BROTHER LS-2725 (01) PDF Document

The service manual for the BROTHER LS-2725 uses specific symbols to guide you through repairs and adjustments. Here is what they mean:

To remove the covers on your BROTHER LS-2725, please follow these steps in order:

1. Remove the accessory table (A).

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

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

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

To ensure proper timing on your BROTHER LS-2725, the clearance between the needle and the shuttle hook point should be 0.02 to 0.1mm.

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 either the right or left to adjust the clearance between the needle and the shuttle hook.

Note: The center of the needle should align with the center of the shuttle hook shaft.

On your BROTHER LS-2725, the shuttle driver should rotate smoothly with no play felt in the raceway. To adjust this:

1. Loosen the setscrews of the driver shaft gear.

2. Adjust the clearance of the driver shaft.

3. Retighten the setscrews.

Standard:

When the pattern selection dial on your BROTHER LS-2725 is set to 4 (Zigzag), the needle swing should meet these standards:

• Less than 0.05 mm while the needle moves down from the needle plate to its lowest position.

• Less than 0.15 mm while the needle moves up from its lowest position to the needle plate.

These clearances should be consistent on both sides of the needle plate hole.

Adjustment:

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.

Standard:

When the pattern selection dial is set at 4 (Zigzag), the needle on your BROTHER LS-2725 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:

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.

Standard:

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:

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.

Standard:

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 shuttle hook point should be within 0.8 and 1.2 mm.

Adjustment:

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.

Standard:

The timing belt should slacken approximately 4 – 6mm under a 2N (200g) load.

Adjustment:

1. For 220/240V models, loosen the setscrews on the motor holder.

2. For 120V models, loosen the nuts on the motor holder.

3. Move the motor to make the adjustment.

4. Retighten the setscrews and nuts.

Standard:

The feed dog teeth should be 0.9 – 1.1mm above the needle plate at their highest position.

Adjustment:

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 adjustment.

4. Retighten the fixation screw of the eccentric nut.

5. Retighten the setscrew.

Standard:

The clearance between the presser foot and the needle plate should be between 6.0 and 6.5mm.

Adjustment:

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: Check that the presser foot and feed dogs are aligned.

Standard:

When a buttonhole is sewn using the “b ⇒ ac ⇒ d” setting on the pattern selection dial, the left backward stitching and right forward stitching should appear identical.

Adjustment:

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/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 4 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.

Standard:

The width of the buttonhole’s right forward stitching should appear identical to that of the left backward stitching. The difference should be less than 0.2 mm.

Adjustment:

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.

Standard:

A thread tension amount between 0.05 and 0.1N (5 and 10g) should be measured at dial position 0.

Adjustment:

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 the stopring and the tension dial sheet.

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

Standard:

The bobbin should be wound evenly, up to 75 – 85% of the outer diameter of the bobbin.

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.

Standard:

Lower thread tension should be 0.3 – 0.35N (30 – 35g).

How to Check and Adjust:

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

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