9940/0/0 9/0/00
Tle of ontents REMOVING THE EXTERIOR PARTS... A. Light Cover... B. Bse... C. Top Cover (Flp)... 4 D. Hinge Cover... 4 E. Thred Tension Cover... 4 F. Side Enlosure... 5 G. Hndle nd Unit Cover... 5 H. Needle Plte... 6 I. Front Enlosure... 7 J. Rer Enlosure... 8 K. Front pnel (from Front Enlosure)... 8 REPLACING THE EXTERIOR PARTS... 9 K. Front pnel (to Front Enlosure)... 9 J. Rer Enlosure... 9 I. Front Enlosure... 0 H. Needle Plte... 0 G. Hndle nd Unit Cover... F. Side Enlosure... E. Thred Tension Cover... D. Hinge Cover... C. Top Cover (Flp)... B. Bse... A. Light Cover... 4 CHECK AND ADJUSTMENT... 5. HEIGHT OF NEEDLE BAR... 5. GAP BETWEEN NEEDLE AND HOOK... 6. TIMING OF THE HOOK... 7 4. HEIGHT OF THE FEED DOG... 8 5. NEEDLE PLATE AND NEEDLE POSITION... 9 6. TIMING OF THE UPPER AND LOWER SHAFT... 0 7. ADJUSTING THE FORWARD REVERSE STITCH... 8. BOBBIN WINDER... 9. HEIGHT AND DIRECTION OF PRESSER FOOT... 0. HEIGHT OF NEEDLE THREADER... 4. ADJUSTMENTS FOR BUTTONHOLE LEVER POSITION... 5. MOTOR BELT TENSION... 6. TIMING BELT TENSION... 6 4. BACKLASH OF HOOK GEAR... 7 5. UPPER THREAD TENSION UNIT... 8 6. ADJUSTING THE LOWER THREAD TENSION... 8 7. FLATNESS OF THE BASE... 8 LOCATING THE DEFFECTED ELECTRICAL PART... 9. To turn off the udile eep... 9. The self-dignosti progrm... 9. Messges on LCD (9940/990)... 4. Eletril Prts Connetion... 4 SINGER is registered Trdemrk of The Singer Compny Ltd.
REMOVING THE EXTERIOR PARTS The exterior prts should e removed in sequene s followings. CAUTION: Alwys disonnet the min led plug from eletril outlet when removing the exterior prts. A. Light Cover. Loosen the light over set srew ().. Pull light over s shown so tht the light over hook () will ome off. B. Bse. Remove the extension tle.. Tilt the mhine kwrd nd remove the se set srews (,, ). Remove the se.. Crefully disonnet the onnetor with holding the lever (d). This onnetor onnets terminl ox nd power iruit ord. d
C. Top Cover (Flp). Open the top over.. Push the right side of top over kwrd nd remove the hinge (). SERVICE MANUAL. Slide the top over to the right nd remove the hinge (). D. Hinge Cover. Insert the tip of srew driver nd pull up the front side of hige over. E. Thred Tension Cover. Remove the srew ().. Push the Thred tension over kwrd ; hooks (, ) will ome off.. Pull up the over. 4
F. Side Enlosure. Remove the srew ().. Push the side enlosure slightly kwrd to ome off the hooks (, ).. Pull the side enlosure to the right nd remove it. G. Hndle nd Unit Cover. Remove the unit over set srews (, ) nd hndle d set srews (, d).. Stnd up the hndle.. Push the right side of unit over kwrd so tht the hook of unit over will ome off nd pull up. 5
4. Next, push the left side of unit over kwrd nd pull up it to ome off from the thred guide over. 4 5. Slide the hndle nd unit over to the left nd remove them. 5 6 6. Crefully disonnet the onnetor whih onnets to the ontrst ontrol ord. H. Needle Plte. Remove the presser foot.. Remove the srews (, ) holding the needle plte.. Lift up the right side of needle plte nd remove it. 6
I. Front Enlosure. Loosen the srew ().. Push the left side of rer enlosure () nd pull the front enlosure (hook- will ome off).. Pull up the front enlosure nd ome off the hook-d. 4. Pull the enlosure to the left nd ome off the hook-e. 4 e d 5. Push the rer enlosure to the left nd ome off the hook-f. 5 f 6. Disonnet the onnetors (g, h) from the mhine nd remove the front enlosure. 6 g h 7
