Brother CS8000 Series Service Manual page 204

Repair Manual
Problem
11 Sewing sounds
Inappropriate sounds
• Thread take-up Thread take-up lever shaft noise
noise
• Loose screws
• Outer rotary Outer rotary hook noise
hook vertical
rattle noise
• Outer rotary hook vertical rattle
• Upper shaft Upper shaft noise
noise
• Upper shaft bushing out of oil
• Rattle along the thread take-up
• Motor noise Motor noise
• Belt too tight
• Motor fan noise
• Lower shaft Lower shaft noise
noise
• Lower shaft axial rattle
• Joint noise Joint noise
• Lower shaft joint rattle
• Vertical feed Vertical feed cam noise
cam noise
• Vertical feed cam out of oil
• Horizontal feed Horizontal feed arm noise
arm noise
• Bad horizontal feed arm
• Noise from Noise from contact between needle
contact between plate and feed dog
needle plate and
feed dog
• Back/front and left/right rattle in
• Bad feed dog front-back position
• Bad feed dog left-right
• Slippage in needle plate
• Needle contact Noise of contact between needle and
noise outer rotary hook
• Bad needle interference
• Loose needle interference
12 Threading not Thread pushed out at the hook end.
possible.
• Vertical slippage in needle
(threader hook)
Hook extends beside the hook.
• Large gap between right side of
• Needle curvature
• Needle slant (hole slant with
• Hook assy. disconnection
• Vertical slippage in needle
Does not go into needle hole because
of hook tip curvature.
Threading impossible even though
hook goes into needle hole.
When the threading Needle thread shaft tangling
lever returns, it stops
part way through.
Bad thread guide shape
Hook guide and hook release plate
touch
Bad lever guide shaft shape
Needle thread shaft and top gap too
small
6 - 4
Primary factors and causes
counter weight shaft
feed dog
adjustment
adjustment
attachment
adjustment
adjustment screw
thread block
needle and hook guide
slanted attachment of needle
block)
thread block
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Repair method
Retighten the thread take-up lever
shaft (3-49)
Reattach outer rotary hook (3-74)
Lubricate the sliding surfaces of the
bushing and thread take-up counter
weight
Reattach the thread take-up counter
weight (3-54)
Readjust the motor belt (4-5)
Replace main motor (3-31)
Reassemble the lower shaft (3-71)
Reassemble the lower shaft joint
(3-71)
Lubricate vertical feed cam
Replace horizontal feed arm (3-69)
Reattach the feed dog assy.(3-77)
Adjust feed dog front and back (4-19)
Readjust feed dog left and right
(4-19)
Reattach needle plate (3-77)
Adjust needle interference (4-16)
Readjust needle interference (4-16)
Readjust the needle thread block
(4-23)
Replace hook assy. (3-58)
Needle replacement
Replace needle bar (3-61)
Replace hook assy. (3-58)
Readjust the needle thread block
(4-23)
Replace hook assy. (3-58)
Replace needle bar supporter assy.
(3-58)
Replace hook assy. (3-58)
Replace hook assy. (3-58)
Replace lever guide shaft (3-57)
Replace needle bar supporter assy.
(3-58)
Items for Inspection method and
Inspection standards
Operating noise There should be no
abnormal noise at fast,
middle and slow speed in 3
point drop (test mode 3).
Threading function When threading is carried
out with Schappe Spun
Sewing Thread #60 / #11
needle and Schappe Spun
Sewing Thread #30 / #16
needle, the threading lever
should move smoothly and
threading through the
needle hole should be
possible. (4-23)