LCD UNIT
Contents
1. Message key Contrast VR CN2 Mode switch unit Pattern sensor 1 LINE LCD TYPE 62 CH1 Signal source CN3 BH lever switch DISPLAY SYSTEM B key key A key key Contrast VR fi PE B42J063 1 g 91 low 9 ma 12 2 e 0 19 p 9 75 0 mie VRI IBS digno 6020 oro 8 pe 0000000000 BE SEN P5 I pa er 0000000000 p P5 x 1 6 1 P22 1 P1 5 C DDD 14 000000 lt 20000000 1 2 C Xn o P2 BH lever switch P1 P3 Signal source Mode switch unit Pattern sensor LCD control PCB cam car car cir Cap Cap Dur Dun Dan Can cap car Cap cab 7i Tam map apap ap an Car Car Dar carp To LCD control LCD module 4 LINE LCD TYPE2. Top bobbin NO YES Top bobbin YES NO Top bobbin YES YES Top bobbin Table of Machine Specifications 65 BL6200 8338 BL6700 B341 7110109
3. i E 4 d AED IR 2 1 L n i Needle bar clamp j 174 Spreng e eG assembly AL T a ra VW EP Z finger if cam Le ee 4 P oTi Needle bar i A 1 Selecting Generating mechanism of needle bar thread take up lever and zigzag movements 8341 B349 B351 B352 Thread take Eccentric up lever counter weight Upper shaft Worm gear Pulley Needle bar crank rod Pattern cam Needle bar clamp Needle bar Zigzag connecting Needle bar supporter tod assembly Z finger Selecting cam Needle Zigzag dial Pulley Upper shaft Worm gear Thread take up lever Eccentric counter Needle bar supporter 4 ft Needle bar crank rod Needle bar clamp Pattern cam Zigzag connecting ers rod assembly Needle bar ES Control roller Tension control cam T Tension control link Needle tl Selecting cam B Mechanism of feed dog oscillating hook movement Outer rotary hook assembly Feed pattern cam Lower shaft gear Feed finger H
4. 31 10 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 screw for vertical feed finger 3 Adjust the height of the feed dog by turning vertical feed finger 4 Tighten the screw 32 11 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 4 Presser foot should be parallel to feed dog Tighten the screw 8338 B346 B347 B348 33 8341 B349 B351 B352 12 ADJUSTMENT OF THREAD TENSION DIAL B341 B349 B351 B352 STANDARD When thread tension dial is set to AUTO and presser foot is lowered upper thread tension should be 10 13g using polyester thread 60 ADJUSTMENT 1 Set thread tension dial to AUTO put polyester thread between tension discs and lower presser foot 2 Loosen the screw for thread tension control screw 3 Measure thread tension using tension gauge and adjust tension to 10 13g by turning thread tension control screw 4 Tighten the screw 10 13 g Polyester thread 60 8338 B346 B347
5. Pattern BH lever Bobbin winder sensor SW SW 3 DISPLAY SYSTEM BY MICRO COMPUTER 8352 An 8 bit micro computer in models installed with an LCD liquid crystal display regulates the LCD controller driver which controls the information shown on the display lt 4 LINE DISPLAY SYSTEM BLOCK CHART LCD panel LCD LCD controller segment driver 4 driver NJU6426F NJU6417F LCD unit Power supply board Contrast circuit and i ROM volume motor control gt circuit 5 8 bit MCU m M38002SFP otor contro A B J T i EEPROM QD P C board X24COOP lt keys onim MEME A WA cec BH lever Bobbin winder Pattern sensor SW SW 4 MAIN MOTOR CONTROLLED BY MICRO COMPUTER 8341 B349 B351 B352 The sewing machine s main motor requires a constant rotation at all speeds regardless of the changes in the load power supply or temperature In addition to make the machine easy to use it should take into account that the machine should run slowly when it starts and the needle should be in the up position when it stops To execute these requirements the main motors of these sewing machines are controlled by a micro computer MOTOR CONTROL BLOCK CHART Reset circuit 21 NP
6. Drop the needle into the paper by turning the pulley Set the pattern dial to the straight stitch and set zigzag width dial to 5 so the needle moves to the left Drop the needle into the paper by turning the pulley Loosen the nut of adjusting screw Adjust left straight needle position by turning screw Turn the screw to the right needle position is moved to the right Tighten the nut all ANA ANN B346 B338 B346 B338 B341 B341 B347 B347 B348 B348 B349 B349 B351 B351 B352 B352 45 24 FORWARD AND REVERSE FEEDING FOR STRAIGHT STITCH STANDARD When stitch length dial is set to 2 there should be no difference between forward and reverse feed ADJUSTMENT 1 Set pattern dial to straight stitch 2 Setstitch length dial to 2 3 Sew straight stitch on a piece of paper then sew reverse straight stitch by pushing reverse button 4 Adjustthe screw to achieve above standard X NE cum B346 B338 46 25 ADJUSTMENT OF BOBBIN WINDING STANDARD Thread should be wound parallel to the bobbin and be wound 75 85 of the outer diameter of bobbin ADJUSTMFNT 1 In case bobbin thread is wound unbalanced loosen the screw for bobbin winder thread guide slightly Move bobbin winder thread guide vertically so that the bobbin thread is balanced when it is wound Tighten the screw Loosen the screw for bobb
