JUKI MF-7700 Series Engineer's Manual page 72

Troubles (1) Troubles (2)
From the previous page
5-12) Irregular stitches in top
covering stitches
5-13) Bulge
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Cause (1)
12-A) Spreader A-1) Flaw in pointed end of spreader
12-B) Spreader adjustment B-1) Spreader stroke is too large.
12-C) Thread guide C-1) Flaw, burr in slot
12-D) Top covering thread take-up D-1) Drawing-in amount of top covering
12-E) Needle thread tension E-1) Needle thread tension is too weak.
12-F) Threading F-1) Incorrect threading
12-G) Top covering thread tension G-1) 1st thread tension is too weak.
12-H) Looper thread cam H-1) Drawing-in amount of looper
thread guide position
12-I) Stitch tongue of presser foot I-1)
13-A) Throat plate A-1) Stitch tongue is too short.
13-B) Threading B-1) Incorrect threading
13-C) Needle thread tension C-1) Tension is too strong.
13-D) Looper thread tension D-1) Tension is too strong.
13-E) Looper thread cam E-1) Drawing-in amount of upper thread
thread guide position
Cause (2)
obstructs smooth thread threading.
Flaw
thread is too much or too little.
thread is too much.
Thread threading is not smooth due
to incorrect shape of stitch tongue.
is too little.
Corrective measures
Replace when modified or its shape is changed too
much.
Refer to the standard adjustment figures.
Replace when modified or its shape is changed too
much.
Refer to the standard adjustment figures.
Increase tension.
Refer to threading diagram.
Increase tension.
Reduce drawing-in amount of thread.
Replace when modified or its shape is changed too
much.
Use throat plate provided with long stitch tongue.
Refer to threading diagram.
Reduce tension.
Reduce tension.
Increase drawing-in amount.