Page 2 - GENERAL INFORMATION; there may be changes of specifications for improvements.; CONTENTS; PRINCIPAL MECHANISMS; CAUTION; printed circuit board with bare hands.
GENERAL INFORMATION · This service manual is complied for repairing service of domestic sewing machines PS2200, 2300, 2400 , 2500, STAR 110, 120E, 130E and 140E. · Use this manual with Parts Catalogue for fault findings when you make a repair. · This machine is manufactured based on up-to-date produ...
Page 3 - POWER TRANSMISSION CHART
- 1 - I. PRINCIPAL MECHANISMS 1. MECHANICAL CHART ............................................................................ 2 2. POWER TRANSMISSION CHART .......................................................... 3 3. MICROCOMPUTER-CONTROLLED MAIN MOTOR (B375, B376 AND B377) ........................
Page 6 - (B) Mechanism of feed dog and oscillating hook movement
- 4 - (B) Mechanism of feed dog and oscillating hook movement
Page 9 - TROUBLES AND CHECK POINTS
- 7 - II. TROUBLES AND CHECK POINTS 1. Machine skips stitches. ........................................................................... 9 2. Fabric does not feed. .............................................................................. 9 3. Fabric does not feed straight. ......................
Page 13 - Be sure to turn off the power and remove the connector from the PCB.
- 11 - PROBLEM CAUSE CORRECTION 17. The light does not turn on even afterthe power is turnedon.(B375, B376 andB377) Light is off.(B373) 1. The voltage on both ends of connector SOURSE is not 120V or 230V ACwhen the AC cord is inserted. 2. The resistance on both ends of the power switch is not less t...
Page 18 - HOW TO ADJUST THE ELEMENTS; ADJUSTMENT OF THE TIMING BETWEEN THE UPPER AND
- 16 - III. HOW TO ADJUST THE ELEMENTS 1. ADJUSTMENT OF EACH CONTROL UNIT ............................................ 18 2. ADJUSTMENT OF THE TIMING BETWEEN THE UPPER AND LOWER SHAFTS ..................................................................................... 19 3. ADJUSTMENT OF THE MOTOR...
Page 20 - ADJUSTMENT OF EACH CONTROL UNIT
- 18 - 1. ADJUSTMENT OF EACH CONTROL UNIT 2. Back and forth seam at automatic reverse pattern 5. Bar tack feeding at buttonhole 3. Forward feeding 4. Forward and reverse feeding at buttonhole 1. Adjustment for straight stitch at left position
Page 21 - STANDARD; of the lower shaft should be 5; ADJUSTMENT; cam so that it is 5
- 19 - 2. ADJUSTMENT OF THE TIMING BETWEEN THE UPPER AND LOWER SHAFTS STANDARD When the mark on the horizontal feed cam of the upper shaft is horizontal, the mark on the thread cutter cam of the lower shaft should be 5 ° above horizontal. (Turn the pulley counterclockwise.) ADJUSTMENT 1. Remove the ...
Page 22 - ADJUSTMENT OF THE MOTOR BELT AND TIMING BELT TENSIONS
- 20 - 3. ADJUSTMENT OF THE MOTOR BELT AND TIMING BELT TENSIONS STANDARD There should be 4 ~ 6 mm of slack on the motor belt and 3 ~ 4 mm of slack on the timing belt when the center of each belt is pushed with about 200 g pressure. ADJUSTMENT Timing belt 1. Loosen the screw on the tension pulley. 2....
Page 23 - ADJUSTMENT OF THE NEEDLE POSITION AND NEEDLE SWING; Set pattern dial to zigzag stitch.; Loosen three set screws on worm gear.; NOTE; When needle goes down
- 21 - 4. ADJUSTMENT OF THE NEEDLE POSITION AND NEEDLE SWING STANDARD Set pattern dial to zigzag stitch. The needle should drop in the center of the needle plate hole when the zigzag width dial is set to "0". The needle should drop in the needle hole balanced when the zigzag width dial is se...
Page 24 - Drop the needle into the paper by turning the pulley.
- 22 - 5. MAXIMUM STITCH WIDTH WHEN SET AT STRAIGHT (LEFT) AND ZIGZAG STITCH STANDARD Left end of straight stitch should be the same position as left end of zigzag stitch. ADJUSTMENT 1. Lower the feed dog using the drop lever, then place a piece of paper on the needle plate and lower the presser foo...
