JUKI lbh-1790 series Engineer's Manual page 21

Adjustment Procedures
1. Adjust the origin sensor with the respective initial data of thread
releasing position (-86) and thread trimming position (40)
referring to 3) Needle thread trimming adjustment mode.
2. Loosen setscrews 1 in needle thread trimmer sensor installing
plate 2 and move needle thread trimmer sensor installing plate
2 up or down so that A is almost equal to B when the motion
of cam is maximized in each direction.
1. Start up 3) Needle thread trimming adjustment mode and set
the trimmer to thread holding position (0).
2. At the start of sewing, loosen setscrews 1 and adjust so that
the trimmer is placed 0 to 3 mm to the right from the center of
knife groove. (Adjust in accordance with roll-in of needle thread.)
Results of Improper Adjustment
™ If A and B are not equal to each
other, step-out of needle thread
trimming motor may occur.
™ If the adjustment is improper,
needle thread at the start of
sewing protrudes from the
seam.
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