Brother b831 Service Manual page 22

(3) THREAD TRIMMER
t\
5 mm
Procedures
1. As shown above, placetension release rocking lever O. main bar return spring O- main lever assembly O. and rubber
O into base bracket 0 and insert through with main lever shaft O and then install with screw O.
2. Install thread trimmer solenoid O with screw O.
3. Place groove ofsub lever 0 totheslide block ofmain lever assembly 0 andpasssublever shaftO through sub lever 0
and base bracket 0. Install with screw 0.
4. Install connecting rod 0 to lever L 0 and lever R 0 with screw 0-
5. Install length adjusting connecting rod 0 to lever R 0 and sub lever 0 with screw ©.
6. Attach knife return spring 0.
7. Adjust with screw O so that there is a space of 5 mm between rubber O and base bracket 0.
8. When main lever shaft 0 is pressed, adjust with screw 0 so that the roller of knife main lever 0 can easilyenter the
recess of knife driving cam 0.
Red dot
—0.5 mm
T mark
Thread presser spring
Slider
n
5 mm
Terminal pin (black)
12-pin plug
Terminal pm (white).
Procedures
9. Fit fork lever and screw 0 to the forked part of the plunger.
Place pin lever and screw 0 and shaft 0 to fork lever 0.
Fasten with screw 0 so that there is a space of 0.5 mm between base bracket 0 and fork lever 0.
Push main lever shaft 0 and turn lower shaft 0 until it is difficult to turn.
Align the T mark on the pulley with the dot on the machine head and attach the timing belt 0.
Loosen screw 0 and adjust with moving knife rocking arm 0 so that there isa clearanceof0.5 mmbetweenthe slider
and slider base 0 (right and left).
15. Install spring peg 0 with screw 0.
16. Install tension release connecting rod 0 with screw 0.
17. Install spring 0 and spring 0.
18. Install the terminal pin to the 1 2-pin plug.
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