Brother KE-430F Service Manual page 180

17. TROUBLESHOOTING
Problem
Upper thread is not
trimmed.
Thread jamming.
Poor seam finish on
reverse side of
material.
Incorrect thread
tightness.
Machine does not
operate when power is
turned on and foot
switch is depressed.
170
Cause
Movable knife is blunt.
Fixed knife is blunt.
Movable knife does not pick up the
thread.
The movable knife does not pick up the
thread because of skipped stitches at
the sewing end.
Movable knife position is incorrect.
Sub-tension is too weak.
Thread take-up spring tension and
height are incorrect.
Incorrect needle and rotary hook timing.
Shuttle race thread guide
separating the threads.
Shuttle race thread guide is separating
the threads insufficiently.
Upper thread is not properly tight.
Uneven needle thread.
Needle thread is too long.
Needle is striking the button. (BE-438F)
Upper thread tension is too weak.
Lower thread tension is too weak.
Thread take-up spring tension and
height are incorrect.
Machine head switch does not work.
KE-430F, BE-438F
Remedy
Replace the movable knife.
Sharpen or replace the fixed knife.
Adjust the position of the shuttle race
thread guide.
Adjust the needle bar lift amount.
Refer to "Skipped stitches occur".
Adjust the position of the movable
knife.
Turn the sub-tension nut to adjust the
tension.
Adjust the tension and height of the
thread take-up spring.
Adjust the needle bar lift amount.
is not Adjust the position of the shuttle race
thread guide.
Adjust the position of the shuttle race
thread guide.
Adjust the upper thread tension.
Adjust the sub-tension.
Adjust the sub-tension.
<When using the thread nipper
device>
Turn the tension nut to adjust the upper
thread trailing length to 35 – 38 mm.
Refer to "5-5. Checking the sewing
pattern (BE-438F)" in the CD instruction
manual.
Adjust the upper thread tension.
Adjust the lower thread tension.
Adjust the tension and height of the
thread take-up spring.
Check if the machine head switch cord
is disconnected.
Adjust the position of the switching
plate.
Replace the machine head switch if it is
broken.
Ref.
P. 111
P. 111
P. 108
P. 107
P. 169
P. 110
CD
Instruction
manual
P. 105
P. 107
P. 108
P. 108
CD
Instruction
manual
CD
Instruction
manual
CD
Instruction
manual
CD
Instruction
manual
CD
Instruction
manual
CD
Instruction
manual
P. 105
CD
Instruction
manual
P. 127