JUKI DDL-8000A, Руководство инженера

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Trouble Cause (1) Cause (2) Check and corrective measures
From the previous page
1-5) Knot tying between
the needle and bobbin
threads is not easy at
sewing start.
5-A) The sewing speed at sewing start is
too fast to knot the needle and bobbin
threads together.
Conduct 1 or 2 stitches of soft-start (800 sti/min) at the
sewing start.
5-B) If the thread trimming speed is fast,
thread is cut short at thread trimming.
The factory-configured thread trimming speed (No. 49 :
210sti/min, No. 50 : 180sti/min) is lowered.
2. The needle thread slips
off the needle at the sew-
ing start.
2-1) The length of the needle
thread passing through
the needle varies after
thread trimming.
1-A) Too high 1st thread tension due to
delayed thread trimming timing causes
the thread to be cut before engage-
ment between the moving and counter
knives. (midway cut)
Stop the motor, fully push the thread trimming solenoid
by hand when the needle reaches the lowest point,
trim the thread while turning the hand wheel slowly,
and stop the hand wheel when the thread take-up lever
comes to the upper dead point.
If the length of the needle thread passing through the needle
at this moment is 10 mm or more shorter than that of the
pedal operation, hasten the timing of thread trimming or de-
crease the 1st thread tension because this is a midway cut.
2-2) The cause and measures
are the same as those for
the item, "1. Skipping of
one or more stitches oc-
curs at the start of sewing".
2-A) The blade of the counter knife has been
sharpened excessively, and thread is
trimmed only by the counter knife.
Re-sharpen the blade of the knife in accordance.
2-B) The knife thread guide, moving knife,
or hook has a flaw.
Remove the scratches or burrs, or replace the defec-
tive component.
2-C) The needle is too thick. Change the needle.
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