SERVICE MANUAL 9940/20/10
Contents
1. 6 The forward reverse stitch length is adjusted by turning the screw d 4mm hex wrench e If the reverse stitch is finer than the forward stitch turn the screw to the left e If the reverse stitch is coarser than the forward stitch turn the screw to the right 7 When correct height is obtained retighten the lock screw c and replace the base 21 SERVICE MANUAL 8 BOBBIN WINDER If bobbin winds unevenly adjust as follows 1 If bobbin winds as shown turn the adjusting screw a to the left 2 If bobbin winds as shown turn the adjusting screw a to the right 3 If the bobbin thread is wound too little or too much loosen the screw b on bobbin winder stop c and adjust as follows 4 f the bobbin thread is wound too much slide the bobbin winder stop c to the left 5 If the bobbin thread is wound too little slide the bobbin winder stop c to the right 6 Retighten the screw b 22 SERVICE MANUAL 9 HEIGHT AND DIRECTION OF PRESSER bio The height of the presser foot from the needle plate should be 6 5 mm when it is lifted up The presser foot should be facing frontward the edge of foot is parallel with the feed dog slot on needle plate If adjustment is needed follow these procedures 2 Remove the light cover 3 Loosen the screw a located behind of the machine 4 Adjust the height and direction of presser foot 5 Retighten the screw a 62. a b 3 Move the motor up or downward and tentatively tighten the screws Check the belt tension as follows The belt does not touch to the casting or other parts The belt must have flexibility of 5 6 mm when average pressure is applied on its side 4 When correct tension has been obtained tighten the bolts a b securely 13 TIMING BELT TENSION If the timing belt tension is too tight or too loose the machine will run heavily or the timing of hook and feed E motion will be changed incorrectly A Ma 3 mb Adjust as follows m Remove the front enclosure 2 Loosen the screw a tightening the tension pulley bracket 3 Push the tension pulley bracket so that the edge of bracket should be 0 1 mm higher than the casting and retighten the screw a 4 When you have adjusted the timing belt tension re check the timing of the upper and lower shaft Sec 6 and the timing of the hook Sec 3 again 26 SERVICE MANUAL 14 BACKLASH OF HOOK GEAR If there is too much play on the hook gear on the turning direction it may be the cause for machine not to sew properly and or making excessive sewing noise 1 Free play at the tip of hook may be 0 0 5 mm If it is not so adjust as follows 2 Remove the front enclosure 3 Loosen the screw a and turn the lower shaft eccen tric ball bushing up or down by hooking the tip of driver into the left side groove b of bushing Turn u
3. adjust as follows 3 Loosen the screw b tightening the tension pulley bracket HAPPY PB 0RJ T Edi m 4 Slip out the timing belt from lower shaft timing pulley 5 Turn the lower shaft timing pulley so that the mark faces toward you 6 Hook the timing belt on the pulley 7 Push the tension pulley bracket so that the edge of bracket should be 0 1 mm higher than the casting 8 Retighten the screw b 9 Check the timing again and replace the front enclo sure 10 When you have adjusted it check the timing of the hook again Sec 3 20 SERVICE MANUAL 7 ADJUSTING THE FORWARD REVERSE STITCH When stretch stitch sewing the lengths of the forward and reverse stitches should be the same Feed Adjust Check and adjust as follows We recommend checking Height of the Feed dog Sec 4 before you make this adjustment 9 9 909 2 2 OO O 1 Turn on the power switch with pressing the buttons as shown LCD wiil indicate the message Feed Adjust Feed Adjust O yO Feed Adjust ANY EO O 2 2 B5 2 Attach the general purpose foot and set a piece of paper under the foot Feed Adjust 3 Start the machine and open holoes of test pattern The holes a and b should be same position If they are not so adjust as follows 4 Remove the base 5 Loosen the lock screw c 2 5 mm hex wrench
