JUKI LBH-1790A Series Instruction Manual page 76

Troubles
10. Needle thread breaks 1. Tension at the start of sewing is too low.
at the start of sewing,
or the wrong side of
seam is dirty.
11. Knife drops even 1. Check whether the thread breakage detector
when needle thread is
cut.
12. Needle breaks. 1. Check whether needle is bent.
2. Check whether needle comes in contact with
3. Check whether needle thread trimmer comes
4. Check whether needle comes in the center of
5. Needle stop position is too low and needle
13. Knife drops plural 1. Check whether the cloth cutting knife dropping
times.
Causes
plate is properly adjusted.
the blade point of hook.
in contact with needle when it opens.
the needle hole of throat plate.
comes in contact with needle thread trimmer
when it closes.
is set to plural dropping.
Corrective measures
○ Increase tension at the start of sewing.
○ Adjust the detector plate.
(Refer to the Engineer's Manual.)
○ Replace the needle.
○ Adjust the needle-to-hook timing.
○ Adjust the installing position of needle
thread trimmer.
○ Re-adjust the installing position of throat
plate base.
○ Release the plural time setting.
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