bs, 1900Bn-Bs, 1900Bn-Bf) And The Lower Thread Holder Position (Lk-1903Bn-Bs)

    (41) Adjustment of the shuttle upper spring position (LK-1903B-BS, 1900B- BS, 1900B-BF, 1903BN-BS, 1900BN-BS, 1900BN-BF) and the lower thread holder position (LK-1903B-BS, 1903BN-BS) WARNING : As the work is performed while the power is ON, never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches.
  • Page 73 Adjustment procedures Results of Improper adjustment 1. Remove the feed bracket, the feed plate, and the throat plate. Ad- If there is a front and rear dis- just the positioning of shuttle upper spring ❷ with two setscrews placement or a right and left dis- ❶...

  • Page 74: 42) B Obbin Case With An Idling Prevention Spring

    Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. The LK-1900B Series use bobbin cases with an idling prevention springs. Adjust the tension of the an idling prevention spring as follows: If the bobbin races Increase the spring tension.

  • Page 75: D Escription Of The Functions

    4. Descruption of the functions (1) To use the functions of the serviceperson level By pressing button on the sewing screen for three seconds, a mode screen for the service level 1 will be displayed; for six seconds, a mode screen for the service level 2 will be displayed. Pressing restores the sewing screen.

  • Page 76: Contrast Adjustment

    (2) Contrast adjustment It is possible to adjust the contrast of panel display in five steps. 1) Calling the contrast adjustment screen ❼ Select the contrast adjustment from the menu on the mode screen and EDIT key ❽ is pressed, the contrast adjustment screen A is displayed.

  • Page 77: K Ey Lock Setting

    (4) Key look setting In the case of setting the key-lock function, operation of the key for changing the data can be disabled. 1) Starting the key lock screen ❻ Turn ON the DIPSW1-1 of MAIN board while the power is OFF, and turn ON the power. When MODE key ❹...
  • Page 78 Items that can be key lock is as follows. Items that can be the key lock Display Items that can be the key lock Pattern No. Item data (It can be individual setting.) Direct pattern data (It can be individual set- ting.) Memory switch 1 (It can be individual setting.) Counter...

  • Page 79: H Ow To Check The Version Infoemation

    4) Selecting the individual key lock item ❼ Item data, direct pattern data and memory switch data are possible to perform the key lock setting indi- vidually for detailed item of each data. In the case the item data, direct pattern data and memory switch data are selected to be the items for ❽...

  • Page 80: How To Use The Communication Function (Communication Functions Other Than Nfc)

    Vector form data VD00 XXX .VDT Data on needle entry points created with the PM-1. The data form is commonly used among JUKI sewing machine. Memory switch data * LK00 XXX .MSW Memory switch (Level 1/Level 2) data All sewing machine data * LK00XXX .MSP...
  • Page 81 3) Selecting the communication direction ❻ ❼ Press ITEM SELECT key ❻ to display picto- graph A which shows the communication direction selection. Press DATA CHANGE key ❼ to select the ❽ communication direction. Communication direction that can be selected are as follows.
  • Page 82 [In the case that the type of communication is pro- gram data.] When READY key ❷ is pressed, progress of rewriting is displayed. When rewriting of data is completed, turn OFF the power. When turning ON the power again, program after rewriting is performed.
  • Page 83 (Supplement) Short-cut for program rewrite 1) Save a piece of MAIN program in a USB memory and connect it to the panel. 2) The rewrite of the MAIN program starts when the power is turned on while P4 key is pressed. (Caution) 1.

  • Page 84: Registering An Nfc Terminal

    (7) Registering an NFC terminal You can put restrictions so that only a registered NFC terminal can use the NFC function. ① Selecting the Enabled or Disabled state of a restriction in using an NFC terminal ❶ ❺ 1. Hold down the ❾...
  • Page 85 3. Move an NFC terminal to register close to a panel. When you succeed in communication, the input request screen for an NFC ter- minal registered name is displayed. 4. Press the ❻ to display the edit screen for an NFC registered name. ❻...
  • Page 86 ③ Changing the registered name of an NFC terminal 1. Press the ❶ on the NFC terminal registration screen to select the registered name of an NFC terminal to change, and press the ❺ to display the NFC registration name edit screen. For an operating method, refer to 4.-(7)- ②...