4. with a 2 5 mm hex wrench Turn the hook race by hand so that the tip of hook will align with the right side of needle In this position hold the hook race with your left hand and turn the handwheel toward you to obtain the correct gap 1 3 mm Tighten the screws and check the timing again 10 Replace the front enclosure SERVICE MANUAL 17 SERVICE MANUAL 4 HEIGHT OF THE FEED DOG If the feed dog does not come up over the needle plate enough it will result in insufficient and or uneven feed of fabrics 1 The feed dog should come up over the needle plate 1 0 1 1 mm when its highest position If it does not come up enough adjust as follows 2 Remove the needle plate 3 Lower the presser foot lifter Turn the handwheel until the feed dog comes to its highest position If the feed dog is too low Turn the adjusting screw a 1 5mm hex wrench clockwise until correct height is obtained Turn the screw b clockwise until the cam follower c touches the feed rocking cam Right d To check it remove the front enclosure and see frontward If the feed dog is too high Turn the screws a and b counterclockwise in a few turns Push the left side of feed base strongly e feed dog will come down Check that the feed dog came lower than the correct height If it is not so turn the screws counterclockwise again and lower the feed base After the feed dog is lower than the correct
5. Check if the presser foot lifter has a slight play in down position 23 SERVICE MANUAL 10 HEIGHT OF NEEDLE THREADER If the height of needle threader is not correct the hook on threader will not enter the needle eye Adjust as follows Remove the light cover 2 Remove the 2 screws a b and remove the take up lever cover and bracket c by sliding it upward Bottom hook of cover will come off 3 Set the pattern at Utility No 2 straight stitch on left needle position 4 Raise the needle to its highest point by turning the handwheel 5 Loosen the screw d on the needle threader bar stopper e with a 1 5 mm hex wrench 6 Adjust the height of stopper e so that the hook enter the needle eye 7 Tighten the screw d and check the height of needle o threader again 9 mm j l v CAUTION b Mc Be careful with direction of stopper when tighten the screw If direction of stopper NOT right machine makes noise and or threader does NOT work smoothly The correct direction is that the screw d is facing frontward 8 Replace the take up lever cover and screws 9 Replace the light cover A If the hook has bent change the threader hook assembly To remove the hook assembly pull it downward 24 1 If the machine dose not sew even with the buttonhole lever all the way down it means that the buttonhole lever is not positioned properly Also if the buttonhole lever is n
6. ICE MANUAL LOCATING THE DEFFECTED ELECTRICAL PART 1 To turn off the audible beep You can operate the machine without the audible beep 1 Turn off the power switch 2 Tum on the power switch with pressing the buttons indicated in the right chart 3 To return the normal mode turn off the power switch and turn on without pressing any button 2 The self diagnostic program This machine has the self diagnostic program to locate the defected electronic part If your machine functions are not normally run this program 1 Turn off the power switch 2 Tum on the power with pressing the buttons as indicated in the right chart When this program has started correctly the LCD will indicate the conditions of each electrical part as below O Model 9910 only By pressing the Stitch length button indicating screen will change alternately See next page to check each electrical part To quit this program turn off the power switch bfSTsWwOY K F 110100111 0 255 z F LED 29 Condition of switches and sensors The condition of each switch and sensor is indicated as follows b Buttonhole lever switch Rear 1 Neutral O Lever is pulled f Buttonhole lever switch Front 1 Neutral O Lever is pushed Lower the buttonhole lever and check these switc
