Needle Strikes Upper Thread Trimmer - Brother HE-800B Service Manual

11-16. Needle strikes upper thread trimmer

Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Upper thread trimmer
assembly
Longitudinal feed arm
Cam
Opening cam
Work clamp home
position
Check
Installation position
upper thread trimmer
assembly
Upper thread trimmer
operating force
Installation position of the
longitudinal feed arm
Upper thread trimmer
opening timing
Upper thread trimmer
gradual opening timing
Upper thread trimmer
operation
Work clamp home position
position
of Adjust the installation position of upper thread trimmer
assembly by moving the setting plate assembly.
・ Upper thread
adjustment
・Upper thread trimmer cutting depth adjustment
Remove any scratches and burrs, and adjust the upper
thread trimmer M to open when the projection is
pressed with a force of 4N or less.
Move the upper thread trimmer driving link so that it
stops at the face plate. In this position, tighten the bolts
so that the small slot in the upper thread trimmer lever
and the edge of the washer are aligned.
Adjust so that the cam opens the stop plate properly.
Adjust the timing so that the upper thread trimmer
gradually start opening when the feed mechanism
moves about 1.5 - 2.5 mm.
Apply grease to the inclined face of the opening cam.
After the home position has been detected, press the
THREAD key to lower the work clamp, and then adjust
the distance between the upper thread trimmer and the
center of the needle to 5.5 - 6.0 mm.
HE-800B
11. TROUBLESHOOTING
Remedy
trimmer longitudinal
Aligned
Upper thread
trimmer lever
Washer
5.5 - 6.0 mm
(Continued on next page)
Page
position
98, 99
4005Q
–
4010Q
97
4011Q
102
101
101
–
4012Q
160