  • Page 87: Pattern Selection From The Usb Thumb Drive

    (8) Pattern selection from the USB thumb drive It is possible to be sewing by selecting the vector data stored in the media that is connected to the USB thumb drive. In addition, the pattern that is sewn can be backed up to sewing machine body until it is changed to other patterns.

  • Page 88: Memory Switches

    5. Memory switches (1) Memory switch start and change ❻ 1. To display the mode screen (service level 2) When MODE key ❹ is continuously pressed for 6 seconds, "15 memory switch 2" is displayed on the mode screen. ❽ 2.

  • Page 89: Table Of Memory Switch Functions

    (2) Table of memory switch functions Various operations of the sewing machine can be set by programming the memory switch. The initial setting values at the time of shipment differ with models. (Level 1) Function Setting range Initial value Remarks U001 Max.
  • Page 90 Function Setting range Initial value Remarks U026 Height of work clamp foot at the time of 2-step stroke 50 to 90 Height is lowered when the set value is increased. U030 Selection of base point of pattern enlargement/reduction : Origin : Sewing start point U031 Sewing machine operation can be stopped with panel key (clear key).
  • Page 91 Function Setting range Initial value Remarks U048 Route of origin return by means of clear key can be selected. This function is used when straight line : Straight line return : Reverse return of pattern return from the midway of pattern to the start of sewing is not possible.
  • Page 92 Function Setting range Initial value Remarks U239 Choice of language : Not yet selected (display in English) : Japanese : English : Chinese (simplified characters) : Chinese (traditional Chinese) : Spanish : Italian : French : German : Portuguese : Turkish : Vietnamese : Korean : Indonesian...
  • Page 93 (Level 2) Function Setting range Initial value Remarks K021 Standard pedal, work clamp foot switch position 10 to 250 When the setting value is increased, the amount of pedal tread becomes larger. K022 Standard pedal, 2-step stroke switch position 10 to 250 When the setting value is increased, the amount of pedal tread becomes larger.
  • Page 94 Function Setting range Initial value Remarks K059 Moving limit range in -Y direction (front side) -20 to 10 mm In the state of shipment, no work clamp foot configura- (1903 : -3) tion is considered. K060 Jump feed speed of XY 100 to 4000 2000 (Setting possible in the unit of 10 pps)
  • Page 95 Function Setting range Initial value Remarks K099 Y moving amount of material feed of shorter thread re- -3.0 to 3.0 LK-1900BB : 0.6 Only LK-1900BB and 1903 maining thread trimmer BB are displayed. LK-1903BB : 0.9 Y moving amount from the last stitch before shorter thread remaining thread trimmer Set up in "+"...

  • Page 96: Supplement For The Memory Switch

    (3) Supplement for the memory switch ① Bird’s nest short tail function timing chart (summary) (LK-1900B-B, 1903BN-B) Thread trimmer Presser foot thread trimming motor Memory switch_K98=50 Thread spreading Feed motor Presser foot goed up Thread clamp motor Memory switch K100 : X travel amount Memory switch K99 : Y travel amount Needle thread end is trimmed Needle thread end is released...
  • Page 97 ② For permission of “Direct type and No.” of K103 direct pattern Select a direct pattern and display S007/S002 operating △▽ keys ❻ . Select “Pattern type and No.” operating +/- keys ❼ . (Caution) If "Pattern type • No." is changed, other items (enlargement/reduction scale, thread ten- sion, etc.) will be initialized.

  • Page 98: Check Program

    6. Check program (1) Starting the Check program ❻ 1) How to select the check items When MODE key ❹ is held pressed for three seconds in the state that SET READY LED  goes out, buzzer will sound and "13 Check program" is displayed on the mode screen.

