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LH4-B800E
5 - 11
5. Troubleshooting guide
Cause
Check
Solution
page
Upper thread
trimmer
assembly
Upper thread trimmer
assembly position
Refer to "5-8. Needle thread runout"
Upper thread scissors
operating force
Adjust so that scissors
M open when the
projection is pressed
with a force of 4 N or
less, and remove any
scratches and burrs.
-
Longitudinal
feed arm
Longitudinal feed arm
position
Adjust properly
Move the upper thread trimmer
driving link so that it stops at the
face plate.
In this position, tighten the eye bolt
so that the small slot in the upper
thread trimmer lever and the edge
of the washer are aligned.
4-13
Thread take-
up position in
stopped
condition
Upper shaft pulley
stopping position
Refer to "5-8. Needle thread runout Machine stopping position"
Cam
Upper thread scissors
opening timing
adjustment
The cam should open
the stop plate properly.
Refer to "4-13-8. Adjusting the upper thread
scissors opening timing"
Opening cam
Upper thread scissors
gradual opening timing
Refer to "4-13-7. Adjusting the upper thread scissors gradual opening
timing"
Presser foot
home
position
sensor
Presser foot home
position sensor
position
After setting to the
home position, press
the RESET key to
lower the presser foot,
and adjust so that the
distance from the
upper thread trimming
scissors to the center
of the needle is 5.5 -- 6
mm at this time.
4-5
Upper thread
trimmer lever
Upper thread trimmer
lever operating force
The upper thread
trimmer lever should
gently open when the
stop plate is separated
from the stopper.
-
5-11. Needle strikes upper thread trimmer
Aligned
Upper thread
trimmer lever
Washer
4 N
5.5 - 6 mm
Summary of Contents for LH4-B800E
Page 55: ...LH4 B800E 2 30 2 DISASSEMBLY ...
Page 87: ...LH4 B800E 3 32 3 ASSEMBLY ...