JUKI AMS-221F-2516 Instruction Manual page 106

Trouble
① The needle thread at the sewing
9. The thread clamp
is entangled with
needle thread.
① The tension of thread take-up
10. Uneven length of
the needle thread
① The tension of thread tension
11. The length of
needle thread
does not become
② The tension of thread take-up
short.
③ The tension of thread take-up
① Idling of bobbin is large.
12. The knotting
section of bobbin
② The bobbin thread tension is too
thread at 2nd
stitch at the
③ The needle thread tension at 1st
sewing start
appears on the
right side.
① Needle entry of the last needle
13. Wiper fails to
work. (Return is
defective.)
① Thread waste accumulates near
14. Thread trimmed
at the beginning
of sewing is not
collected.
② Trimmed thread is caught
③ Trimmed thread flies to the
④ Length of needle thread remaining
① Trimmed thread is connected to
15. Thread trimmed
at the beginning
of sewing is
entangled.
② Thread blown by the air blower is
Cause
start is too long.
spring is too low.
controller No. 1 is too low.
spring is too high.
spring is too low and motion is
unstable.
low.
stitch is too high.
is the same as that of the sewing
start, and the resistance of thread
and cloth is large.
the thread trimmer connecting
bar.
between the shuttle race and the
counter knife.
operator side. (Or on the left-hand
side of the operator)
at the needle is too short. The
thread untwists and separates
into single yarns.
the end of needle thread and is
entangled.
entangled in the seam.
Corrective measures
○ Tighten thread tension controller No. 1
and make the length of needle thread 40
to 50 mm.
○ Increase the tension of the thread take-
up spring.
○ Increase the tension of thread tension
controller No. 1.
○ Decrease the tension of thread take-up
spring.
○ Increase the tension of thread take-up
spring and lengthen the stroke as well.
○ A just the position of the moving knife.
○ Increase the bobbin thread tension.
○ Decrease the needle thread tension at
1st stitch.
○ Turn OFF the thread clamp.
○ Shift the needle entry point of the last
needle.
○ Defective air pressure setting may be the
cause of trouble. Set the air pressure to
the optimum value (0.2 - 0.3 MPa).
○ Adjust the position of shuttle race.
○ Adjust the position of upper spring.
○ Adjust the length of needle thread
remaining at the needle to the optimum
value (40 mm to 50 mm)
○ Change the knife or the throat plate asm.
with an appropriate one.
○ Faulty thread trimming may be the cause.
(Refer to "4. Thread is not trimmed".)
○ Adjust the position of upper spring.
○ Maximize the gap in the bobbin thread
retaining plate through which the thread
passes. (In the case of thick thread)
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