Brother B-500, Service Manual

Page: 190 / 211

6 - 4
Repair Manual
8 Even if the drop
knob is returned to
the left, the feed
dog stays down
and does not return
(no material feed) Drop knob damage Replace drop knob (2-49) (3-61) Drop function With the needle bar in
the top position and the
drop lever to the right,
check that the feed dog
is down, and moving
the drop lever to the left
and turning the pulley
one turn by hand, that
the feed dog returns to
the original height.
Operation trouble of virtical lever Adjust vertical lever operation
(2-49) (3-61)
Bad vertical adjuster screw assy. Replace vertical adjuster screw
assy. (2-48) (3-61)
Vertical rod misalignment Adjust vertical adjuster screw
assy.
(2-48) (3-61)
Vertical feed cam surface out of
grease Apply grease (3-61)
9 Bad pattern shape
Blocked by satin
pattern
Fine BH stitches
Straight line feed
too small
Stitches uneven
Vertical rattle in feed dog
Loose feed dog attachment
screw Adjust feed dog attachment
screw
(4-21)
Back/front rattle
in feed dog With the feed dog up,
check that there is no
rattle when the feed
dog is lightly moved
back and forth.
Vertical rattle in feed bar Reattach feed bar
(2-48) (3-62)
Damage to horizontal feed cam Replace lower shaft assy.
(2-52) (3-57)
Rattle in feed adjuster assy. Reattach feed adjuster assy.
(2-53) (3-55)
Horizontal rattle in feed dog
Loose feed dog attachment
screw Adjust feed dog attachment
screw
(4-21)
Left-right rattle in
feed dog With the feed dog up,
check that there is no
rattle when the feed
dog is lightly moved left
and right.
Horizontal rattle in feed bar Reattach feed bar
(2-48) (3-62)
Bad feed dog height adjustment Adjust feed dog height (4-22) Feed dog height With the feed dog in the
highest position, check
that the feed dog
comes out 0.9 – 1.1
mm from the top of
needle plate A at the
center of the needle
plate A needle hole.
(4-22)
Bad feed dog front-back position
adjustment Adjust feed dog front-back
position
(4-21)
Feed dog front-
back position Rotating the pulley by
hand in a 0 mm feed
position (test mode 8)
with the feed dog
aligned with needle
plate A, check that the
gap between the
middle tooth and the
needle plate is 3.2 – 3.8
mm.
(4-21)
Bad feed dog left-right position
adjustment Adjust feed dog left-right
position
(4-21)
Feed dog left-
right position Confirm that the feed
dog has a 0.3 – 0.7 mm
gap left and right
parallel to the needle
plate A needle hole.
(4-21)
Bad feed adjustment Adjust feed (4-17) Feed Check that the
difference in forward
and reverse feed is
within 5 mm in the feed
forward/reverse
adjustment.
(4-17)
Problem Primary factors and causes Repair method Items for
Inspection
Inspection method
and standards