Brother HE-800A User Manual page 108

Cause
Upper thread feeding Thread take-up amount
Rotary hook Needle bar height and
needle bar lift amount
Thread chips on rotary
hook edge
Machine stopping Upper
position stopping position
Lower thread Lower
amount
Lower thread snapping
Lower
opening timing
Sewing start speed Slow speed
Slow start stitches
Bar tack thread Bar tack thread tension is
tension too strong.
Upper thread Upper thread breaks.
breakage
Check
Loosen the screw to decrease thread take-up
amount so that upper thread does not pull out of
scissors assembly at the sewing start.
Adjust the needle and hook timing.
1. Adjust the needle bar height to "1" on the gauge.
2. Adjust the needle bar lift amount to "2" on the
gauge.
Remove thread chips.
shaft pulley Adjust the needle up sensor position.
thread retaining Adjust the lower thread retaining amount.
Use memory switch No. 02 to retard the work
clamp lifting speed.
Process the lower thread retainer, lower thread
clamp and lower thread presser plate so that they
do not snap the lower thread.
thread clamp Adjust so that the lower thread clamp plate opens
when the feed mechanism moves 6 – 7 mm.
Use parameter number 60 to reduce the slow
speed.
Use parameter number 59 to increase the number
of slow start stitches.
Make the bar tack tension as weak as possible.
Refer to "16-1. Upper thread breakage".
HE-800A
Remedy
Increase
Decrease
16. TROUBLESHOOTING
Page
Screw
-
4000Q
72, 73
-
77
-
4003Q
79
77
44
44
62
92, 93
100