Troubleshooting; Troubleshooting During Sewing - Brother S-7220D Instruction Manual

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Troubleshooting

• Please check the following points before calling for repairs or service.
• Simplified details can be checked on the panel.
• If the following remedies do not fix the problem, turn off the power switch and consult a qualified technician or
the place of purchase.
• Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the
wall outlet before opening the control box cover. 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 these operations. The
machine may operate if the treadle is depressed by mistake, which could result in injury.

Troubleshooting during sewing

Items with a "*" in the "Page" column should only be checked by a qualified technician.
Problem
Upper thread is not tight.
Lower thread is not tight.
Loops appear in seam.
Skipped stitches occur
while sewing
DANGER
CAUTION
Possible cause
• 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 upper thread tension too strong? Or is the
lower thread tension too weak?
Adjust the upper thread tension or lower thread
tension.
• 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 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.
• Is the needle tip bent? Is the needle tip blunt?
If the needle tip is bent or blunt, 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.
Page
See Checking the
condition of the needle and
upper thread on page 50.
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