Page 25 - ADJUSTMENT OF THE ROTARY HOOK (NEEDLE AND OUTER ROTARY; mm and the hook should not hit the needle.; hook point is less than 0.1 mm without contacting each other.
- 23 - 6. ADJUSTMENT OF THE ROTARY HOOK (NEEDLE AND OUTER ROTARY HOOK CLEARANCE) STANDARD When the pattern dial is set to the straight stitch, the zigzag width dial is set to the maximum, and the needle is between 2.8 and 3.2 mm above its lowest point, the pointed end of rotary hook should meet with...
Page 26 - ADJUSTMENT OF THE NEEDLE BAR HEIGHT; Loosen the screw on the needle bar clamp.
- 24 - 7. ADJUSTMENT OF THE NEEDLE BAR HEIGHT STANDARD When the pattern dial is set to the straight stitch, the zigzag width dial is set to the maximum and the pointed end of the rotary hook contacts the right side of the needle, the distance from the top of the needle eye to the bottom of the outer...
Page 27 - Loosen the screw for adjustment of the nut.
- 25 - 8. FORWARD AND REVERSE SEWING FOR TRIPLE ZIGZAG STRETCH STITCH STANDARD When pattern dial is set to triple zigzag stretch stitch, there should be no difference between forward and reverse feed. ADJUSTMENT 1. Set the pattern dial to the zigzag stitch, the zigzag width dial to the maximum, and ...
Page 28 - ADJUSTMENT OF FEED; Loosen the nut for forward feed adjusting screw.
- 26 - 9. ADJUSTMENT OF FEED STANDARD When stitch length dial is set to "0", stitch length should be 0 mm. ADJUSTMENT 1. Set the pattern dial to the zigzag stitch, the zigzag width dial to the maximum and the stitch length dial to "0". 2. Loosen the nut for forward feed adjusting scr...
Page 29 - POSITION OF INNER ROTARY HOOK STOPPER; Loosen the screw on inner rotary hook stopper.
- 27 - 10. POSITION OF INNER ROTARY HOOK STOPPER STANDARD Inner rotary hook stopper should hold inner rotary hook by 1.9 ~ 2.1 mm as shown in drawing. ADJUSTMENT 1. Loosen the screw on inner rotary hook stopper. 2. Adjust the position of inner rotary hook stopper. (Face A on inner rotary hook and fe...
Page 30 - POSITION OF FEED DOG; Loosen two screws on the horizontal feed plate.
- 28 - 11. POSITION OF FEED DOG STANDARD When the upper shaft is rotated once with the maximum feed, the feed dog should not contact the needle plate on the left and right. When the feed dog is in its initial feed position (as far forward as possible), the clearances between the feed dog and the nee...
Page 31 - HEIGHT OF FEED DOG; Loosen the screw for vertical feed finger.
- 29 - 12. HEIGHT OF FEED DOG STANDARD Feed dog should be higher than the needle plate by 0.9 ~ 1.1 mm when the feed dog is raised to its highest position. ADJUSTMENT 1. Raise the feed dog using the drop lever, then raise the feed dog to its highest position by turning the pulley. 2. Loosen the scre...
Page 32 - HEIGHT OF PRESSER BAR; Loosen the screw on presser bar guide bracket.
- 30 - 13. HEIGHT OF PRESSER BAR STANDARD The clearance between presser foot and needle plate should be 6.0 ~ 6.5 mm. ADJUSTMENT 1. Raise presser foot. 2. Loosen the screw on presser bar guide bracket. 3. Adjust height of presser bar. (Presser foot should be parallel to feed dog.) 4. Tighten the scr...
Page 33 - counterclockwise from the topmost needle bar position).; Loosen the screw on the rotary shutter.
- 31 - 14. POSITION OF N.P. (NEEDLE POSITION) SHUTTER (B375, B376 AND B377) STANDARD The needle position shutter works when the needle bar is 1.9 mm below its highest position (approx. 37° counterclockwise from the topmost needle bar position). ADJUSTMENT 1. Turn the pulley counterclockwise until th...
Page 34 - ADJUSTMENT OF THE THREAD TENSION DIAL; Loosen the screw for thread tension control screw.
- 32 - 15. ADJUSTMENT OF THE THREAD TENSION DIAL STANDARD When thread tension dial is set to "4" and presser foot is lowered, upper thread tension should be 33 ~ 38g using polyester thread #60. ADJUSTMENT 1. Set thread tension dial to "4", put polyester thread between tension discs a...
Page 36 - SETTING OF THE STITCH LENGTH DIAL HOLDER; Install the stitch length dial holder using the two screws.