  • Page 99: Input Signal Check

    (2) Input signal check It is possible to check the input conditions of the pedal switches and various sensors etc. ❻ 1) Selecting the sensor item Press ITEM SELECT key ❻ to select the sensor to perform the confirmation. (Sensor items that are displayed on the left side of screen is changed over.) ❾...

  • Page 100: X/Y Motor Origin Adjustment

    (3) X/Y motor origin adjustment Inching operation of X/Y motor, origin retrieval operation, and Positioning of X/Y encoder are performed. ❻ ❼ 1) When ITEM SELECT key ❻ is pressed, X-motor is driven in 0.1 mm steps. Position information of the X-motor encoder is displayed in section A.

  • Page 101: Continuous Operation

    (4) Continuous operation After the setting of continuous operation, the condition moves to the continuous operation mode. Turn OFF the power to close the continuous operation mode. ❻ ❼ 1) Press READY key ❷ to bring the aging in the enabled state. Then, display the check pro- gram screen.

  • Page 102: Main Motor Rpm Check

    (5) Main motor rpm check Used to set up the sewing machine rpm number. Only the main motor is driven at the preset rpm number and the actually measured rpm number is displayed. ❼ 1) Press DATA CHANGE key ❼ to enter the preset rpm number.

  • Page 103: Work Clamp Foot/Thread Trimming Motor Origin Adjustment

    (7) Work clamp foot/thread trimming motor origin adjustment Inching operation of the work clamp foot/thread trimming motor, operation of origin retrieval, and the status of work clamp foot origin sensor and thread trimming sensor are displayed. ❻ ❼ 1) Carry out origin retrieval of work clamp foot/thread trimming motor by the start switch.

  • Page 104: Needle Thread Clamp Motor Origin Adjustment

    (8) Needle thread clamp motor origin adjustment Inching operation of the needle thread clamp motor, operation of origin retrieval, and the status of needle thread clamp encoder are displayed, and origin retrieval of the needle thread clamp motor is carried out. ❼...

  • Page 105: Miscellaneous

    7. Miscellaneous (1) Various printed wiring boards 1) FLT-T board (asm.) This board is the power supply filter board for 3-phase specification. ❸ ❶ ❷ No. Connector and fuse name Connection destination, name Remarks ❶ CN1 Power switch Power inlet ❷ CN16 SDC board Power outlet ❸ F1, F2, F3 20A time-lag fuse Non-removable 2) FLT-CE board (asm.) This board is the power supply filter board for Europe. Perform the noise reduction. ❶ ❸...
  • Page 106 3) MAIN board (asm.)_Standard specification (MC-670) Overall controls are carried out, such as stepping motor drive of 4-axes (X-axis, Y-axis, work clamp foot/ thread trimming and needle thread clamp), control of active tension, storing of memory switch, etc. ❷ ❸ ❹ ❾ ❼ ❻ ❺ ❶ ❽ No. Connector and Connection destination, name Remarks other name ❶ CN30 For machine head INT board ❷ CN31 SDC power supply 2 ❸ CN32 Not installed For CPU debugging ❹ CN33 ❺ CN34 Operation panel ❻ CN35 Not installed Not installed ❼...
  • Page 107 3) MAIN board (asm.)_LK-1900BB, 1903BB (MC-672)/LK-1900BNB, 1903BNB (MC-672N) This board has been added connectors (CN52 to CN55) of air equipment to the MAIN board of standard model. ❷ ❸ ❾ ❹ ❽ ❻ ❺ ❶ ❼ Connector and Connection destination, name Remarks other name ❶ CN30 For machine head INT board ❷ CN31 SDC power supply 2 ❸ CN32 Not installed For CPU debugging ❹ CN33 ❺ CN34 Operation panel ❻ CN36 BR interface ❼...
  • Page 108 4) SDC board (asm.) Perform the generation of power supply and the control of sewing machine main motor in response to an instruction from MAIN board. ❾ ❷ ❶ ❼ ❺ ❹ ❽ ❸ ❻ Connector and Connection destination, name Remarks other name ❶ CN10 Not used ❷ CN11 MAIN board signal ❸ CN12 Not used ❹ CN13 MAIN board power supply 1 ❺ CN14 Jumper connector For 100V switching (Caution) ❻ CN15 Main motor encoder ❼...
  • Page 109 5) INT board (asm.) The board is attached to the rear side of machine head, relay connector of various sensors signal and EEPROM with machine head specification data is installed. ❹ ❺ ❸ ❻ ❷ ❼ ❶ Connection destination, name Remarks ❶ CN70 For MAIN board ❷ CN71 Work clamp foot origin sensor ❸ CN72 Thread trimming position sensor ❹ CN73 Machine head safety switch ❺ CN75 X-axis motor encoder ❻ CN76 Y-axis motor encoder ❼ CN77 Needle thread clamp motor encoder – 95 –...

