Janome 3128 User manual

SERVICE MANUAL
MODEL 3128

CONTENTS
WHAT TO DO WHEN ......................................................................................1-3
SERVICE ACCESS
FACE COVER .................................................................................... 4
REAR COVER ................................................................................... 5
FRONT COVER ................................................................................. 6
MECHANICAL ADJUSTMENT
TOP TENSION ................................................................................... 7
BOBBIN TENSION ............................................................................. 8
PRESSER BAR HEIGHT AND ALIGNMENT ..................................... 9
NEEDLE SWING .............................................................................. 10
NEEDLE DROP ............................................................................... 11
CLEARANCE BETWEEN NEEDLE AND HOOK (NO.1) ................. 12
CLEARANCE BETWEEN NEEDLE AND HOOK (NO.2) ................. 13
FEED DOG HEIGHT ........................................................................ 14
NEEDLE BAR HEIGHT .................................................................... 15
NEEDLE TIMING TO SHUTTLE ...................................................... 16
BUTTONHOLE FEED BALANCE .................................................... 17
ADJUSTMENT OF RIGHT HAND LINE TACK WIDTH
AND CAM FOLLOWER RELEASE AMOUNT ............... 18
MOTOR BELT TENSION ................................................................. 19
WIRING ............................................................................................................. 20
OILING .............................................................................................................. 21

MODEL 3128
1
CONDITION CAUSE HOW TO FIX REFERENCE
1. Skipping 1. Needle is not inserted Insert the needle properly.
properly.
stitches 2. Needle is bent or worn. Change the needle.
3. Incorrectly threaded. Rethread.
4. Needle or thread are Use the recommended sewing
inappropriate for fabric needle and thread.
being sewn.
5. Sewing on stretch fabric. Use a #11 blue tip needle.
6. Inappropriate needle bar See mechanical adjustment P.15
height. “Needle bar height.”
7. Inappropriate needle to See mechanical adjustment P.16
hook timing. “Needle timing to shuttle.”
8. Inappropriate needle to See mechanical adjustment P.12,13
hook clearance. “Clearance between needle
and hook.”
2. Fabric not 1. Incorrect feed dog height. See mechanical adjustment P.14
moving “Feed dog height.”
2. Thread on bottom side of Make sure to bring both needle
fabric is jammed up. and bobbin threads under the
foot when starting sewing.
3. Feed dog teeth are worn. Change the feed dog.
WHAT TO DO WHEN

MODEL 3128
2
CONDITION CAUSE HOW TO FIX REFERENCE
3. Breaking 1. Initial sewing speed is Start with medium speed.
upper too fast.
thread 2. Thread path is incorrect. Use the proper thread path.
3. Needle is bent or dull. Replace with a new needle.
4. Upper thread tension is Adjust upper thread tension P.7
too strong. correctly.
5. Needle size is inppropriate Use appropriate needle and
for fabric. thread for fabric in use.
6. Needle eye is worn. Change the needle.
7. Needle hole in needle Repair the hole or replace the
plate is worn or burred. needle plate.
4. Breaking 1. Incorrectly threaded Thread bobbin case correctly.
bobbin bobbin case.
thread 2. Too much thread is Adjust the position of stopper.
wound on the bobbin.
3. Lint is stuck inside the Clean the hook race.
hook race.
4. Thread quality is too low. Change to a high quality
sewing thread.
5. Thread is jamming around Clear out the jamming thread.
the bobbin.
6. Bobbin thread tension is Adjust bobbin thread tension P.8
too strong. correctly.

MODEL 3128
3
CONDITION CAUSE HOW TO FIX REFERENCE
5. Needle 1. Needle is hitting the needle See mechanical adjustment P.11
breaks plate. “Needle drop.”
2. Needle is bent or worn. Change the needle.
3. Needle is hitting the hook See mechanical adjustment P.12, 13
race. “Clearance between needle
and hook”.
4. The fabric moves while the See mechanical adjustment P.10
needle is piercing it, or the “Needle swing”.
needle zigzags while in
fabric.
5. Fabric is being pulled too Guide the fabric gently
strongly while sewing. while sewing.
6. Noisy 1. Backlash between shuttle See mechanical adjustment P.13
Operation hook gear and lower shaft “Clearance between needle
gear is too great. and hook (No.2)”.
2. Lower shaft gear is loose. Eliminate the looseness.
3. Inappropriate belt tension. See mechanical adjustment P.19
“Motor belt tension”.
4. Upper shaft gear is loose. Eliminate the looseness.
5. Not enough oil. Oil all moving parts.
7. Deformation 1. Inappropriate zigzag See mechanical adjustment P.10
pattern synchronization. “Needle swing”.
2. Inappropriate See mechanical adjustment P.18
disengagement of cam “Disengagement of cam”.
follower.
3. Upper thread tension is Adjust upper thread tension P.7
too strong. correctly.

