HE-800B
11. TROUBLESHOOTING
81
11-4. 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
Items with a “*” in the “Page” column should only be handled by a qualified technician.
Cause Check
Remedy
Page
Lower thread retainer
Lower thread retaining
amount
Adjust the lower thread retaining amount.
*
Lower thread clamp
opening timing
Adjust so that the lower thread clamp plate opens
when the feed mechanism moves 6 - 7 mm.
70*
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.
*
11-5. Uneven seams (3) ……Seam lifts up at the sewing start
Seam lifts up and does not tighten at the sewing start
Items with a “*” in the “Page” column should only be handled by a qualified technician.
Cause Check
Remedy
Page
Upper thread trimmer
gradual opening timing
Adjust the timing so that the upper thread trimmer
gradually start opening when the feed mechanism
moves about 1.5 - 2.5 mm.
69*
Upper thread trimmer
Upper thread trimmer
operation
Apply grease to the inclined face of the opening cam.
69*
Upper thread feeding
Thread take-up amount
Loosen the screw to decrease thread take-up amount
so that upper thread does not pull out of trimmer
assembly at the sewing start.
*
4003Q
3999Q
Lower thread
clamp
Screw
4000Q
Screw
Increase
Decrease