Janome NH15 Troubleshooting guide

1
SERVICE MANUAL
&
MODEL: NH15
PARTS LIST

2
CONTENTS
WHAT TO DO WHEN ...................................................................................... 3-5
SERVICE ACCESS
FACE COVER ............................................................................................... 6
TOP COVER ................................................................................................. 6
BASE COVER............................................................................................... 7
REAR COVER .............................................................................................. 8
FRONT COVER ............................................................................................ 9
MECHANICAL ADJUSTMENT
NEEDLE THREAD TENSION .................................................................... 10
BOBBIN TENSION...................................................................................... 11
PRESSER BAR HEIGHT AND ALIGNMENT ............................................. 12
NEEDLE SWING ........................................................................................ 13
NEEDLE DROP POSITION ........................................................................ 14
CLEARANCE BETWEEN NEEDLE AND SHUTTLE............................. 15-16
FEED DOG HEIGHT................................................................................... 17
NEEDLE BAR HEIGHT............................................................................... 18
NEEDLE TIMING TO SHUTTLE ................................................................. 19
BUTTONHOLE FEED BALANCE ............................................................... 20
DISENGAGEMENT OF CAM FOLLOWER................................................. 21
MOTOR BELT TENSION............................................................................. 22
WIRING....................................................................................................... 23
PARTS LIST ............................................................................................... 24-41

3
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 THE SEWING NEEDLE AND THREAD.
FABRIC BEING SEWN.
5. SEWING ON STRETCH USE A #11 BLUE TIP NEEDLE.
FABRIC
6. INAPPROPRIATE NEEDLE SEE MECHANICAL P.18
BAR HEIGHT ADJUSTMENT
“NEEDLE BAR HEIGHT.”
7. INAPPROPRIATE NEEDLE SEE MECHANICAL P.19
TO HOOK TIMING ADJUSTMENT “NEEDLE
TIMING TO SHUTTLE.”
8. INAPPROPRIATE NEEDLE SEE MECHANICAL P.15,16
TO SHUTTLE CLEARANCE ADJUSTMENT “CLEARANCE
BETWEEN NEEDLE AND
SHUTTLE.”
2. FABRIC NOT 1. INCORRECT SEE MECHANICAL P.17
MOVING FEED DOG HEIGHT ADJUSTMENT “FEED DOG
HEIGHT.”
2. THREAD ON BOTTOM SIDE MAKE SURE TO BRING
OF FABRIC IS JAMMED UP. BOTH NEEDLE AND BOBBIN
THREADS UNDER THE FOOT
WHEN START SEWING.
3. FEED DOG TEETH ARE CHANGE THE FEED DOG.
WORN.
WHAT TO DO WHEN

4
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 USE THE PROPER THREAD
INCORRECT. PATH.
3. NEEDLE IS BENT OR DULL. REPLACE WITH A NEW NEEDLE.
4. UPPER THREAD TENSION IS ADJUST UPPER THREAD P.10
TOO STRONG. TENSION CORRECTLY.
5. NEEDLE SIZE IS USE APPROPRIATE NEEDLE
INAPPROPRIATE FOR AND THREAD FOR FABRIC
FABRIC. 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 CASE
BOBBIN BOBBIN CASE. CORRECTLY.
THREAD 2. TOO MUCH THREAD IS ADJUST THE POSITION OF
WOUND ON THE BOBBIN. STOPPER.
3. LINT IS STUCK INSIDE THE CLEAN THE HOOK RACE.
HOOK RACE.
4. THREAD QUALITY IS CHANGE TO A HIGH QUALITY
TOO LOW. SEWING THREAD.
5. THREAD IS JAMMING CLEAR OUT THE JAMMING
AROUND THE BOBBIN. THREAD.
6. BOBBIN THREAD TENSION IS ADJUST BOBBIN THREAD P.11
TOO STRONG. TENSION CORRECTLY.
5. NEEDLE 1. NEEDLE IS HITTING THE SEE MECHANICAL P.14
BREAKS NEEDLE PLATE. ADJUSTMENT “NEEDLE DROP.”
2. NEEDLE IS BENT OR WORN. CHANGE THE NEEDLE.
3. NEEDLE IS HITTING THE SEE MECHANICAL P.15, 16
SHUTTLE RACE. ADJUSTMENT “CLEARANCE
BETWEEN NEEDLE AND SHUTTLE”.
4. THE FABRIC MOVES WHILE SEE MECHANICAL P.13
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.
WHAT TO DO WHEN

