Thread Breakage - Toyota SD Service Manual

Troubleshooting

3.Thread breakage

[Example of phenomenon]
Step Item
Upper
1. Upper thread
thread
tension dial
tension
Flaw on
2. Needle plate needle
plate
Is home-use sewing machine needle (HA × 1)used?
Is the needle installed correctly?
Is the needle bent or deformed?
Is the combination of needle and thread adequate for the
fabric?
Is the upper thread tension set correctly?
Are upper and lower threads threaded properly?
Diagnosing Method
<Condition>
Upper thread tension dial: "5"
Thread: Cotton yarn # 60
<Diagnosis>
Pass the upper thread from the spool of
thread to the thread guide, pull the
thread vertically and measure the ten-
sion (A) when the value has stabilized.
(Using a measuring instrument)
<Diagnosis>
Check the needle plate by touching
around the needle plate hole.
10
[Check item before adjustment]
Standard
A = 0.85 to 1.15
N
Flaw not
allowed.
Reference
Page
[Adjustment]
page.33
Repair with
sand paper
(#800).