Causes Of Troubles And Troubleshooting; Sewing Machine Troubleshooting - SunStar KM-560 User Manual

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Causes of Troubles and Troubleshooting

1) Sewing machine troubleshooting

No Symptom
Direction and height of
needle
Needle
1 Needle breaks
Timing of the feed dog
Gap between needle and
hook
Threading method
Needle
Direction and height of
needle
Upper thread tension
Lower thread tension
2
Thread breaks
Working capacity of take-
up lever spring
Hook
Feed dog
Needle plate
Thread tension
Thread take up spring
Poor thread
3
tension
adjustment
Gap between opener and
hook
Direction and height of
needle
Needle
Threading
Hook timing
Gap between the needle
Upper thread
and the hook
falls out when
4 starting to sew
Remaining upper thread
or sewing is length after trimming
skipped
Lower thread holder
Check the up-stop
position of the needle
Check the oil felt tension
of upper thread
32
Checkpoints
Needle is inserted into wrong position.
Needle is bent
Bad timing of feed dog
Bad timing of needle and hook
The heads of the needle and the hook
interfere each other.
Wrong threading
Bent needle
The direction and height of the needle
inserted is wrong.
Too tight upper thread tension
Too tight lower thread tension
Too much working capacity
There is a scratch on the hook edge
There is a scratch on the needle hole of the
feed dog
There is a scratch on the thread case and
around the needle plate.
Upper and lower thread tensions are bad.
Thread take up spring tension is
inadequate.
The gap between the opener and hook is
inadequate.
Needle is inserted into wrong direction.
Needle is bent
Wrong direction
The timing between the needle and hook is
bad.
Needle and hook head are too far apart.
The length of the remaining upper thread is
too short.
After trimming, lower thread holder does not
hold the lower thread.
Due to problems in the up-stop position of
the needle, the thread take up lever pulls
the upper thread out of the needle when the
sewing starts.
The upper thread oil felt is pressing the
thread too strongly.
Root cause
Reinsert the needle correctly and push in to
its highest level.
Change the needle.
Adjust the timing of feed dog.
Adjust the timing of needle and hook.
Adjust the location of the hook.
Thread the needle correctly.
Change the needle.
Insert the needle correctly.
Reduce the tension of upper thread.
Reduce the tension of lower thread.
Adjust the stroke level.
Remove the scratch on the hook edge.
Remove the scratch on the feed dog.
Remove the scratch on the needle plate.
Adjust the upper and lower thread tension.
Adjust the thread take up spring tension.
Adjust the gap between the opener and
hook.
Reinsert the needle correctly and push in to
its highest level.
Change the needle.
Insert the thread in the right way.
Adjust the timing between the needle and
hook.
Adjust the position of the hook.
Increase the adjustment volume of the
upper thread on the control box.
Adjust the location and tension of the lower
thread holder.
Readjust the needle' s up-stop film position.
Adjust the felt tension.
Corrective action