SunStar HC Series User Manual page 65

Error Type
Trimmer return
Poor connection of sensor
failure
Bad circuit board
Bad sensor or sensor
position
Dirty area around the sensor
Short upper
Movable blade is too fast
thread after or too slow to separate the
trimming due to
upper thread
separation
failure
Incorrect position of picker
Picker failure
Thread break
Upper thread is too short
before trimming
check main and sub
tension adjuster
dent or damage to
movable blade
Lower thread is too short
doesn't unwind smoothly
too weak or too elastic
Cause
Check connection
Change circuit board
change sensor
clean around the sensor
adjust location of the sensor unit
Adjust insert angle of movable
blade (295°)
Adjust picker position
Check and change fuse F1
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
Inspection & Repair Reference
Check fuse spec
Check for dent
Too short lower thread
cannot make stitches
right after trimming