Brother 2340CV User manual

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CONTENTS
HOW TO USE THIS MANUAL........................................ 2
HOW TO ADJUST...... .................................................... 3
Height of needle bar .................................................... 3
Position of the lowerlooper .......................................... 4
Timing of the double chain looper ............................... 5
Timing of the lowerlooper ............................................ 6
Height of feed dog (with a differential feed dog).......... 7
Feed timing.................................................................. 8
Height of presser bar................................................... 9
Thread tension adjustment........................................ 10
Position of thread take-up ......................................... 11
Position of looper thread take-up............................... 12
Adjustment and replacement for the timing belt ........ 13
Changing the light bulb.............................................. 14

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This service manual is compiled as a guide for the repair and service of Brother Cover Stitch Machine model
2340CV. Almost all troubles or problems occurring on Homelock sewing machines which arise as the result
of the user's lack of knowledge or experience can be solved by following instruction book. It should be
followed carefully because many faults are caused by misuse or carelessness. We therefore recommend you to
refer to the "Check list for better sewing" in the Instruction Book before you attempt any adjustment from this
manual.
However, if it is necessary to adjust the mechanism, use this manual together with the PARTS CATALOGUE
for each model. Find the fault in question in the Fault-finding chart and follow the corrective measures in this
manual.
1. Adjust each model number circled in each illustration and instruction.
2. Symbols:
Move the part to its highest position
Move the part to its lowest position
Move the part to the extreme right
Move the part to the extreme left
Move the part to the right or left
Move the part up or down
HOW TO USE THIS MANUAL

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Height of needle bar
1. Raise the needle to its highest position.
2. Loosen the screw on the needle bar.
3. Position the needle bar so that the clearance between the point of the needle and the surface of the needle plate is
as follows:
5.8 - 6.2 mm
NOTE • When making this adjustment, keep the needle bar at its highest position by holding the handwheel. Use the
left needle of the three needles to adjust the height. After completing adjustment, check that the needle
lowers to the center of the needle descents.
PARTS CODE FOR GAUGE: XB1282001
25.8 - 6.2 mm
3
1
3
Left needle
(Three needle models)
How to use the gauge
SCHMETZ
130/705H #90
Needle plate
Needle descents
HOW TO ADJUST......

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HOW TO ADJUST...... Position of the double chain looper
1. Before adjusting the timing, position the double chain looper correctly.
2. Too much adjustment will cause damage to other parts or cause the needle to skip stitches.
How to use the gauge
1. Position the gauge as shown in the illustration.
2. Firmly tighten the screw.
Double chain looper
Set screw
DL lever
7mm

5
HOW TO ADJUST...... Timing of the double chain looper
Adjust the needle and double chain looper
1. When the needle is raised to 2.8 - 3.2 mm above its lowest position, place the pointed end of the double chain
looper against the right side of the needle. The point of the double chain looper should be between 0 - 0.05 mm
from the needle.
2. Firmly tighten bolt 5 × 16
Right needle
3 mm ±0.2
Movable
needle guard
Movable
needle guard
Double chain
looper
Left needle
(Three needle models)
0 - 0.05 mm
Bolt 5 × 16
0 - 0.05 mm
0 - 0.05 mm

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HOW TO ADJUST...... Timing of the double chain looper
How to use the gauge
1. Raise the presser bar and remove the presser foot and presser foot holder.
2. Lower the needle bar to its lowest position.
3. Position the spacer and gauge and tighten the screw.
4. Remove the spacer.
5. Raise the needle bar until the needle clamp contacts the gauge. Continue making the adjustment described on the
previous page. (The spacer is 3.0 mm thick.)
Presser bar
Gauge
Spacer
3
4
2
Needle bar
3.0 mm
5
Gauge
Needle clamp

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HOW TO ADJUST...... Height of feed dog (with a differential feed dog)
Adjustment for height of main feed dog
1. Open the cloth plate cover, and raise needle at its highest position by turning handwheel.
2. Set the sewing pitch at "3".
3. Loosen screw 4 × 4 of vertical adjusting shaft.
4. Use a gauge to adjust the height of the feed dog so that the tips of the teeth are 0.9 - 1.1 mm above the surface of
the needle plate while turning the vertical adjusting shaft with a screwdriver.
5. After adjustment, tighten screw 4 × 4 of vertical adjusting shaft securely.
NOTE • Stitches will tend to pucker in fine fabrics or feed dog will touch needle plate, in case feed dog reaches to
higher position.
• Fabrics will not be fed sufficiently or feed dog will touch other parts like double chain looper, in case feed dog
reaches to lower position.
• Set the cut mark on the vertical adjusting shaft to the front, and then adjust the vertical adjusting shaft.
Adjustment for height of differential feed dog
Differential feed dog should be the same level as upper surface of needle plate when main feed dog goes
down and reaches the same level as upper surface of needle plate. Adjust by loosening set screw of
differential feed dog.
NOTE • Adjust at position of "1.0" of feed ratio.
• Differential feed dog should not be inclined when tightening set screw of differential feed dog.
• In case difference between height of main feed dog and differential feed dog is too much, fabrics will not be
fed correctly
Differential feed
dog
Main feed dog
Set screw
Vertical adjusting shaft
Set screw
How to the gauge
Gauge
Feed dog Set screw
Screw 4 × 4

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HOW TO ADJUST...... Feed timing
The standard timing of the feeding: Main feed dog should be at the same level as upper surface of needle plate
when needle goes down and point of it touches upper surface of needle plate.
As the needle is descending and about to enter the needle plate hole, the feed dog must be positioned as shown
in the illustration.
NOTE • Before the adjustment, check the Height of the feed dog and set the "Sewing pitch" at "3".
• Fabrics will not be fed straightly in case feed dog is inclined.
1. Open the cloth plate cover and loosen the set screw, socket M 5 × 6 (two) of the feed eccentric wheel by means of
a hexagonal wrench.
2. Turn the feed eccentric wheel to adjust the timing as shown in the illustration.
• In case of early timing, in other words when the feed dog is still positioned over the needle plate, turn the wheel in
direction A.
• In case of late timing, in other words when the feed dog is already positioned under the needle plate, turn the wheel in
direction B.
3. Tighten the set screw, socket M 5 × 6 (two) well.
A
Set screw, socket
M 5 × 6
BFeed eccentric wheel
Feed dog, front Feed dog, back
Right needle
(Three needles models)
Feed link
Hexagonal wrench
0.2 - 0.4mm
Needle plate

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HOW TO ADJUST...... Height of presser bar
Before adjustment, remove the panel assembly. Then turn the handwheel and raise the needle to its highest
position.
1. Raise the presser lever and loosen the set screw 5.95 securing the presser bar winding.
2. To adjust the height of the presser bar, raise the presser lever, and, at the point where the presser bar is horizontal,
raise or lower it until the first step is 4.8 - 5.0 mm above the needle plate. Check also to make sure that the needle
descents of the presser bar are not noticeably out of alignment with the needle descents of the needle plate.
3. After the adjustment has been completed, tighten the set screw 5.95 securely that holds the presser bar winding in
place.
Set screw 5.95
1
Presser bar
guide bracket
2
2’
Presser foot c
Presser bar
4.8 - 5.0 mm (1st step)
Needle
descents
How to use the gauge
Gauge
Presser
bar c
Needle plate