JUKI LU-2800 Series, Engineer'S Manual

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WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine.
Trouble Cause Checking Corrective measures
6. Loose stitches (Needle thread
rises.)
6-1) Needle thread has not been fully
pulled up.
Increase the needle thread ension.
Use the optional walking foot. (Top-divided type)
7. Irregular stitches 7-1) Stroke of the thread take-up spring is
improper.
1-A) Check the stroke of the thread
take-up spring.
Adjust the thread take-up spring to move to ap-
proximately 1 mm from the initial position when
hook draws thread maximumly.
7-2) Thread paths have been poorly fin -
ished.
2-A) Check the finish of the respec -
tive thread paths.
Finish with a fine emery paper or buff.
7-3) Bobbin fails to move smoothly. 3-A) Check the change of bobbin
thread tension.
Replace the bobbin or the hook with new ones.
7-4) Bobbin thread tension is too low. Increase the tension of the bobbin thread.
7-5) Bobbin has been wound too tight or
too weak.
5-A) Check the state of bobbin wind-
ing.
Decrease or increase the tension applied to the
bobbin winder.
7-6) Direction of setting bobbin is reverse. 6-A) Check the setting. Properly set the bobbin.
8. Loose stitches at the time of
corner stitching
8-1) Needle thread on the stopping side is
drawn out more than is necessary.
1-A) Check the stroke of the thread
take-up spring.
In crease the stroke of the thread take-up spring.
1-B) Check the hook timing. Retard the hook timing.
Use the optional walking foot. (Top divided type)
Adjustment of the thread take-up spring
o
Decrease the tension of the thread take-up spring and decrease the stroke of the spring to improve irregular stitches.