7. Replace the motor control unit Replace the motor control unit Be sure to turn off the power and remove from the PCB the connector 20 III HOW TO ADJUST THE ELEMENTS I EPI EM DIM cL ADJUSTMENT OF EACH CONTROL UNIT 4 STEP BH MODEL ADJUSTMENT OF EACH CONTROL UNIT 1 STEP BH MODEL ADJUSTMENT OF THE TIMING BETWEEN THE UPPER AND LOWER SHAFTS TENSION ON MOTOR BELT AND TIMING BELT TIMING OF NEEDLE AND FEED POSITION OF ZIGZAG NEEDLE SWING Sipi EDITI lI POSITION OF ROTARY HOOK DIU RETI II III IU IIT HEIGHT OF NEEDLE BAR EHE A POSITION OF INNER ROTARY HOOK STOPPER rrr eee ee eer T POSITION OF FEED DOG cates HEIGHT OF FEED DOG uam penus HEIGHT OF PRESSEHR ADJUSTMENT OF THREAD TENSION DIAL ADJUSTMENT OF AUTO TENSION Tr err POSITION OF PATTERN INDICATION PLATE ecsxk isenz Esszexkibtaxechtbsaseeni ures CLEARANCE BETWEEN CAM AND CAM FINGER POSITION CAM FINGER FOR FEED CAM AND PATTERN SETTING OF EEED BEACHET uisa inches FORWARD AND REVERSE SEWING FOR RICK RACK STITCH ADJUSTMENT OF FEED REOS ROC RUE UU E WR UU BOE UD RR re RN RON UN ee BUTTONHOLE A
8. B348 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 Setthread tension dial to 4 put polyester thread between tension discs and lower presser foot 2 Loosen the screw for thread tension control screw 3 Measure thread tension using tension gauge and adjust tension to 33 38g by turning thread tension control screw 4 Tighten the screw lo 33 38 g Polyester thread 60 13 ADJUSTMENT OF AUTO TENSION 8341 B349 B351 B352 ADJUSTMENT OF ROLLER FOR THREAD TENSION CONTROL STANDARD Thread polyester thread 60 between roller and thread holder Turn the pully counterclockwise The thread should be locked when the top of the needle eye comes down 0 1 5 mm down from the surface of needle plate Remove presser foot and lower presser foot bar ADJUSTMENT 1 Set pattern dial to straight stitch and lower the presser foot after threading polyester thread 60 properly 2 Turn the pulley counterclockwise and adjust needle position at the top of needle eye 0 1 5 mm down from the surface of needle plate 3 Loosen the screw for roller adjusting shaft 4 Turn the roller adjusting shaft by screw driver and adjust the roller position in between lock and release condition with drawing thread Adjust the roller so it is within one cycle of the roller adjusting shaft 5 Tighten the screw NOTE
9. Be sure to turn off the power and remove from the PCB the connector 18 PROBLEM 31 The speed at which the machine operates cannot be adjusted 32 The needle does not stop in the up position 33 The machine does not operate if the reverse sewing button is pressed or does not operate at a slow speed if the button is pressed while the machine is running However the machine does not operate at slow speed when the foot controller is being used CAUSE The output from the transformer is incorrect The voltage between pins 5 and 6 of the transformer should be approximately 8V AC The voltage between the S V and GND on the motor control unit is incorrect It should be 530 25 V DC The voltage between pins 2 and 3 on the SS VR PCB does not stay between 0 and 5 V DC when the power is turned on and the speed adjustor is slid to the maximum Other causes The position of the NP sensor shutter is incorrect The motor control unit 1s installed incorrectly It is loose or slanted Inferior BW switch The resistance between pins 1 and 2 of connector CN5 black should be less than 19 when the BW switch is turned on and co when the BW switch is turned off Other causes The BT switch dose not work Inferior BT switch The resistance between pins 1 and 2 of connector CN6 red should be less than 10 when the BT switch is turned on and when the BT switch is turned off Other caus
10. 14 16 The stitch shown in the pattern indication window is different from the one being sewn e HH 14 17 No characters appear on the LCD mme 15 18 The message keys do not work m 15 19 The LCD contrast cannot be adjusted EE ARE RAM LEER ERA REA 15 20 The wrong pattern name appears on the LCD 6 15 21 The Bobbin Winding message continues to appear on the LCD 16 22 he Bobbin Winding message does not appear on the LCD when the machine is set for bobbin winding 1 line LCD 16 23 Message Bobbin Winding Selected does not appear when bobbin winding is set 4 line LCD m 16 24 Message Lower BH Lever does not appear when buttonhole is set and buttonhole lever is not lowered 1 line LCD 16 25 Message Lower Buttonhole Lever does not appear when buttonhole is set and buttonhole lever is not lowered 4 line LCD 8 16 26 Message Lower BH Lever appears when buttonhole lever is lowered 17 27 The light does not turn on even after the power is turned on 17 11 34 35 The needle does not stop in the up position 3 The machine does not operate if the reverse sewing button is The mator does not PUR eese nen nenne J The motor does not run d or it does not run at a high speed The speed at which the machine operates cannot be adjusted pressed or does not operat
11. 63 MOTOR CONTROL UNIT 230V AC Inlet Transformer Fuse Power switch yj FA 8 1 L g gt pk E gt CN2 Main motor Pc a 5 Bobbin winder switch gt BET Se Y CN6 no m Reverse switch CN4 Lamp unit I i From SS VR connector Pin jack assembly CN7 4 BH lever switch only LCD model GND JW21 5V JW15 120V AC Inlet Transformer Fuse Power switch NI p CN2 Main motor gt To LCD unit OR LCD control PCB only LCD model Pin jack assembly CN4 E Lamp unit gt m CN5 Bobbin winder switch zh UAM CN6 Ss it Reverse switch 5 From SS VR connector E To LCD unit or LCD control only LCD model GND JW21 5V JW15 To LCD unit OR LCD control PCB only LCD model MODE SWITCH UNIT 1 LINE LCD TYPE 4 LINE LCD TYPE 64 TEST Language Machine Specifications Settings This Test Mode is used to switch the language in which LCD displays appear and to switch the machine specifications Language specification 1 ENGLISH Machine uos Duy specification ces m Setting the
