Troubleshooting; Sewing - Brother S-7200A Service Manual

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.
Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet
before opening the face plate of the control box. Touching areas where high voltages are present can result in
severe injury.
Turn off the power switch and disconnect the power cord before carrying out troubleshooting.
The machine may operate if the treadle is depressed by mistake, which could result in injury.

12-1. Sewing

Problem
1 Upper thread is not tight.
2 Lower thread is not tight.
3 Loops appear in seam.
4 Skipped stitches
while sewing
53
Is the upper thread tension too weak, or is the lower thread tension
too strong?
Adjust the upper thread tension or lower thread tension.
0573M
Is the lower thread tension too weak, or is the upper thread tension
too strong?
Adjust the lower thread tension or upper thread tension.
0574M
Is the thread path not smooth enough?
Use a file with a fine grain or sandpaper to polish smooth the
thread path.
Is the bobbin not turning smoothly?
Pull out the lower thread to check that there is no slackness in
the thread tension, or replace the bobbin or bobbin case.
0977M
occur 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 thread take-up spring too weak?
Adjust the tension of the thread take-up spring.
0470M
DANGER
CAUTION
Possible cause
S-7200A
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