Brother S-7780A Instruction Manual page 70

6. STANDARD ADJUSTMENTS
Lowest position of
needle bar
Reference
line (a)
Direction of cam
rotation
-
0.5mm 1.0mm
61
Raised 5mm
Reference
line (b)
Should not touch
1790D
<Thread trimming cam position adjustment>
1. Raise the needle bar 5 mm from its lowest position so that
the reference line (b) is aligned with the bottom edge of
the needle bar bush, and then push the plunger (1) of the
thread trimmer solenoid in the direction of the arrow with
your finger.
Adjust the position of the thread trimmer cam (2) at this
time so that the roller shaft (4) of the thread trimming cam
lever assembly (3) touches the hollow (c) of the thread
trimmer cam (2) and so that the clearance between the
edge of the thread trimmer (2) and the roller (4) is 0.5 to
1.0 mm, and then tighten the set screw (5). (Fig. [A])
2. Check that the edge of the thread trimmer cam (2) and the
roller shaft (4) do not touch when the roller shaft (4)
returns to the right. (Fig. [B])
* Tighten the two set screws (5) to approximately 4 N.m.
S-7780A