- 34 - 17. SETTING OF THE STITCH LENGTH DIAL HOLDER STANDARD The mark on the feed adjusting cam faces straight forward when the stitch length dial is set to "SS". ADJUSTMENT 1. Turn the stitch length dial to "SS". 2. Adjust the feed adjusting cam so that its mark faces straight forwa...
Page 37 - POSITION OF THE PATTERN INDICATION PLATE; Loosen the screw on the indication gear B.
- 35 - 18. POSITION OF THE PATTERN INDICATION PLATE STANDARD Each pattern number should be in the center of the pattern indicator window each time the pattern dial is set. ADJUSTMENT 1. Set the pattern dial to "3". (The second position when turning the pattern dial clockwise after fully turn...
Page 39 - The feeding of a bar tack should be less than 10 stitches/1 mm.; Turn the bar tack adjusting screw to adjust the bar tack.
- 37 - 20. BUTTONHOLE ADJUSTMENT (BAR TACK FEEDING) STANDARD The feeding of a bar tack should be less than 10 stitches/1 mm. ADJUSTMENT 1. Set the pattern dial to "1", then sew a buttonhole. 2. Turn the bar tack adjusting screw to adjust the bar tack. NOTE Turn the screw to the left to move ...
Page 40 - The pressure needed to pull the BH lever forward should be 50 ~ 110 g.; Adjust the position of BH lever according to drawings below.
- 38 - 21. BUTTONHOLE ADJUSTMENT (THE LENGTH OF THE BUTTONHOLE AND THE PRESSURE OF THE BH LEVER) STANDARD The length of buttonhole should be 21 ~ 23 mm, when the button is 20.0 mm in diameter. The pressure needed to pull the BH lever forward should be 50 ~ 110 g. ADJUSTMENT 1. Loosen the screw on BH...
Page 41 - ADJUSTMENT OF THE BOBBIN WINDING; Loosen the screw for the bobbin presser slightly.
- 39 - 22. ADJUSTMENT OF THE BOBBIN WINDING STANDARD Thread should be wound parallel to the bobbin and be wound 75 ~ 85% of the outer-diameter of bobbin. ADJUSTMENT 1. In case bobbin thread is wound unbalanced, loosen the screw for bobbin winder thread guide slightly. 2. Move bobbin winder thread gu...
Page 43 - Adjust the switch by moving it left to right.
- 41 - 24. ADJUSTMENT OF THE BOBBIN WINDING SWITCH (B375, B376 AND B377) STANDARD When bobbin winder is moved to bobbin presser, bobbin winding switch should be on. When bobbin winder is returned, the clearance between bobbin winder and switch should be 1.0 ~ 1.5 mm. ADJUSTMENT 1. Move bobbin winder...
Page 44 - The PF switch should bend 1 ~ 2 mm when the presser foot is raised.
- 42 - 25. ADJUSTMENT OF THE PF (PRESSER FOOT) SWITCH (B375, B376 AND B377) STANDARD The PF switch should bend 1 ~ 2 mm when the presser foot is raised. ADJUSTMENT 1. Loosen the screw on the PF switch. 2. Raise the presser foot. 3. Adjust so that the PF switch bends 1 ~ 2 mm. 4. Tighten the screw on...
Page 45 - thread cutter operation lever stops.; latch is engaged, then release the lever.; automatically resets itself.
- 43 - 26. ADJUSTMENT OF THE THREAD CUTTER SWITCH (B377) STANDARD When the thread cutter operation lever is operated while the needle is lowered and the latch is engaged, the thread cutter switch should go on between the point where the latch is engaged and the position where the thread cutter opera...
Page 46 - FORWARD AND REVERSE FEEDING FOR STRAIGHT STITCH; Loosen the screw on the reverse sewing finger.
- 44 - 27. FORWARD AND REVERSE FEEDING FOR STRAIGHT STITCH STANDARD There should be no difference in the length of a forward stitch as compared to a backward stitch when the stitch length dial is set to "2". ADJUSTMENT 1. Set the pattern dial to "2". 2. Set the stitch length dial to ...
Page 47 - ADJUSTMENT OF THE INNER ROTARY HOOK TENSION; After adjusting the tension, apply locking paint to the screw.
- 45 - 28. ADJUSTMENT OF THE INNER ROTARY HOOK TENSION STANDARD When polyester thread (#60) threaded through the inner rotary hook is slowly pulled with a tension gauge, the tension should be 10 ~ 12 g. ADJUSTMENT 1. Using polyester thread (#60), thread the inner rotary hook as usual, then slowly pu...
