JUKI dsu-142 Instruction Manual page 53

140401
Trouble
* 4. A few stitches are
skipped
* 5. The thread slips off
the needle upon
being trimmed.
* 6. The needle thread
cannot be trimmed.
(The bobbin thread
can be trimmed.)
* 7. Both needle and
bobbin threads
cannot be trimmed.
* 8. Thread cannot be
trimmed sharply.
* 9. The bobbin thread
cannot be trimmed
when using a thin
thread. (The nee-
dle thread can be
trimmed.)
10. Stepped parts is
clogged.
11. The material is
damage by the
feed.
Causes
① The bobbin thread is too short.
② The bobbin thread breaks.
③ A nylon thread is used when sewing light-
weight material.
① The tension of the auxiliary thread tension
controller is too high.
② The thread trimming timing is too early.
③ The returning force of the thread take-up
spring is too high.
④ The operating stroke of the picker is small.
① The last stitch has been skipped. (The
clearance between the needle and the
hook is too large.)
② Andaria thread is used.
① The thread trimming timing is wrong.
② The knife has been damaged.
③ The knife pressure is inadequate.
④ The movement of the rotary knife is short.
⑤ The thread trimming solenoid fails to work.
① The thread trimming timing is wrong.
② The knife pressure is inadequate.
③ The knife blade is blunt.
① The take-up thread amount is excessive.
① The presser foot slips when riding on the
stepped part.
① Pressure of the presser foot is excessive.
② The walking foot and the feed dog has
sharp edges.
○ Replace the bobbin by a standard one (alumi-
num).
○ Decrease the bobbin thread tension and also
decrease the thread trimming speed.
○ Use the soft start function.
○ Decrease the tension.
○ Refer to the chapter on "22. ADJUSTING THE
THREAD TRIMMING CAM".
○ Refer to the chapter on "9. THREAD THE MA-
CHINE HEAD".
○ Refer to the chapter on "25. ADJUSTING THE
OPERATING STROKE OF THE PICKER".
○ Refer to the chapter on "18. NEEDLE-TO-HOOK
RELATIONSHIP".
○ Make the timing of thread trimming earlier than
the standard timing.
Set the timing of thread trimming to the position
obtained by turning the handwheel in the re-
verse direction by 7 mm from the position where
the red marker dot on the machine arm aligns
with the white marker dot on the handwheel.
○ Refer to the chapter on "22. ADJUSTING THE
THREAD TRIMMING CAM".
○ Replace the knife.
○ Increase the knife pressure.
○ Refer to the chapter on "24. ADJUSTING MAX
MOVING STROKE OF THE ROTARY KNIFE".
○ Check the motor solenoid for proper operation.
○ Refer to the chapter on "22. ADJUSTING THE
THREAD TRIMMING CAM".
○ Increase the knife pressure.
○ Replace the knife.
○ Shift the arm thread guide (A) from the standard
position by approximately 4 mm to the right.
○ Increase the amount of alternating vertical
motions of the walking foot and the presser foot.
(Refer to "16. ADJUSTING THE WALKING
FOOT AND THE PRESSER FOOT".)
○ Use B152514500A presser foot (option) and
B152614500A walking foot (option).
○ Adjust the presser foot pressure.
○ Buff up the sharp edges of walking foot and teeth
of the feed dog.
– 17 –
Corrective measures