Uneven Seams (1) - Brother HE-800B Service Manual

11. TROUBLESHOOTING
11-3. Uneven seams (1) ...... At the sewing start
Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Upper thread trimmer
Upper thread feeding
Lower thread (bobbin
slip)
151
Check
Installation height
Upper thread trimmer
opening timing
Upper thread trimmer
operation
Thread take-up amount
Lower thread tension
Bobbin holder spring
Lower thread retainer
position
Bobbin presser position
Bobbin insertion
Remedy
Adjust the upper thread trimmer installation height.
Adjust to an appropriate opening timing.
Apply grease to the inclined face of the opening cam.
Loosen the screw to decrease thread take-up amount
so that upper thread does not pull out of trimmer
assembly at the sewing start.
Decrease
Adjust the lower thread tension appropriately.
Add tension to the bobbin holder spring.
Add tension to the spring by the same
amount that the bobbin tab is projecting.
Make a gap
Adjust the lower thread retainer position.
* Adjust lower thread retainer so that a 35 - 40 mm
thread leader is left after trimming.
Adjust the bobbin presser position.
Insert the bobbin correctly.
HE-800B
Screw
Increase
4000Q
4001Q
35 – 40 mm
4002Q
Page
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INSTRUCTION
MANUAL CD
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INSTRUCTION
MANUAL CD