JUKI LK-1900AN Engineer's Manual page 116

Trouble
From the previous page
8. Defective stitches with the syn-
thetic thread
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Cause (1)
7-6) Selection of the needle
hole guide is improper.
7-7) Shape of the feed plate is
defective.
7-8) Feed timing is defective.
8-1) Thread breakage due to
heat
8-2) Hangnail of thread
8-3) Thread floating occurs at
the sewing start.
Cause (2)
6-A) Hole diameter of the needle hole
guide to the needle to be used
and thread is small.
7-A) Material to be sewn is stiff and
closely contacted with the needle
plate, and there is no clearance
between them to pass the thread.
7-B) Material to be sewn is highly elastic
and closely contacted with the nee-
dle plate, and there is no clearance
between them to pass the thread.
8-A) Feed timing is too fast.
1-A) The sewing speed is too fast.
1-B) The needle used is too thick.
2-A) Thread path is defective.
2-B) Finish of the needle hole is de-
fective.
2-C) Loop of the needle thread falls
down.
3-A) Penetration resistance of the thread
against the cloth is too small.
Check and corrective measures
Replace the needle hole guide with a new
one having a larger needle hole.
Raise the material to be sewn by means of
the feed plate.
Raise the material to be sewn by means of
the feed plate.
Use the memory switch to change the feed
timing.
Slow down the maximum speed.
Use a thin needle or a super needle for the
synthetic thread.
Use silicon.
Use a needle cooler.
Polish the thread path of each component
with polishing powder.
Replace the needle.
Move the thread guide A to the left.
Use a thinner needle. (Lower the number of
needle to be used.)
Needle thread clamp ON.