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TROUBLESHOOTING  GUIDE

Problem

Cause

Check

Solution

Page

  Needle  thread

  escapes at  start

  of  sewing.

  Tension  disc  does  not

  open  sufficiently. 

  Tension  disc

  opening

  Adjust  tension  release.

  Excessive  pretension

  Adjust  pretension.

15

  Needle  too  heavy  for

  thread

  Use  smaller  size

  needle.

  Up  needle  stop  position
  too  high,  thread  removed   
  by  thread  take-up.

  Thread  take-up
  height  at  up  needle
  stop  position

  Delay  up  needle  stop

  position  timing.

  Thread  cutter

  mechanism does

  not  function.

  Thread  cutter  solenoid

  dose  not  function.

  Check  with  tester

  Replace  thread  cutter

  solenoid.

  Thread  cutter  signal  not

  transmitted.

  Check  circuits;  refer
  to  motor  adjustment
  manual

  Thread  wiper does

  not  function.

  Needle  thread  remainder

  too  long.

  Adjust  pretension

15

  Excessive  material,

  presser  foot  resistance

  Replace  with  presser 
  foot  having  back
  channel.

  Timing  too  early;  wipes 
  thread  before  tension
  disc  closes.

  Adjust  timing.

  Thread  wiper  operation

  too  short

  Adjust  operation  time.

Summary of Contents for LS2-H540

Page 1: ...PART BOOK LS2 H540 LS2 H5400 SINGLE NEEDLE HIGH SPEED LONG ARM UPPER LOWER FEED LOCKSTITCH SEWIMG MACHINE WITH THREAD TRIMMER 1 OPERATION MANUAL...

Page 2: ...1...

Page 3: ...e symbol at left means beware of injury This symbol indicates something that you must not do This symbol indicates something that you must do The picture inside the circle indicates the nature of the...

Page 4: ...5 off A S 43 2 40 25 OFF A S A S 3...

Page 5: ...cur install the belt covers to the machine head and motor Be sure to wear protective goggles and gloves when handling the lubricating oil and grease so that they do not get into your eyes or onto your...

Page 6: ...edle when not using the machine and when leaving the machine unattended For machines with automatic presser lifter do not touch the solenoid section because if becomes hot during operation and may cau...

Page 7: ...ician to carry out any maintenance and inspection of the electrical system Turn off the power switch and disconnect the power cord from the wall outlet at the following times otherwise the machine may...

Page 8: ...your nearest UNICORN dealer The positions of the labels may vary slightly depending on the model of sewing machine or motor 1 2 Be sure to connect the ground If the ground connection is not secure you...

Page 9: ...VER 4 OPERATION PANEL 13 PRESSER FOOT 22 THREAD TAKE UP LEVER COVER 5 PULLEY 14 WALKING FOOT 23 WALKING FOOT PRESSURE ADJUSTING THUMB SCREW 6 STITCH LENGTH ADJUSTING DIAL 15 NEEDLE BAR 24 PRESSER FOOT...

Page 10: ...NEEDLE BAR STROKE 38 FEED DOG HEIGHT 1 PRESSER FOOT HEIGHT USING HAND 6 USING KNEE 16 NEEDLE TYPE DP 17 22 STITCH ADJUSTMENT DIAL LUBRICATION SYSTEM AUTOMATIC BED DIMENSIONS 517 179 THREAD TRIMMER SYS...

Page 11: ...R CUSHIONS IF THE OIL LEVEL IS BELOW POSITION REPLENISH THE OIL UP TO THE POSITION AND 2 INSTALLING THE V BELT 15 20 1 THE ROTATIONAL DIRECTION OF THE MACHINE IS COUNTER CLOCKWISE AS SHOWN IN FIG TO A...

Page 12: ...INSTALLING THE BOBBIN WINDER ATTACH THE BOBBIN WINDER ON THE TABLE WITH TWO SCREWS 4 INSTALLING SPOOL STAND ASSEMBLY ATTACH THE THREAD SPOOL STAND ASSEMBLY AT THE RIGHT REAR CORNER OF THETABLE WITH TH...

Page 13: ...UNT OF OIL TO THE THREAD TAKE UP AND NEEDLE BAR CRANK BY TURNING ADJUSTING PIN IF THE MARKED DOT COINCIDES WITH THE DIRECTION OF THE NEEDLE BAR CRANK THE OILING WILL BE MAX BY TURNING THE PIN TO THE C...

Page 14: ...perate if treadle is pressed by mistake which could result in injury 13 HOW TO USE THE MACHINE 1 HOW TO ATTACH THE NEEDLE LOOSEN THE SCREW AND HOLDING THE NEEDLE WITH THE LONG GROOVE SIDE TOWARD THE L...

Page 15: ...IDE TO THE RIGHT OR LEFT TO WIND THE THREAD ONTO THE BOBBIN MAKE ADJUSTMENT BY TIGHTENING THE SCREW IN CASE OF ROTATION THE MACHINE WITHOUT SEWING KEEP THE PRESSER FOOT RAISED 3 HOW TO ROUTE THE UPPER...

Page 16: ...BBIN WILL REMOVE WHEN THE LATCH IS RELEASED 6 HOW TO ADJUST THE LENGTH AND REVERSE SEWING STOP THE MACHINE AND PUSH THE REVERSE LEVER DOWNWARD AND THEN TURN THE DIAL TO THE DESIRED STITCH THE MATERIAL...

