Needle Breakage - Brother HE-800A Service Manual

Cause
Longitudinal feed
arm
Needle bar height in
machine stopped
condition
Cam
Opening cam
Work clamp home
position sensor
Upper thread trimmer
lever

5-17. Needle breakage

Cause
Needle
Rotary hook
Check
Installation position of the
longitudinal feed arm
Upper shaft pulley
stopping position
Upper thread scissors
opening timing
Upper thread scissors
gradual opening timing
Upper thread scissors
operation
Work clamp home
position sensor position
Upper thread trimmer
lever operating force
Check
Needle installation
Needle bar height and
needle bar lift amount
Gap between needle and
rotary hook
Remedy
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 the needle up sensor position.
Adjust so that the cam opens the stop plate properly.
Adjust the timing so that the upper thread scissors
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 setting the sewing machine to the home
position, press the RESET key and then adjust the
distance between the upper thread trimmer and the
center of the needle when the work clamp is lowered
to 5.5 - 6.0 mm.
Adjust so that the upper thread trimmer lever opens
gently when the stop plate is separated from the
stopper.
Remedy
As viewed from the direction of the face plate, insert
needle fully into needle bar so that the notched part
of needle faces frontward.
Adjust the needle and hook timing.
1. Adjust the needle bar height to "1" on the gauge.
2. Adjust the needle bar lift amount to "2" on the
gauge.
Adjust the gap between needle and rotary hook to
0.01 - 0.08 mm. (Adjust to as large as possible
without causing skipped stitches to occur.)
* Check that rotary hook point does not strike needle
in zigzag motion.
HE-800A
5. TROUBLESHOOTING
Aligned
Upper thread
trimmer lever
Washer
4011Q
5.5 – 6.0 mm
4012Q
4013Q
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