Janome HD718 User manual

SERVICE MANUAL
&
PARTS LIST
MODEL: HD718
First Edition: 19 May 2017

CONTENTS
WHAT TO DO WHEN ............................................................................................ 1-3
SERVICE ACCESS
FACE COVER ...................................................................................... 4
TOP COVER ......................................................................................... 4
BASE PLATE ........................................................................................ 5
BED COVER ......................................................................................... 5
BELT COVER ....................................................................................... 6
FREE ARM COVER ............................................................................. 6
FRONT COVER.................................................................................... 7
REAR PANEL ....................................................................................... 8
MECHANICAL ADJUSTMENT
TOP TENSION ..................................................................................... 9
PRESSER BAR HEIGHT AND ALIGNMENT ....................................... 10
NEEDLE SWING .................................................................................. 11
STRAIGHT STITCHING ....................................................................... 12
DISTRIBUTION OF NEEDLE SWING .................................................. 13
STRETCH STITCH BALANCE ............................................................. 14, 15
FEED DOG HEIGHT ............................................................................ 16
CLEARANCE BETWEEN NEEDLE AND HOOK ................................. 17
NEEDLE TO HOOK TIMING ................................................................ 18
NEEDLE BAR HEIGHT ........................................................................ 19
BACKLASH (LOWER SHAFT GEAR) .................................................. 20
BUTTONHOLE STITCH BALANCE ..................................................... 21
NEEDLE POSITION ............................................................................. 22
ZERO FEEDING ................................................................................... 23
REPLACEMENT AND ADJUSTMENT OF THE NEEDLE
THREADER PLATE .............................................................................. 24
BUTTONHOLE FUNCTION (1) ............................................................ 25
BUTTONHOLE FUNCTION (2) ............................................................ 26
MOTOR BELT TENSION ..................................................................... 27
REPLACING TRANSFOMER ................................................................................ 28
WIRING OF TERMINAL BLOCK .......................................................................... 29
OILING .............................................................................................................. 30
PARTS LIST .......................................................................................................... 31~53

1
WHAT TO DO WHEN
CONDITION CAUSE HOW TO FIX REFERENCE
1. Skipping 1. Needle is not inserted Insert the needle properly.
stitches properly.
2. Needle is bent or worn. Change the needle.
3. Incorrectly threaded. Rethread.
4. Needle or thread are Use the recommended
inappropriate for sewing needle and thread.
fabric being sewn.
5. Sewing on stretch fabric. Use a #11 blue tip needle.
6. Presser foot pressure Adjust the presser bar
is too weak. level to make the
pressure stronger.
7. Inappropriate needle See mechanical adjustment P.19
bar height. “Needle bar height”.
8. Inappropriate needle See mechanical adjustment P.18
to hook timing. “Needle to hook timing”.
9. Inappropriate needle See mechanical adjustment P.17
to hook clearance. “Needle clearance to hook.”
2. Fabric not 1. Presser foot pressure Adjust the presser bar
moving is too weak. level to make the
pressure stronger.
2. Incorrect feed dog height. See mechanical P.16
adjustment “Feed dog height.”
3. Feed dog is in down position. Raise the feed dog level.
4. Thread on bottom side Make sure to bring
of fabric is jammed up. both needle and bobbin
thread under the foot
when starting sewing.
5. Feed dog teeth are worn. Change the feed dog.

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 worn. Replace with a new needle.
4. Upper thread tension is Adjust the upper thread tension
too strong. correctly.
5. Needle size is inappropriate Use appropriate needle
for fabric. for fabric and thread in use.
6. Needle eye is worn. Change the needle.
7. Needle hole in needle Repair the hole or
plate is worn or burred. replace the needle plate.
4. Breaking 1. Incorrectly threaded Thread bobbin correctly.
bobbin bobbin.
2. Too much thread is Adjust the position of
around on the bobbin. bobbin winder stopper.
3. Lint is stuck inside the Clean the shuttle.
bobbin holder.
4. Thread quality is Change to a high quality
too low. sewing thread.
5. Thread is jamming Remove the jamming
around the bobbin. thread.
5. Needle 1. Needle is hitting the See mechanical P.13
breaks needle plate. adjustment “Needle
position.”
2. Needle is bent or worn. Change the needle.
3. Needle is hitting the See mechanical P.17
shuttle. adjustment “Needle
clearance to shuttle.”
4. The fabric moves while See mechanical P.11
the needle is piercing adjustment “Needle swing.”
it, or the needle zigzags
while in fabric.
5. Fabric is being pulled too Guide the fabric gently
strongly while sewing. while sewing.
thread

