HE-800C
11. TROUBLESHOOTING
95
11-24. Work clamp is not raised (2)
…… Pulse motor stepping sound can be heard
Items with a “*” in the “Page” column should only be handled by a qualified technician.
Cause Check
Remedy
Page
Upper thread trimmer
Interference between upper
thread trimmer and work
clamp
Adjust the installation height of the upper thread
trimmer (remove the upper thread trimmer and check).
* Be particularly careful when sewing joints.
69*
Upper thread trimmer
operation
Apply grease to the inclined face of the opening cam.
70*
Lower thread trimmer
Interference between fixed
knife set, lower thread
clamp, lower thread
presser and lower thread
retainer.
Repair or replace the parts.
*
Rubbish, dust or thread
scraps present
Remove all rubbish, dust and thread scraps from the
lower thread trimmer.
*
Loose screws
Check for loose screws in
the upper thread trimmer,
lower thread trimmer and
work clamp lifter
mechanisms.
Securely tighten all screws.
*
Work clamp lifting
height setting
Check the work clamp
lifting height setting.
Change the settings of memory switch Nos. 001, 002,
003, 004.
* If the work clamp lifting height is too high, the lower
thread trimming operation and the work clamp lifting
will become stiff, and the work clamp motor may go
out of step.
57
Threading
Lower thread threading
Insert the bobbin correctly and pass the lower thread
through the bobbin case correctly.
* If the bobbin is inserted back-to-front, it will spin
loosely and the work clamp motor may go out of step.
25
Lower thread tension
・
Reduce the lower thread tension.
* If the lower thread tension is much too strong, the
work clamp motor may go out of step.
・
Use memory switch No. 060 to reduce the work
clamp lifting speed setting to make the lifting speed
slower.
・
Buff this section A to reduce the
thread retaining resistance.
26
*
*
Upper
thread
trimmer Upper thread trimmer
operation
Carry out opening timing adjustment for the upper
thread trimmer.
70
Work clamp home
position sensor
Work clamp home position
sensor position
Adjust the work clamp home position sensor position.
*
4022Q
Remove the shoulder
screw to check.
Lower thread
trimmer link A assembly
Lower thread
trimmer
connecting rod
4023Q
A