5
CONDITION CAUSE HOW TO FIX REFERENCE
6. NOISY 1. BACKLASH BETWEEN SEE MECHANICAL P.16
OPERATION SHUTTLE HOOK GEAR AND ADJUSTMENT “CLEARANCE
LOWER SHAFT GEAR IS TOO BETWEEN NEEDLE AND
GREAT. SHUTTLE (NO.2)”.
2. LOWER SHAFT GEAR IS ELIMINATE THE LOOSENESS.
LOOSE.
3. INAPPROPRIATE BELT SEE MECHANICAL P.24
TENSION. ADJUSTMENT “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 P.13
PATTERN SYNCHRONIZATION. ADJUSTMENT “NEEDLE
SWING”.
2. INAPPROPRIATE SEE MECHANICAL P.23
DISENGAGEMENT OF CAM ADJUSTMENT
FOLLOWER. “DISENGAGEMENT OF CAM
FOLLOWER".
3. UPPER THREAD TENSION ADJUST UPPER THREAD P.10
IS TOO STRONG. TENSION CORRECTLY.
WHAT TO DO WHEN

6
FACE COVER
SETSCREW(B)
CAP(A)
SETSCREW(C)
THREAD GUIDE
SERVICE ACCESS
FACE COVER
TO REMOVE:
1. REMOVE THE FACE COVER BY REMOVING THE CAP (A) AND SETSCREW (B).
TO ATTACH:
2. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
TOP COVER
TO REMOVE:
1. REMOVE THE SETSCREWS (C).
2. SLIDE THE CORNER OF THE TOP COVER SLIGHTLY IN THE DIRECTION OF ARROW.
BE CAREFUL THAT THE THREAD GUIDE SHOULD NOT INTERFERE WITH THE TOP
COVER WHEN REMOVING.
3. TAKE THE TOP COVER OUT.
TO ATTACH:
4. FOLLOW THE ABOVE PROCEDURE IN REVERSE.

7
(A)
BASE COVER
SERVICE ACCESS
BASE COVER
TO REMOVE:
1. LOOSEN THE SETSCREWS (A).
2. REMOVE THE BASE PLATE.
TO ATTACH:
3. MOUNT THE BASE PLATE AND SECURE IT WITH SETSCREWS.

8
(B)
(A)
(C)
(D)
(E)
(F)
(G)
(H) (I)
(J)
(C)
SERVICE ACCESS
REAR COVER
TO REMOVE:
1. REMOVE THE FACE COVER AND SETSCREW (A) (SEE PAGE 4).
2. OPEN THE SHUTTLE COVER AND REMOVE THE SETSCREWS (B), (C) AND (D).
3. REMOVE THE CAPS AND SETSCREWS (E), (F), (G),
4. REMOVE THE SETSCREWS (H) AND (I).
5. OPEN THE TOP COVER (SEE PAGE 5). LOOSEN THE SETSCREW (J).
6. REMOVE THE REAR COVER.
TO ATTACH:
7. MOUNT THE REAR COVER IN REVERSE PROCEDURE OF THE REMOVING.

