Janome NH40 Service Manual
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Janome NH40 Service Manual

Janome NH40 Service Manual

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SERVICE MANUAL
MODEL: NH40

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Summary of Contents for Janome NH40

  • Page 1 SERVICE MANUAL MODEL: NH40...

  • Page 2: Table Of Contents

    CONTENTS What to do when ..........................1 - 3 SERVICE ACCESS Face Cover ............................. 4 Bed Cover .............................. 5 Free-arm Cover ............................6 Front Cover ............................. 7 Rear Cover ............................. 8 MECHANICAL ADJUSTMENT Presser Bar Height ..........................9 Needle Drop Position ..........................10 Needle to Hook Timing .........................

  • Page 3: What To Do When

    WHAT TO DO WHEN Condition Cause How to fix Reference 1. Skipping 1. Needle is not inserted properly. Insert the needle properly. Stitches 2. Needle is bent or worn. Change the needle. 3. Incorrectly threaded. Rethread. 4. Needle or thread are Use the recommended sewing needle inappropriate for fabric being and thread.
  • Page 4 Condition Cause How to Fix Reference 3. Breaking 1. Initial sewing speed is too fast. Start with medium speed. upper thread. 2. Thread path is incorrect. Use the proper thread path. 3. Needle is bent or dull. Replace with a new needle. 4.
  • Page 5 Condition Cause How to fix Reference 6. Noisy 1. Backlash between hook gear and See mechanical adjustment P. 14 operation lower shaft gear is too great. “backlash (lower shaft gear)”. 2. Lower shaft gear is loose. Eliminate the looseness. 3. Inappropriate belt tension. See part removal and replacement P.

  • Page 6: Service Access

    SERVICE ACCESS (1) FACE COVER TO REMOVE: 1. Remove the cap and setscrew (A) and remove the face cover while pushing the rib (B) up. TO INSTALL: 2. Attach the face cover, engaging the hook (C) and the rib (B) with the rear cover and tighten screw (A) 3.

  • Page 7: Bed Cover

    SERVICE ACCESS (2) BED COVER TO REMOVE: 1. Remove the 4 setscrews (A), remove the bed cover. TO INSTALL: 2. Follow the above procedures in reverse. Setscrew (A) Setscrew (A) Setscrew (A) Bed cover Setscrew (A)

  • Page 8: Free-Arm Cover

    SERVICE ACCESS (3) FREE-ARM COVER TO REMOVE: 1. Remove the needle plate. 2. Remove the bed cover (see page 5). 3. Loosen the setscrew (A) and (B). TO INSTALL: 4. Follow the above procedures in reverse. Needle plate Setscrew (A) Setscrew (B) Free-arm cover...

  • Page 9: Front Cover

    SERVICE ACCESS (4) FRONT COVER TO REMOVE: 1. Remove the face cover, bed cove and free-arm cover (see page 4–6). 2. Loosen the setscrew (A) and (B) then remove the setscrew (D) and (E). 3. Remove the cap and loosen setscrew (C). 4.

  • Page 10: Rear Cover

    SERVICE ACCESS (5) REAR COVER TO REMOVE: 1. Remove the front cover (see pages 7). 2. Loosen setscrews (A). 3. Remove the setscrews (B), (C), (D) and (E), then remove the rear cover. TO INSTALL: 4. Follow the above procedure in reverse. Setscrew (A) Setscrew (C) Rear cover...

  • Page 11: Mechanical Adjustment

    MECHANICAL ADJUSTMENT PRESSER BAR HEIGHT AND ALIGNMENT When the presser foot is raised, the clearance between the presser foot and the needle plate should be 5.7-6.3 mm. When the presser foot is lowered, the edge of the foot and the feed dog window on the needle plate should be parallel.

  • Page 12: Needle Drop Position

    MECHANICAL ADJUSTMENT NEEDLE DROP POSITION Set the stitch pattern to " ". The standard needle drop position should be at center of the needle plate hole. Select zigzag stitch " ", and set the stitch width at " 5.0 ". The clearance between the needle and the edge of the needle hole in the needle plate should be at least 0.2 mm on either side.

  • Page 13: Needle To Hook Timing

    MECHANICAL ADJUSTMENT NEEDLE TO HOOK TIMING When the machine is set for zigzag stitch (maximum zigzag width) at the right needle position, the amount of ascending travel of the needle bar from its lowest position at the right needle drop to the position where the tip of the hook meets the right side of the needle should be 1.4 to 2.0mm.

  • Page 14: Needle Bar Height

    MECHANICAL ADJUSTMENT NEEDLE BAR HEIGHT When the tip of the hook meets the right side of the needle in ascending travel of the needle from its right and lowest position, the distance between the top of the needle eye and the tip of the hook should be in the range of 3.0 to 3.6 mm. 1.

  • Page 15: Clearance Between Needle And Hook Point

    MECHANICAL ADJUSTMENT CLEARANCE BETWEEN NEEDLE AND HOOK POINT * The clearance between the needle and the point of hook should be –0.1 to +0.05 mm. PREPARATION: 1. Remove the needle plate, bobbin holder, and bed cover, and replace the needle with the test pin. 2.

  • Page 16: Backlash (Lower Shaft Gear)

    MECHANICAL ADJUSTMENT BACKLASH (LOWER SHAFT GEAR) TO CHECK: 1. Turn the power switch off. 2. Remove the needle plate and bobbin holder. 3. Turn the handwheel slowly toward you until the tip of the hook is between both ends of feed dog. 4.

  • Page 17: Feed Dog Height

    MECHANICAL ADJUSTMENT FEED DOG HEIGHT The highest position of the feed dog should be between 0.80 and 0.90 mm from the surface of the needle plate. 1. Remove the bed cover (see page 5). 2. Turn the power switch on. 3.