12. Figure A 55 34 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 8 0 mm from the needle plate CHECK Refer to illustration Case A Hook position is too high Hook hits needle and can t get through needle eye Case B Hook position is too low Hook gets through needle eye but it catches bottom part of needle Needle Top of hook A B Needle X 56 35 NEEDLE THREADER ADJUSTMENT THE HOOK POSITION IN VERTICAL DIRECTIOIN CASE A Hook point is too high 1 Setthe 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 if part and part b is parallel CASE B Hook point is too low 1 Setthe needle position at right and loosen the screw 2 Adjust needle threader slightly up and check the clearance between the top of hook and top of needle eye is zero 3 Checkif part a and part b is parallel NOTE Unless part a and part b is parallel hook will not work O 3m Lu 90 Top of needle eye 0 mm of hook Figure Figure 57 IV HOW TO CHANGE THE PARTS 1 REMOVING THE COVERS 59 2 LAM
13. Improper use of reverse sewing button Lower thread tension is too tight Too much thread is wound on bobbin Thread is tangled Bobbin does not turn in inner rotary hook Inferior thread 13 CORRECTION Set the needle correctly Change the needle Reset threading correctly Select correct combination of needle thread fabric Use stretch fabric needle optional stretch presser foot Refer to P 28 Refer to P 29 Refer to P 28 Set proper stitch length Refer to P 32 Change the fabric Change the feed dog Raise the feed dog with the drop lever Change the presser foot and the feed dog Thread correctly Change the needle Set the needle correctly Adjust tension control dial correctly Thread correctly Change the needle Change the needle plate Clean or replace Check or change the thread Set the needle bar and outer rotary hook correctly Refer to P 28 Change inner rotary hook Guide the fabric Push reverse sewing button as far as it will allow Adjust the tension by loosening the tension spring screw on inner rotary hook Change to other bobbin or adjust bobbin winder Thread correctly Change the bobbin Check or change the thread PROBLEM CAUSE CORRECTION indication window 1s different from the one being plate are not aligned correctly Adjust the pattern indicator Refer to P 36 8 Needle breaks 1 Touch pa
14. Turn screw clockwise 4 Tighten the nut 4 step BH model X X 4 step BH model 43 22 BUTTONHOLE ADJUSTMENT THE LENGTH OF THE BUTTONHOLE AND THE PRESSURE OF THE BH LEVER 1 STEP BH MODEL 8338 B341 B347 B348 B349 B351 B352 STANDARD The length of buttonhole should be 21 23 mm when the button is 20 0 mm in diameter The pressure needed to pull BH Lever forward should 50 110 g ADJUSTMENT Loosen the screw on BH change arm Adjust the position of BH lever according to below drawings Tighten the screw Loosen the screw for the eccentric nut Adjust eccentric nut so that the pressure needed to pull the BH Lever forward is 50 110 g The eccentric nut should not be rotated more than half a turn Tighten the screw Adjust the timing of the BH lever using the BH notch screw c ROM BH notch screw 21 23mm BH lever 44 23 MAXIMUM STITCH WIDTH WHEN SET STRAIGHT LEFT AND ZIGZAG STITCH STANDARD Left end of straight stitch should be same position as left end of zigzag stitch ADJUSTMENT 1 nog Lower the feed dog using the drop lever then place a piece of paper on the needle plate and lower the presser foot Set pattern dial to zigzag stitch and set zigzag width dial to 5 the needle is at the left side
15. adjustment screw Tighten the nut 0 3 0 5 mm 16 POSITION FINGER FOR FEED CAM AND PATTERN CAM STANDARD Feed cam finger and zigzag cam finger should be center position of each cam ADJUSTMENT Check the position of feed cam finger and zigzag cam finger by turning pattern dial Loosen the screw on selecting lever holder Set the Z cam finger and F cam finger to the center position of each cam by adjust selecting lever holder Tighten the screw Make sure cam finger is located at the center position of each cam by turning pattern dial c ROM lt lt The shape of the cams on the B346 differ slightly E at 47 5 As 38 17 SETTING OF FEED BRACKET STANDARD When stitch length dial is set to 0 each mark on feed dial gear feed gear feed cam and feed finger should meet in line ADJUSTMENT 1 Setstitch length dial to 2 Setthe mark on the feed cam to feed finger 3 Setthe mark on the feed gear to the mark on feed cam 4 Setthe mark on the feed dial gear to the mark on feed gear 5 Fixthe feed bracket by tightening two screws Screw 5 Mark Feed gear Feed finger 3 Mark 39 18 FORWARD AND REVERSE SEWING FOR RICK RACK STITCH STANDARD When pattern dial is set to rick rack stitch there should be no difference between forward and reverse feed ADJUSTMENT 1 Set pattern dial t
16. applicable in needle 14 16 Do not touch needle threader when machine is running 3 4 5 Do not turn the balance wheel when you use needle threader 6 7 Needle 9 might be hard to thread 8 Needle should be located above needle plate more than 8 0 mm for threading Thread Needle 9 x 11 x 14 x 16 18 5 53 100 120 32 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 x 1 14 and check by changing all of these After Checking A In case that hook gets through eyelet of all needles 68 Nothing is the matter B In case that hook does not get through eyelet of all needles Adjust by bending hook C In case that hook does not get through eyelet of some needles Needles through which the hook does not get are bad ADJUSTMENT In case the hook is bad after above checking adjust the hook by forming with pliers In this case do not form hook guard 54 33 NEEDLE THREADER EXCHANGE HOW TO EXCHANGE NEEDLE THREADER Remove needle and lower the presser foot Push down needle threader to take out Place new one so that guide is immediately under the guide pin as shown Figure A Push needle threader all the way up so that guide is placed in the pin Bom
