DB2-B727, B728
56
12. TROUBLESHOOTING
12. TROUBLESHOOTING
• Please check the following points before calling for repairs or service.
• If the following suggestions do not solve the problem, turn off the machine power supply and contact your nearest
Brother service center.
CAUTION
Turn off the power switch and disconnect the power cord before carrying out troubleshooting, otherwise the
machine will operate if the treadle is pressed by mistake, which could result in injury.
* When using a clutch motor, the motor will keep turning even after the power is switched off as a result of
the motor’s inertia. Wait until the motor stops fully before starting work.
Problem Possible cause Page
¡ Is the upper thread tension too weak, or is the lower thread tension
too strong?
Adjust the upper thread tension or lower thread tension.
¡ Is the needle and feed mechanism timing correct?
Advance the needle timing.
1. Upper thread is not tight.
27
36
27
–
18
22 · 23
29
–
32
35
38
39
2. Lower thread is not tight.
¡ Is the lower thread tension too weak, or is the upper thread tension
too strong?
Adjust the lower thread tension or upper thread tension.
3. Skipped stitches occur while
sewing
¡ Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or broken, replace the needle.
¡ 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 presser foot pressure too weak?
Adjust the presser foot pressure.
¡ Is the needle too thin?
Replace the needle with a needle that is one rank thicker.
¡ Is the presser foot too high?
Adjust the height of the presser foot.
¡ Is the needle and rotary hook timing incorrect?
Adjust the height of the needle bar.
Adjust the needle and rotary hook timing.
¡ Is the thread tension spring too weak?
Adjust the tension of the thread tension spring.
0573M
0470M
0574M
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