3
CONDITION CAUSE HOW TO FIX REFERENCE
6. Noisy 1. Backlash between See mechanical P.20
operation Shuttle hook gear and adjustment “Backlash
lower shaft gear is too (lower shaft gear).”
great.
2. Lower shaft gear is Eliminate the looseness.
loose.
3. Inappropriate belt See mechanical P.27
tension. adjustment “Motor
belt tension.”
4. Not enough oil Oil all moving parts.
5. Upper shaft is loose Eliminate the looseness
7. Deformation 1. Inappropriate feed See mechanical P.14, 15
pattern balance. adjustment “Stretch
stitch balance.”
2. Inappropriate zigzag See mechanical P.11
synchronization. adjustment “Needle
swing.”
3. Upper thread tension See mechanical
is too strong. Adjustment “Top tension.”
8. Improper 1. Buttonhole stitch See mechanical P.25, 26
balance is not correct. adjustment “Buttonhole
stitch balance.”

4
SERVICE ACCESS
FACE COVER
1. Open the face cover (A).
2. Remove the setscrews (B).
3. Take the face cover (A) off.
(A)
(B)
(A)
(B) (C)
(D)
(E)
(F)
1. Open the face cover (A).
2. Remove setscrews (B) and (C).
3. Take the top cover (D) off.
* When you replace the top cover, set the projection (E) into the groove (F) of the belt
cover.
TOP COVER

5
SERVICE ACCESS
BASE PLATE
1. Remove 4 setscrews (A).
2. Remove the base plate (B).
BED COVER
1. Remove 2 setscrews (D).
2. Remove the bed cover (E).
* When you replace the bed cover, set the drop lever (F) in the left position as illustrated.
(A)
(A)
(A)
(A) (B)
(D)
(E)
(F)

6
SERVICE ACCESS
BELT COVER
Loosen setscrew (A) and remove setscrew (B). Pull the right side of belt cover in the direction
of arrow, to and take the latch off. Then remove the belt cover.
* When you attach the belt cover, set the projection into the groove of the front cover.
FREE ARM COVER
1. Remove setscrew (A) and the needle plate.
2. Remove the bed cover (See page 5).
3. Remove setscrew (B) and the free arm cover.
Belt cover
Projection (B)
(A)
Latch
(A)
(B)
Needle plate
Free arm cover

7
SERVICE ACCESS
FRONT COVER
1. Open the face cover .
2. Remove the top cover (See page 4), and the belt cover. (See page 6)
3. Remove setscrew (A), (B).
4. Loosen setscrews (C), (D) then remove the front cover (E).
5. Pull the front cover off the latch (F) of the rear cover.
6. Remove the lower part of the thread guide (G).
* To replace, follow this procedure in reverse.
(A)
(B)
(C)
(D)
(E)
(F)
(G)

8
SERVICE ACCESS
REAR PANEL
1. Open the face cover.
2. Remove the top cover unit (See page 4), The belt cover (See page 6) and the front cover.
(See page 7)
3. Remove setscrews (A) ,(B), (C), and loosen setscrews (D) - (F).
4. Lower the presser foot lever and pull away the rear panel unit from the machine frame.
Twist and remove the arm cover part from the presser foot lever.
* When you attach the rear panel, put the “Window” on the plastic panel over the presser foot
lever. Then, tighten 6 screws.
(A)
(B)
(C)
(D)
(E)
(F)
Twist and remove the arm cover
part from the presser foot lever.
Presser foot lever
Rear panel unit

