Troubles And Corrective Measures - JUKI LBH-772NV-1 Manual De Instrucciones

^. TROUBLES AND CORRECTIVE MEASURES

Troubles
1. Needle thread breaks.
A. T h e n e e d l e t h r e a d
breaks at random in the
parallel portion of a
buttonhole.
B. T h e n e e d l e t h r e a d
b r e a k s a t t h e f i r s t
bartack stitches.
C. T h e n e e d l e t h r e a d
breaks at the start of
sewing.
2. The needle thread slips out
of the needle eyelet at the
start of sewing.
3. The needle thread is not
cut at the time of thread
trimming.
4. The gimp cannot be cut.
5. When the gimp cutter
opens, it fails to cut the
gimp.
6. The needle breaks.
Causes
1 Thread tension is not properly adjusted.
2 Blade point of the hook has scratches.
1 The position of the gimp guide finger is too
far left from the left stitch base line and the
needle thread is caught at the top end of
the guide finger causing needle thread
breakage when shifting the stitch base line
between the left stitch base line and the
right stitch base lien.
1 Thread tension is improperly adjusted. Th
needle thread tension is particularly too low.
1 The tension controller No. 2 provides an
excessive thread tension.
2 The needle thread and the gimp cord are
drawn by the same portion of the pull-in
plate and cut.
3 The gimp guide finger is positioned too
high, preventing the needle thread and the
bobbin thread from making knots.
1 The moving knife fails to mesh with the
stationary knife.
2 The moving knife or the stationary knife has
worn out.
1 The moving knife fails to mesh with the
stationary knife.
2 The gimp used is too thick.
3 The gimp guide finger is improperly
positioned at the time of stop motion.
1 The moving knife or the stationary knife has
worn out.
2 The needle comes in contact with the blade
point of the hook.
3 When the gimp cutter opens, the cutter
comes in contact with the the needle.
1 The needle is bent.
2 The needle comes in contact with the blade
point of the hook.
3 When the gimp cutter opens, the cutter
comes in contact with the the needle.
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™ Adjust first the bobbin thread tension 0.3 to
0.45 N, then, adjust the needle thread
tension. (Page 13)
™ Buff up the blade point of the hook to
remove scratches.
™ Change the position of the gimp guide finger
closer to the left stitch base line ensuring
that the gimp is neatly sewn in the stitches.
(Page 25)
™ Increase the needle thread tension.
(Page 13)
(In many cases, the tension provided by the
tension controller No. 2 is too low.)
™ Decrease the thread tension provided by
the tension controller No. 2, and increase
the tension provided by the tension
controller No.1 while visually checking the
stitches. (Page 13)
™ Cut the needle thread and the bobbin thread
separately. (Page 29)
If the gimp guide finger is positioned too far
to the left at the time of stop-motion, shift it
to the right.
™ Loosen the gimp guide holder and lower
the gimp guide finger to the extent that it
does not come in contact with the retaining
spring or the work clamp check. (Page 25)
™ Adjust the position of the thread trimming
yoke so that the moving knife and the
stationary knife properly mesh with each
other. (Page 19)
™ Replace the moving knife or the stationary
knife with a new one. (Page 33)
™ Adjust the position of the thread trimming
yoke to allow the knives to mesh properly
with each other. (Page 19)
™ The cutter is capable cutting a gimp
approximately as thick as Vinylon #5. So,
replace the gimp with a thinner gimp cord.
™ Raise the position of the gimp guide finger.
At the time of stop motion, adjust the
position of the gimp guide finger.
(Pages 25 and 29)
™ Replace the moving knife or the stationary
knife with a new one. (Page 33)
™ Adjust the position of the gimp guide finger
to allow the gimp to be neatly sewn in the
stitches. (Page 25)
™ Properly adjust the needle-to-hook timing.
(Page 17)
™ Replace the needle with a new one.
™ Properly adjust the needle-to-hook timing.
(Page 17)
™ Check whether the stop-motion position is
correct and also whether the locking plate
properly meshes with the guide plate
locking pin when the cutter actuates.
(Page 18)
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Corrective measures