J. Rer Enlosure. Lower the presser foot lifter.. Remove the srews (,, ). (srew- is longer thn others.). Pull the rer enlosure kwrd nd remove it. K. Front pnel (from Front Enlosure). Disonnet the onnetors from the front pnel (: Reverse swith ord) (: Controller jk ssy.) TYPE A (Seured y 4 srews). Remove the 4 srews (, d, e, f ).. Push the lower hook (g) downwrd nd push the upper hooks (h, i) upwrd to ome off. i h d g f e TYPE B (Loked y hooks). Push the lower hooks (j, k, l) downwrd to ome off them.. Push the upper hooks upwrd to ome off them. j k l 4. Pull up the front pnel kwrd nd remove it. ( hooks on front pnel will ome off) 4 8
REPLACING THE EXTERIOR PARTS The exterior prts should e repled in reverse sequene when removing. (K. to A.) K. Front pnel (to Front Enlosure). Pss the ords through the openings of front enlosure.. Ride the hooks of front pnel on the front enlosure. TYPE A (Seured y 4 srews). Push front enlosure round the hook nd fit them in ple. Retighten the 4 srews. TYPE B (Loked y hooks). Push front enlosure round the hook nd fit them in ple. 4. Connet the onnetors (: Reverse swith ord) (: Controller jk ssy.) 4 J. Rer Enlosure. Lower the presser foot lifter.. Reple the rer enlosure.. Retighten the srews (,, ). (Srew- is longer thn others nd reple loosely.) 9
I. Front Enlosure. Connet the onnetors (g, h) to the mhine. g h. Reple the front enlosure so tht the 4 hooks will fit in ple.. Push lower end of front enlosure rm kwrd nd retighten the srew (). H. Needle Plte. Insert the hook () of needle plte to the mhine.. Retighten the srews (, ). 0
G. Hndle nd Unit Cover. Set the hndle to the unit over nd insert the hndle hinge pin into the left side hole of hndle from left side.. Ple the hndle nd unit over onto the top of mhine.. Connet the onnetor to the ontrst ontrol ord. 4. Insert the hinge pin on the mhine into the right side hole of hndle. 4 5. Reple the unit over so tht the eh hook fit into ple. 5 6 d 6. Retighten the hndle set srews (, d) nd unit over set srews (, ).
F. Side Enlosure. Reple the side enlosure so tht the eh hook fit into ple.. Retighten the srew (). SERVICE MANUAL E. Thred Tension Cover. Reple the thred tension over so tht the eh hook fit into ple.. Retighten the srew (e). D. Hinge Cover. Insert the rer hook into the mhine nd push the hinge over.
C. Top Cover (Flp). Slide the top over to the left so tht the hook () will fit onto the pin of unit over. SERVICE MANUAL. Pull the right side of top over nd snp on the hook () onto the pin of unit over. B. Bse. Tilt the mhine kwrd.. Connet the onnetor so tht the hook (d) will fit into ple.. Reple the se nd retighten the srews. d
A. Light Cover. Loosen the light over set srew ().. Reple the ligth over so so tht the hook () will fit into ple.. Retighten the srew (). 4
CHECK AND ADJUSTMENT. HEIGHT OF NEEDLE BAR Height of needle r ould e the use for stithes to skip. Chek s the following proedures.. Set the pttern to [Utility stith No.] whih is stright stith on enter needle position.. Rise the needle r to its highest point y turning the hndwheel towrd you. Remove the presser foot. Remove the needle plte. Lift up the oin holder nd remove it.. Turn the hndwheel towrd you until the needle omes to its lowest point. 4. Then, the sping etween the surfe of hook re nd the top edge of needle eye must e (4.9±0. mm). 4 4.9±0. mm If this sping is not orret, djust s follows. 5. Remove the light over. 6. Remove the srews (, ) nd remove the tke up lever over nd rket () y sliding it upwrd. (Bottom hook of over will ome off) 6 7. Rise the needle r 4.9mm from its lowest point y turning the hndwheel. Loosen the srew (d) on the needle r holder. ( mm hex. wrenh) Adjust the needle r so tht the top edge of needle eye is ligned with the surfe of hook re. Retighten the srew (d) nd hek the height gin. 7 d CAUTION: Do not hnge the needle r diretion t this djustment. The long groove of needle must e fing frontwrds. 8. Reple the tke up lever over nd srews. 5