9
MECHANICAL ADJUSTMENT
TOP TENSION
TO CHECK:
1. Set the tension dial at “4” and raise the presser foot.
2. Pass the thread (A) between the discs and draw the thread (A) down around the check spring
holder as in fig. 1.
3. Lower the presser foot and bring the thread (A) up.
4. Top tension should be 75 - 90g when pulling the thread (A) up in the direction of (B).
If it is not within the above limits, adjust as follows.
* Use polyester sewing thread #50 (white).
ADJUSTMENT PROCEDURE:
1. Remove the front cover unit. (See page 7)
2. Pull the spring (C) away from the lead screw (D) in the direction of allow as illustrated.
3. If the top tension is too loose, turn the lead screw (D) in the direction (E).
If the top tension is too tight, turn the lead screw (D) in the direction (F).
(C)
(D)
Thread tension dial (4)
(E)
(F)
(C)
Tighten
Loosen
Detach
(D)
Pull this way
(B)
(A)
FIg.1

10
MECHANICAL ADJUSTMENT
PRESSER BAR HEIGHT AND ALIGNMENT
TO CHECK:
1. Raise the presser foot lever (B).
2. The distance between the zigzag foot (A) and the needle plate (C) should be 6.0 mm.
If not, adjust as follows.
ADJUSTMENT PROCEDURE:
1. Open the face cover.
2. Raise the presser foot lever (B) and loosen the hexagonal socket screw (D) on the presser
bar holder (E).
3. Adjust the distance between the zigzag foot (A) and the needle plate (C) to 6.0 mm.
4. Tighten the setscrew (D) securely.
NOTE: When you tighten the setscrew (D), make sure the zigzag foot (A) runs parallel with
the feed dog.
(A)
(C)
(B)
(D)
(E)
(F) Feed dog slits
The feed dog slits and
the edge of presser
foot should be parallel.
6 mm

11
MECHANICAL ADJUSTMENT
NEEDLE SWING
TO CHECK:
If the needle bar starts sideways while the needle is in the fabric at sewing the zigzag pattern,
adjust the needle swing:
(The needle should start swinging when 2 to 3mm above the needle plate.)
ADJUSTMENT PROCEDURE:
1. Remove the top cover (See page 4), set the pattern selector dial at " " and select the
maximum zigzag width.
2. Loosen the two hexagonal socket screws on the upper shaft worm.
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 to 3 mm above the needle plate after the needle has came
from the right side of the needle hole.
4. Tighten the two hexagonal socket screws on the upper shaft worm.
5. Attach the top cover (unit).
NOTE: For removal and replacement of the top cover (unit), see to page 2. After the
adjustment of the timing of lateral needle swing, make sure that there is no backlash
between the upper shaft worm and the other gear without any backlash between
them.
Upper shaft
worm
Hexagonal
socket screw
Gear
The backlash
is decreased.
The backlash
is increased.
(NOTE)
If the upper shaft worm deviates
laterally when turning the upper
shaft, the backlash between the
gears will change.
2-3 mm
(Right outflow start position)

12
MECHANICAL ADJUSTMENT
STRAIGHT STITCHING
TO CHECK:
1. Set the stitch width dial at " 0 " and the stitch selector at" " .
2. Turn the handwheel toward you.
3. The needle should not swing side to side at this setting.
ADJUSTMENT PROCEDURE:
1. Remove the top cover. (See page 4)
2. Loosen the setscrew (A).
3. Move the zigzag width rod (B) until the needle ceases its zigzag movement when you turn the
handwheel toward you.
4. Tighten the setscrew (A) securely.
(B)
(A)

13
MECHANICAL ADJUSTMENT
DISTRIBUTION OF NEEDLE SWING
TO CHECK:
1. Set the stitch width dial to " 0 " and the stitch selector at " ".
2. Raise the needle to its highest position.
3. Place the darning plate on the needle plate.
4. Place a piece of paper on the darning plate and lower the presser foot.
5. Lower the needle to mark needle point (A) on a piece of paper by turning handwheel.
6. Raise the needle to its highest position.
7. Turn the stitch width dial to 6.5.
8. Lower the needle to mark needle points (B) and (C) on the piece of paper by turning the
handwheel.
9. The distance between A-B and A-C should be equal.
ADJUSTMENT PROCEDURE:
1. Open the face cover and loosen hexagonal socket screw (D).
2. Move the needle bar supporter (E) either direction until the distances A to B and A to C
become equal.
3. Tighten hexagonal socket screw (D) securely.
ABC
(D)
(E)

