JUKI LK-1900B 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 (1) Cause (2) Check and corrective measures
1. Thread comes off at the
start of sewing.
1-1) Stitch skipping at the 1st stitch Decrease the sewing speed at the start of sew-
ing.
1-A) Penetration resistance of the thread against the
cloth is small.
Use a thinner needle. (Lower the needle count
to be used.)
1-2) Length of thread remaining at the nee-
dle is not sufcient.
2-A) Tension controller No. 1 provides an excessive ten-
sion.
Properly adjust the tension controller No. 1.
2-B) Floating of the AT thread tension disc is insufcient. Adjust the amount of AT thread tension oating.
2-C) Stroke of the thread take-up spring is excessive. Adjust the stroke of the thread take-up spring.
2-D) The thread take-up spring tension is insufcient. Adjust the thread take-up spring tension.
2-E) Level difference between the needle hole guide and
the counter knife is excessively high.
Adjust the height of the counter knife.
2-F) Needle thread tension is high and the thread is
excessively stretched.
Adjust the needle thread tension.
2-G) Thread spreading section of the moving knife has
scratches.
Polish the thread spreading section of the mov-
ing knife with buff or replace the knife.
1-3) Length of bobbin thread remaining is
not sufcient.
3-A) Level difference between the needle hole guide and
the counter knife is excessively high.
Adjust the height of the counter knife. (Other-
wise, widen the gap.)
3-B) Lower face of the needle hole guide has scratches. Polish the needle hole guide with a buff or re-
place it.
3-C) Thread spreading section of the moving knife has
scratches.
Polish the thread spreading section of the mov-
ing knife with buff or replace the knife.
3-D) Shuttle upper spring has scratches. Polish the shuttle upper race with a buff or re-
place it.
3-E) The bobbin thread tension is excessive. Adjust the bobbin thread tension.
3-F) The bobbin or bobbin case has scratches. Polish it with a buff or replace it.
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(2) Sewing conditions

JUKI LK-1900B series Specifications

General

Brand	JUKI
Model	LK-1900B series
Category	Sewing Machine
Language	English