Troubles And Corrective Measures - JUKI LZ-2280A Series Instruction Manual

8. TROUBLES AND CORRECTIVE MEASURES

Trouble
① When the thread gets entangled in the thread take-up lever. Remove the entanglement.
Thread
② When the needle thread is threaded in a wrong way.
breakage
③ When the thread gets entangled in the sewing hook.
④ When the needle thread is excessively tight or loose.
⑤ When the needle thread slips in the rotary tension.
⑥ When the tension of the thread take-up spring is
excessively high or low.
⑦ When the stroke of the thread take-up spring is
excessively large or small.
⑧ When the timing of the sewing hook and the needle is
not matched.
⑨ When there is a scratch on the thread path of hook,
bobbin case, thread take-up lever or any other part.
⑩ When the thread is not suitable.
a. The quality of the thread is poor.
b. The thread is too thick for the needle.
c. The thread is broken by heat.
⑪ When the stitch is skipped.
① When the needle is inserted in a wrong way.
Stitch
skipping
a. The needle is not entirely inserted into the needle bar. Fully insert the needle.
b. The needle eye is not facing straight to the operator. Let the needle eye face straight to the
c. The needle is facing backwards.
② When the needle itself is not suitable.
a. The needle is bent.
b. The quality of the needle is not good.
c. The needle is too thin for the thread.
d. Blunt needle is used.
③ When the hook blade point is not sharp enough or
damaged.
④ When the timing of the sewing hook and the needle is
not matched.
⑤ When the height of the needle bar is not correct.
⑥ When the clearance between the needle and the sewing
hook is too great.
Loose stitch ① When the needle thread tension is too low.
② When the tension of the thread take-up spring is too low. Increase the tension of the spring.
③ When the tension of the bobbin thread is too high.
④ When the timing of the sewing hook and the needle is
not matched.
⑤ When the thread is too thick for the needle.
⑥ Thread slips out of the rotary tension.
Cause
– 25 –
Corrective measures
Thread it correctly.
Remove the entanglement.
Adjust the thread tension.
Increase the tension of the pretension disk.
Adjust the tension of the take-up spring. 12
Adjust the stroke of the take-up spring.
(8 to 12 mm)
Adjust the timing.
Remove such a scratch or replace the
component.
Use a thread of good quality.
Use a suitable thread or needle.
Use JUKI Silicone Oil Lubricant unit.
Refer to the following paragraphs,
Stitch skipping.
operator.
Let the long groove on the needle face
to the operator.
Replace it with a new needle.
Use a needle of good quality.
Use a suitable needle or thread.
Replace it with a new needle.
Resharpen the hook or replace it.
Adjust the timing properly.
Adjust the height of the needle bar.
Adjust the clearance.
Increase the needle thread tension.
Decrease the bobbin thread tension.
Adjust the timing correctly.
Use a suitable needle or thread.
Increase the tension of the pretension disk. 12
See
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