Brother International S-7200B Instruction Manual - English - Page 66

Is the upper or lower thread tension too weak or too strong?, gauge window, add more oil.

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14. TROUBLESHOOTING Problem 9 Lower thread is tangled at the sewing start. Spinning of bobbin during thread trimming Lower thread 0751M 10 Upper and lower threads are breaking. 0471M 11 Incorrect thread trimming (Upper and lower threads are both not being trimmed) 12 Incorrect thread trimming (Upper thread or lower thread is not being trimmed) Possible cause Is the bobbin spinning direction correct when the lower thread is being pulled? Set the bobbin so that it turns in the opposite direction to the rotary hook. Is there too much thread wound onto the bobbin? The bobbin winding amount should not be more that 80 %. Is the anti-spin spring attached? Attach the anti-spin spring. 2124M Is the bobbin turning smoothly? If the bobbin is not turning smoothly, replace the bobbin. Is a bobbin other that the light-alloy bobbins specified by Brother being used? Use only bobbins which are specified by Brother. Is the needle bent or is the needle tip broken? Replace the needle if it is bent or broken. Is the needle properly installed? If it is incorrect, install the needle correctly. Is the machine properly threaded? If it is incorrect, thread the thread correctly. Is the rotary hook sufficiently lubricated? (-[]0[], []3[] specifications) If the oil gauge is down to the lower reference line in the oil gauge window, add more oil. Is the upper or lower thread tension too weak or too strong? Adjust the upper thread or lower thread tension. Is the upper thread may be loose because the thread take-up spring operating range is too small? Adjust the position of the thread take-up spring. Is the rotary hook, feed dog or other part damaged? If they are damaged, smooth them with an oiled grindstone or replace the damaged parts. Is the thread path damaged? If the thread path is damaged, smooth it with sandpaper or replace the damaged part. Is the fixed knife or movable knife damaged or worn? Replace the fixed knife or the movable knife. Is the needle properly installed? If it is incorrect, install the needle correctly. Is the fixed knife or movable knife blunt? Replace the fixed knife or the movable knife. Page 14 14 13 13 13 15 8 37 50* * * * 13 * 59 S-7200B

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S-7200B
14. TROUBLESHOOTING
59
Problem
Possible cause
Page
9
Lower thread is tangled at
the sewing start.
Spinning of bobbin during
thread trimming
y
Is the bobbin spinning direction correct when the lower thread is
being pulled?
Set the bobbin so that it turns in the opposite direction to the
rotary hook.
y
Is there too much thread
wound onto the bobbin?
The
bobbin
winding
amount should not be
more that 80 %.
y
Is
the
anti-spin spring attached?
Attach the anti-spin spring.
y
Is the bobbin turning smoothly?
If the bobbin is not turning smoothly, replace the bobbin.
y
Is a bobbin other that the light-alloy bobbins specified by Brother
being used?
Use only bobbins which are specified by Brother.
14
14
13
13
10
Upper and lower threads
are breaking.
y
Is the needle bent or is the needle tip broken?
Replace the needle if it is bent or broken.
y
Is the needle properly installed?
If it is incorrect, install the needle correctly.
y
Is the machine properly threaded?
If it is incorrect, thread the thread correctly.
y
Is the rotary hook sufficiently lubricated? (-[]0[], []3[] specifications)
If the oil gauge is down to the lower reference line in the oil
gauge window, add more oil.
y
Is the upper or lower thread tension too weak or too strong?
Adjust the upper thread or lower thread tension.
y
Is the upper thread may be loose because the thread take-up spring
operating range is too small?
Adjust the position of the thread take-up spring.
y
Is the rotary hook, feed dog or other part damaged?
If they are damaged, smooth them with an oiled grindstone or
replace the damaged parts.
y
Is the thread path damaged?
If the thread path is damaged, smooth it with sandpaper or
replace the damaged part.
13
15
8
37
50*
*
*
11
Incorrect thread trimming
(Upper and lower threads
are
both
not
being
trimmed)
y
Is the fixed knife or movable knife damaged or worn?
Replace the fixed knife or the movable knife.
*
12
Incorrect thread trimming
(Upper thread or lower
thread
is
not
being
trimmed)
y
Is the needle properly installed?
If it is incorrect, install the needle correctly.
y
Is the fixed knife or movable knife blunt?
Replace the fixed knife or the movable knife.
13
*
Lower
thread
0751M
0471M
2124M