JUKI MF-7800D Series, Engineer'S Manual

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5-5) Skipping in top covering 5-A) Spreader A-1) Incorrect shape of pointed end of Replace it with the genuine part.
switch (Right) spreader disables scooping a
thread.
5-B) Needle B-1) Needle bend, improper needle Replace the needle with the new one,
attaching and wrong needle Use UY128GAS.
5-C) Spreader adjustment C-1) Incorrect light, protruding amount, Refer to the standard adjustment figures.
longitudinal position, stroke and
timing.
5-D) Spreader thread guide D-1) Incorrect height, position Refer to the standard adjustment figures.
5-E) Needle height E-1) Needle bar position is too low. Refer to the standard adjustment figures.
5-F) Threading F-1) Incorrect threading Refer to threading diagram.
5-G) Needle clamp thread guide G-1) Incorrect height, position, front Refer to standard adjustment figures.
and rear
5-H) Spreader thread tension H-1) Spreader thread tension is too Increase tension.
weak.
5-I) Spreader take-up thread I-1) Incorrect drawing-in amount of Refer to the standard adjustment figures.
drawing-in amount thread
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Trouble (1) Trouble (2) Cause (1) Cause (2) Corrective measures
Skipping in top covering stitch by right needle
Skipping in top covering stitch by right needle
Simultaneous skip by left and middle needle
Right needle
Left Middle Right
Spreader does not fetch the top covering thread.
Failure of
catching thread
Right needle
Right needle does not stride over the top
covering thread.
Incorrect Incorrect
Correct Correct