17. e MECHANICAL CHART B341 8349 8351 B352 e POWER TRANSMISSION CHART DISPLAY SYSTEM BY MICRO COMPUTER eee DISPLAY SYSTEM BY MICRO COMPUTER DNE TS MAIN MOTOR CONTROLLED BY MICRO COMPUTER 1 MECHANICAL CHART 8338 B346 B347 B348 This part is not installed on the B346 since it is a 4 step BH model BH stopper assembly Eccentric counter Upper shaft weight Horizontal feed cam Bobbin winder Thread take up lever Worm gear Pulley Upper shaft metal Pattern cam Selecting dial Needle bar BH change lever Needle threader lever Motor belt Selecting cam Selecting unit Tension pulley aS L Al Outer rotary Indication gear hook assem Lower shaft metal Timing pulley D Horizontal feed plate Horizontal feed arm Vertical feed finger Vertical feed cam Lower shaft Drop lever 1 MECHANICAL CHART 8341 B349 B351 B352 These parts not installed on the B341 B351 B352 since they LCD models BH stopper assembly Upper shaft Horizontal feed cam Eccentric counter weight Bobbin winder Thread take up lever 2 ee Needle bar crank rod MA mos eo NG ANN TS Worm gear deb gt Dede Gea EH Thread take up spring DIN OP sh AN lt holder ERE e 5 5216 Nad ROR iy 47 p AS
18. BH MODEL B346 STANDARD When pattern is set to b and d there should be no feeding difference between left and right legs ADJUSTMENT 1 Set pattern dial to d 2 Setstitch length dial to F 3 Set BH adjusting eccentric stud to fig 3 4 Set pattern dial to b and sew left row of buttonhole then check the difference of sewing pitch between right and left rows 5 Loosen the nut for adjusting screw X Q X 6 Adjust forward and reverse feeding by turning the screw 7 Tighten the nut E BH adjusting eccentric stud unido 4 step 4 step BH model model 4 step BH model 42 21 BUTTONHOLE ADJUSTMENT FEEDING 1 STEP BH MODEL 8338 B341 B347 8348 8349 B351 B352 STANDARD The feeding of bar tack should be less than 1 mm 10 feedings ADJUSTMENT 1 Set pattern dial to 1 Buttonhole 2 Loosen the nut for bar tack feeding adjusting screw 3 Adjustthe screw If forward feeding is obtained mmn Turn screw counterclockwise If back feeding is obtained m Turn screw clockwise 4 Tighten the nut 1 step BH model 4 STEP BH MODEL B346 STANDARD The feeding of bar tack should be less than 1 0 mm 10 feedings ADJUSTMENT 1 Set pattern dial to ac 2 Loosen the nut for bar tack feeding adjusting screw 3 Adjustthe screw If forward feeding is obtained em Turn screw counterclockwise If back feeding is obtained m
19. DJUSTMENT FORWARD AND REVERSE FEEDING BUTTONHOLE ADJUSTMENT BAR TACK FEEDING 0er BUTTONHOLE ADJUSTMENT THE LENGTH OF THE BUTTONHOLE AND THE PRESSURE OF THE BH LEVER E HIERO ET MAXIMUM STITCH WIDTH WHEN SET AT STRAIGHT LEFT EU e cra CESARE NODE TET FORWARD AND REVERSE FEEDING FOR STRAIGHT STITCH ADJUSTMENT OF BOBBIN WINDING NR RR re ee ere RR T POSITION OF NEEDLE POSITION SHUTTER m ADJUSTMENT OF BH LEVER SWITCH eer err eee eer ere errr T ADJUSTMENT OF REVERSE SEWING SWITCH ee rc rrr errr errr ADJUSTMENT OF BOBBIN WINDING SWITCH Mover vysavapusipu ADJUSTMENT OF INNER ROTARY HOOK TENSION n TREL Nm EET NEEDLE THREADER CHECKING THE HOOK POSITION IN HORIZONTAL DIRECTION eene NEEDLE THREADER EXCHANGE mmm me mee eee NEEDLE THREADER CHECKING THE HOOK POSITION IN VERTICAL DIRECTION mmm NEEDLE THREADER ADJUSTMENT THE HOOK POSITION IN VERTICAL DIRECTION mmm 21 1 ADJUSTMENT EACH CONTROL UNIT 4 STEP BH MODEL 8346 5 Back and forth seam at automatic reverse pattern 2 Clearance between pattern cam and cam finger 6 Forward and reverse feeding at buttonhole 7 Bar tack feeding at buttonhole 4 Adjustment for straight stitch at left position 3 Position of cam finger for pattern cam 22 1 ADJUSTMENT OF EACH CONTROL UNIT 1 STEP MOD
20. EL B338 B341 B347 B348 B349 B351 B352 5 Back and forth seam at automatic reverse pattern 1 Clearance between feed cam and cam finger 6 Forward and reverse feeding at buttonhole 7 Bar tack feeding at buttonhole 2 Clearance between pattern cam and cam finger 4 Adjustment for straight Stitch at left position These parts are not installed on the 3 Position of cam finger for B351 and B352 since they are LCD models pattern cam 23 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 at its topmost position the mark on timing pulley D of the lower shaft should be at its bottommost position Turn pulley counterclockwise ADJUSTMENT 1 Remove the timing belt from the horizontal feed cam the tension pulley and timing pulley D 2 Position the mark on the horizontal feed cam so it is at its topmost position and the mark on timing pulley D so it is at its bottommost position 3 Install the timing belt onto the horizontal feed cam the tension pulley and timing pulley D Mark Horizontal feed cam Tension pulley Timing pulley D 24 3 TENSION ON MOTOR BELT AND TIMING BELT STANDARD There should be 4 6 mm of slack on the motor belt 3 4 mm of slack on timing belt when the center of each belt is just pushed with about 200g pressure ADJUSTMENT Loosen two scr
