12
Replacing electronic components
Thread tension unit
To remove:
1. Remove the belt cover, top cover, base plate and front
cover (see pages 1, 2, 3 and 6).
2. Disconnect the printed circuit board G3 (thread
tension motor) connector and printed circuit board G1
(thread cut detecting sensor
)
connector (see page 8).
3. Remove the sping on the thread tension release lever
(see fig. 1).
4. Remove the setscrews A and B (see fig. 2 and 3).
Remove the thread tension unit.
To attach:
1. Follow the above procedure in reverse.
Check the following parts after this adjustment.
• Check the upper thread tension (see page 21).
• Check the thread tension release mechanism (see
page 22).
• Check the presser foot lifter detecting switch (see
page 29).
• Check the knee lifter position (see page 30).
Thread tension unit
Thread tension
release lever
Fig. 1
Fig. 2
Fig. 3
Setscrew A
Setscrew B
Spring
