BROTHER JS-23 (01) PDF Document

The symbols used in the service manual for your BROTHER JS-23 indicate specific actions for adjustments and repairs. Understanding these symbols will help you follow the instructions correctly.

The following table shows the update history for the BROTHER JS-23 service manual.

To access the internal components of your BROTHER JS-23 for service, follow this order for removing the covers:

1. Remove the accessory table (A).

2. Loosen and remove the screw to remove the face plate (B).

3. Loosen and remove the screws to remove the front cover (C).

4. Loosen and remove the screws, lower the presser foot lifter, then remove the rear cover (D).

For proper stitch formation on your BROTHER JS-23, the clearance between the needle and shuttle hook point should be 0.02 to 0.1mm. The center of the needle should also align with the center of the shuttle hook shaft.

Adjustment Steps:

1. Set the pattern selection dial to 6.

2. Turn the balance wheel to set the needle and the shuttle hook to the correct timing position.

3. Turn the needle bar supporter stud slightly to the right or left to adjust the clearance between the needle and the shuttle hook to the specified 0.02 to 0.1mm.

To ensure smooth operation of your BROTHER JS-23, the shuttle driver should rotate smoothly with no play in the raceway.

Adjustment Steps:

1. Loosen the setscrews of the driver shaft gear.

2. Adjust the clearance of the driver shaft.

3. Retighten the setscrews.

To ensure correct needle movement during zigzag stitches on your BROTHER JS-23, the needle swing must be adjusted correctly. When the pattern selection dial is set to 4 (Zigzag), the needle swing should be 0.05 mm or less while the needle moves down from the needle plate to its lowest position. While the needle moves up from its lowest position to the needle plate, the needle swing should be 0.15 mm or less. These clearances apply to both sides of the needle plate hole.

Adjustment Steps:

1. Set the pattern selection dial to 4 (Zigzag).

2. Loosen the three set screws on the worm gear.

3. Turn the worm gear to adjust the needle swing.

4. Tighten the three set screws on the worm gear.

Note: Make sure that the biting worm gear aligns with the pattern cam gear.

To center the needle movement on your BROTHER JS-23, follow this procedure. When the pattern selection dial is set to 4 (Zigzag), the needle should move within a range of 5.0 to 5.4 mm across the needle plate. When lowered, the needle should not be too close to either the left or right edge of the needle plate hole.

Adjustment Steps:

1. Set the pattern selection dial to 4.

2. Turn the balance wheel to lower the needle until it is just above the needle plate.

3. Loosen the locknut for the adjusting screw on the zigzag connecting rod.

4. Using a screwdriver, turn the screw and adjust the needle movement range with respect to the needle plate hole.

5. Tighten the locknut.

The standard for the loop lift on your BROTHER JS-23 is as follows: When the pattern selection dial is set at 4 (Zigzag) and the needle is raised 1.7 to 2.1 mm from its lowest position on the left side, the shuttle hook point should align with the side of the needle.

Adjustment Steps:

1. Set the pattern selection dial to 4 (Zigzag), then lower the needle to its lowest position at the left side of the needle plate.

2. Loosen the set screw on the drive connecting rod.

3. Raise the needle between 1.7 and 2.1 mm and align the shuttle hook point with the side of the needle.

4. Tighten the set screw.

To set the correct needle bar height on your BROTHER JS-23, follow these instructions. When the pattern selection dial is set at 4 (Zigzag), and the needle is on the right side and contacts the shuttle hook, the clearance between the top of the needle eye and the shuttle hook point should be within 0.8 and 1.2 mm.

Adjustment Steps:

1. Set the pattern selection dial to 4 (Zigzag), then lower the needle to its lowest position at the right side of the needle plate.

2. Turn the balance wheel until the needle contacts the shuttle hook.

3. Loosen the set screw on the needle bar.

4. Move the needle bar either up or down until the clearance between the top of the needle eye and the shuttle hook point is within 0.8 and 1.2 mm.

5. Tighten the set screw.

The timing belt on your BROTHER JS-23 should slacken approximately 4 – 6mm under a 2N (200g) load.

