Upper Thread Mis-Winding; Work Clamp Is Not Raised (1) Pulse Motor Stepping Sound Cannot Be Heard - Brother HE-800A Instruction Manual

１６-２２. Upper thread mis-winding
Cause
Upper thread
scissors
Stitch quality
Work clamp
Underlay
Bar tack
１６-２３. Work clamp is not raised (1) Pulse motor stepping sound cannot be heard
Cause
Work clamp lifting
height setting
Presser lifter pulse
motor
Treadle
Check
Installation height
Upper thread scissors
gradual opening timing
Upper thread scissors
opening timing
Upper thread trimmer
assembly movement
Lateral position of upper
thread scissors
Upper thread tension
Zigzag width in the zigzag
stitch portion
Uneven material feeding
Underlay is being sewn.
Straight bar tacking is
being carried out
Check
Check the work clamp
lifting height setting.
Cord connection
Presser lifter pulse motor
driving gear
Does the work clamp rise
when the treadle is
depressed backward?
Remedy
Adjust the upper thread scissors installation height.
Adjust the timing so that the upper thread scissors
gradually start opening when the feed mechanism
moves about 1.5 - 2.5 mm.
Adjust so that the cam opens the stop plate properly.
Polish blade of upper thread trimmer M and upper
thread guide with buffer.
Check for burrs on the top surface of upper thread
trimmer M.
Replace the parts.
Adjust the lateral position of the upper thread
scissors.
Approx. 1 mm
Decrease tension to such a degree that it does not
influence stitch quality.
Use parameter number 05 to increase the zigzag
width to such a degree that it does not influence the
seam shape.
Increase work clamp pressure. (Press material so
that the material is properly stretched.)
When using knits or woven materials, replace the
parts with the –3 specification parts:
Length feed plate (for specification -3), work clamp
assembly (for knits), needle plate 1.2 (for
specification -3)
Use parameter number 52 to reduce the underlay
sewing start pitch to about 0.5.
Use parameter number 48 to reduce the underlay
sewing speed.
* If sewing knitted wear, the upper thread may get
caught easily, so you may need to process the
end of the thread.
When carrying out straight bar tacking, the upper
thread may get caught easily, so you may need to
process the end of the thread.
Remedy
Change the settings of memory switch Nos. 04, 05,
06.
Check the cord connections and contacts.
Check if the drive gear screw is loose.
If it rises, use memory switch No. 08 to adjust the
threshold value for lowering the work clamp to a
positive value.
HE-800A
16. TROUBLESHOOTING
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