HE-800A
5. TROUBLESHOOTING
107
Cause
Check
Remedy
Page
Lower thread tension
Adjust the lower thread tension appropriately.
Instruction
manual
Bobbin holder spring
Add tension to the bobbin holder spring.
-
Lower thread retainer
position
Adjust the lower thread retainer position.
* Adjust lower thread retainer so that a 35 – 40 mm
thread leader is left after trimming.
96
Bobbin presser position
Adjust the bobbin presser position.
98
Bobbin insertion
Insert the bobbin correctly.
Instruction
manual
Lower thread (bobbin
slip)
Work clamp lifting speed
Reduce the setting for memory switch No. 02.
Instruction
manual
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
Check
Remedy
Page
Lower thread retainer Lower thread retaining
amount
Adjust the lower thread retaining amount.
96
Lower thread clamp
opening timing
Adjust so that the lower thread clamp plate opens
when the feed mechanism moves 6 – 7 mm.
97
Lower thread clamp
Lower thread clamping
force
⋅
If the lower thread clamp and lower thread presser
are bent, replace them.
⋅
Check that the screws are tightened.
-
4003Q
3999Q
Lower thread
clamp
Screw
4001Q
Add tension to the spring by the same
amount that the bobbin tab is projecting
Make a gap
4002Q
35 - 40mm