. GAP BETWEEN NEEDLE AND HOOK If the needle hits ginst the hook, it my e the use of needle nd thred rekges. If the gp etween needle nd hook is too ig, it will use to skip stithes. Chek nd djust s follows: Prior to mke this djustment, hek tht the needle is not ent nd the needle is inserted orretly.. Remove the needle plte nd oin holder.. Set the pttern t [Utility No. ]. (Stright stith on left needle position.). Turn the hndwheel towrd you until the needle will ross over the hook. 4. Then, hek the gp etween needle nd hook is out 0.0 to 0.0 mm. 4 If the needle is hitting ginst the hook or if the gp is too muh, djust s follows: 5. Remove the light over. View from upwrd 0.0-0.0 mm 6. Adjust the gp y turning the djusting srew () with mm hex. wrenh. 6 If the gp is too ig, turn the srew to the left with viewing from frontwrd. If the needle is hitting the hook, turn the srew to the right with viewing from frontwrd. 7. Reple the oin holder nd needle plte nd light over. 6
. TIMING OF THE HOOK Prior to mking this djustment, e sure tht the needle r is set t the orret height. (Se. ) Chek the timing of hook s follows:. Remove the needle plte nd oin holder.. Set the pttern t [Utility No. ]. (Stright stith on left needle position.). Turn the hndwheel towrd you until the needle is t its lowest point. 4. Then, turn the hndwheel slowly to turn the hook ounter-lokwise until the tip of hook is ligned with the right side of needle. At this time, the gp etween the tip of hook nd the top edge of needle eye should e (.±0. mm). 4 If the gp is too smll or too lrge, djust s follows: 5. Remove the front enlosure..±0. mm 6. Loosen the two srews () on the lower shft ger with.5 mm hex. wrenh. 6 7. Turn the hook re y hnd so tht the tip of hook will lign with the right side of needle. 8. In this position, hold the hook re with your left hnd nd turn the hndwheel towrd you to otin the orret gp (. mm). 9. Tighten the srews nd hek the timing gin. 0.Reple the front enlosure. 7
4. HEIGHT OF THE FEED DOG If the feed dog does not ome up over the needle plte enough, it will result in insuffiient nd/or uneven feed of fris.. The feed dog should ome up over the needle plte (.0-. mm) when its highest position. If it does not ome up enough, djust s follows:. Remove the needle plte..0-. mm. Lower the presser foot lifter. Turn the hndwheel until the feed dog omes to its highest position. e If the feed dog is too low; Turn the djusting srew () (.5mm hex. wrenh) lokwise until orret height is otined. Turn the srew () lokwise until the m follower () touhes the feed roking m (Right)(d). (To hek it, remove the front enlosure nd see frontwrd.) If the feed dog is too high; Turn the srews () nd () ounterlokwise in few turns. Push the left side of feed se strongly (e) (feed dog will ome down) Chek tht the feed dog me lower thn the orret height. If it is not so, turn the srews ounterlokwise gin nd lower the feed se. After the feed dog is lower thn the orret height, djust the feed dog height sme s If the feed dog is too low. 4 d 4. Chek tht the m followers (), (e) hve to e even height nd they hve no opening to eh m (d), (f). e 5. Re-hek the height nd motion of feed dog y turning the hndwheel. f d 8
