SERVICE MANUAL
MODEL: NH7
CONTENTS
WHAT TO DO WHEN
................................................................................. 1-3
SERVICE ACCESS
FACE PLATE .................................................................................. 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
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 USE A #11 BLUE TIP NEEDLE.
FABRIC
6. INAPPROPRIATE NEEDLE SEE MECHANICAL P.15
BAR HEIGHT ADJUSTMENT
“
NEEDLE BAR HEIGHT.”
7. INAPPROPRIATE NEEDLE SEE MECHANICAL P.16
TO HOOK TIMING ADJUSTMENT “NEEDLE
TIMING TO SHUTTLE.”
8. INAPPROPRIATE NEEDLE SEE MECHANICAL P.12,13
TO HOOK CLEARANCE ADJUSTMENT “CLEARANCE
BETWEEN NEEDLE AND
HOOK.”
2. FABRIC NOT 1. INCORRECT SEE MECHANICAL P.14
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
THREAD UNDER THE FOOT
WHEN STARTING SEWING.
3. FEED DOG TEETH ARE CHANGE THE FEED DOG.
WORN.
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 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. 7
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
AROUND 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. 8
TOO STRONG. TENSION CORRECTLY.
5. NEEDLE 1. NEEDLE IS HITTING THE SEE MECHANICAL
P.11
BREAKS NEEDLE PLATE. ADJUSTMENT “NEEDLE DROP.”
2. NEEDLE IS BENT OR WORN. CHANGE THE NEEDLE.
3. NEEDLE IS HITTING THE SEE MECHANICAL
P.12, 13
HOOK RACE. ADJUSTMENT “CLEARANCE
BETWEEN NEEDLE AND HOOK”.
4. THE FABRIC MOVES WHILE SEE MECHANICAL
P.10
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.
3
CONDITION CAUSE HOW TO FIX REFERENCE
6. NOISY 1. BACKLASH BETWEEN SEE MECHANICAL P.13
OPERATION SHUTTLE HOOK GEAR AND ADJUSTMENT “CLEARANCE
LOWER SHAFT GEAR IS TOO BETWEEN NEEDLE AND HOOK
GREAT. (NO.2)”.
2. LOWER SHAFT GEAR IS ELIMINATE THE LOOSENESS.
LOOSE.
3. INAPPROPRIATE BELT SEE MECHANICAL P.19
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.10
PATTERN SYNCHRONIZATION. ADJUSTMENT “NEEDLE
SWING”.
2. INAPPROPRIATE SEE MECHANICAL P.18
DISENGAGEMENT OF CAM ADJUSTMENT
FOLLOWER. “DISENGAGEMENT OF CAM
3. UPPER THREAD TENSION ADJUST UPPER THREAD P.7
IS TOO STRONG. TENSION CORRECTLY.
4
SERVICE ACCESS
FACE PLATE
TO REMOVE:
1. REMOVE THE CAP AND SETSCREW. REMOVE THE FACE PLATE.
TO ATTACH:
2. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
CAP
SETSCREW
FACE PLATE
5
SERVICE ACCESS
REAR COVER
REAR COVER
TO REMOVE:
1. REMOVE THE FACE COVER (SEE PAGE 4).
2. OPEN THE SHUTTLE COVER AND REMOVE THE SETSCREWS (A).
3. REMOVE THE SETSCREWS (B), (C), (D) AND RUBBER CUSHION (E) (2 PCS.), AND
THEN REMOVE THE REAR COVER.
TO ATTACH:
4. MOUNT THE REAR COVER IN REVERSE PROCEDURE OF THE REMOVING.
A
C
E
D
E
B
CAP
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