MODEL 3128
4
SERVICE ACCESS
TO REMOVE
1. Remove the setscrew "A".
2. Take the face cover "B" off.
Note: When removing the face cover, pull it up and unhook from the hook "C".
TO ATTACH
3. Follow the above procedure in reverse.
C
A
B
FACE COVER

MODEL 3128
5
SERVICE ACCESS
REAR COVER
TO REMOVE
1. Remove the face cover (see page 4).
2. Remove the setscrews "A", "B", "C", "D", "E" and rubber cushion "F" (2 pcs.), and then
remove the rear cover.
TO ATTACH
3. Follow the above procedure in reverse.
A
REAR COVER
C
F
D
F
B
E

MODEL 3128
6
SERVICE ACCESS
FRONT COVER
TO REMOVE
1. Remove the face cover and rear cover (see pages 4, 5.)
2. Pull out the pattern selector dial.
3. Loosen the setscrews "A", "B" and remove the setscrews "C", "D" and the rubber cushion
"E", then remove the front cover.
TO ATTACH
4. Follow the above procedure in reverse.
A
BE
D
C
PATTERN SELCTOR DIAL

MODEL 3128
7
AB
D
C
TOP TENSION
TO CHECK:
The standard upper thread tension should be 65 - 95g when pulling the thread (cotton thread #50)
in the direction of "A" with setting the tension dial at "3". (Make sure the foot should be lowered.)
If the tension is out of the standard range, adjust it as follows:
ADJUSTMENT PROCEDURE:
1. Remove the front cover (see page 6).
2. Turn the adjusting nut "B" in the direction of "C" when the upper thread tension is too tight.
Turn the adjusting nut "B" in the direction of "D" when the upper thread tension is too loose.
3. Attach the front cover.
MECHANICAL ADJUSTMENT

MODEL 3128
8
BOBBIN TENSION
TO CHECK:
Set the bobbin in the bobbin case and pass the thread (cotton #50) through the tension spring.
The bobbin thread tension should be 45 - 55g when pulling the thread in the direction of "A".
If the tension is out of the range, adjust it as follows:
ADJUSTMENT PROCEDURE:
1. Turn the adjusting screw "B" in the direction of "C" when the bobbin thread tension is too
tight.
2. Turn the adjusting screw "B" in the direction of "D" when the bobbin thread tension is too
loose.
MECHANICAL ADJUSTMENT
COTTON THREAD #50
A
B
C
D

MODEL 3128
9
PRESSER BAR HEIGHT AND ALIGNMENT
TO CHECK:
1. Raise the presser foot lever.
2. The distance between the presser foot "C" and the needle plate "D" should be 6.0mm
(0.24").
ADJUSTMENT PROCEDURE:
1. Remove the face cover (see page 4).
2. Remove the lamp "A" off.
3. Raise the presser foot lever and loosen the setscrew "B" on the presser bar holder.
Adjust the distance between the presser foot "C" and the needle plate "D" to 6.0mm (0.24").
4. Tighten the setscrew "B" securely.
5. Tighten the lamp.
6. Attach the face plate.
Note: When you tighten the setscrew "B", make sure that both sides of the presser foot are
parallel to the feed dog slots "E" on the needle plate.
MECHANICAL ADJUSTMENT
B
A
D
C
E
6.0 MM

MODEL 3128
10
NEEDLE SWING
TO CHECK:
Adjust the needle swing according to the following procedure, if the needle bar starts
moving sideways while the needle is in the fabric at sewing the zigzag pattern (with
maximum zigzag width).
ADJUSTMENT PROCEDURE:
1. Set the pattern selector dial with maximum zigzag width, and remove the front cover
(see page 6).
2. Loosen two setscrews.
3. Adjust the needle swing by turning the handwheel, while holding the worm so as not
to rotate it, until the needle swing starts at 2 - 3 mm above the needle plate after the
needle has come out of the right side of the needle hole.
4. Tighten two setscrews.
5. Mount the front cover.
Note: After adjusting the needle swing, check that the upper shaft worm and gear
rotate smoothly without any backlash between them.
MECHANICAL ADJUSTMENT
UPPER SHAFT WORM
GEAR
SETSCREW (2 PCS.)
2 - 3 MM