Page 48 - imperfect performance.; Thread
- 46 - 29. NEEDLE THREADER CAUTION 1. Needle threader accepts only circle marked needle and thread combinations. 2. * marked combinations is not recommended since it might lead to the breakage of needle threader or imperfect performance. 3. Lower the presser foot when you use needle threader. 4. Nyl...
Page 49 - (CHECKING THE HOOK POSITION IN HORIZONTAL DIRECTION); After Checking
- 47 - 30. NEEDLE THREADER (CHECKING THE HOOK POSITION IN HORIZONTAL DIRECTION) STANDARD The measure from inside of the hook guard to the center point of hook is 0.42 mm. CHECK Prepare 5 pcs. of brand-new sewing HA ´ 1 (#14) and check by changing all of these. After Checking A. In case that, hook ge...
Page 50 - HOW TO EXCHANGE THE NEEDLE THREADER; When replacing the needle threader, follow the procedure below.; Remove the needle and lower the presser foot.
- 48 - 31. NEEDLE THREADER (REPLACEMENT) HOW TO EXCHANGE THE NEEDLE THREADER When replacing the needle threader, follow the procedure below. 1. Remove the needle and lower the presser foot. 2. With the index fingers of both hands, push down on the needle threader to remove it. 3. To install a new ne...
Page 51 - (CHECKING THE HOOK POSITION IN VERTICAL DIRECTION); Case A
- 49 - 32. NEEDLE THREADER (CHECKING THE HOOK POSITION IN VERTICAL DIRECTION) STANDARD 1. The clearance between the top of hook and the top of needle eye is zero. 2. Threading is capable when needle is located higher than 9.0 mm from the needle plate. CHECK (Refer to the illustration.) Case A Hook p...
Page 52 - (ADJUSTMENT OF THE HOOK POSITION IN VERTICAL DIRECTION); Set the needle position at right and loosen the screw.
- 50 - 33. NEEDLE THREADER (ADJUSTMENT OF THE HOOK POSITION IN VERTICAL DIRECTION) CASE A (Hook point is too high) 1. Set the needle position at right and loosen the screw. 2. Adjust needle threader slightly down and check the clearance between the top of hook and top of needle eye is zero. 3. Check...
Page 53 - ADJUSTMENT OF THE THREAD CUTTER NOTCH CAM POSITION (B377); Loosen the two screws on the thread cutter notch cam.
- 51 - 34. ADJUSTMENT OF THE THREAD CUTTER NOTCH CAM POSITION (B377) STANDARD The thread cutter latch should be disengaged when the needle bar is 1.6 mm below its highest position (approx. 34° counterclockwise from the topmost needle bar position). ADJUSTMENT 1. Turn off the power, then turn the pul...
Page 54 - ADJUSTMENT OF THE THREAD CUTTER FRAME INSTALLATION; Position the thread cutter frame assembly.
- 52 - 35. ADJUSTMENT OF THE THREAD CUTTER FRAME INSTALLATION POSITION (B373, B375 AND B376) STANDARD 1. The thread cutter frame should be positioned so that there is no space between it and the side of the arm. 2. It should be positioned so that the space between the thread cutter frame and the out...
Page 55 - HOW TO CHANGE THE PARTS
- 53 - IV. HOW TO CHANGE THE PARTS 1. REMOVING THE COVERS ..................................................................... 542. LAMP REPLACEMENT............................................................................ 553. LEAD WIRES ARRANGEMENT .................................................
Page 56 - REMOVING THE COVERS; Pull the thread cutter operation lever off toward you.; INSTALLING THE FRONT COVER
- 54 - 1. REMOVING THE COVERS 1. Remove the face plate screw, then remove the face plate by pulling it off to the left. 2. Remove the free-arm cover screw, then remove the free-arm cover by pulling it off to the left. 3. Pull the thread cutter operation lever off toward you. 4. Loosen the two front ...
Page 57 - Attach new sew-light bulb to lamp socket
- 55 - 2. LAMP REPLACEMENT 1. Loosen the screw of face plate. 2. Remove face plate. 3. Attach new sew-light bulb to lamp socket B373 B375, B376 AND B377
Page 58 - LEAD WIRES ARRANGEMENT
- 56 - 3. LEAD WIRES ARRANGEMENT (B377, B375, B376) * B377 only (B373) * * *
