Uneven Seams (4); Uneven Seams (6); Uneven Seams (7) - Brother HE-800B Service Manual

11. TROUBLESHOOTING
11-6. Uneven seams (4) ...... Uneven sewing pitch at the sewing start
Bird's nests form at the sewing start, and after 5 - 6 mm the sewing pitch suddenly increases
Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Lower thread clamp
11-7. Uneven seams (5)......Poor rounding of seam
Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Thread tension
Threading
Stitch patterns
Tension release
11-8. Uneven seams (6) ...... Around rear tack or front tack
Items with a "*" in the "Page" column should only be handled by a qualified technician.
Cause
Tension release
Threading
Zigzag thread tension
Upper thread trimmer
11-9. Uneven seams (7) ...... Loose thread end at end backtack
Cause
Backtack shape
153
Check
Lower thread clamp
opening timing
Check
Zigzag thread upper thread
tension
Zigzag tension disc
opening
Lower thread tension
Upper thread threading
Lower thread threading
Purl stitch, whip stitch
Tension release timing
Check
Tension release timing
Upper thread threading
Lower thread threading
Zigzag tension disc
opening
Upper thread trimmer
operation
Check
Checking the number of
end backtack stitches
Checking the end backtack
width
Remedy
Advance the timing at which the lower thread clamp
starts to open.
Remedy
Adjust the upper thread tension appropriately.
・Check the opening of the zigzag tension discs.
・Replace the tension release solenoid.
Adjust the lower thread tension appropriately.
Thread the upper thread correctly.
Thread the lower thread correctly.
Set using parameter number 53.
Use parameter numbers 54 to 57 to set the timing for
changing the thread tension.
Remedy
Use parameter numbers 54 to 57 to set the timing for
changing the thread tension.
Thread the upper thread correctly.
Thread the lower thread correctly.
・Adjust the tension disc opening amount.
・Check the opening of the zigzag tension discs.
・Replace the tension release solenoid.
Apply grease to the inclined face of the opening cam.
Remedy
Adjust the setting values for parameter numbers 51
and 52.
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