69
Short upper
thread after
trimming due to
separation failure
Thread break
before trimming
① Movable blade is too fast or
too slow to separate the
upper thread
② Incorrect position of picker
③ Picker failure
① Upper thread is too short
• check main and sub
tension adjuster
• dent or damage of
movable blade
② Lower thread is too short
• doesn’t unwind smoothly
• too weak or too elastic
■ Adjust insert angle of
movable blade (295°)
■ Adjust picker position
■ Check and change X, Y
drivers
■ Adjust upper thread tension
■ remove dent using
whetstone or sandpaper or
change movable blade
■ adjust or change bobbin
case spring
■ change lower thread
■ Check fuse spec.
■ Too short lower
thread cannot make
stitches right after
trimming
Inspection & Repair CauseError Type Reference
Check for dent
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