7. SERVICE MANUAL 9940 20 10 SINGER 9 20 2003 SERVICE MANUAL Table of contents REMOVING THE EXTERIOR PARTS en eres 3 MA AA dA a a 3 DBO nado Ee ee Dea A 3 E Top COVEr Riad PR 4 D ANOS COVER eps cia di de m NA 4 E Thread Tension Cover ccccccccscccceeccenceceececeeceeeeeeseeeeeneeteneeseneenseeeaeetans 4 A O rr E LUI 9 G Hande and nit COV Cl aia 9 El Neede Plil crainn tette e FOR M ER Dei via er ane er OR Ra 6 ELO LENCIOS US e AR A T d Rear ENCIOSURO a a S ne 8 K Front panel from Front Enclosure erre 8 REPLACING THE EXTERIOR PARTS oie eee noi 9 K Front panel to Front Enclosure cccccccccecseeeeeeeeeeeeeeseeseeeeaaeeeeessaeeees 9 J IRSA REN COS US toV cer ncn ctia rudis ORE ND Ab RS 9 la FLO ENCIOS US ie do an SOR A A 10 H Needle Plate e nennen nnne nnne nnns 10 G Handle and Unit Cover oocccocccccccccoccncocnccocnconcncononononnononnonnnnoncnnoncnnnnnnnnons 11 Fe SIE EMCO SUNS aia T REM 12 E Thread Tension Cover ccccccccsscecscceeseecsseececeeaececeeeteeeeteeeeseetseeeaness 12 Ds TINGS COVER assino o T ETT 12 Gi MOP COV Er RIAD obesa asas e a a O ee 13 BD DAS as 13 AN ias cas dl A A 14 CHECK AND ADJUSTMENT canti 15 Ts HEIGHT OF NEEDLE BAI adan oen 15 2 GAP BETWEEN NEEDLE AND HOOK eee 16 3 TIMING OF THE HOOK ousa sl sta Duos santas nea sash cues Sas bod
8. as follows 5 Set the pattern at Utility No 2 Straight stitch on left Turn the handwheel toward you until the needle will Then check the gap between needle and hook is Adjust the gap by turning the adjusting screw a with Replace the bobbin holder and needle plate and light Remove the needle plate and bobbin holder needle position cross over the hook about 0 10 to 0 20 mm Remove the light cover View from upward 2 mm hex wrench If the gap is too big turn the screw to the left with viewing from frontward If the needle is hitting the hook turn the screw to the right with viewing from frontward cover SERVICE MANUAL 16 3 TIMING OF THE HOOK Prior to making this adjustment be sure that the needle bar is set at the correct height Sec 1 Check the timing of hook as follows Remove the needle plate and bobbin holder Set the pattern at Utility No 2 Straight stitch on left needle position Turn the handwheel toward you until the needle is at its lowest point Then turn the handwheel slowly to turn the hook counter clockwise until the tip of hook is aligned with the right side of needle At this time the gap between the tip of hook and the top edge of needle eye should be 1 3 0 2 mm If the gap is too small or too large adjust as follows 5 Remove the front enclosure Loosen the two 2 screws a on the lower shaft gear
9. h by pulling or pushing this lever S Stop sensor 1 not intercepted O intercepted T Timing sensor 1 not intercepted O intercepted s Speed sensor 1 not intercepted O intercepted These sensors are intercepted by the slit plates on the upper shaft Stop sensor Stop slit Timing sensor Timing slit Speed sensor Speed slit Turn the handwheel and check the response of each sensor W Bobbin Winder Switch 1 Bobbin winder spindle is in right position O Spindle is in left position Move the bobbin winder spindle left or right and check this switch w Bobbin Winding Stop Switch 1 Bobbin winder stop is not pushed Bobbin winding is not full O Bobbin winder stop is pushed to the right Bobbin winding is full Move the bobbin winder stopper to the right and check this switch O Presser foot switch 1 Presser foot is lowered O Presser foot is lifted Lower or lift the presser foot lifter and check the response of this swtich Y Upper thread sensor Only 9940 1 Thread check spring is pulled O Thread check spring is not pulled Thread the upper thread until thread check spring threading route No 4 and hold both end of thread Pull or release left end of thread and check the response of this sensor SERVICE MANUAL 30 SERVICE MANUAL K Response of each button By pressing each button number will be indicated as below 2017 130 014 62018 150 016 C te O 19 20 F Conditi
10. height adjust the feed dog height same as If the feed dog is too low 4 Check that the cam followers c e have to be even height and they have no opening to each cam d f 5 Re check the height and motion of feed dog by turning the handwheel 18 SERVICE MANUAL 5 NEEDLE PLATE AND NEEDLE POSITION 1 When the straight stitches is set at center needle position Utility No 1 the needle should fall into the center of needle plate hole the distance needle and edge of hole at each side If it is not so adjust as follows 2 Set the pattern at Utility No 1 3 Remove the presser foot and the light cover 4 Loosen the center screw a 5 Turn the adjusting screw b left or right until the needle falls center position into the hole When you turn the screw to the right needle wiil move to the left When you turn the screw to the left needle wiil move to the right 6 Retighten the screw a and re check the position of needle 7 When you have adjusted the this position check the timing of the hook again Sec 3 19 SERVICE MANUAL 6 TIMING OF THE UPPER AND LOWER SHAFT The upper and lower shaft must be positioned correctly as follows 1 Remove the front enclosure 2 Turn the handwheel toward you until the needle is its lowest point At this time the mark a very small molded line on edge on the lower shaft timing pulley must be facing toward you If it is not so