9
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
SERVICE ACCESS
FRONT COVER
TO REMOVE:
1. REMOVE THE FACE COVER AND TOP COVER (SEE PAGE 4 AND 5).
2. LOOSEN THE SETSCREW (A).
3. REMOVE THE SETSCREW (B),
REMOVE THE REAR COVER (SEE PAGE 6).
LOOSEN THE SETSCREW (C), (E) AND (H). REMOVE THE SETSCREW (D).
4. OPEN THE SHUTTLE COVER. REMOVE THE SETSCREW (F).
5. REMOVE THE BASE COVER AND THE SETSCREW (G) (SEE PAGE 5).
TO ATTACH:
6. MOUNT THE FRONT COVER IN REVERSE PROCEDURE OF THE REMOVING.

10
MECHANICAL ADJUSTMENT
TOP TENSION
THE TOP TENSION SHOULD BE BETWEEN 65 AND 95G WHEN PULLING THE THREAD UP IN
THE DIRECTION OF C.
* USE POLYESTER SEWING THREAD #50 (WHITE).
* IF IT IS NOT WITHIN THE ABOVE LIMIT, ADJUST AS FOLLOWS.
1. SET THE TENSION DIAL “3”.
2. REMOVE THE COVER.
3. LOWER THE PRESSER FOOT.
• IF THE TOP TENSION IS TOO LOOSE, TURN THE LEAD SCREW IN THE DIRECTION (A).
• IF THE TOP TENSION IS TOO TIGHT, TURN THE LEAD SCREW IN THE DIRECTION (B).
4. CHECK THE TOP TENSION AND ATTACH THE COVER.
WHITE POLYESTER THREAD SIZE 50
PULL THE THREAD AT THE SPEED OF 110 MM/
SEC IN THE DIRECTION OF ARROW
(A)
(B)

11
(B)
(E)
(D)
(C)
COTTON THREAD #50
MECHANICAL ADJUSTMENT
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 (B).
IF THE TENSION IS OUT OF THE RANGE, ADJUST IT AS FOLLOWS:
ADJUSTMENT PROCEDURE:
1. TURN THE ADJUSTING SCREW (C) IN THE DIRECTION OF (D) WHEN THE BOBBIN THREAD
TENSION IS TOO TIGHT.
2. TURN THE ADJUSTING SCREW (C) IN THE DIRECTION OF (E) WHEN THE BOBBIN THREAD
TENSION IS TOO LOOSE.

12
(C)
(A)
(D)
(E)
(F)
6.0 MM
(B)
MECHANICAL ADJUSTMENT
PRESSER BAR HEIGHT AND ALIGNMENT
TO CHECK:
1. RAISE THE PRESSER FOOT LIFTER (A).
2. THE DISTANCE BETWEEN THE PRESSER FOOT (D) AND THE NEEDLE PLATE (E) SHOULD
BE 6.0 MM (0.24˝).
ADJUSTMENT PROCEDURE:
1. REMOVE THE FACE COVER (SEE PAGE 6).
2. REMOVE THE SETSCREWS (B) AND THE LAMP SOCKET, THEN LOOSEN THE SCREW (C)
ON THE PRESSER BAR HOLDER.
ADJUST THE DISTANCE BETWEEN THE PRESSER FOOT (D) AND THE NEEDLE PLATE (D)
TO 6.0 MM (0.24˝).
3. TIGHTEN THE SCREW (C) SECURELY.
4. TIGHTEN THE SETSCREW (B) TO SECURE THE LAMP SOCKET.
5. ATTACH THE FACE COVER.
NOTE:
WHEN YOU TIGHTEN THE SCREW (C), MAKE SURE THAT BOTH SIDES OF THE PRESSER
FOOT ARE PARALLEL TO THE FEED DOG SLOTS (F) IN THE NEEDLE PLATE (E).

13
UPPER SHAFT WORM
GEAR
SETSCREW
(2PCS.)
2–3 MM
MECHANICAL ADJUSTMENT
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 T
TOP 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 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.