5. NEEDLE PLATE AND NEEDLE POSITION. When the stright stithes is set t enter needle position (Utility No.), the needle should fll into the enter of needle plte hole (the distne needle nd edge of hole t eh side). If it is not so, djust s follows:. Set the pttern t [Utility No.].. Remove the presser foot nd the light over. 4. Loosen the enter srew (). 5. Turn the djusting srew () left or right until the needle flls enter position into the hole. 4 5 6 When you turn the srew to the right, needle wiil move to the left. When you turn the srew to the left, needle wiil move to the right. 6. Retighten the srew () nd re-hek the position of needle. 7. When you hve djusted the this position, hek the timing of the hook gin. (Se. ) 9
6. TIMING OF THE UPPER AND LOWER SHAFT SERVICE MANUAL The upper nd lower shft must e positioned orretly s follows.. Remove the front enlosure.. Turn the hndwheel towrd you until the needle is its lowest point. At this time, the mrk ( - very smll molded line on edge) on the lower shft timing pulley must e fing towrd you. If it is not so, djust s follows:. Loosen the srew () tightening the tension pulley rket. 4. Slip out the timing elt from lower shft timing pulley. 4 5 5. Turn the lower shft timing pulley so tht the mrk fes towrd you. 6. Hook the timing elt on the pulley. 7. Push the tension pulley rket so tht the edge of rket should e 0- mm higher thn the sting. 7 8 8. Retighten the srew () 0- mm 9. Chek the timing gin nd reple the front enlosure. 0. When you hve djusted it, hek the timing of the hook gin. (Se. ) 0
7. ADJUSTING THE FORWARD REVERSE STITCH When streth stith sewing, the lengths of the forwrd nd reverse stithes should e the sme. Chek nd djust s follows. 9940 Feed Adjust We reommend heking Height of the Feed-dog (Se. 4) efore you mke this djustment.. Turn on the power swith with pressing the uttons s shown. LCD wiil indite the messge Feed Adjust. + 990 Feed Adjust. Atth the generl purpose foot nd set piee of pper under the foot. 990 Feed Adjust. Strt the mhine nd open holoes of test pttern. The holes () nd () should e sme position. If they re not so, djust s follows. 4. Remove the se. 5. Loosen the lok srew () (.5 mm hex. wrenh). 6. The forwrd-reverse stith length is djusted y turning the srew (d). (4mm hex. wrenh), If the reverse stith is finer thn the forwrd stith, turn 6 the srew to the left. If the reverse stith is orser thn the forwrd stith, d d turn the srew to the right. 7. When orret height is otined, retighten the lok srew () nd reple the se. 5 6 7 d
8. BOBBIN WINDER If oin winds unevenly, djust s follows:. If oin winds s shown, turn the djusting srew () to the left.. If oin winds s shown, turn the djusting srew () to the right.. If the oin thred is wound too little or too muh, loosen the srew () on oin winder stop () nd djust s follows. - 6 4. If the oin thred is wound too muh, slide the oin winder stop () to the left. 5. If the oin thred is wound too little, slide the oin winder stop () to the right. 6. Retighten the srew ().
9. HEIGHT AND DIRECTION OF PRESSER FOOT SERVICE MANUAL. The height of the presser foot from the needle plte should e 6.5 mm when it is lifted up. The presser foot should e fing frontwrd (the edge of foot is prllel with the feed dog slot on needle plte). If djustment is needed, follow these proedures:. Remove the light over. 6.5 mm. Loosen the srew () loted ehind of the mhine. 5 4. Adjust the height nd diretion of presser foot. 5. Retighten the srew (). 6. Chek if the presser foot lifter hs slight ply in down position.
