JUKI MF-7900 Series Engineer's Manual page 194

WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine
Trouble (1) Trouble (2)
From the previous page
5-5) Skipping in top covering
switch (Right)
To the next page
Cause (1)
5-A) Spreader A-1) Incorrect shape of pointed end of
5-B) Needle B-1) Needle bend, improper needle attach-
5-C) Spreader adjustment C-1) Incorrect height, protruding amount,
5-D) Spreader thread guide D-1) Incorrect height and position
5-E) Needle height E-1) Needle bar position is too low.
5-F) Threading F-1) Incorrect threading
5-G) Needle clamp thread G-1) Incorrect height, position, front and
guide
5-H) Spreader thread tension H-1) Spreader thread tension is too weak.
5-I) Spreader take-up thread I-1) Incorrect drawing-in amount of thread
drawing-in amount
Cause (2)
spreader disables scooping a thread.
ing and wrong needle
longitudinal position, stroke and timing.
rear
Check and corrective measures
Replace it with the genuine part.
Replace the needle with the new one,
Use UY128GAS.
Refer to the standard adjustment figures.
Refer to the standard adjustment figures.
Refer to the standard adjustment figures.
Refer to threading diagram.
Refer to the standard adjustment figures.
Increase tension.
Refer to the standard adjustment figures.