JUKI LK-1900A, Engineer'S Manual, Page: 105 / 124

– 101 –
7-7) Shape of the feed plate is 7-A) Material to be sewn is stiff and Raise the material to be sewn by means of the feed
defective. closely contacted with the throat plate.
plate, and there is no clearance
between them to pass the thread.
7-B) Material to be sewn is highly Raise the material to be sewn by means of the feed
elastic and closely contacted plate.
with the throat plate, and there
is no clearance between
them to pass the thread.
7-8) Feed timing is defective 8-A) Feed timing is too fast. Use the memory switch to change the feed timing.
8. Defective stitches with the synthetic 8-1) Thread breakage due to heat 1-A) The sewing speed is too fast. Slow down the maximum speed.
thread
1-B) The needle used is too thick. Use a thin needle or a super needle for the synthetic
thread.
Use silicon.
Use a needle cooler.
8-2) Thread makes burrs. 2-A) Thread path is defective. Polish the thread path of each component with polishing powder.
2-B) Finish of the needle hole is defective. Replace the needle.
2-C) Loop of the needle thread falls down. Move the thread guide A to the left.
8-3) Thread floating occurs at the 3-A) Penetration registance of the Use a thinner needle. (Lower the number of needle to be used.)
sewing start. thread against the cloth is too
small.
Needle thread clamp device ON.
8-4) Stitch skipping due to the heat. 4-A) Sewing speed is too fast. Change the maximum speed (electrical components.)
4-B) Needle is too thin. Use a thicker needle. (Raise the number of needle to be used.)
4-C) Loop of the needle thread falls down. Attach the needle with the long groove orienting slightly
to the right (approximately 20
°
).
Use a needle cooler.
8-5) Uneven stitch tightness due 5-A) Sewing speed is too fast. Reduce the speed by means of the speed variable resistor.
to the stretch of thread.
5-B) Tension of the tension controller Decrease the tension of tension controller No. 2.
No. 2 is excessive.
Trouble Cause (1) Cause (2) Check and corrective measures
From the previous page