MODEL 3128
11
NEEDLE DROP
TO CHECK:
When the needle swings in maximum zigzag width, the distance between the both ends of needle hole
in the needle plate and the needle drop positions should be equal. If not, make an adjustment as
follows:
ADJUSTMENT PROCEDURE:
1. Remove the face cover (see page 4).
2. Set the pattern selector dial at maximum zigzag width position.
3. Turn the setscrew to adjust the left and right needle drop positions.
4. Attach the face cover.
Note: Check the hook timing after this adjustment.
MECHANICAL ADJUSTMENT
SETSCREW
BOTH CLEARANCE SHOULD BE EQUAL

MODEL 3128
12
MECHANICAL ADJUSTMENT
CLEARANCE BETWEEN NEEDLE AND
NEEDLE PLATE IS 0.15 MM OR MORE.
FIGURE "D"
-0.05 - 0.10 MM
PROJECTIONS
(2 SPOTS)
BASE PLATE
SETSCREW "A" (2 PCS.)
DIRECTION "B"
NEEDLE BAR SUPPORTER
ADJUSTING PLATE
CLEARANCE BETWEEN NEEDLE AND HOOK (NO.1)
TO CHECK:
The clearance between needle and shuttle hook should be -0.05 - 0.10 mm.
If not, make an adjustment as follows:
ADJUSTMENT PROCEDURE:
1. Remove the face cover (see page 4).
2. Set the pattern selector dial at maximum zigzag width, and turn the handwheel toward you to bring
the needle at left needle position.
3. Loosen 2 setscrews, slide the needle bar supporter adjusting plate in the direction of arrow as
shown below, and adjust the clearance between needle and shuttle hook to 0 - 0.15 mm tighten
setscrews.
* If the clearance is too large (more than 0.1 mm), slide the needle bar supporter adjusting plate in
the direction of "B".
* If the clearance is too small (less than 0 mm), slide the needle bar supporter adjusting plate in the
direction of "C".
Note: When adjusting the clearance, be sure to slide the needle bar supporter adjusting plate while
guiding the two projections along the edge of the base plate.
Note: Clearance between needle and needle plate is 0.15 mm or more as shown in figure "D". If not,
adjust the clearance between needl and shuttle hook by using method of adjustment No.2 in
page 13. After readjustment, check if the clearance between needle and needle plate is 0.15
mm or more.
4. Attach the face plate.
DIRECTION "C"

MODEL 3128
13
CLEARANCE BETWEEN NEEDLE AND HOOK (NO.2)
TO CHECK:
Use this adjustment method No.2 if the clearance cannot be adjusted with the method No.1.
The clearance between needle and shuttle hook should be -0.05 - 0.10 mm.
ADJUSTMENT PROCEDURE:
1. Set the pattern selector dial at maximum zigzag width, and turn the handwheel toward you to bring
the needle to the left needle position.
2. Open the shuttle cover and loosen the lower shaft bushing (front) setscrew "A". Then slide the
lower shaft to the right side slightly (approximately 0.5 mm) not to disengage the gears, and tighten
the setscrew temporary.
3. Loosen the setscrews "B"(2 pcs.) through the holes in the rear cover, and slightly move the shuttle
body up or down to adjust the clearance between needle and shuttle hook to -0.05 - 0.10 mm, and
tighten the setscrews "B" temporary.
4. Turn the handwheel to check the clearance between shuttle race spring and needle in left and right
positions. If the clearance is not equal, adjust it by turning the shuttle race body.
5. Tighten the shuttle race setscrews "B" (2 pcs).
6. Loosen the setscrew "A" on lower shaft bushing and slide the gear back to the original position
while adjusting the backlash.
7. Tighten the setscrew "A" firmly.
Note: The rotary play of the hook driver should be 0.3 mm or less and lower shaft turns smoothly.
After the adjustment, check the hook timing.
MECHANICAL ADJUSTMENT
SETSCREW "A"
-0.05 - 0.10 MM
CLEARANCE SHOULD BE EQUAL
SHUTTLE RACE SPRING
NEEDLE
LOWER SHAFT BUSHING
(FRONT)
SHUTTLE RACE
SETSCREW "B"
(2 PCS.)
HOLES IN THE
REAR COVER