11. hread guide cover 5 Slide the handle and unit cover to the left and remove them 6 Carefully disconnect the connector which connects to the contrast control board H Needle Plate 1 Remove the presser foot 2 Remove the 2 screws a b holding the needle plate 3 Lift up the right side of needle plate and remove it SERVICE MANUAL SERVICE MANUAL Front Enclosure 1 Loosen the screw a 2 Push the left side of rear enclosure b and pull the front enclosure hook c will come off 3 Pull up the front enclosure and come off the hook d 4 Pull the enclosure to the left and come off the hook e 5 Push the rear enclosure to the left and come off the hook f 6 Disconnect the 2 connectors g h from the machine and remove the front enclosure SERVICE MANUAL J Rear Enclosure 1 Lower the presser foot lifter 2 Remove the 3 screws a b c screw c is longer than others 3 Pull the rear enclosure backward and remove it K Front panel from Front Enclosure 1 Disconnect the 2 connectors from the front panel a Reverse switch board b Controller jack assy TYPE A Secured by 4 screws 2 Remove the 4 screws c d e f 3 Push the lower hook g downward and push the upper hooks h i upward to come off TYPE B Locked by hooks 2 Push the lower 3 hooks j k downward to come off them 3 Push the upper 3 hooks upward to come off them 4 Pull up the front pa
12. ition 2 Raise the needle bar to its highest point by turning the handwheel toward you Remove the presser foot Remove the needle plate Lift up the bobbin holder and remove it 3 Turn the handwheel toward you until the needle comes to its lowest point 4 Then the spacing between the surface of hook race and the top edge of needle eye must be 4 9 0 1 mm If this spacing is not correct adjust as follows 5 Remove the light cover 6 Remove the 2 screws a b and remove the take up lever cover and bracket c by sliding it upward Bottom hook of cover will come off 7 Raise the needle bar 4 9mm from its lowest point by turning the handwheel Loosen the screw d on the needle bar holder 2 mm hex wrench Adjust the needle bar so that the top edge of needle eye is aligned with the surface of hook race Retighten the screw d and check the height again CAUTION Do not change the needle bar direction at this adjustment The long groove of needle must be facing frontwards 8 Replace the take up lever cover and screws 15 If the needle hits against the hook it may be the cause of needle and thread breakages If the gap between needle and hook is too big it will cause to skip stitches Check and adjust as follows Prior to make this adjustment check that the needle is not bent and the needle is inserted correctly 1 If the needle is hitting against the hook or if the gap is too much adjust
13. lectrical Parts Connection a CPU Board b Power Circuit Board c Power Switch Assy d Terminal Box Assy e Motor f F Pulse Motor g Z Pulse Motor h LED Board Assy i BH Switch Assy Presser Foot Switch Assy k Thread Sensor Board Assy 9940 Only j Reverse Switch Board Assy m LCD Assy n Contrast Control Board Assy o Display Board Assy o a a a e ez p Controller Jack Assy A 34
