12-10
Error Type
Cause
①
Poor connection of sensor
②
Bad circuit board
③
Bad sensor or sensor
position.
Dirty area around the
sensor.
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 to
movable blade
②
Lower thread is too short
�
doesn
’
t unwind
smoothly
�
too weak or too elastic
Inspection & Repair
Check connection
Change circuit board
�
change sensor
�
clean around the sensor
�
adjust location of the sensor
unit
Adjust insert angle of movable
blade (293
�
)
Adjust picker position
�
Check and change fuse F1,
F3
�
Check/change solenoid and
solenoid connection
�
Check connection and change
joint board
Adjust upper thread tension
remove dent using whetstone or
sandpaper or change movable
blade
�
adjust or change bobbin case
spring
�
clean/check for dent in thread
guide on the bobbin case
�
Change lower thread
Ref. 11-3, 11-2)
Ref. 11-1, 11-1-1)
Ref. 11-4, 11-3)
※
Check fuse spec.
Ref. 9-1, 9-1)
�
Too short lower thread
cannot make stitches
right after trimming
Reference
Trimmer return
failure
Short upper
thread after
trimming due to
separation
failure
Thread break
before trimming
Check for dent