  • Page 110: T Able Of Bar-Tacking Standard Pattern Specifications

    ( 2) Table of bar-tacking standard pattern specifications 1900B/BN 1901B/BN 1902B/BN Length- Cross- Number of Pattern S, F, H, W, B S, H wise wise stitches 1(51) Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking Large size bar-tacking...

  • Page 111: Table Of Standard Patterns

    (3) Table of standard patterns Sewing Sewing size (mm) size (mm) (Caution) 2 (Caution) 2 Stitch diagram Work clamp Stitch diagram Work clamp foot No. foot No. 2.0 16 28 20 4.0 (51) 2.0 10 36 20 4.0 2.5 16 42 20 4.0 3.0 24 56 20 4.0...
  • Page 112 Sewing Sewing size (mm) size (mm) (Caution) 2 (Caution) 2 Stitch diagram Work clamp Stitch diagram Work clamp foot No. foot No. ø12 (Caution) 1. Sewing size shows the dimensions when the scale rate is 100%. 2. For work clamp foot No., refer to "9.- (7) Table of the work clamp foot"...

  • Page 113: Sub-Class Information

    8. Sub-class information ( 1) Models classified by button sizes (LK-1903B, 1903BN) Model name LK-1903B-301 LK-1903B-302 Optional Button size classification For Extra-small buttons For small buttons For medium-sized For large buttons (accessories) buttons Outside diameter that can be adjusted ø8 to ø9 ø9 to ø10 ø10 to ø15 ø10 to ø20 ø10 to ø20 ø15 to ø32...

  • Page 114: T Able Of Standard Patterns (Lk-1903B)

    ( 2) Table of Standard Patterns (LK-1903B, 1903BN) The number of stitches and the standard sewing lengths X and Y are as specified in the table below. Sewing Standard Standard Sewing Standard Standard Pattern Stitch Pattern Stitch thread length length thread length length shape shape (pcs.) X (mm) Y (mm) (pcs.)

  • Page 115: Optional Features

    9. Optional features (1) Table of optional parts Name of parts Type Part No. Remarks Feed plate blank Without knurl / processed 14120109 Sewing area lengthwise 20 × crosswise 40 With knurl / processed 14120307 Sewing area lengthwise 20 × crosswise 40 t = 1.2 Without knurl / stainless steel 14120505...
  • Page 116 Name of parts Type Part No. Remarks Finger guard (1) A=56.5 B=64 13533104 A=59 B=74 13548300 For large size bar-tacking Finger guard (2) A=66.5 B=43 13573407 For length- wise bar-tacking Finger guard (3) A=21.5 B=35.5 14120000 For specially ordered work clamp foot SM8040302TP Work clamp foot blank...

