JUKI LS-2342 Instruction Manual page 31

Troubles
6. Thread is not cut sharply.
7. Thread remains uncut
after thread trimming.
(Bobbin thread trimming
failure when stitch length
is comparatively short.)
8. Thread breaks at the start
of sewing after thread
trimming.
9. When a heave-weight
material is sewn, the ma-
terial warps.
10. One or two stitches skip
at the beginning of sew-
ing (in the case of starting
sewing from the material
edge)
11. Three or more stitches
skip at the beginning of
sewing (in the case of
starting sewing from the
material edge)
12. When using thick thread,
thread is inadequately
tensed.
Causes
① The blades of moving knife and counter
knife have been improperly adjusted.
② The knives have blunt blades.
③ Bobbin thread tension is too low.
① Initial position of the moving knife has
been improperly adjusted.
② Bobbin thread tension is too low.
① The needle thread is caught in the hook.
① The feed amount of the top feed is inade-
quate.
① Needle thread and bobbin thread fail to
intertwine with each other.
② Thread tension given by the tension con-
troller No. 1 is too high.
③ Clamp spring pressure is excessively
weak.
④ The position of counter knife improper.
① Thread tension given by the tension con-
troller No. 1 is too high.
② Clamp spring pressure is excessively
strong.
① The clearance in the bobbin case opener
is too small.
② The bobbin thread tension is too low.
– 29 –
Corrective measures
○ Refer to
"4-8. Position of the count-
er knife and adjustment of the knife
pressure (LS-2342S-7, 2342H-7)"
p.19.
○ Replace the moving knife and counter
knife with new ones, or correct the cur-
rent ones.
○ Increase the bobbin thread tension.
○ Refer to
"4-8. Position of the count-
er knife and adjustment of the knife
pressure (LS-2342S-7, 2342H-7)"
p.19.
○ Increase the bobbin thread tension.
○ Shorten the length of thread remaining
on the needle after thread trimming.
Refer to "4-2. Thread tension"
○ Decrease the feed dog height and
reduce the feed amount of the bottom
feed. (Refer to the Engineer's Manual
for the adjustment procedure.)
○ Refer to
"3-6. Threading the machine
head" p.10.
○ Retain the needle thread on the materi-
al.
○ Remove the needle thread from the
thread guide (asm.). (Part  on p.10)
○ Increase the number of soft-start stitch-
es. (Refer to the Instruction Manual for
the SC-922.)
○ Decrease the thread tension given by
the tension controller No. 1.
○ Increase the clamp spring pressure.
○ Adjust the position of counter knife ap-
propriately.
○ Decrease the thread tension given by
the tension controller No. 1.
○ Decrease the clamp spring pressure.
○ Refer to
"4-7. Adjusting the bobbin
case opener" p.18.
○ Increase the bobbin thread tension.
p.15.