21. P REPLACEMENT RR 60 3 LEAD WIRES ARRANGEMENT 61 LCD UNIT CE AERA Ode _ _ 62 DISPLAY SYSTEM NECS NI DUERME 6 lt CONTROL UNIT P EEG EE RES AM FAR RR REN PERRA E RUE 64 TEST MODE Language Machine Specifications Settings 07 65 58 1 REMOVING THE COVERS 1 Remove the base plate by loosening four screws 2 Remove the face plate by loosening the screw 3 Remove the rear cover by loosening six screws 4 Remove the front cover by loosening the screw NOTE INSTALLING THE FRONT COVER B338 B346 B347 B348 B349 A Setthe pattern dial to the zigzag stitch and check that the line on the selecting cam aligns with the upper end of the release lever B Setthe pattern on the front cover to the zigzag stitch 59 er LAMP REPLACEMENT Loosen the screw of face plate Remove face plate Attach new sew light bulb to lamp socket B338 B346 B347 B348 B341 B349 B351 B352 60 3 LEAD WIRES ARRANGEMENT B338 B346 8347 B348 8341 B349 B351 B352 This is not on the B349 This is not on the B349 These parts differ slightly on the B351 61 LCD UNIT Language change SW
22. SAP MEX is mis P C d Em Upper shaft metal Needle bar support 4 EK wot Pattern cam mA p amp jo QT Selecting dial Control roller Needle bar A O BH change lever api Motor belt Needle threader lever mpe Selecting cam Feed bar mi Selecting unit Tension pulley Outer rotary hook assem Z Sus Indication gear Lower shaft metal Timing pulley D Lower shaft Vertical feed cam Drop lever Rotary shutter Horizontal feed arm 2 POWER TRANSMISSION CHART A Generating mechanism of needle bar thread take up lever and zigzag movements B338 B346 B347 B348 Thread take up Eccentric lever counter weight Upper shaft Worm gear Pulley Needle bar crank rod Pattern cam Needle bar clamp Needle bar Zigzag connecting Needle bar supporter rod assembly 2 finger Needle Selecting cam ionn gear Eccentric counter weight fe Thread take up lever pP na x ox fl Pam E 2 pper n Needle bar supporter ar c shan C E m Wi Ane B UN HE L bar crank rod M Wf 2 er y i eee
23. SERVICE MANUAL FOR BL6200 B 338 BL6700 B 341 4 1998 III IV GENERAL INFORMATION This service manual is complied for repairing service of DOMESTIC SEWING MACHINE BL6200 6700 51000 1250 1800 1950 2000 2100 STAR 10 15 20 20E 40E MYSTAR 15 Use this manual with Parts Catalogue for fault findings when you make a repair This machine is manufactured based on up to date product specifications at the time of this issue but there may be changes of specifications for improvements Contact manufacturer or local sales company for such changes Brother industries Ltd Nagoya Japan CONTENTS PRINCIPAL 65 1 TROUBLES AND CHECK POINTS 11 HOW TO ADJUST THE ELEMENTS 21 HOW TO CHANGE 6 58 CAUTION Always use rubber gloves when handling a printed circuit board and do not touch the metal portion of the printed circuit board with bare hands Keep the human body earthed to avoid generating static electricity Pack a printed circuit board with aluminum foil and avoid impact with it while storing or transporting Do not touch or damage the metal portion of a printed circuit board with a screwdriver or any other tool during repairing PRINCIPAL MECHANISMS A emet MECHANICAL CHART B338 B346 8347 B348
24. Test Mode 1 Turn off the power supply 2 Lower the BH lever 3 Turn on the power supply while holding down both the T and A keys on the display panel to enter the Test Mode The LCD display will appear as shown in Figure 1 A B Figure 1 Setting the Language 1 Press either the A key forward sequence or the B key reverse sequence until the desired language is displayed on the LCD Setting the Machine Specifications The teaching contents displayed on the LCD are determined by three possible combinations 1 whether or not there is a zigzag manual dial 2 whether or not there is a Drop Feed function and 3 the construction and operation of the bobbin case CB hook or Top bobbin 1 Press the J key forward sequence or the key reverse sequence to set the desired specifications When all of the settings have been completed turn off the power supply to cancel the Test Mode Table of Language Specifications 1 ENGLISH 9 SUOMEKSI FINNISH 2 DEUTSCH GERMAN 10 SVENSK SWEDISH 3 FRANCAIS FRENCH 11 CESTINA CZECH 4 ITALIANO ITALIAN 12 SLOWAKIAN SLOVAK 5 NEDERLANDS DUTCH 13 MAGYAR HUNGARIAN 6 ESPANOL SPANISH 14 SLOVENSKO SLOVENE 7 DANSK DANISH 15 PORTUGUES PORT 8 NORSK NORWEGIAN 16 JAPANESE Zigzag Dial Drop Feed Lever Bobbin Operation NO NO
25. Turn the pulley counterclockwise 2 3 times Check if the roller should lock thread when top of needle eye 0 1 5 mm down from the surface of needle plate Also check if thread tension is proper on 2 pcs of broad with needle 14 90 polyester thread 60 Polyester thread 60 o 071 5 mm 35 14 POSITION OF PATTERN INDICATION PLATE 8338 B346 B347 B348 B349 STANDARD Each pattern on indication plate should be indicated at the center of the indication window ADJUSTMENT 1 Set pattern dial to zigzag stitch and check baseline on selecting cam which should meet with upper end of release lever 2 Loosen two screws on indication gear 3 Setthe symbol of zigzag stitch at the center of the indication window by turning indication gear 4 Tighten two screws NOTE After adjustment make sure each pattern is indicated at the center of the indication window by turning pattern dial 8346 B338 8347 8348 8349 Indication window Base line 15 STANDARD When pattern dial is set to rick rack stitch and cam finger is released clearance between cam finger and pattern cam amp feed cam should be 0 3 0 5 mm ADJUSTMENT 1 2 3 4 Set pattern dial to rick rack stitch and release cam finger from pattern and feed cam Loosen the nut to release adjustment screw Adjust clearance by turning release