Page 17: ...EN 8 HOW TO ADJUST THE LOWER THREAD ADJUST THE LOWER THREAD BY TURNING THE SCREW SO THAT WHEN HOLDING THE END OF THREAD AND THEN FALLING DOWN THE BOBBIN CASE IT CAN GO DOWN SLOWLY ITS OWN WEIGHT OF BO...

Page 18: ...power cord from the wall outlet at the following times otherwise the machine may operate if the treadle is pressed by mistake which could result in injury When carrying out inspection adjustment and m...

Page 19: ...OF ROTARY HOOK WITH THE CENTER OF THE NEEDLE WHEN MEETING THE LINE OF THE NEEDLE BAR WITH THE LOWEST POSITION OF NEEDLE BUSHING AS SHOWN IN FIG ADJUST THE CLEARANCE BETWEEN THE ROTARY HOOK AND THE NEE...

Page 20: ...THE WALKING FOOT AND PRESSER FOOT CAN BE ADJUSTED BY USING THE ADJUSTING DIAL LOCATED ON THE ARM FRONT 2 FACE THE DESIRED NUMBER PRINTED ON THE DIAL TO THE MATCHING MARK LOCATED ON THE ARM FRONT 3 TH...

Page 21: ...NG ROCK SHAFT CRANK 4 THE BUILT IN SPRING PULLS DOWN THE PRESSER FOOT UNTIL IT MAKES CONTACT WITH THE NEEDLE PLATE THEN TIGHTEN SET SCREW 5 THIS COMPLETES THE ADJUSTMENT I E THE PROTRUSION OF THE PRES...

Page 22: ...LOW CAUTION IF THE FEED REGULATOR BRACKET IS POORLY POSITIONED THE RESULTANT ALTERNATING MOVEMENTS MAY BE TOO SHORT OR LONG CAUSING DEFECTIVE MACHINE OPERATION 1 LOCATE THE SPECIAL SCREW ON THE CAM NE...

Page 23: ...ND SHIFT TO ADJUST THE POSITION OF THE PIVOT BRACKET UPWARD OR DOWNWARD UPPER POSITION FEED PITCH SMALL LOWER POSITION FEED PITCH LARGE 8 ADJUSTING FEED TIMING THE STANDARD POSITION OF THE ECCENTRIC F...

Page 24: ...ck that they operate correctly before using the machine Turn off the power switch and disconnect the power cord from the wall outlet at the following times otherwise the machine may operate if the tre...

Page 25: ...ONE REVOLUTION WITH THE THREAD SOLENOID ACTIVATED THE MOVABLE KNIFE LEFT WILL TRIM THREAD OF NEEDLE 1 Thread Trimmer Solenoid 2 Thread Trimmer Cam Lever 3 Thread Trimmer Cam 4 Thread Trimmer Lever 5 M...

Page 26: ...indentation of the thread trimming clutch over the roller shaft when the space between the side faces of the thread trimming clutch and the roller shaft is 0 6 0 8 tighten the screw so that the inden...

Page 27: ...immer solenoid manually so that the roller shaft in the indentation of the thread trimming clutch With the thread trimming solenoid depressed turn the machine pulley adjust the movable knife and the f...

Page 28: ...d knife 2 1 2 Raise the presser foot using the presser bar lifter Remove the screw and the needle plate Turn the machine pulley until the needle bar reaches its highest position Press the thread trimm...

Page 29: ...1 TO ADJUST IT LOOSEN THE NUT AND PROPERLY SHIFT THE FLEXIBLE WIRE IF THE TENSION DISCS ARE TOO NARROWLY SET THE UPPER THREAD MAY BE LIABLE TO BE BROKEN RESULTING IN DETACHED NEEDLE THREAD ALSO IF TH...

Page 30: ...WEEN THE TOP OF NEEDLE PLATE AND NEEDLE SHOULD BE 10 12 5 IF YOU NEED TO ADJUST IT TURN OFF THE POWER SWITCH AND ADJUST IT ADJUSTING OF THE NEEDLE UP POSITION 2 LOOSEN THE SCREW JUST ONE TURN MOVING T...

Page 31: ...30 13 13 18 18 18 14 13 13 15 16 16 12...

Page 32: ...imimg 18 Thread wiper too high Thread wiper position Adjust thread wiper position with screw Thread breakage Improper threading Threading Rethread 14 Bent needle Blunt needle tip jammed eye Needle Rep...

Page 33: ...32 13 13 1 13 14 18 18 18 15 16...

Page 34: ...oor presser foot contact Presser bar pressure Tighten presser foot adjustment screw Presser bar height Adjust presser bar height Improper needle to rotary hook timing Needle bar rise Adjusting the rot...

Page 35: ...34 15 16 15 16 puff 18 13 26 28 26...

Page 36: ...tary hook stop gap too small Gap Adjusting the rotary hook timing 18 Improper thread cutting a Needle bobbin threads not cut b Needle thread not cut c Bobbin thread not cut Movable knife fixed knife d...

Page 37: ...36 15 1 15...

Page 38: ...eedle stop position Delay up needle stop position timing Thread cutter mechanism does not function Thread cutter solenoid dose not function Check with tester Replace thread cutter solenoid Thread cutt...

Page 39: ...38...

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