14
EccEntric pin
ScrEw
Both clEarancES Should BE Equal
MECHANICAL ADJUSTMENT
NEEDLE DROP POSITION
TO CHECk:
whEn thE nEEdlE SwingS in maximum zigzag width, thE diStancE BEtwEEn Both
EndS of thE nEEdlE holE on thE nEEdlE platE and thE nEEdlE drop poSitionS
Should BE Equal.
if not, adjuSt aS followS:
ADJUSTMENT PROCEDURE:
1. rEmovE thE facE covEr (SEE pagE 6).
2. SEt thE pattErn SElEctor dial at maximum zigzag width.
3. looSEn thE ScrEw.
4. turn thE EccEntric pin to adjuSt thE nEEdlE drop.
5. tightEn thE ScrEw.
6. attach thE facE covEr.
NOTE:
chEck thE hook timing aftEr thiS adjuStmEnt.

15
MECHANICAL ADJUSTMENT
CLEARANCE BETWEEN NEEDLE AND SHUTTLE
(ADJUSTMENT METHOD NO. 1)
TO CHECk:
thE clEarancE BEtwEEn thE nEEdlE and ShuttlE racE Should BE –0.05 to +0.10 mm.
if not, adjuSt aS followS:
ADJUSTMENT PROCEDURE:
1. rEmovE thE facE covEr (SEE pagE 6).
2. SEt thE pattErn SElEctor dial at " ".
3. looSEn ScrEw (a), and movE thE nEEdlE Bar SupportEr in thE dirEction of
thE arrowS to gEt a clEarancE BEtwEEn –0.05 to +0.10 mm.
* if clEarancE iS too widE, movE thE nEEdlE Bar SupportEr in thE
dirEction (B).
* if clEarancE iS too narrow, movE thE nEEdlE Bar SupportEr in thE
dirEction (c).
NOTE:
aftEr thiS adjuStmEnt, chEck that thE clEarancE BEtwEEn thE nEEdlE and
nEEdlE platE iS 0.15 mm or morE aS Shown in figurE (d).
if not, adjuSt thE clEarancE BEtwEEn nEEdlE and ShuttlE racE BY uSing
adjuStmEnt mEthod no. 2 (SEE pagE 16).
4. attach thE facE covEr.
ScrEw (a)
dirEction (c)
dirEction (B)
nEEdlE Bar SupportEr
–0.05 to +0.10 mm
figurE (d)
clEarancE BEtwEEn nEEdlE and
nEEdlE platE Should BE 0.15 mm or
morE.

16
MECHANICAL ADJUSTMENT
CLEARANCE BETWEEN NEEDLE AND SHUTTLE
(ADJUSTMENT METHOD NO.2)
TO CHECk:
uSE thiS adjuStmEnt mEthod no. 2 if thE clEarancE cannot BE adjuStEd
BY mEthod no.1.
thE clEarancE BEtwEEn thE nEEdlE and ShuttlE racE Should BE –0.05
to +0.10 mm.
ADJUSTMENT PROCEDURE:
1. SEt thE pattErn SElEctor dial at " ".
2. rEmovE thE rEar covEr (SEE pagE 8).
3. looSEn thE ScrEw (a) on thE lowEr Shaft BuShing and SlidE thE gEar aBout
0.5 mm to thE right to crEatE SomE BacklaSh BEtwEEn thE gEarS.
4. lowEr thE nEEdlE and looSEn thE two ShuttlE racE SEtScrEwS (B).
pull up or puSh down thE ShuttlE racE to adjuSt thE clEarancE BEtwEEn
thE nEEdlE and thE ShuttlE racE in thE rangE of – 0.05 to + 0.10 mm.
5. SEt thE pattErn SElEctor dial at " ", turn thE handwhEEl to chEck if thE
clEarancE BEtwEEn thE nEEdlE and innEr EdgES of thE ShuttlE racE Spring
at thE lEft and right nEEdlE dropS arE Equal. if not, adjuSt BY turning thE
ShuttlE racE unit.
6. tightEn thE two ShuttlE racE SEtScrEwS (B).
7. SlidE thE gEar Back to thE original poSition whilE adjuSting thE BacklaSh.
8. tightEn ScrEw (a) firmlY.
9. attach thE rEar covEr.
NOTE:
thE rotarY plaY of thE tip of thE ShuttlE drivEr Should BE 0.3 mm or lESS
and thE lowEr Shaft Should turn SmoothlY. aftEr thE adjuStmEnt, chEck thE
hook timing.
–0.05 to +0.10 mm
clEarancE Should BE Equal
ShuttlE racE
SEtScrEwS (B) (2) lowEr Shaft
BuShing (front)
nEEdlE
ShuttlE
racE Spring
SEtScrEw (a)
lowEr
Shaft
BoSS