14. nel backward and remove it 3 hooks on front panel will come off SERVICE MANUAL REPLACING THE EXTERIOR PARTS The exterior parts should be replaced in reverse se quence when removing K to A K Front panel to Front Enclosure 1 Pass the cords through the openings of front enclo sure 2 Ride the 3 hooks of front panel on the front enclosure TYPE A Secured by 4 screws 3 Push front enclosure around the hook and fit them in place Retighten the 4 screws TYPE B Locked by hooks 3 Push front enclosure around the hook and fit them in place 4 Connect the 2 connectors a Reverse switch board b Controller jack assy J Rear Enclosure 1 Lower the presser foot lifter 2 Replace the rear enclosure 3 Retighten the 3 screws a b c Screw c is longer than others and replace loosely SERVICE MANUAL Front Enclosure 1 Connect the 2 connectors g h to the machine 2 Replace the front enclosure so that the 4 hooks will fit in place 3 Push lower end of front enclosure arm backward and retighten the screw a H Needle Plate 1 Insert the hook c of needle plate to the machine 2 Retighten the screws a b 10 G Handle and Unit Cover 1 Set the handle to the unit cover and insert the handle hinge pin into the left side hole of handle from left side 2 Place the handle and unit cover onto the top of machine 3 Connect the connector to the contrast control b
15. nnect the main lead plug from electcrial outlet when removing the exterior parts A Light Cover 1 Loosen the light cover set screw a 2 Pull light cover as shown so that the light cover hook b will come off B Base 1 Remove the extension table 2 Tiltthe machine backward and remove the 3 base set screws a b c Remove the base 3 Carefully disconnect the connector with holding the lever d This connector connects terminal box and power circuit board C Top Cover Flap 1 Open the top cover 2 Push the right side of top cover backward and remove the hinge a 3 Slide the top cover to the right and remove the hinge b D Hinge Cover 1 Insert the tip of screw driver and pull up the front side of hige cover E Thread Tension Cover 1 Remove the screw a 2 Push the Thread tension cover backward 2 hooks b C will come off 3 Pull up the cover SERVICE MANUAL F Side Enclosure 1 Remove the screw a 2 Push the side enclosure slightly backward to come off the 2 hooks b c 3 Pull the side enclosure to the right and remove it G Handle and Unit Cover 1 Remove the unit cover set screws a b and handle set screws c d 2 Stand up the handle 3 Push the right side of unit cover backward so that the hook of unit cover will come off and pull up SERVICE MANUAL 4 Next push the left side of unit cover backward and pull up it to come off from the t
16. oard 4 Insert the hinge pin on the machine into the right side hole of handle 5 Replace the unit cover so that the each hook fit into place 6 Retighten the handle set screws c d and unit cover set screws a b SERVICE MANUAL 11 F Side Enclosure 1 Replace the side enclosure so that the each hook fit into place 2 Retighten the screw a E Thread Tension Cover 1 Replace the thread tension cover so that the each hook fit into place 2 Retighten the screw e D Hinge Cover 1 Insert the rear hook into the machine and push the hinge cover SERVICE MANUAL 12 C Top Cover Flap 1 Slide the top cover to the left so that the hook b will fit onto the pin of unit cover 2 Pull the right side of top cover and snap on the hook a onto the pin of unit cover B Base 1 Tiltthe machine backward 2 Connect the connector so that the hook d will fit into place 3 Replace the base and retighten the 3 screws SERVICE MANUAL 13 SERVICE MANUAL A Light Cover 1 Loosen the light cover set screw a 2 Replace the ligth cover so so that the hook b will fit into place 3 Retighten the screw a 14 SERVICE MANUAL CHECK AND ADJUSTMENT 1 HEIGHT OF NEEDLE BAR Height of needle bar could be the cause for stitches to skip Check as the following procedures 1 Set the pattern to Utility stitch No 1 which is straight stitch on center needle pos
17. on of Foot Controller Foot controller is not connected the number 255 will appear Connect the foot controller the number will change to 75 Press the pedal of controller the number will de crease accroding to the pressure on the pedal When pressed maximum the number 0 will be indicated S This is not used these models 31 SERVICE MANUAL Checking Starting point of Z and F pulse motors 1 When self diagnositic program is running By pressing the button a Z pulse motor will move to starting point By pressing the button b F pulse motor will move to starting point Checking LED Light 1 When self diagnositic program is running By pressing the button c once LED d will turn on By pressing the button c again LED e will tum on By pressing the button c once more LED will turn off 32 SERVICE MANUAL 3 Messages on LCD 9940 9920 Winding the bobbin 2 Lower the buttonhole lever O Raise the presser foot lifter and set the buttonhole foot to correct position 4 Release the foot controller pedal al Lower the presser foot O Machine cannot memory any more N Select pattern Oo Release the reverse button O Rethread the upper thread 9940 only 10 Release the needle up down button 33 SERVICE MANUAL 4 E
