Lower Thread Is Lifted Up At The Sewing Start - Brother HE-800A Service Manual

Cause
Lower thread (bobbin
slip)
5-4. Uneven seams (2) ...... Lower thread is lifted up at the sewing start
The end of the lower thread protrudes above the seam at the sewing start
Cause
Lower thread retainer Lower
Lower thread clamp
Check
Lower thread tension
Bobbin holder spring
Lower thread retainer
position
Bobbin presser position
Bobbin insertion
Work clamp lifting speed
Check
thread retaining
amount
Lower thread clamp
opening timing
Lower thread clamping
force
Remedy
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.
Reduce the setting for memory switch No. 02.
Remedy
Adjust the lower thread retaining amount.
Adjust so that the lower thread clamp plate opens
when the feed mechanism moves 6 – 7 mm.
⋅ If the lower thread clamp and lower thread presser
are bent, replace them.
⋅ Check that the screws are tightened.
Lower thread
clamp
HE-800A
5. TROUBLESHOOTING
4001Q
35 - 40mm
4002Q
4003Q
Screw
3999Q
Page
Instruction
manual
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Instruction
manual
Instruction
manual
Page
96
97
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