Baby Lock BL7800, Service Manual

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2. TENSION OF MOTOR BELT AND TIMING BELT
STANDARD
There should be a 4-6 mm slack in the motor belt when the center of the motor belt is pressed with a force of 200g.
There should be a 3-4 mm slack in the timing belt when it is pressed with a force of 200g.
ADJUSTMENT
Timing belt
1. Loosen the screw of the belt adjusting pulley.
2. Adjust the position of the belt adjusting pulley.
3. Tighten the screw of the belt adjusting pulley.
Motor belt
1. Loosen the two screw securing the motor holder.
2. Adjust the belt tension by moving the motor holder.
3. Tighten the two screws.
Adjustment Points
1. If the timing belt tension is too loose, the belt may jump while sewing on denim and other thicker fabrics or
overlapping fabric. And then the feed timing or the timing of the needle and rotary hook may prevent sewing.
2. If the motor belt tension is too tight, the torque becomes too much, causing the motor to rotate slower and
generate an irregular noise.
3. If the motor belt tension is too loose, the belt may jump while sewing on denim and other thicker fabrics or
overlapping fabrics. And then the upper shaft may not rotate smoothly, or may not rotate.