  • Page 117: Connection Of The Optional Pedal

    (2) Connection of the optional pedal ① PK-57 pedal DANGER : To prevent personal injuries caused by electric shock hazards or abrupt start of the sewing ma- chine, carry out the work after turning OFF the power switch and a lapse of 5 minutes or more. To prevent accidents caused by unaccustomed work or electric shock, request the electric expert or engineer of our dealers when adjusting the electrical components.
  • Page 118 5） Set the memory switches as follows. Select the framed items. U019 Selection of pedal : Standard pedal : Standard pedal (2-step stroke) : Optional pedal : Optional pedal (2-step stroke) U020 Slection of start pedal : Standard pedal　　　　　: Optional pedal U024 Optional pedal 1 operation : OFF when depressing pedal again　　　　　: OFF when detaching from pedal...
  • Page 119 ② 2-Pedal unit 1） Set the memory switches as follows. Select the framed items. U019 Selection of pedal : Standard pedal : Standard pedal (2-step stroke) : Option pedal : Option pedal (2-step stroke) U020 Selection of Start pedal : Standard pedal　　　　　: Option pedal U024 Optional pedal 1 operation : OFF when depressing pedal again　　　　　: OFF when detaching pedal...
  • Page 120 ③ 2-Pedal unit 1） Set the memory switches as follows. Select the framed items. U019 Selection of pedal Standard pedal : Standard pedal (2-step stroke) : Optional pedal : Optional pedal (2-step stroke) U020 Selection of start pedal : Standard pedal　　　　　: Optional pedal U024 Ootional pedal 1 operation : OFF when depressing pedal again　　　　　: OFF when detaching from pedal...

  • Page 121: Connection Of The Magnet Wiper (Cannot Be Connected With Lk-1901B)

    (3) Connection of the magnet wiper (cannot be connected with LK-1901B) Connect the magnet wiper connector to the MAIN board CN47 (2P). 1） Set the memory switches as follows. Select the framed items. U051 Wiper operation method can be selected : Without wiper at the time of thread trimming on the way : With wiper at the time of thread trimming on the way ①...

  • Page 122: Connection Of The Marking Light

    (5) Connection of the marking light The sewing machine has three output ports to which three 5-v marking lights can be connected. 0.5A at maximum is applicable per marking light, and 2.5 AV at maximum is applicable with 3 marking lights in total.

  • Page 123: Connection Of The Needle Cooler (Turns On While Machine Is Running)

    (6) Connection of the needle cooler (turns ON while machine is running) Connect the needle cooler solenoid valve to the MAIN board CN36 (8P). It is originally for BR35 connector. The needle cooler cannot be used with BR35. 1） Wiring diagram MAIN PWB CN36 Diode for protection against reverse connection...

  • Page 124: Table Of The Work Clamp Foot

    (7) Table of the work clamp foot Work clamp 13518659 (asm.) 13548557 (asm.) 13542964 (asm.) foot Feed plate 14116107 14116404 14116800 14116305 14116206 (With knurl) (Without knurl) (Without knurl) (With knurl) (With knurl) 21.2 11.4 Sewing spec- S, B F, B ification * Finger guard 13533104...
  • Page 125 Work clamp 13548151(asm.) 13542451 (asm.) 13571955 (asm.) 13561360 (asm.) foot Feed plate 13548003 13554803 14116602 14116503 14116909 14116701 (With knurl) (With knurl) (With knurl) (Without knurl) (Without knurl) (Without knurl) 27.4 37.3 Sewing spec- S, B H / W S, B F, B ification * Finger guard...

  • Page 126: Maintenance

    10. Maintenance (1) Replacing the fuse DANGER : 1. To avoid electrical shock hazards, turn OFF the power and open the control box cover after about five minutes have passed. 2. Open the control box cover after turning OFF the power without fail. Then, replace with a new fuse with the specified capacity.

  • Page 127: Greasing Parts

    ❷ Unirex N3 (Grease D) ······· Used for the feeding gear block. · 10g tube JUKI Part No.: 13525506 ❸ JUKI Grease A ······· Used for high-speed sliding parts and their peripheral parts. Used, in particular, for the specific areas with highly loaded parts.