0. HEIGHT OF NEEDLE THREADER If the height of needle threder is not orret, the hook on threder will not enter the needle eye. Adjust s follows:. Remove the light over.. Remove the srews (, ) nd remove the tke up lever over nd rket () y sliding it upwrd. (Bottom hook of over will ome off). Set the pttern t [Utility, No.] (stright stith on left needle position). 4. Rise the needle to its highest point y turning the hndwheel. 5. Loosen the srew (d) on the needle threder r stopper (e) with.5 mm hex. wrenh. 5 6 7 d 6. Adjust the height of stopper (e) so tht the hook enter the needle eye. 7. Tighten the srew (d) nd hek the height of needle threder gin. e CAUTION: Be reful with diretion of stopper when tighten the srew. If diretion of stopper NOT right, mhine mkes noise nd/or threder does NOT work smoothly. The orret diretion is tht the srew (d) is fing frontwrd. A 8. Reple the tke up lever over nd srews. 9. Reple the light over. A. If the hook hs ent, hnge the threder hook ssemly. To remove the hook ssemly, pull it downwrd. 4
. ADJUSTMENTS FOR BUTTONHOLE LEVER POSITION. If the mhine dose not sew even with the uttonhole lever ll the wy down, it mens tht the uttonhole lever is not positioned properly. Also, if the uttonhole lever is not positioned properly, the mhine will sew uttonhole s shown or inorretly. 9940. Turn on the power swith with pressing the uttons s shown. The self-dignosti progrm will run.. Atth the uttonhole foot. + 990 4. Lower the presser foot nd the uttonhole lever. 990 5. Push the presser foot frme kwrd out m while lifting the presser foot lever slightly. Then slowly move the frme frontwrd. Lower the lever when self- 5 dignosti progrm hnges to 0 from. 0 0 6. At this time, the presser foot frme should e out mm kwrd from the extreme end. 6 7 If it is not in orret position, djust s follows: 7. Push the presser foot frme mm kwrd from the extreme end, nd lower the presser foot. 8. Remove the light over. mm 9. Turn the eentri pin () left or right so tht the selfdignosti progrm just hnges to 0 from. 9 0.Re-hek the uttonhole lever position when djustments hve een ompleted. 5
. MOTOR BELT TENSION 4 If the motor elt tension is too tight or too loose, mhine will not run smoothly. Adjust s follows:. Remove the front enlosure.. Loosen the srews (, ). Move the motor up or downwrd nd tenttively tighten the srews. Chek the elt tension s follows: The elt does not touh to the sting or other prts. The elt must hve flexiility of 5-6 mm when verge pressure is pplied on its side. 4. When orret tension hs een otined, tighten the olts (, ) seurely. 5-6 mm. TIMING BELT TENSION If the timing elt tension is too tight or too loose, the mhine will run hevily or the timing of hook nd feed motion will e hnged inorretly. Adjust s follows:. Remove the front enlosure.. Loosen the srew () tightening the tension pulley rket.. Push the tension pulley rket so tht the edge of rket should e 0- mm higher thn the sting nd retighten the srew (). 4. When you hve djusted the timing elt tension, rehek the timing of the upper nd lower shft (Se. 6) nd the timing of the hook (Se. ) gin. 0- mm 6
4. BACKLASH OF HOOK GEAR If there is too muh ply on the hook ger on the turning diretion, it my e the use for mhine not to sew properly nd/or mking exessive sewing noise. 0-0.5 mm. Free ply t the tip of hook my e 0-0.5 mm. If it is not so, djust s follows.. Remove the front enlosure.. Loosen the srew () nd turn the lower shft eentri ll ushing up or down y hooking the tip of (-) driver into the left side groove () of ushing. Turn upwrd: The ply will inrese Turn downwrd: The ply will derese. 4. Re-tighten the srew () tenttively nd hek tht the orret ply hs otined. 5. Tighten the srew () seurely. 6. When you hve djusted the klsh of hook ger, hek the timing of the hook gin. (Se. ) 7
5. UPPER THREAD TENSION UNIT The upper thred tension regultor unit hs een djusted to the est sewing onditions t the position [AUTO]. However, if you wish to hnge this, do it s follows:. Remove the thred tension over.. Adjust the tension y turning the tension regultor srew () either to the front or k. For stronger tension, turn srew kwrd For weker tension, turn srew frontwrd. 6. ADJUSTING THE LOWER THREAD TENSION The oin thred tension is orretly djusted t the ftory nd normlly it would not e neessry for you to mke djustments yourself. If djustments re neessry djust s follows.. Remove the needle plte.. To otin weker oin thred tension, turn the srew () whih is loted on the front prt of oin se ounter lokwise, nd for stronger tension, turn srew lokwise.. Reple the needle plte. 7.FLATNESS OF THE BASE. Remove the Extension Tle.. Ple the mhine on tle.. Adjust the height of the ruer feet (, d) y turning the djusting srews (, ) so tht the se will e stilized. d 8
