JUKI DLN-6390 Manuel D'utilisation page 98

Troubles Causes (Items to be checked)
Needle breakage Check whether cloth s properly rolled.
Check whether relaton of poston between
needle and needle hole s proper.
Check whether the poston of the hemmng
bnder s proper.
Sttch skppng
Check whether clearance between needle
and blade pont of hook s proper.
Check whether blade pont of hook has a
scratch or s blunt.
Check whether thread tenson s too hgh.
Check whether the poston of the hemmng
bnder s proper.
(Check whether the hemmng bnder
nterferes wth the presser foot (asm.).)
Check whether clearance between needle
Thread breakage
and blade pont of hook s proper.
Check whether blade pont of hook has a
scratch or s blunt.
Check whether thread tenson s too hgh.
Check whether the poston of the hemmng
bnder s proper.
(Check whether the hemmng bnder
nterferes wth the presser foot (asm.).)
Check whether needle attachng s proper.
(Direction, insufficient insertion, etc.)
Check whether the tenson of thread tenson
No.  s low. (In case of thread trmmer)
Check whether qualty of thread s not good.
Check whether thread s cut from heat.
Loopng
Check whether knd or sze of needle s proper.
(balloon sttch)
Check whether relaton of poston between
needle and needle hole s proper.
Check whether needle cooler ar pressure s
too hgh.
Check whether thread tenson s too low.
Check whether the tenson of thread take-up
sprng s low or the stroke s small.
Check whether the tenson of thread s proper.
34
Corrective measures
Adjust by handlng so that hemmng of the bottom
can be properly performed.
(Feed force s not stablzed when cloth becomes
thck due to the falure of rollng.)
Adjust the poston of throat plate and presser foot
(asm.) to a proper one.
(The proper poston of needle n terms of needle
hole n the throat plate s n the center of both sdes
and that n terms of needle hole n the presser foot
(asm.) s slghtly to the rght sde.)
Adjust the poston to a proper one.
(Needle s apt to break when needle perces the
lmt of edge of the fold.)
Make the clearance between needle and blade pont
of hook come near to "0" when thread s caught.
Remove the scratch or replace the hook wth a new
one.
Decrease the thread tenson.
Adjust the poston to a proper one.
(When the hemmng bnder nterferes wth the
presser foot (asm.), the presser foot (asm.) rses
from the throat plate, or the moton s lmted.)
Make the clearance between needle and blade pont
of hook come near to "0" when thread s caught.
Remove the scratch or replace the hook wth a new
one.
Decrease the thread tenson.
Adjust the poston to a proper one.
(When the hemmng bnder nterferes wth the
presser foot (asm.), the presser foot (asm.) rses
from the throat plate, or the moton s lmted.)
Properly attach the needle.
A d j u s t t h e t e n s  o n t o s u c h a n e x t e n t t h a t
unsteadness of thread does not occur.
Use a good qualty thread.
Increase the amount of ol n the hook.
Replace the needle wth a proper one.
SCHMETZ UY80GVS s recommended.
(Sewng performance s stablzed when usng a
thck one f possble.)
Adjust the poston of throat plate and presser foot
(asm.) to a proper one.
(The proper poston of needle n terms of needle
hole n the throat plate s n the center of both sdes
and that n terms of needle hole n the presser foot
(asm.) s slghtly to the rght sde.)
Set the ar pressure to a proper one (t s better to
set t to rather low).
Increase the thread tenson.
Adjust the tenson or the stroke to a proper value.
(0.2N and 8 mm are recommended.)
Re-adjust the tenson of thread to a proper one.
(If the thread tenson s too low, needle thread s
not fully drawn up, and f t s too hgh, the twst s
tghtened and loopng s apt to occur.)
Ref. page
–
–
5
23
23
21
5
23
23
21
5
17
21
–
16
17
–
38
21
21
21