JUKI LK-1900AN Engineer's Manual page 115

Trouble
From the previous page
7. Poorly tense stitches
To the next page
Cause (1)
6-3) Moving knife does not
spread threads.
6-4) Stitch skipping at the final
stitch
6-5) Bobbin thread cannot be cut.
7-1) Tension controller No. 2 is
maladjusted.
7-2) Tension controller No. 2 is
floating.
7-3) Thread take-up spring is
maladjusted.
7-4) Clearance between the
inner hook and the shuttle
driver is defective.
7-5) Selection of the needle to
be used is improper.
Cause (2)
3-A) Initial position of the moving
knife is maladjusted.
3-B) Thread trimmer cam position is
inadequate.
3-C) Position of the shuttle upper
spring is defective.
4-A) Timing of the needle to the inner
hook and the clearance between
them are defective.
4-B) Work clamp foot is large.
4-C) Loop of the needle thread falls
down.
5-A) Bobbin thread tension is low.
5-B) Needle hole size of the needle
hole guide is large.
1-A) Tension of the tension controller
No. 2 is low.
4-A) The clearance between the inner
hook and the shuttle driver is too
small.
5-A) Needle to be used is thin.
Check and corrective measures
Adjust the initial position of the moving
knife.
Adjust the thread trimmer cam position.
Adjust the position of shuttle upper spring.
Adjust the timing and the clearance.
Let the beginning of stitch come closer to
the work clamp foot by moving the pattern.
Attach the needle with the long groove ori-
enting slightly to the right (approximately 20°)
Strong then the bobbin thread tension.
Replace the needle hole guide with a new
one having a smaller hole diameter.
Properly adjust the tension of tension con-
troller No. 2.
Adjust the thread tension releasing mecha-
nism.
Adjust thread take-up spring tension and
stroke.
Properly adjust the clearance of inner hook
and shuttle driver.
Replace the needle with a thicker one.