JUKI DX-4000QVP Instruction Manual page 133

Case
● The needle threading
lever will not return to
the original position and
the machine can not
turn properly.
(This is in case the
hook of needle threader
remains in the needles
eye.)
● The machine will not
start even when start/
stop button is pressed.
● Thread breaks.
● Stitch is skipped.
● Thread tension is not
good.
● Puckering occurs.
● The needle thread is
caught in the bobbin
winding thread guide
during sewing.
● sign is shown on
the LCD display.
Cause (Reason)
● Hand wheel is turned by mistake
while the needle threading lever is
in down position. (in the process of
threading to the needle.)
● The foot controller is plugged in.
● The machine is incorrectly threaded.
● There is knot or knurl on the thread.
● Thread tension is not adjusted ap-
propriately.
● The needle is bent or the tip of nee-
dle is broken.
● The needle is installed incorrectly.
● Threading of bobbin thread is not
correct.
● The bobbin can not turn smoothly
inside the hook holder.
● The needle size does not match the
thread.
● Thread take-up is not threaded.
● The needle thread is threaded in
correctly.
● The bobbin thread is threaded
incorrectly.
● The direction of spool cap doesn't
match the spool.
● The stitch length is too large on
lightweight fabrics.
● The needle tip is broken.
● The needle thread may be caught
in the bobbin winding thread guide
depending on the size of the spool
cap.
● Safety mechanism works when
machine stops due to motor lock.
Or, when the voltage fault has
occurred.
Solution
● Turn hand wheel slightly away
from you. (to the opposite side
when sewing).
● Start/stop button can function
when foot controller is removed.
● Rethread the machine correctly.
● Remove knot or knurl from thread.
● Adjust thread tension manually
according to fabrics and thread to
be used.
● Change needle.
● Install needle correctly.
● Check the correct way of setting
bobbin thread.
● Check the correct way of winding
bobbin thread.
● Check the combination of thread
and needle.
● Rethread the machine correctly.
● Rethread the machine correctly.
● Check the correct way of setting
bobbin thread.
● Attach the spool cap in a correct
direction.
● Make the stitch length smaller
(shorter).
● Change needle.
● Put the separately available net
on the spool cap to prevent this
problem.
● The safety mechanism will be
reset in a short while and the
machine will return to normal.
(At this time, the start/stop button
will not light up.)
Refer-
ence
page
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21
37
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41
30
30
34
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31
38
37
34
37
45
30
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132