LOCATING THE DEFFECTED ELECTRICAL PART. To turn off the udile eep You n operte the mhine without the udile eep.. Turn off the power swith.. Turn on the power swith with pressing the uttons indited in the right hrt.. To return the norml mode, turn off the power swith nd turn on without pressing ny utton. + 9940 990 SERVICE MANUAL 990. The self-dignosti progrm This mhine hs the self-dignosti progrm to lote the defeted eletroni prt. If your mhine funtions re not normlly, run this progrm.. Turn off the power swith.. Turn on the power with pressing the uttons s indited in the right hrt.. When this progrm hs strted orretly, the LCD will indite the onditions of eh eletril prt s elow. * Model 990 only. By pressing the Stith length (+) utton, inditing sreen will hnge lterntely. + 9940 990 990 4. See next pge to hek eh eletril prt. 5. To quit this progrm, turn off the power swith. 990 9940 990 9
Condition of swithes nd sensors f The ondition of eh swith nd sensor is indited s follows. : Buttonhole lever swith -Rer =Neutrl 0=Lever is pulled. f: Buttonhole lever swith -Front =Neutrl 0=Lever is pushed. f Lower the uttonhole lever nd hek these swith y pulling or pushing this lever. S: Stop sensor =not interepted 0=interepted T: Timing sensor =not interepted 0=interepted S T s s: Speed sensor =not interepted 0=interepted These sensors re interepted y the slit pltes on the upper shft. Stop sensor = Stop slit, Timing sensor = Timing slit, Speed sensor = Speed slit Turn the hndwheel nd hek the response of eh sensor. s T S W: Boin Winder Swith =Boin winder spindle is in right position 0=Spindle is in left position Move the oin winder spindle left or right nd hek this swith. w: Boin Winding Stop Swith =Boin winder stop is not pushed (Boin winding is not full) 0=Boin winder stop is pushed to the right (Boin winding is full.) Move the oin winder stopper to the right nd hek this swith. W w W w O:Presser foot swith =Presser foot is lowered O Y Y 0=Presser foot is lifted Lower or lift the presser foot lifter nd hek the response of this swtih. O Y: Upper thred sensor (Only 9940) =Thred hek spring is pulled 0=Thred hek spring is not pulled Thred the upper thred until thred hek spring (threding route No. 4) nd hold oth end of thred. Pull or relese left end of thred nd hek the response of this sensor. 0
K: Response of eh utton By pressing eh utton, numer will e indited s K 990 elow. 7 4 8 5 6 6 7 8 9 0 9 0 5 K 9940 K 990 5 4 6 4 5 6 7 8 6 7 8 9 0 9 7 8 6 7 8 9 0 9 0 5 5 F: Condition of Foot Controller Foot ontroller is not onneted : the numer 55 will pper. Connet the foot ontroller : the numer will hnge to 75. Press the pedl of ontroller : the numer will derese roding to the pressure on the pedl. When pressed mximum, the numer 0 will e indited. F S: This is not used these models.
Cheking Strting point of Z nd F pulse motors 9940. When self-dignositi progrm is running; By pressing the utton (), Z pulse motor will move to strting point. 990 By pressing the utton (), F pulse motor will move to strting point. 990 Z F Cheking LED Light. When self-dignositi progrm is running; 990 By pressing the utton () one, LED (d) will turn on. d e By pressing the utton () gin, LED (e) will turn on. By pressing the utton () one more, LED will turn off. 9940 5 990 d e d e
. Messges on LCD (9940/990). Winding the oin.. Lower the uttonhole lever.. Rise the presser foot lifter nd set the uttonhole foot to orret position. 4. Relese the foot ontroller pedl. 4 5. Lower the presser foot. 5 6. Mhine nnot memory ny more. 6 7. Selet pttern. 7 8. Relese the reverse utton. 8 9. Rethred the upper thred (9940 only) 9 0.Relese the needle up/down utton. 0
4. Eletril Prts Connetion. CPU Bord. Power Ciruit Bord. Power Swith Assy. d. Terminl Box Assy. e. Motor f. F Pulse Motor g. Z Pulse Motor h. LED Bord Assy. i. BH Swith Assy. j. Presser Foot Swith Assy. k. Thred Sensor Bord Assy. (9940 Only) l. Reverse Swith Bord Assy. m. LCD Assy. n. Contrst Control Bord Assy. o. Disply Bord Assy. p. Controller Jk Assy. m n o k l j i h g f e p d 4