– 96 –
1-4) Material to be sewn is not
Remove the slack of the material to be sewn.
properly stretched.
1-5) Unstable needle thread clamp
5-A) Thread tends to be extended
Increase the needle thread clamp needle number to
or sliding efficiency is worse.
3~4 stitches.
Lower the speed of the first stitch. (600 ~ 1000rpm)
5-B) Pitch of the first stitch is too small.
Lower the needle thread tension of the first stitch.
Increase the pitch of the first stitch.
1-6) Threading the needle bar
Refer to the item “Threading the needle bar thread
thread guide is wrong.
Guide”.
1-7) Bobbin runs idle and the bobbin
Use a stronger idling prevention spring.
thread is drawn out.
7-A) Initial positioning of the mov-
Adjust the initial position of the moving knife.
ing knife is inadequate.
2. Needle breakage
2-1) Inadequate clearance between
Adjust the clearance between needle and shuttle driver.
the shuttle driver and the
needle
2-2) Inadequate clearance between
Adjust the clearance between the needle and the
the needle and the inner hook.
inner hook.
2-3) Feed timing is defective
3-A) Feed timing is slow in regard
Change the feed timing by the use of the memory switch.
to the work pressure.
2-4) Needle coming in contact
Adjust the moving knife position.
with the moving knife
Adjust the work clamp foot (feed bracket) position.
2-5) Needle coming in contact
Adjust the wiper position.
with the wiper
2-6) Needle is bent
6-A) The needle thread tension is
Adjust the tension to a proper level.
too high.
6-B) The presser bar treads on the
Increase the crosswise clearance between the wiper
needle thread at the beginning
and the needle. 23 ~ 25mm
of sewing and the wiper is caught.
2-7) Needle is too thin.
Change the needle No. to the suitable one to the material.
From the previous page
Trouble
Cause (1)
Cause (2)
Check and corrective measures
Summary of Contents for LK-1900A
Page 20: ... 16 10 Hook adjustment Standard Adjustment 0mm 0mm 7 5mm 0 05 0 1mm For DPX5 For DPX17 ...
Page 90: ... 86 Grease Grease Grease Grease Grease 8 Needle thread clamp mechanism area ...
Page 91: ... 87 Grease Grease A Grease Grease Grease Grease 9 LK 1901A relations ...
Page 92: ... 88 10 LK 1903A relations Grease Grease ...
Page 114: ... 111 12 Circuit diagrams 1 Block diagram A ...
Page 115: ... 112 2 Power supply circuit diagram A ...
Page 116: ... 113 3 Power supply circuit diagram B ...
Page 117: ... 114 4 Power supply circuit diagram C ...
Page 118: ... 115 5 Servo motor circuit diagram ...
Page 119: ... 116 6 Sensor pedal VR circuit diagram ...
Page 120: ... 117 7 MAIN PANEL board circuit diagram ...
Page 121: ... 118 8 Motor solenoid circuit diagram Thread trimmer Lifting the work clamp foot motor ...