Brother HE-800A - Manual (Page 115)

HE-800A
16. TROUBLESHOOTING
107
ውዒ-ዎዐ. Work clamp is not raised (2) Pulse motor stepping sound can be heard
Cause Check Remedy Page
Machine stopping
position Rotary hook touches
lower thread retainer at
the stop position Adjust the needle up stop position.
77
Work clamp lifting
speed is too fast. Work clamp lifting speed
setting Use memory switch No. 02 to retard the work clamp
lifting speed.
79
Interference between
upper thread scissors and
work clamp Check the standard adjustments with the upper
thread scissors removed.
* Be particularly careful when sewing joints.
75
Upper thread
scissors
Upper thread scissors
operation Apply grease to the inclined face of the opening
cam.
76
Interference between
fixed knife set, lower
thread clamp, lower
thread presser and lower
thread retainer. Repair or replace the parts.
-
Lower thread
trimmer
Rubbish, dust or thread
scraps present Remove all rubbish, dust and thread scraps from
the lower thread trimmer.
-
Loose screws Check for loose screws in
the upper thread trimmer,
lower thread trimmer and
work clamp lifter
mechanisms. Securely tighten all screws.
-
Work clamp lifting
height setting Check the work clamp
lifting height setting. Change the settings of memory switch Nos. 04, 05,
06.
* If the work clamp lifting height is too high, the
lower thread trimming operation will not be timed
together with the work clamp rising and the pulse
motor may go out of step.
79
Lower thread threading Insert the bobbin correctly and pass the lower
thread through the bobbin case correctly.
* If the bobbin is inserted back-to-front, it will spin
loosely and the presser lifter may go out of step.
60
Threading
Lower thread tension
Reduce the lower thread tension.
* If the lower thread tension is too strong, the motor
may go out of step.
Use memory switch No. 02 to reduce the work
clamp lifting speed setting to make the lifting speed
slower.
61
79
4021Q
Retainer
Inner rotary
hook presser
4022Q
Remove the shoulder
screw to check.
Lower thread
trimmer link A assembly
Lower thread
trimmer
connecting rod
4023Q
Buff this section to reduce the
thread retaining resistance.