JUKI IT-100D Engineer's Manual

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4. Irregular stitches
The needle thread tension and bobbin
thread tension are insufficient.
Failed bobbin and bobbin case
The thread take-up spring has been
improperly adjusted.
Tension controller components are
defective.
The pre-tension disk is defective.
The position of the bobbin case holder
stopper is too near to the needle.
The installing direction of the bobbin in the
bobbin case is not correct.
Bobbin has been unevenly wound causing
hindrance.
The bobbin is deformed.
Failed engagement between the bobbin and
the bobbin case
The stroke of the thread take-up spring is
too large.
Tension of the thread take-up spring is too
high.
Thread slips in the tension disk.
Irregular rotation of the machine because
of the failed tension disk.
Irregular rotation of the machine because
of worn-out felt.
Failed position of the tension controller.
The pre-tension disk comes in contact with
the machine arm.
The orientation of the pre-tension disk is
defective. As a result, the disk rises in
accordance with the tension it applies.
Increase the needle thread tension and bobbin thread tension.
Adjust so that a bobbin is evenly wound with thread.
Replace the bobbin with a new one and increase the bobbin
winding tension.
Replace the bobbin or bobbin case with a new one.
Reduce the stroke of the thread take-up spring.
Lower the tension of the thread take-up spring.
Increase the tension provided by the pre-tension disk or lower
the tension provided by the thread tension controller.
Replace the tension disk with a new one.
Replace the felt with a new one.
Adjust the position of the tension controller to prevent the tension
disk from keeping held raised.
Re-fix the pre-tension disk at a position where the disk does not
come in contact with the machine arm.
Correct the pre-tension disk or adjust the position of the disk.
Adjust the position of the bobbin case holder stopper.
Re-install the bobbin in the bobbin case while facing it in the
correct direction.
Trouble Description Cause 1 Cause 2 Corrective measure and adjusting procedure

JUKI IT-100D Specifications

General

Brand	JUKI
Model	IT-100D
Category	Sewing Machine
Language	English