S-7200C
14. TROUBLESHOOTING
64
Problem Possible
cause
Page
5 Skipped stitches at sewing
start
Thread unravelling at
sewing start
y
Is the thread take-up spring tension too strong?
Reduce the tension of the thread take-up spring.
y
Is the thread take-up spring operating range too large?
Lower the position of the thread take-up spring.
y
Are the trailing lengths of the upper threads too short after thread
trimming?
Adjust the pretension.
y
Are the threads not being trimmed cleanly?
Sharpen the fixed knives, or replace the fixed and movable
knives if necessary.
y
Is the needle too thick?
Try using a needle with a count that is one lower than the
current needle.
y
Is the length of thread trailing out from the bobbin case after thread
trimming too short?
If the bobbin is spinning loosely, replace the anti-spin spring in
the bobbin case.
y
Is the sewing speed too fast at the sewing start?
Use the slow start feature. (G50 operation panel)
Set so that slow start is enabled. (G10 operation panel)
y
Is the needle up stop position too high?
Adjust the needle up stop position.
56*
56*
44
*
15
27*
35*
28, 39*
6 Uneven
seam
y
Is the presser foot pressure too weak?
Adjust the presser foot pressure.
y
Is the feed dog too low?
Adjust the feed dog height.
y
Is the bobbin scratched?
If the bobbin is damaged, smooth it with an oiled grindstone or
replace it.
44
58*
7 Large degree of puckering
(excess tension)
y
Is the upper thread tension too strong?
Make the upper thread tension as weak as possible.
y
Is the lower thread tension too strong?
Make the lower thread tension as weak as possible.
y
Is the needle tip blunt?
Replace the needle if it is blunt.
y
Is the needle too thick?
Replace with as thin a needle as possible.
y
Are the thread take-up spring tensions too strong?
Make the thread take-up spring tension as weak as possible.
y
Is the thread take-up spring operating range too large?
Lower the position of the thread take-up spring to as low a
position as possible.
y
Is the presser foot pressure too strong?
Adjust the presser foot pressure.
y
Is the sewing speed too fast?
Use the sewing speed control keys to gradually reduce the
sewing speed. (G50 operation panel)
Gradually reduce the maximum sewing speed (G10 operation
panel)
y
Is the angle of the feed dog correct?
Tilt the front of the feed dog down slightly.
43
43
56*
56*
44
20
38*
59*
0749M
0473M
0978M