  • Page 128: Parts To Which Grease Is Applied

    (4) Parts to which grease is applied 1) Work clamp foot lifter area ❶ ❶ ❶ ❶ ❶ ❶ ❸ ❶ ❶ Grease ❶ ❸ JUKI Grease A 2) Wiper area ❶ ❶ ❶ ❶ ❶ ❶ Grease – 114 –...
  • Page 129 3) Thread tension area ❶ ❶ ❶ Grease 4) Thread trimmer area ❸ ❸ ❸ ❶ ❶ Grease ❸ JUKI Grease A – 115 –...
  • Page 130 5) Feed area ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❷ ❶ ❷ ❶ ❶ Grease ❷ Grease D – 116 –...
  • Page 131 6) Needle bar and main shaft area ❸ ❸ ❸ ❸ ❸ ❸ ❸ ❸ ❸ ❸ JUKI Grease A 7) Lower shaft area ❸ ❸ JUKI Grease A ❸ ❸ – 117 –...
  • Page 132 8) Needle thread clamp mechanism area (For LK-1900BB, 1903BB) ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ ❶ Grease – 118 –...
  • Page 133 9) LK-1901B relations ❶ ❶ ❶ Grease ❶ ❶ ❶ ❶ ❶ ❶ – 119 –...
  • Page 134 10) LK-1903B relations ❶ ❶ ❶ ❶ Grease – 120 –...
  • Page 135 11) LK-1900BB, 1903BB relations ❸ ❸ ❸ ❸ ❸ ❸ JUKI Grease A – 121 –...

  • Page 136: Grease-Up Procedures For The Specified Position

    (Caution) 1. If the memory switch No. 245 is not reset at “0” after the replenishment of grease, Error No. E220 or No. E221 will be displayed again. 2. For the replenishment of grease to the parts specified below, use the attached JUKI Grease A (Part No. 40006323). If any grease other than the specified item is replenished, this can be a cause of destruction of parts.

  • Page 137: Error List

    11. Error list Error Indica- Description of error Corrective measure Remarks code tion E007 Machine lock error Turn OFF the power switch The main shaft of the sewing ma- and remove the cause of chine does not rotate due to some troubles.
  • Page 138 E063 Machine head identification error Turn the power OFF and The type of machine head and the contact JUKI or your dis- type of control box do not match. tributor. E204 Connection alert for the USB Re-operation is enabled thumb drive which is used for after resetting.
  • Page 139 Error Indica- Description of error Corrective measure Remarks code tion E303 Z-phase detection error Turn OFF the power Detection of the upper dead point switch. Check whether the of the sewing machine cannot be pin CN15 of SDC board is performed.
  • Page 140 Error Indica- Description of error Corrective measure Remarks code tion E405 Prohibition of deletion of direct Re-operation is enabled patterns after resetting. The direct pattern is set in the cycle sewing data. Encoder trouble A E730 Turn OFF the power switch. Encoder A or B phase cannot be Check whether the pin detected.
  • Page 141 Error Indica- Description of error Corrective measure Remarks code tion E913 Needle thread clamp origin re- Turn OFF the power switch trieval error and check whether CN77 of Needle thread clamp origin sensor INT board or CN45 of MAIN does not change. board is disconnected or loose.

  • Page 142: 2. T Roubles And Corrective Measures

    12. Troubles and corrective measures (1) Mechanical parts WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 1.
  • Page 143 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures From the previous page 3-4) Travelling torque in Y-direction is ex- 4-A) The pulse motor is pressed against the Adjust backlash of the feed motor cessive.

