Work Clamp Is Not Raised; Pulse Motor Stepping Sound Can Be Heard - Brother HE-800B Instruction Manual

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
Upper thread trimmer
Lower thread trimmer
Loose screws
Work clamp lifting
height setting
Threading
Upper thread trimmer
Work clamp home
position sensor
Check
Interference between
upper thread trimmer and
work clamp
Upper thread trimmer
operation
Interference between fixed
knife set, lower thread
clamp, lower thread
presser and lower thread
retainer.
Rubbish, dust or thread
scraps present
Check for loose screws in
the upper thread trimmer,
lower thread trimmer and
work clamp lifter
mechanisms.
Check the work clamp
lifting height setting.
Lower thread threading
Lower thread tension
Upper thread trimmer
operation
Work clamp home position
sensor position
Remedy
Adjust the installation height of the upper thread
trimmer (remove the upper thread trimmer and check).
* Be particularly careful when sewing joints.
Apply grease to the inclined face of the opening cam.
Repair or replace the parts.
Lower thread
trimmer link A assembly
Remove all rubbish, dust and thread scraps from the
lower thread trimmer.
Securely tighten all screws.
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.
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.
・ 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.
4023Q
Carry out opening timing adjustment for the upper
thread trimmer.
Adjust the work clamp home position sensor position.
HE-800B
11. TROUBLESHOOTING
Lower thread
trimmer
connecting rod
Remove the shoulder
screw to check.
4022Q
A
Page
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69*
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