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Problem
5.
Skipped stitches at sewing
start
Thread unravelling at sewing
start
6.
Uneven seam
7.
Large degree of puckering
(excess tension)
8.
Seam position is incorrect.
● Are the thread take-up spring tensions too strong?
Reduce the tension of the thread take-up springs.
● Is the thread tension spring operating range too large?
Lower the position of the thread tension spring.
● Are the trailing lengths of the upper threads too short after thread
trimming?
Adjust the pretension.
● Are the threads not being trimmed cleanly?
Sharpen the fixed knives, or replace the fixed and movable knives if
necessary.
● Is the needle too wide?
Try using a needle with a count that is one lower than the current
needle.
● Is the length of thread trailing out from the bobbin case after thread
trimming too short?
If the bobbin is spinning loosely, replace the stopper spring in the
bobbin case.
● Is the sewing speed too fast at the sewing start?
Use the slow start feature.
● Is the needle up stop position too high?
Adjust the needle position sensor.
● Is the presser foot pressure too weak?
Adjust the presser foot pressure.
● Is the feed dog too low?
Adjust the feed dog height.
● Is the bobbin scratched?
If the bobbin is damaged, smooth it with an oiled grindstone or
replace it.
● Is the upper thread tension too strong?
Make the upper thread tension as weak as possible.
● Is the lower thread tension too strong?
Make the lower thread tension as weak as possible.
● Are the thread take-up spring tensions too strong?
Make the thread take-up spring tension as weak as possible.
● Is the thread tension spring operating range too large?
Lower the position of the thread tension spring to as low a position
as possible.
● Is the presser foot pressure too strong?
Adjust the presser foot pressure.
● Is the sewing speed too fast?
Reduce the sewing speed slightly.
● Is the angle of the feed dog incorrect?
Tilt the front of the feed dog down slightly.
● Is the presser foot pressure too strong?
Adjust the presser foot pressure.
● Is the angle of the feed dog incorrect?
Tilt the front of the feed dog up slightly.
● Is the needle and feed mechanism timing correct?
Retard the needle timing.
DB2-DD7100A
Possible cause
15. TROUBLESHOOTING
Page
99
99
88
96 • 97
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37 • 60
110
88
103
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87
87
99
99
88
43
104
88
104
107
144
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