Adjustment Steps:

1. Loosen the setscrews on the motor holder (for 220/240V models).

2. Loosen the nuts on the motor holder (for 120V models).

3. Move the motor to make the adjustment.

4. Retighten the setscrews and nuts.

For proper fabric feeding on your BROTHER JS-23, the feed dog teeth should be 0.9 – 1.1mm above the needle plate at their highest position.

Adjustment Steps:

1. Loosen the setscrew on the vertical feed arm.

2. Loosen the fixation screw of the eccentric nut.

3. Turn the eccentric nut to make the height adjustment.

4. Retighten the fixation screw of the eccentric nut.

5. Retighten the setscrew.

The clearance between the presser foot and the needle plate on your BROTHER JS-23 should be between 6.0 and 6.5mm.

Adjustment Steps:

1. Raise the presser foot.

2. Loosen the screw on the presser bar guide bracket.

3. Adjust the height of the presser bar.

4. Tighten the screw.

Note: After adjustment, check that the presser foot and feed dogs are aligned.

To ensure your BROTHER JS-23 sews a balanced buttonhole, the left backward stitching and right forward stitching should appear identical. When a buttonhole is sewn using the b -> ac -> d setting on the pattern selection dial, both sides should match.

Adjustment Steps:

1. Set the buttonhole adjustment dial to “0”.

2. Set the pattern selection dial to “b” and sew the left side of the buttonhole.

3. Loosen the screw on the reverse sewing regulator shaft.

4. Using a screwdriver, turn the reverse sewing regulator shaft to adjust the left backward stitching (b) until it feeds 35 to 45 stitches per 20 mm.

5. Tighten the screw.

6. Set the pattern selection dial to “d” and sew the right side of the buttonhole. (Caution: Satin stitch density will change according to the pitch length adjustment of the left backward stitching.)

7. Loosen the fixation screw of the eccentric nut.

8. Use the nut to make adjustments so that the length of the right forward stitching is the same as the left backward stitching.

9. Tighten the screw.

For a symmetrical buttonhole on your BROTHER JS-23, the width of the right forward stitching should appear identical to that of the left backward stitching, with a difference of less than 0.2 mm.

Adjustment Steps:

1. Install the darning plate onto the needle plate and lower the presser foot onto a piece of paper.

2. Set the pattern selection dial to “b”.

3. Turn the balance wheel until the needle contacts the paper.

4. Set the pattern selection dial to “d”.

5. Turn the balance wheel until the needle contacts the paper.

6. Using a screwdriver, turn the adjusting screw to change the stitch width of the right side.

Note: Turn the adjusting screw to the right to make the stitch width of the right side more narrow.

The standard thread tension for your BROTHER JS-23 should be between 0.05 and 0.1N (5 and 10g) when measured at dial position 0.

Adjustment Steps:

1. Remove the tension dial sheet and the stopring.

2. Remove the tension dial.

3. Turn the adjusting nut left or right to make the adjustment.

4. Remount the tension dial at the zero position, then replace the stopring and the tension dial sheet.

Note: Cotton thread #50 should be used when adjusting the tension. Do not include the take-up spring torque in the measurement.

For optimal performance of your BROTHER JS-23, the bobbin should be wound evenly, up to 75 – 85% of its outer diameter.

Adjustment for Even Winding:

1. Loosen the set screw of the pretension slightly.

2. Shift the pretension up or down until even winding is achieved.

3. Retighten the set screw.

Adjustment for Amount of Thread:

4. Loosen the set screw of the bobbin presser.

5. Adjust the bobbin presser until the correct amount of thread is wound.

6. Retighten the set screw.

The standard lower thread tension for your BROTHER JS-23 is 0.3 – 0.35N (30 – 35g). To check the tension, pull cotton thread #50 from the bobbin case with a tension gauge slowly.

Adjustment Steps:

1. Set cotton thread #50 in the bobbin case and pull it with a tension gauge.

2. Adjust the adjustment screw on the bobbin case to achieve a tension of 0.3 – 0.35N (30 – 35g).