  • Page 144: Sewing Conditions

    (2) Sewing conditions WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 1. Thread comes off at the 1-1) Stitch skipping at the 1st stitch Decrease the sewing speed at the start of sew- start of sewing.
  • Page 145 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures From the previous page 1-4) Material to be sewn is not properly Remove the slack of the material to be sewn.
  • Page 146 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures From the previous page 2-5) Needle comes in contact with the wip- Adjust the wiper position.
  • Page 147 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 4. Thread breakage 4-1) Scratches on the inner hook 1-A) Scratches on section A (Contact of the inner hook After polishing the blade point of the inner hook with the needle)
  • Page 148 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures From the previous page 4-6) Finish of the needle hole is rough. Replace the needle.
  • Page 149 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 6. Defective thread trim- 6-1) Sharpness of the knife is defective. 1-A) Worn-out of the moving and counter knives.
  • Page 150 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 7. Poorly tense stitches 7-1) Tension controller No. 2 is maladjust- 1-A) Tension of the tension controller No.
  • Page 151 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures From the previous page From the previous page 2-C) Loop of the needle thread falls down.
  • Page 152 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Trouble Cause (1) Cause (2) Check and corrective measures 11. Long needle thread at the 11-1) Sharpness of the knife is defective. 1-A) Worn-out of the counter knife.

  • Page 153: Electrical Components

    (3) Electrical components (Refer to "Block diagram".) WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock.
  • Page 154 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 155 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 156 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 157 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 158 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 159 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)
  • Page 160 WARNING : When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident leading to electrical shock. If the work is performed while the power is ON, never touch other than necessary parts. Trouble Cause (1) Cause (2)

  • Page 161: Circuit Diagrams

    13. Circuit diagrams ( 1) Block diagram_Standard specification (MC-670) INT cable (asm.) [It is connecting directly to INT board.] INT board (asm.) (White) (Work clamp (Black) (押え・スタートスイッチ) foot, Encoder start switch) (OP) X-feed motor Ｘ送りモーター 2-phase (White) Unipolar (White) Work clamp foot lifter sensor (compl.) 押え上げセンサー結合...

  • Page 162: Block Diagram_Lk-1900Bb, 1903Bb (Mc-672)

    ( 2) Block diagram_LK-1900BB, 1903BB (MC-672) LK-1900BB,1903BB Solenoid valve cord A (asm.) 電磁弁コードA組 2 port solenoid valve 2ポートソレノイドバルブ 40153196 INT cable (asm.) [It is connecting directly to INT board.] PV120205000 CN46 (Black) INTケーブル組（INT基板直付） CN46 (黒) (Air shorter thread (AIR残短糸切り・吸引ノズル) remaining thread trimmer, CN30 CN70 (OP) suction nozzle) (OP) CN52 (Black)

  • Page 163: Block Diagram_Nfc Type (Mc-672)

    ( 3) Block diagram_NFC Type (MC-672) Control BOX 40189857 : Single-phase 40189858 : Three-phase LK-1900BNB, 1903BNB 40189859 : CE Solenoid valve code A (asm.) 2 port solenoid valve 40153196 PV120205000 INT cable (asm.) [It is connecting directly to INT board.] CN46(Black) (Air shorter thread remaining CN30 CN70 thread trimmer, suction nozzle)

  • Page 164: Power Supply Circuit Diagram (Single-Phase)

    ( 4) Power supply circuit diagram (Single-phase) SDC board MAIN board Light blue Brown Orange Yellow Black – 150 –...

  • Page 165: P Ower Supply Circuit Diagram (Single-Phase Ce)

    ( 5) Power supply circuit diagram (Single-phase CE) SDC board SDC基板 MAIN基板 MAIN board CN11 CN37 AUDET_N AUDET_N ADDET_N ADDET_N LSW_N LSW_N TSW_N TSW_N PWF_N PWF_N RES_N RES_N RSW_N RSW_N SP0_N SP0_N SP1_N SP1_N SP2_N SP2_N SP3_N SP3_N SP4_N SP4_N SP5_N SP5_N USW_N USW_N ERR_N ERR_N PDET_N PDET_N MBRK_N MBRK_N...

  • Page 166: P Ower Supply Circuit Diagram (3-Phase)

    ( 6) Power supply circuit diagram (3-phase) SDC board SDC基板 MAIN board MAIN基板 CN11 CN37 AUDET_N AUDET_N ADDET_N ADDET_N LSW_N LSW_N TSW_N TSW_N PWF_N PWF_N RES_N RES_N RSW_N RSW_N SP0_N SP0_N SP1_N SP1_N SP2_N SP2_N SP3_N SP3_N SP4_N SP4_N SP5_N SP5_N USW_N USW_N ERR_N ERR_N PDET_N PDET_N MBRK_N MBRK_N...

