JUKI DU-1481 Series, Instruction Manual

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9. Troubleshooting
No. Phenomenon Item to be checked Cause Corrective measure
1 Needle breakage
Orientation and height of
needle
Needle insertion position is not
correct.
Re-insert the needle properly.
Needle The needle is bent.
Change the needle with a
new one.
Feed dog timing Feed dog timing is wrong
Adjust the feed dog timing
appropriately.
Needle bar lifting position
Timing between the needle
and the hook is not correct.
Adjust the needle-to-hook
timing appropriately.
Needle height
The needle bar lower dead
point is not correct
Adjust the needle bar lower
dead point appropriately.
Clearance between the
needle and the hook
The clearance provided
between the needle and the
hook is not correct.
Adjust the clearance provided
between the needle and the
hook appropriately.
2 Thread breakage
Threading of the machine
head
Machine head is not threaded
correctly.
Correctly thread the machine
head.
Needle
The needle is bent or the nee-
dle tip has broken.
Change the needle with a
new one.
Orientation and height of
needle
Needle insertion position is not
correct.
Re-insert the needle properly.
Needle thread tension
The needle thread tension is
too high.
Decrease the needle thread
tension.
Bobbin thread tension
The bobbin thread tension is
too high.
Decrease the bobbin thread
tension.
Operating quantity of the
thread take-up spring
The operating quantity of the
thread take-up spring is too
large.
Adjust the thread take-up
spring appropriately.
3
Sewing perfor-
mance failure
Thread tension
The needle / bobbin thread
tensions are not correct.
Adjust the needle / bobbin
thread tensions appropriately.
Tension of the thread take-
up spring
Tension of the thread take-up
spring is inadequate.
Adjust the tension of the
thread take-up spring appro-
priately.
Clearance between the
inner hook holder and the
hook
The clearance provided be-
tween the inner hook holder
and the hook is not adequate.
Adjust the clearance provided
between the inner hook hold-
er and the hook appropriately.
4
Slip-off of thread
or stitch skipping
at the beginning
of sewing
Orientation and height of
needle
Needle insertion position is not
correct.
Re-insert the needle properly
and push it up until it will go
no further.
Needle The needle is bent.
Change the needle with a
new one.
Threading of the machine
head (needle)
Threading direction is wrong.
Insert the thread following the
correct threading procedure.
Clearance between the
needle and the hook
The timing between the needle
and the hook is not correct.
Adjust the needle-to-hook
timing appropriately.
Length of needle thread
remaining at the needle (on
the material)
The length of needle thread
remaining at the needle (on
the material) is too short.
Decrease the thread tension
provided by the tension con-
troller No.1.
Check the upper stop posi-
tion of the needle.
The thread take-up lever
draws thread out of the needle
eyelet due to improper upper
stop position of the needle.
Re-adjust the upper stop po-
sition of the needle appropri-
ately.