26. e at a slow ann if the button is pressed while the machine is running mm The machine stops immediately after bobbin winding is started Hie macane does not when the foot controller is Even after the machine is started it stops LE 18 19 19 19 20 PROBLEM Machine skips stitches Fabric does not feed Fabric does not feed straight Upper thread breaks at start Upper thread breaks during sewing Upper thread breaks during reverse sewing Lower thread breaks o r Oo c QV UA d Ne CAUSE Improper setting of the needle Bent or blunt needle Improper threading Improper combination of needle thread fabric Stretch fabric is used Improper timing of the needle and rotary hook Improper height of the needle bar Improper clearance between the needle and rotary hook Stitch length is set at O Improper height of feed dog Thick fabric Feed dog is worn out The feed dog is lowered Uneven pressure on right left side of presser foot Improper threading Bent or blunt needle Improper setting of needle Thread tension is too tight Thread is tangled Inferior needle eye Inferior needle slot of needle plate Inferior upper thread path Inferior thread Needle hits needle plate or outer rotary hook There are scratches on inner rotary hook Fabric is pulled excessively
27. e should drop in the needle hole balanced When the zigzag width dial is turned from O to 5 while the needle is in the right position horizontal movement of the needle should be less than 0 1 mm Needle swing on the way up from lowest position to needle plate should be less than 0 15 mm and that on the way down from needle plate to lowest position should be less than 0 05 mm ADJUSTMENT 1 Set pattern dial to zigzag stitch 2 Loosen the zigzag gear lever fixing screw 3 Move the zigzag connecting rod to its lowest position where the roller of zigzag connecting rod contacts unit base F while keeping the zigzag width dial at the minimum 0 and while preventing backlash the gear 4 Tighten the screw 5 Setzigzag width dial to 5 and set the right position of needle by turning the pulley 6 Turn zigzag width dial from to 5 and adjust eccentric nut so that the needle does not swing 7 Setzigzag width dial to 5 and adjust eccentric nut so that the needle drops in the needle hole balanced 8 Loosen three set screws on worm gear 9 Adjust needle swing by turning worm gear 10 Tighten three screws NOTE Make sure that there is no clearance between worm gear and pattern cam gear 2 3 9 5 B346 8338 341 7 B347 S B348 4 S WOKS B349 we tS a B351 Ou B352 TT 47 cr When needle goes down less than 0 05 mm When needle comes up lt le
28. es CORRECTION Replace the motor control unit Replace the motor control unit Replace the SS VR PCB unit Replace the motor control unit Check and adjust if necessary Refer to P 48 Install the motor control unit correctly Replace the BW switch Refer to P 51 Replace the motor control unit Check and adjust if necessary Refer to P 50 Replace the BT switch Refer to P 50 Replace the motor control unit Be sure to turn off the power and remove from the PCB the connector 19 PROBLEM 34 machine stops 35 immediately after bobbin winding is started The machine does not operate when the foot controller is de pressed CAUSE If the machine stops approx 1 second after bob bin winding starts the BW switch is not operating correctly The resistance between pins 1 and 2 of connector CN5 black should be less than 1 Q when the BW switch is turned on and when the BW switch is turned off Other causes The foot controller is not operating properly The resistance between the two ends of the foot controller plug is not less than 10 The resistance between pins 2 and 3 of the pin jack assembly on the PCB F C should be less than 1 Q when the foot controller is plugged in and when it is not plugged in Other causes CORRECTION Replace the BW switch Refer to P 51 Replace the motor control unit Replace the foot controller
29. ews on the motor holder Adjust tension on timing belt by moving motor holder Tighten two screws Loosen the screw on tension pulley Adjust tension on timing belt by moving tension pulley Tighten the screw 3 4mm 25 4 TIMING OF NEEDLE AND FEED B341 B349 B351 B352 STANDARD When the needle bar is at its highest position the mark on the horizontal feed cam should be at its topmost position Horizontal feed should start when needle bar reaches at the position of 7 17 from its highest position Turn the pulley counterclockwise ADJUSTMENT 1 2 3 ONO Set pattern dial to straight stitch and stitch length to 4 Loosen two screws on eccentric counter weight Adjust the eccentric counter weight so the needle is at its highest point when the mark on the horizontal feed cam of the upper shaft is at its topmost position Tighten two screws Make sure that timing was adjusted correctly by turning the pulley counterclockwise Loosen two screws of thread control cam Fit the both marks of thread control cam and eccentric counter weight by turning the thread control cam Tighten two screws 2 Horizontal feed cam Base line counter weight Thread control cam 26 5 POSITION OF ZIGZAG NEEDLE SWING STANDARD Set pattern dial to zigzag stitch The needl
