Brother NX600 Service Manual page 209

Repair Manual
Problem Primary factors and causes
14 Needle thread Bad needle stop position
lever operation
• NP sensor damage
catches part way
• Grease or dirt adhering to
through.
NP sensor
• Rotation shutter damage
• Bad needle thread block
rotational position
Needle thread Needle thread lever knob
lever knob out of attachment loose
place
15 Either upper thread Upper thread tension is high/low
tension or lower (check the screw lock on the
thread tension tension disk tension adjustment
screw).
AT pulse motor connector
disconnection
Bad AT pulse motor
Bad main PCB
Lower thread tension is too
strong / weak
(Check inner rotary hook screw
lock)
Upper thread or lower thread
unsuitable
16 Actual sewing
• Needle Needle breaks.
breakage
• Inner rotary hook slips
because the inner rotary
hook and inner rotary hook
bracket back/front overlap is
too small
• Inner rotary hook slips
because the inner rotary
hook and inner rotary hook
bracket vertical overlap is
too small
• Thread catches on thread
bobbin
(thread falls down to the
right because the spool
pressure is insufficient)
• Thread catches on spool
presser
(scratches on spool presser)
Needle catches and bends
before or after sewing.
• Thread Thread breakage.
breakage
• Thread catches on thread
stitch skipping
bobbin
(thread falls down to the
right because the spool
pressure is insufficient)
• Thread catches on spool
presser (scratches)
• Outer rotary hook scratches Replace outer rotary hook assy.
• Wrong thread guide path
Repair method
Replace NP PCB assy. (3-25)
Remove grease and dirt
Replace upper shaft assy. (3-5)
Adjust the needle thread block
(4-29)
Replace needle thread lever
knob
(3-40)
Upper thread tension with
Schappe Spun Sewing Thread
#60 is 0.53 - 0.62 N (53 - 62 g)
Insert connector securely
Plug connector securely in
Replace AT pulse motor
Replace main PCB
Lower thread tension with
Schappe Spun Sewing Thread
#60 is 0.1 – 0.12 N (10 – 12 g)
(4-16)
Replace upper thread or lower
thread
Adjust inner rotary hook bracket
assy. position
(4-28)
Adjust inner rotary hook bracket
assy. position
(4-28)
Rethread
Replace spool presser
Needle replacement
Rethread
Replace spool presser
(3-70)
Rethread
Items for Inspection method
Inspection and standards
Upper thread Check that the thread
tension tension is good during
actual sewing.
Lower thread
tension
Actual sewing Check that the needle
(straight line / does not break during
zigzag) actual sewing.
Check that there are no
abnormal sounds
during actual sewing.
Check that the thread
does not break during
actual sewing.
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