  • Page 18: Needle Swing Timing

    MECHANICAL ADJUSTMENT NEEDLE SWING TIMING The needle should start to swing between 7.7 and 8.7 mm above the surface of the needle plate when the machine is set for zigzag stitching. 1. Remove the front cover (see pages 7). 2. Turn on the power switch, select the pattern " ", and set the machine at the maximum zigzag width.

  • Page 19: Needle Thread Tension

    MECHANICAL ADJUSTMENT NEEDLE THREAD TENSION The top tension should be between 75 and 90g 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.

  • Page 20: Stretch Stitch Feed Balance

    MECHANICAL ADJUSTMENT STRETCH STITCH FEED BALANCE When a stretch pattern is sewn with the feed balancing dial set at the standard setting mark '' '', the pattern should be as indicated with the '' '' mark in the figure below. (If the stitch feed is not balanced, adjust it as follows: 1.

  • Page 21: Adjust The Buttonhole Lever Position

    ADJUSTING BUTTONHOLE LEVER POSITION ADJUSTING BUTTONHOLE LEVER POSITION TO ADJUST THE BUTTONHOLE LEVER GUIDE: 1. Enter the buttonhole sensor adjusting mode. (See below. The LCD should display BH symbol.) 2. Remove the face cover (see page 4) and loosen setscrew (A). 3.

  • Page 22: Replacing The Electronic Components

    REPLACING THE ELECTRONIC COMPONENTS LOCATION OF THE CONNECTORS NOTE: * Do not disconnect the connectors by pulling on the cord. * To disconnect, grasp the connector, not the cord. * Connect the connector to the connector post of the same color on the circuit board. For factory use only Buttonhole sensor Upper shaft sensor...

  • Page 23: Self Diagnostic Tests

    SELF DIAGNOSTIC TESTS Preparation: 1. Turn the power switch off. 2. Move the bobbin winder spindle to the left. 3. Remove the presser foot and raise the presser foot lifter. 4. Turn the hand wheel toward you to raise the needle to its highest position. Notes: •...
  • Page 24 Step and items Procedure Correct Condition Defective Condition to check Turn on the power switch while Sewing lamp does not lit. Sewing lamp and LCD backlight lit. Function of simultaneously pressing the reverse LCD displays “01”. LCD backlight does not lit. button and press the ring button (left) LCD does not display “01”.
  • Page 25 　　　　　　　　　　　　　　　　　　 Step and items Procedure Correct Condition Defective Condition to check Not applicable for this model Turn the handwheel toward you. LCD displays “SC 06”. Buzzer does not sound. Lower the needle bar from its highest Upper shaft Stitch width or length symbol to its lowest position.
  • Page 26 Step and items Procedure Correct Condition Defective Condition to check Attach the foot control to the sewing LCD displays “SC 08”. The foot control symbol does machine. not appear. Foot control Depress the foot control as far as it Buzzer does not sound. goes, then release it.
  • Page 27 Buzzer sounds after few seconds when the self-diagnostic test has been finished. The test result has been determined. Correct: Buzzer sounds and LCD displays “00” Defective: Caution buzzer sounds and LCD displays the defective part number. Refer to page 22-24 and fix the defective part. The defective part number.

  • Page 28: Circuit Board-A

    REPLACING PRINTED CIRCUIT BOARD A TO REMOVE: 1. Remove the front cover (see pages 7). 2. Pull out connectors from the circuit board-A. 3. Remove 6 setscrews and remove the circuit board-A. TO INSTALL: 4. Follow the above procedures in reverse. NOTE: Do not disconnect the connectors by pulling on cord.

  • Page 29: Driving Motor

    REPLACING DC MOTOR AND ADJUSTING MOTOR BELT TENSION DRIVING MOTOR (DC MOTOR) TO REMOVE: 1. Remove the front cover (see pages 7). 2. Loosen 2 setscrews and remove the driving motor and the belt. TO INSTALL: 3. Install the driving motor and the motor belt with 2 setscrews. 4.

  • Page 30: Switching Regulator

    REPLACING SWITCHING REGULATOR (UNIT) TO REMOVE: 1. Remove the rear cover (see pages 8). 2. Loosen 2 setscrews (A) and a setscrew (B), then remove the switching regulator. TO INSTALL: 3. Follow the above procedures in reverse. NOTE: * Cords should not contact the lower shaft, motor belt etc. Setscrew (B) Setscrews (A) Switching regulator...

  • Page 31: Stepping Motor (Zigzag)

    REPLACING STEPPING MOTOR (ZIGZAG) TO REMOVE: 1. Remove the front cover (see pages 7). 2. Remove 2 setscrews (A). 3. Remove E-ring. 4. Remove stepping motor (zigzag). TO INSTALL: 5. Follow the above procedures in reverse. NOTE: * Check the needle drop position after replacing the stepping motor. Setscrews (A) E-ring Stepping motor (zigzag)

  • Page 32: Stepping Motor (Feed)

    REPLACING STEPPING MOTOR (FEED) TO REMOVE: 1. Remove the front cover (see pages 7). 2. Remove 2 setscrews (A). 3. Remove E-ring. 4. Remove stepping motor (feed). TO INSTALL: 5. Follow the above procedures in reverse. NOTE: * Check the stretch stitch balance after replacing the stepping motor. Setscrew (A) Setscrew (A) E-ring...

  • Page 33: Oiling

    OILING Factory lubricated parts will provide years of household sewing without routine oiling. However, whenever the ma- chine is being serviced, check to see if any parts need to be lubricated. OIL: Use good quality sewing machine oil at the points ( A, B, C, D, E, F, G, H, J, K ) indicated by black arrows. GREASE: White grease is recommended for use on gears and cam surfaces.

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