MODEL 3128
14
FEED DOG HEIGHT
MACHINE SETTING
1. Stitch selector: " "
2. Needle bar: At its highest position.
TO CHECK:
1. Lower the presser foot.
2. Turn the handwheel toward you until the needle bar comes to its highest position.
The feed dog should be above the needle in the range of 0.75 - 0.90 mm.
If it is not in the range, adjust as follows.
ADJUSTMENT PROCEDURE:
1. Open the shuttle cover.
2. Adjust the feed dog height by turning the adjusting screw.
* When the feed dog height is higher than the standard range, turns the adjusting screw in
the direction of "B".
* When the feed dog height is lower than the standard range, turn the adjusting screw in
the direction of "C".
MECHANICAL ADJUSTMENT
B
C
ADJUSTING SCREW
0.75 - 0.90MM

MODEL 3128
15
NEEDLE BAR HEIGHT
MACHINE SETTING
1. Stitch selector: " ".
TO CHECK:
When the tip of shuttle hook meets the left side of the needle in ascending travel of the needle
from its left and lowest position, the distance between the top of the needle eye and the tip of
the shuttle hook should be in the range of 2.9 - 3.5 mm.
ADJUSTMENT PROCEDURE:
1. Remove face cover (see page 4).
2. Set the pattern selector dial at maximum zigzag with and needle drop position is at "left".
3. Open the shuttle cover.
4. Remove the shuttle race ring.
5. Turn the handwheel toward you until the tip of the shuttle hook meets the left side of the
needle.
6. Loosen the needle bar connecting stud screw "A".
7. Adjust the height of the needle bar by moving the needle bar upward or downward
without turning it.
8. Tighten the setscrew "A".
9. Attach the shuttle race ring.
10. Attach the face cover.
MECHANICAL ADJUSTMENT
NEEDLE BAR
A
TIP OF SHUTTLE HOOK
MEETS LEFT SIDE OF
NEEDLE
2.9 - 3.5MM

MODEL 3128
16
NEEDLE TIMING TO SHUTTLE
MACHINE SETTING
1. Stitch selector: " ".
TO CHECK:
The height of the needle point from its lowest point of travel should be in the range of 1.45 -
1.95 mm when the tip of the shuttle hook just meets the left side of the needle at the left
needle position.
ADJUSTMENT PROCEDURE:
1. Remove rear cover (see page 5).
2. Set the pattern selector dial at maximum zigzag with and needle drop position is at
"left".
3. Open the shuttle cover.
4. Remove the shuttle race ring.
5. Turn the handwheel toward you until the tip of the shuttle hook meets the left side of
the needle.
6. Loosen the lower shaft crank arm setscrews "A".
7. While holding the shuttle hook so it doesn't turn, turn the handwheel toward you until
the needle comes to its lowest position. Then, further turn the handwheel to raise the
needle about 1.7 mm from its lowest position.
8. Tighten the setscrews "A".
9. Turn the handwheel toward you to check if the height is in the range of 1.45 - 1.95 mm.
If it is not in this range, repeat the above procedure.
10. Attach the shuttle race ring.
11. Attach the rear cover.
MECHANICAL ADJUSTMENT
LOWER SHAFT CRANK ARM
A
1.45-1.95MM
LOWEST POSITION

MODEL 3128
17
BUTTONHOLE FEED BALANCE
TO CHECK:
When sewing buttonhole, the stitches on each side of buttonhole stitch density should be the
same.
The range of 9 - 11 stitches in the right side row "backward feeding"against 10 stitches in the
left side row "forward feeding"is considered acceptable.
ADJUSTMENT PROCEDURE:
1. Confirm the stitches by sewing buttonholes, and remove the cap.
2. Turn the adjusting screw in the direction of "C" in case of "A" (right stitches are rough), or
in the direction of "D" in case of "B" (left stitches are rough).
3. Mount the cap.
MECHANICAL ADJUSTMENT
CAP
NOTCH
ADJUSTING SCREW
D
C
FORWARD FEEDING BACKWARD FEEDING

MODEL 3128
18
MECHANICAL ADJUSTMENT
ADJUSTING SCREW
A
LEFT SIDE LINE
TACK WIDTH
RIGHT SIDE LINE
TACK WIDTH
ADJUSTMENT OF RIGHT HAND LINE TACK WIDTH AND CAM
FOLLOWER RELEASE AMOUNT
* The width of the left and right side line tack of buttonhole should be equal. If there is large
difference between left and right line tack width, the cam follower may be hindered with the
zigzag cam block when you turn the pattern selector dial.
1. Sew a buttonhole and check the difference in both line tack widths.
2. Remove the front cover (see page 6).
3. Adjust the line tack width by turning the adjusting screw.
* The right side of the line tack is fixed so the adjustment should be done on the left side line
tack.
If the left side line tack is wider than the right side:
Turn the adjusting screw in the direction of "A"
If the right side line tack is narrower than the left side:
Turn the adjusting screw in the direction of "B".
B