  • Page 167: S Ervo Motor Circuit Diagram

    ( 7) Servo motor circuit diagram SDC board AC servo motor White Black Orange Blue Purple Encoder Light blue Pink Yellow Black White Green+Yellow – 153 –...

  • Page 168: Stepping Motor Circuit Diagram

    (8) Stepping motor circuit diagram MAIN board (White) MAIN基板 CN42(白) Pink 桃 X-φ1 1.52Ω 赤 X-feed motor X-φ2 Ｘ送りモーター Blue 1.52Ω 青 X-φ3 Yellow 黄 X-φ4 White 白 X-COM1 5 Green 緑 X-COM2 6 (Blue) CN43(青) Pink 桃 Y-φ1 1.52Ω 赤 Y-feed motor Y-φ2 Ｙ送りモーター...

  • Page 169: Main · Operation Panel Circuit Diagram

    ( 9) MAIN · Operation panel circuit diagram MAIN基板 MAIN board CN34 TXD_N TXD_N RXD_N RXD_N RTS_N RTS_N CTS_N CTS_N CLK_N CLK_N S_ERSET S_ERSET PWRF PWRF SL_VR SL_VR SSTATE SSTATE UDET UDET +24V +24V +24V +24V – 155 –...

  • Page 170: Machine Head Sensor Circuit Diagram

    ( 10) Machine head sensor circuit diagram MAIN board Machine head INT board MAIN基板 頭部INT基板 (White) CN30 CN75(白) White 白 CS 1 Gray 灰 X-AN X-AN SCTK Green 緑 MOSI Yellow 黄 X-BN X-BN MISO Brown 茶 X-axis motor encoder Ｘ軸モーターエンコーダー Purple 紫 Y-AN Y-AN X-AN Orange 橙...

  • Page 171: ( 11) A Ir Circuit Diagram (Lk-1900Bb And 1903Bb Only)

    ( 11) Air circuit diagram (LK-1900BB, 1903BB, 1903BNB and 1903BNB only) ( 12) Pneumatic circuit diagram for LK-1900BB/1900BNB Solenoid valve Solenoid valve Unequal union Y for shorter thread for suction PA1000401A0 PA1000602A0 吸引ノズル駆動用 残短メス駆動用 (MBDAS10×4-20W) (CDUJB10-6DM) nozzle driving remaining knife driving Shorter thread Suction pipe cylinder 　　 電磁弁 　　電磁弁 MAIN基板 remaining cylinder Length : 400mm MAIN board Reducer CN46 (Black)

  • Page 172: T Able Type For Longitudinal Installation

    14. Table drawings (1) Table type for longitudinal Installation 1200 1130 1046 ±1 ±3 ±1 ❶ 175.6 ±1 ❹ ❷ 30.5 ❼ ❾ 17.5 ❺   ❸ ❻ 158.8 ±1 ❽ ±0.5 ±0.5 133.5 ±1 ±1 Z-Z(1:2) Ø36 Ø16 ❶ 4×2 drilled hole, depth 10 on the rear side [Stand installing hole] ❻...

  • Page 173: T Able Type For Lateral Installation

    (2) Table type for lateral Installation 1200 1130 916.5  ±1 ❶ ❷ 584.9 263.5  ±0.5 ❹ ❾ 10.5 ❺ ❸ ❻ 18.5  ±0.5 ❽ ❼ 48.7  ±1 259.8  ±1 136.8 ( 583.2 206.8 113.5  ±1   Z-Z （1 ： 2）  ±1 ∅...
  • Page 174 Please do not hesitate to contact our distributors or agents in your area for further information when necessary. Copyright © 2017 JUKI CORPORATION. * The description covered in this engineer's manual is subject to change for improvement of the All rights reserved throughout the world.

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