17
ScrEw (a)
fEEd lifting pin
0.75–0.90 mm
nEEdlE platE
MECHANICAL ADJUSTMENT
FEED DOG HEIGHT
TO CHECk:
1. lowEr thE prESSEr foot.
2. turn thE handwhEEl toward You until thE nEEdlE Bar comES to thE fEEd
dog aBovE thE nEEdlE platE Should BE 0.75–0.90 mm.
if it iS not in thE rangE, adjuSt aS followS.
ADJUSTMENT PROCEDURE:
1. opEn thE ShuttlE covEr.
2. lowEr thE prESSEr foot and turn thE handwhEEl toward You until thE
fEEd dog comES to itS highESt point.
3. looSEn thE ScrEw (a) .
4. turn thE fEEd lifting pin to adjuSt thE hEight of fEEd dog (0.75–0.90 mm).
5. tightEn thE ScrEw (a).
6. turn thE handwhEEl toward You to rEchEck thE hEight of fEEd dog.

18
MECHANICAL ADJUSTMENT
NEEDLE BAR HEIGHT
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 thE facE covEr.
2. SEt thE pattErn SElEctor dial at " ".
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 ScrEw (a).
7. adjuSt thE hEight of thE nEEdlE Bar BY moving thE nEEdlE Bar upward or
downward without turning it.
8. tightEn thE ScrEw (a).
9. attach thE ShuttlE racE ring.
ScrEw (a)
nEEdlE Bar
tip of ShuttlE hook mEEtS
lEft SidE of nEEdlE
2.9–3.5 mm

19
MECHANICAL ADJUSTMENT
NEEDLE TIMING TO SHUTTLE
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. SEt thE pattErn SElEctor dial at " ".
for modEl nExt 40, SElEct dial at " ", width SElEctor dial at " 0 ".
2. rEmovE thE BaSE (SEE pagE 7).
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 ScrEwS (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 ScrEwS (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 BaSE.
lowEr Shaft crank arm
ScrEwS (a) (2)
1.45–1.95 mm
lowESt poSition
lowEr Shaft

20
a B
forward fEEding Backward fEEding adjuSting ScrEw
(d) (c)
MECHANICAL ADJUSTMENT
BUTTONHOLE FEED BALANCE
TO CHECk:
whEn SEwing ButtonholE, thE StitchES on Each SidE of ButtonholE Should
BE thE SamE Stitch dEnSitY.
thE rangE of 9-12 StitchES in thE right SidE row (Backward fEEding)
againSt 10 StitchES in thE lEft SidE row (forward fEEding) iS conSidErEd
accEptaBlE.
ADJUSTMENT PROCEDURE:
1. chEck thE fEEd BalancE BY SEwing ButtonholES.
2. rEmovE thE cap on thE front covEr.
3. turn thE adjuSting ScrEw in thE dirEction of (c) in caSE of (a) (right StitchES
arE coarSE), or in thE dirEction of (d) in caSE of (B) (lEft StitchES arE coarSE).
4. mount thE cap.