14
MECHANICAL ADJUSTMENT
STRETCH STITCH BALANCE
TO CHECK:
1. Set the stitch selector at . Set the stitch length dial at S.S. position, and stretch stitch adjuster
at " ".
2. Place a piece of paper on the needle plate and lower the presser foot.
3 Turn the handwheel to mark needle points on the paper.
4. The needle should penetrate the same holes in forward and reverse direction while turning
the handwheel towards you.
SELECTED PATTERN STITCH LENGTH DIAL

15
(C)
(D)
(E)
(F)
MECHANICAL ADJUSTMENT
STRETCH STITCH BALANCE
ADJUSTMENT PROCEDURE:
1. Remove the cap (F).
2. If the reverse stitch length (B) is shorter than the forward stitch length (A), turn the adjusting
setscrew (E) in the direction of (C).
If the reverse stitch length (B) is longer than the forward stitch length (A), turn the adjusting
setscrew (E) in the direction of (D).

16
FEED DOG HEIGHT
(E) (To raise)
(D)
(To lower)
Adjusting screw (C)
Nut (B)
Setscrew (A)
The highest position of the feed dog should be between 0.8 to 0.9 mm from the surface of
the needle plate when the pressure dial is set at "3" and the presser foot is raised.
1. Set the pressure dial at "3" and lower the presser foot.
2. Remove the bed cover. (See page 5)
3. Turn the handwheel toward you to set the feed dog at the highest position.
4. Loosen the setscrew (A) and nut (B).
5. Adjust the feed dog height by turning the adjusting screw (C).
6. Tighten the nut (B) and setscrew (A).
Presser foot
Feed dog Surface of the
needle plate
MECHANICAL ADJUSTMENT

17
CLEARANCE BETWEEN NEEDLE AND HOOK
The clearance between the test pin and the tip of the hook should be between –0.10 and +0.05 mm.
PREPARATION:
1. Turn on the power switch and set the stitch pattern to maximum zigzag width " ".
2. Remove the needle plate (A) and bobbin holder (B), insert the test pin (C) into the needle bar and
push it up until it stops, then tighten the needle clamp screw.
3. Remove the bed cover (See page 5).
ADJUSTMENT:
1. Loosen the setscrews (D) and (E), then lightly loosen the setscrew (F).
2. Turning the handwheel toward you slowly by hand, move the hook setplate up or down to adjust
the clearance between the test pin (C) and the point of the hook to -0.10 to +0.05 mm.
Repeat the procedure for both the left and right needle positions.
3. Tighten the setscrews (D), (E) and (F) securely.
4. Check the backlash of the hook gear and the lower shaft gear.
If the backlash is too large or small, adjusted the backlash (See page 20).
5. Attach the bed cover.
6. Remove the test pin (C), then attach the bobbin holder (B) and the needle plate (A).
Test pin (C)
–0.10 to +0.05mm
Point of hook
Setscrew (F)
Hook set
plate
Setscrew (D)
Setscrew (E)
Needle plate (A)
Bobbin holder (B)
MECHANICAL ADJUSTMENT

18
The hook timing is that amount of ascending travel of the needle bar from its lowest
position to where the tip of the rotary hook meets the left side of the needle should be
3.25 to 3.55 mm.
1. Remove the needle plate and bobbin holder.
2. Remove the bed cover.
3. Turn the handwheel toward you, and set the needle bar at the lowest position.
4. Loosen the setscrews on the lower shaft timing gear.
5. Raise the needle bar between 3.25 - 3.55 mm from the lowest position of the needle bar.
6. Turn the lower shaft timing gear until the tip of hook meets with the right side of needle.
7. Tighten the setscrews on the lower shaft timing gear.
8. Attach the bed cover, bobbin holder and needle plate.
NEEDLE TO HOOK TIMING
Needle plate
Bobbin holder
Setscrew
Lower shaft gear
Match the tip of
hook at the right
side of needle
Needle #14
3.25–3.55 mm
Lower needle position
MECHANICAL ADJUSTMENT