30. han DCSV 5 Inferior LCD control PCB or LCD Replace the LCD control PCB or LCD module module 18 The message keys 1 line LCD 1 line LCD do not work 1 Message key top does not work Check the message key and key top 2 Inferior LCD unit Replace the LCD unit 4 line LCD 7 4 line LCD 7 1 Each key tops do not work Check each keys and key tops 2 Inferior LCD control PCB Replace the LCD control PCB 19 The LCD contrast 1 line LCD 1 line LCD cannot be adjusted 1 LCD contrast key does not work Check the slide volume and slide key 2 Improper LCD contrast Replace the LCD unit 4 line LCD 4 line LCD 1 LCD contrast key does not work Check the slide volume and slide key 2 Improper LCD control PCB Replace the LCD control PCB 20 The wrong pattern 1 line LCD 1 line LCD name appears on 1 Disconnection of connector CN2 on Connect CN2 on LCD unit the LCD LCD unit 2 Inferior LCD unit or pattern sensor Replace the LCD unit or pattern sensor 4 line LCD 4 line LCD 1 Disconnection of connector P3 on LCD Connect P3 on LCD control PCB control PCB 2 Inferior LCD control PCB or pattern Replace the LCD control PCB or pattern sensor 15 PROBLEM CAUSE CORRECTION 2 The Bobbin lline LCD llineLCD Winding message 1 BW switch does not work Adjust the BW stitch continues to appear Refer to 51 on the LCD 2 Inferior BW switch Replace the BW switch Refer to P 51 3 I
31. in presser slightly Move the bobbin presser to adjust the amount of thread wound on it Tighten the screw DARON 75 85 47 26 POSITION NEEDLDE POSITION SHUTTER B341 B349 B351 B352 STANDARD Needle position shutter works when the needle reaches at the position of 0 4 mm lower than its highest position ADJUSTMENT 1 2 3 4 Turn the pulley counterclockwise and set the needle at the position of 0 4 mm lower than its highest position Loosen the screw of the rotary shutter Turn the rotary shutter slowly and adjust N P shutter to be at the center of photo interrupter Tighten the screw Photo interrupter N P shutter ER 48 27 ADJUSTMENT OF BH LEVER SWITCH 8341 B351 B352 STANDARD When the BH lever reaches its lowest position it should have enough distance from BH lever switch When BH lever is raised BH lever switch should be clearly ON ADJUSTMENT 1 Loosen the screw 2 Move the BH lever switch holder to adjust its position 3 Tighten the screw NOTE Make sure on the LCD if BH lever switch position is correct 49 28 ADJUSTMENT OF REVERSE SEWING SWITCH B341 B349 B351 B352 STANDARD The clearance between the BT switch and the reverse sewing lever B should be 1 0 1 5 mm ADJUSTMENT 1 Loosen the screw for BT switch holder slightly 2 Use a standard screwdriver to move the top of the BT switch and ad
32. just the clearance between the switch and the reverse sewing lever B 3 Tighten the screw Note Check that the BT switch turns on when the reverse sewing button is pressed and the stitch length dial is set to 0 1 0 1 5 mm A 50 29 ADJUSTMENT OF BOBBIN WINDING SWITCH B341 B349 8351 B352 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 to the left 2 Loosen the screw 3 Adjustthe switch by moving it left to right 4 Tighten the screw 1 0 1 5 mm 51 30 ADJUSTMENT OF INNER ROTARY HOOK TENSION 8338 B341 B346 B347 B348 B349 B351 B352 STANDARD When pulling polyester thread 60 through slowly inner rotary hook tension should be 10 120 ADJUSTMENT 1 Thread polyester thread to inner rotary hook correctly and pull it slowly by using tension gauge 2 Adjust thread tension by using screwdriver Polyester thread 60 10 124 52 31 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 Lower the presser foot when you use needle threader Nylon transparent thread is
33. lever switch lever is not Refer to P 49 lowered 1 line 4 Inferior BH lever switch Replace the BH lever switch LCD Refer to P 49 5 Inferior LCD unit Replace the LCD unit Message Lower 1 Disconnection of connector P2 on LCD Connect the P2 on LCD control PCB Buttonhole Lever control PCB does not appear 2 Disconnection of connector CN7 on Connect the CN7 on Motor control unit when buttonhole is Motor control unit set and buttonhole 3 BH lever switch does not work Adjust the BH lever switch lev erisnot Refer to P 49 lowered 4 Inferior BH lever switch Replace the BH lever switch 4 line LCD Refer to P 49 5 Inferior LCD control PCB Replace the LCD control PCB 16 PROBLEM CAUSE CORRECTION 26 Message Lower 1 line LCD 1 line LCD BH Lever appears BH lever switch does not work Adjust the BH lever switch when button hole Refer to P 49 lever is lowered 2 Inferior BH lever switch Replace the BH lever switch Refer to P 49 3 Inferior LCD unit Replace the LCD unit 4lineLCD 4lineLCD 1 BHlever switch does not work Adjust the BH lever switch Refer to P 49 2 Inferior BH lever switch Replace the BH lever switch Refer to P 49 3 Inferior LCD control PCB Replace the LCD control PCB 27 The light does not 1 voltage on both ends of connector Replace either the AC cord or the motor turn on even after CNI is not 100 V AC when the AC control unit the power is tur
34. ned cord is inserted on 2 resistance both ends of the Replace the motor control unit power switch is not less than 1 Q when the power is turned on 3 fuse is broken Replace the motor control unit 4 The light does not turn on The light Replace the light may be damaged or deteriorating or it may have a bad connection Remove the light and measure the resistance on both ends It should be less than 3 0 5 output from the transformer is Replace the motor control unit incorrect When connector CN4 is disconnected from the motor control unit and the power is turned on the voltage between pins 1 and 2 of connector CN4 should be approximately 10V AC 6 Other causes Replace the motor control unit Be sure to turn off the power and remove from the PCB the connector 17 PROBLEM 28 The motor does not run CAUSE The pulley is turned too tightly The resistance between the two ends of motor connector CN2 is not between 25 and 35 Q Inferior SS switch The resistance between pins 4 and 5 of the SS VR PCB unit connector should be less than 1 when the SS switch is turned on and when the SS switch is turned off Inferior BT switch The resistance between pins 1 and 2 of connector CN6 red should be less than 1 Q when the BT switch is turned on and when the BT switch is turned off The resistance between pins 2 and 3 of the pin jack assembly on the PCB F C sh