18. ot positioned properly the machine will sew buttonhole as shown or incorrectly 2 Turn on the power switch with pressing the buttons as shown The self diagnostic program will run 3 Attach the buttonhole foot 4 Lower the presser foot and the buttonhole lever 5 Push the presser foot frame backward about 1cm while lifting the presser foot lever slightly Then slowly move the frame frontward Lower the lever when self diagnostic program b changes to O from 1 6 At this time the presser foot frame should be about 1mm backward from the extreme end If it is not in correct position adjust as follows 7 Push the presser foot frame 1mm backward from the extreme end and lower the presser foot 8 Remove the light cover 9 Turn the eccentric pin a left or right so that the self diagnostic program b just changes to 0 from 1 10 Re check the buttonhole lever position when adjust ments have been completed SERVICE MANUAL 11 ADJUSTMENTS FOR BUTTONHOLE LEVER POSITION bfSTSWWOY K F S 110100111 0255 0 Z F LED er 7 bfSTsWwOY K F iO 110100111 0255 O z F LED AOS 0 mm O 25 SERVICE MANUAL 12 MOTOR BELT TENSION If the motor belt tension is too tight or too loose machine will not run smoothly Adjust as follows Remove the front enclosure 2 Loosen the 2 screws
19. pward The play will increase Turn downward The play will decrease 4 Re tighten the screw a tentatively and check that the correct play has obtained 5 Tighten the screw a securely 6 When you have adjusted the backlash of hook gear check the timing of the hook again Sec 3 27 SERVICE MANUAL 15 UPPER THREAD TENSION UNIT The upper thread tension regulator unit has been adjusted to the best sewing conditions at the position AUTO However if you wish to change this do it as follows 1 Remove the thread tension cover 2 Adjust the tension by turning the tension regulator screw a either to the front or back e For a stronger tension turn screw backward e For a weaker tension turn screw frontward 16 ADJUSTING THE LOWER THREAD TENSION The bobbin thread tension is correctly adjusted at the factory and normally it would not be necessary for you to make adjustments yourself If adjustments are necessary adjust as follows 1 Remove the needle plate 2 To obtain a weaker bobbin thread tension turn the screw a which is located on the front part of bobbin case counter clockwise and for a stronger tension turn screw clockwise 3 Replace the needle plate 17 FLATNESS OF THE BASE 1 Remove the Extension Table 2 Place the machine on table 3 Adjust the height of the rubber feet c d by turning the adjusting screws a b so that the base will be stabilized 28 SERV
20. v Ene lousa 17 4 HEIGHT OF THE FEED DOG asas ia ee 18 5 NEEDLE PLATE AND NEEDLE POSITION eene 19 6 TIMING OF THE UPPER AND LOWER SHAFT eeeeeee 20 7 ADJUSTING THE FORWARD REVERSE STITCH 21 BOBBIN WINDER 5 ivre rtp rn ti rb x c erm d a i rc nia i 22 9 HEIGHT AND DIRECTION OF PRESSER FOOT se 23 10 HEIGHT OF NEEDLE THREADER eeeseeeeeeennne nennen 24 11 ADJUSTMENTS FOR BUTTONHOLE LEVER POSITION 25 12 MOTOR BELT TENSION ocaso ETs oi tob tees 26 TS TIMING BELT TENSION quisas ganda aa deed et e toit het echte 26 14 BACKLASH OF HOOK GEAR do li ld 21 15 UPPER THREAD TENSION UNIT cites sas 324 lt ds nous Thais ond ans 28 16 ADJUSTING THE LOWER THREAD TENSION eene 28 17 PLATNESS OF THE BASE sas a 28 LOCATING THE DEFFECTED ELECTRICAL PART eene 29 1 To turn off the audible beep eres 29 2 The self diagnostic program cccccssecceecseeeeeeeeeeeeeeseeeeessseeeeeesaeeeeeesaaes 29 3 Messages on LCD 9940 9920 e nnm 33 4 Electrical Parts Connection cccoocccoccccocnccocnncncnconcncononcnoncnonnconononnnnnonnnns 34 SINGER is a registered Trademark of The Singer Company Ltd SERVICE MANUAL REMOVING THE EXTERIOR PARTS The exterior parts should be removed in sequence as followings CAUTION Always disco
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