Unicorn LS2-H530 Operation Manual Download Page 31

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TROUBLESHOOTING GUIDE

Problem

Cause

Check

Solution

Page

Needle thread

slack.

Insufficient needle

thread tension

―

Increase needle

thread tension.

Excessive needle

thread tension

―

Decrease bobbin

thread tension.

Bobbin thread

slack.

Excessive needle

thread tension

―

Decrease needle

thread tension.

Insufficient needle

thread tension

―

Increase bobbin

thread tension.

Improper

looping stitch

tightening

Rough thread path

Thread path

Polish with fine

sandpaper.

Poor bobbin rotation

Tension of bobbin

thread leader

Replace bobbin,

rotary hook.

Rotary hook to rotary

hook stop gap too

small

Gap

Adjust needle to

rotary hook timing.

Improper

thread cutting

a. Needle,

bobbin

threads not

cut

b. Needle

thread

not cut

c. Bobbin

thread

not cut

Movable knife, fixed

knife do not overlap.

―

Adjust knives

Movable, fixed knife

edges worn or rough.

Knives

Replace knives.

Movable knife does

not move

Thread cutter

signal

transmission

  Check  electrical
  circuits;  replace
  thread  cutter
  solenoid.

Improper needle

installation

Needle facing

Reinstall needle.

  Last  stitch  skipped,
  needle  thread  not
  caught  by  thread
  cutter.

Thread take-up

spring stroke

Adjust thread

take-up spring.

Movable knife, fixed

knife do not overlap

―

Adjust knives.

Movable, fixed knives

dull.

Knives

Replace knifes.

Movable knife, fixed

knife do not overlap

―

Adjust knives.

Summary of Contents for LS2-H530

Page 1: ...PART BOOK LS2 H530 LS2 H5300 SINGLE NEEDLE SIDE CUTTER LOCK STITCH SEWING MACHINE WITH THREAD TRIMMER 1 OPERATION MANUAL...

Page 2: ......

Page 3: ...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 t...

Page 4: ...5 off A S 34 2 40 25 OFF A S A S...

Page 5: ...all 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 skin ot...

Page 6: ...placing the bobbin and needle 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 dur...

Page 7: ...rician 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 ma...

Page 8: ...act 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...

Page 9: ...ing machine is first turned on verify the rotational direction of the pulley with the power on The pulley should rotate counterclockwise when viewed from the pulley Power must be turned off when the m...

Page 10: ...6 8 Adjusting the stitch length 6 MECHANICAL DESCRIPTION 7 1 Thread trimmer 7 2 Thread wiper 7 ADJUSTMENT 8 15 1 Adjusting the needle bar height 8 2 Adjusting the rotary hook position 8 3 Adjusting th...

Page 11: ...4 8mm 3 16 6 4mm 1 4 1 How to install the belt V V 13mm 16mm Tilt back the machine head and place the belt onto the motor pulley and machine pulley Press belt with a finger force of 5 N and adjust th...

Page 12: ...he oil cover Screw Wipe off any contamination from the magnet and the oil pan Use the oil specified by Spindle15 2 Adjusting lubrication for upper shaft and rotary hook 1 1 Upper shaft lubrication Rem...

Page 13: ...needle raised above the needle plate 2 Upper knife operation To operate the upper knife lower the upper knife set lever The upper knife will now operate in sync with the operation of the machine To s...

Page 14: ...RATION 3 Attaching the needle DB 1 Insert the needle completely making sure that the lengthwise groove of the needle is on the left and secure it using the set screw Use a DBx1 needle 4 Threading the...

Page 15: ...bin case tension spring 3 Pull the thread from the bobbin case tension spring 6 Winding the bobbin thread 1 2 3 4 1 Fit the bobbin in the bobbin winder shaft 2 Depress the joint as far as it will go 3...

Page 16: ...tension at this time is 25 30g To adjust the operation range of the thread take up spring loosen the set screw and turn the thread tension bracket assembly To adjust the tension of the thread take up...

Page 17: ...he thread trimming solenoid activates pressing the thread trimming cam lever stud The roller shaft of the thread trimming cam lever assembly secured by the thread trimming cam lever stud id pushed abo...

Page 18: ...rejector needle bar bush Then firmly tighten the screw A 0 0 5mm 0 0 05mm Align the bottom reference line of the needle bar with surface A of the needle bar oil rejector needle bar bush by turning the...

Page 19: ...een the rotary hook and the rotary hook holder is approx 0 7 0 9mm Set the feed regulating dial to maximum and turn the machine pulley Check that the needle enters the center of the feed dog hole at t...

Page 20: ...epressed fit the indentation of the thread trimming clutch over the roller shaft 3 When the space between the side faces of the thread trimming clutch and the roller shaft is 0 6 0 8mm tighten the scr...

Page 21: ...the indentation of the thread trimming clutch 3 With the thread trimming solenoid depressed turn the machine pulley Adjust the movable knife and the fixed knife so that they overlap when the rotation...

Page 22: ...ve the feed bracket up or down 1 2 2 90 1 When the feed dog is fully raised its angle is properly adjusted if the circle on the feed bracket shaft aligns with the index on the feed rock shaft arm 2 To...

Page 23: ...sition there should be a 9 5 11 5 mm gap between the upper surface of the needle plate and the needle tip with thin or medium materials or a 10 12 mm gap with thick materials If adjustment of needle s...

Page 24: ...Raise the presser foot using the presser bar lifter 2 Remove the screw and the needle plate 3 Remove the screws and the feed dog 4 Remove the screws and the auxiliary needle plate 5 Turn the machine p...

Page 25: ...per feed scale to 0 2 The back edge pf the upper knife should be aligned with the needle center The upper knife can be adjusted by loosening the screw and moving the knife within a range of 2 mm forwa...

Page 26: ...16 4 4 8 8 8 8 4 4 4 6 6 6 2...

Page 27: ...hook timing 8 Thread wiper too high Thread wiper position Adjust thread wiper position with screw Thread breakage Improper threading Threading Rethread 4 Bent needle Blunt needle tip jammed eye Needl...

Page 28: ...18 4 4 1 4 4 8 8 8 6 6...

Page 29: ...resser 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 Adjust needle to rotar...

Page 30: ...20 6 6 6 6 puff 8 11 14 4 13 11 14 11...

Page 31: ...ok stop gap too small Gap Adjust needle to rotary hook timing 8 Improper thread cutting a Needle bobbin threads not cut b Needle thread not cut c Bobbin thread not cut Movable knife fixed knife do not...

Page 32: ...22 6 1 13 6 11 11 11 11...

Page 33: ...read cutter signal not transmitted Check circuits refe to motor adjustment manual Thread wiper does not function Needle thread remainder too long Adjust pretension 6 Timing too early wipes thread befo...

Page 34: ...24...

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