Unraveling Of Thread Trimmed By Upper Thread Trimmer Assembly - Brother HE-800A Service Manual

5-14. Unraveling of thread trimmed by upper thread trimmer assembly

Cause
Upper thread trimmer
assembly
Tension release
timing
Work clamp
Check
Installation position of
upper thread trimmer
assembly
Burr on tips of upper
thread trimmer M and
upper thread trimmer U.
Opening amount of
zigzag tension discs and
bar tack tension discs
(particularly zigzag
tension discs)
Work clamp lifting speed
Remedy
Adjust the installation position of upper thread
trimmer assembly by moving the setting plate
assembly.
⋅ Upper thread trimmer longitudinal position adjust-
ment
⋅ Upper thread trimmer cutting depth adjustment
Polish with buff or replace the part.
⋅ Adjust the zigzag tension discs by moving the
tension stud bracket in and out.
⋅ Adjust the bar tack tension discs opening amount
to 0.5 - 1.0 mm by removing the top cover and
moving the tension release cam.
Zigzag tension
Use memory switch No. 02 to retard the work clamp
lifting speed.
HE-800A
5. TROUBLESHOOTING
4005Q
Check burr on upper
side here
Check burr here
4009Q
Tack tension
0.5 - 1 mm
4008Q
Page
91, 92
-
100
Instruction
manual
113