Troubles And Corrective Measures - JUKI MB1373 Instruction Manual

5. TROUBLES AND CORRECTIVE MEASURES

TROUBLES
1. Thread breakage 1 The yoke slide does not move in the correct
2 The tension lever has been improperly adjusted. ™ Properly adjust the tension lever.
3 The thread tension post No. 2 fails to release
4 Lifting amount of the button clamp jaw unit is
5 The thread nipper catches the thread.
6 The needle does not enter the center of the
7 The needle is too thick for the diameter of the
2. The machine forms a 1 The thread pull-off lever has been improperly
seam after it has run for a
while instead of forming it
2 Tension of the thread tension guide on the
from the start of sewing.
3. Buttons are not sewn 1 The yoke slide does not move in the correct
tightly
2 The thread tension post No. 2 fails to release
3 The thread tension post No. 2 does not give
4 The needle does not enter the center of the
5 The work pressing force is too high or too low. ™ Adjust the work pressing force properly.
4. The last back-tack stitch 1 The tension lever has been improperly adjusted. ™ Properly adjust the tension lever.
is poorly tensed.
2 Timing of the knot-tying plate is incorrect.
3 The nipper has been improperly adjusted.
5. The first stitch trails The thread pull-off lever does not work properly.
relatively long thread from
the right side of the button.
6. Thread trimming failure 1 The thread tension post No. 2 fails to release
in the state of stop-
motion
2 The needle hits the edge of the holes in the
3 The thread nipper fails to press the thread.
4 The work pressing force is too high.
7. Thread trimming failure 1 The moving knife does not separate the
2 The needle does not enter the center of the
3 The last stitch skips.
4 The moving knife thread separation nail is too
8. The needle thread is cut 1 The moving knife is set in wrong place.
in two places on the
wrong side of the fabric.
2 The moving knife thread separation nail is too
9. Button trails too long 1 Timing of the moving knife motion is wrong.
thread after thread
trimming.
2 Lifting amount of the button clamp jaw unit is
10.Length of thread 1 Position of the moving knife is not correct.
remaining, after thread
trimming, on the wrong
2 Lifting amount of the button clamp jaw unit is
side of the material
varies.
CAUSES
way.
the thread at correct timing.
excessive.
The nipper has been improperly adjusted.
(The clearance is too small.)
holes in the button.
hole in the button.
adjusted.
face plate is excessive.
way.
the thread at correct timing.
sufficient tension.
holes in the button.
(The clearance is too large.)
the thread at correct timing.
button.
thread on the fabric with its separation nail.
holes in the button.
high or too low.
high or too low.
excessive.
excessive.
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CORRECTIVE MEASURES
™ Adjust the timing of forward, backward and
sideways of the yoke slide.
™ Make the thread release timing slightly earlier.
™ Adjust the lifting amount of the button clamp jaw
lever to 8 mm.
™ Adjust the position of the nipper bar block.
™ Adjust the button clamp jaw lever holder.
™ Replace the needle by a thinner one.
™ Adjust the thread tension guide on the face plate
so that it provides a lower tension.
™ Properly adjust the tension lever.
™ Adjust the timing of the motion of the yoke slide at
each end.
™ Make the thread release timing slightly later.
™ Tighten the tension nut of tension post No. 2.
™ Adjust the button clamp jaw lever holder.
™ Advance the timing of the knot-tying plate.
(Adjustment of the knot-tying notch)
™ Adjust the nipper with the nipper bar block.
™ Adjust the thread pull-off lever by the nipper bar
block (rear).
™ Make the thread release timing slightly later to
give more tension to the stitches.
™ Adjust the button clamp jaw lever holder.
™ Adjust the nipper bar block.
™ Adjust the work pressing force by the pressure
adjusting nut.
™ Adjust the position of the moving knife.
™ Adjust the button clamp jaw lever holders.
™ Adjust the looper.
™ Adjust the height of the moving knife thread
separation nail.
™ Adjust the position of the moving knife when the
machine is in the stop-motion state.
™ Adjust the height of the thread separation nail.
™ Adjust the position of the moving knife.
when the machine is in the stop-motion state.
™ Adjust the lifting amount of the button clamp jaw
lever to 8 mm.
™ Adjust the position of the moving knife when the
machine completes stop-motion. (10 to 11 mm)
™ Adjust the lifting amount of the button clamp jaw
lever to 8 mm.