35. nferior LCD unit Replace the LCD unit 4lineLCD 4lineLCD 1l BW switch does not work Adjust the BW stitch 2 Inferior BW switch Refer to 51 3 Inferior LCD control PCB Replace the BW switch Refer to 51 Replace the LCD control PCB 22 The Bobbin 1 Disconnection of connector CN1 on Connect CN1 on LCD unit Winding message LCD unit does notappearon 2 Disconnection of connector CN5 on Connect CN5 on Motor control unit the LCD when the Motor control unit machine is set for 3 BW switch does not work Adjust the BW stitch bobbin winding Refer to P 51 1 line LCD 4 Inferior BW switch Replace the BW switch Refer to P 51 5 Inferior LCD unit Replace the LCD unit 23 Message Bobbin 1 Disconnection of connector P1 on LCD Connect the on LCD control PCB Winding Selected control PCB does not appear 2 Disconnection of connector CN5 on Connect the CN5 on Motor control unit when bobbin Motor control unit winding is set 3 BW switch does not work Adjust the BW switch 4 line LCD Refer to P 51 4 Infenor BW switch Replace the BW switch Refer to P 51 5 Inferior LCD control PCB Replace the LCD control PCB Message Lower 1 Disconnection of connector CN3 on Connect the CN3 on LCD unit BH Lever does LCD unit not appear when 2 Disconnection of connector CN7 on Connect the CN7 on Motor control unit buttonhole is set Motor control unit and buttonhole 3 BH lever switch does not work Adjust the BH
36. o rick rack stitch 2 Loosen the nut for adjustment screw 3 Adjust forward and reverse feeding by turning screw 4 Tighten the nut WINS B346 B338 B341 B347 B349 B348 B351 B352 WWW wi 40 19 ADJUSTMENT FEED STANDARD When stitch length dial is set to O stitch length should be 0 mm ADJUSTMENT 1 Setthe pattern dial to the zigzag stitch the zigzag width dial to 5 and the stitch length dial to O 2 Loosen the screw on feed dial gear 3 Turn feed dial gear slightly so that stitch length become 0 mm 4 Tighten the screw 9 2 3 B346 B338 341 B347 P auta B348 B349 B351 B352 41 20 BUTTONHOLE ADJUSTMENT FORWARD REVERSE FEEDING 1 STEP BH MODEL B338 B341 B347 B348 B349 B351 B352 STANDARD When pattern dial is set to 1 Buttonhole there should be no feeding difference between left and right legs ADJUST 1 Set pattern dial to 1 Buttonhole Set stitch length dial to F and lower the B H Lever After that get the trial buttonhole stitch Set BH adjusting eccentric stud to fig 3 Sew the trial buttonhole stitch then check the difference of sewing pitch between right and left rows Loosen the nut for buttonhole feed adjusting screw Adjust forward and reverse feeding by turning the screw Tighten the nut noc 1 step BH model 4 STEP
37. og correctly 5 Forward and reverse feedings differ Refer to P 40 6 Stitch width dial is not set to 5 Operate machine correctly 14 Needle hits needle 1 Release volume is too big Adjust the release volume plate when pattern Refer to P 37 selector dial is turned 15 Fabric gathers 1 Thread tension is too tight Reduce the tension 2 Blunt needle Change the needle 3 Improper combination of needle Select correct combination of needle thread fabric thread fabric 4 Improper threading Reset threading correctly 16 The stitch shown in 1 Release volume is too small Adjust the release volume the pattern 2 The indicate gear and pattern indicator Refer to P 37 sewn 14 Sensor PROBLEM CAUSE CORRECTION 17 No characters llineLCD llineLCD appear on the 1 Improper setting of LCD contrast key Adjust LCD contrast key LCD 2 Disconnection of connector CN 1 Connect on LCD unit 3 Voltage between terminal 2 1 of LW1 Replace the motor control unit on motor control unit is less than DCSV 4 Inferior LCD unit Replace the LCD unit 4 line LCD 4 line LCD 1 Improper setting of LCD contrast Adjust LCD contrast manual manual 2 Disconnection of connector P1 Connect P1 on LCD control PCB 3 Disconnection of connector P5 Connect P5 on LCD module 4 Voltage between terminal 2 1 of LW1 Replace the motor control unit on motor control unit is less t
38. orizontal feed cam Worm gear Pulley Feed dog Feed regulator Forked Motor belt connecting rod Timing belt Horizontal Horizontal Horizontal Dar feed plate feed shaft feed arm Motor Vertical feed Rotary shatter Lower shaft Timing pulley D cam Drop lever Forked connecting rod Vertical feed cam Horizontal feed plate These parts are not installed on the B338 B346 B347 and B348 Motor belt C Automatic 1 step BH mechanism 8338 B341 B347 B348 B349 B351 B352 finger assembly BHZ finger assembly BH change shaft BH change arm BH stopper BH lever BH foot ERE I Remy 2 BH change BH change BH stopper BH cam BHF finger shaft arm assembly BH lever 2 A BH foot 3 DISPLAY SYSTEM BY MICRO COMPUTER 8341 B351 An 8 bit micro computer in models installed with an LCD liquid crystal display regulates the LCD controller driver which controls the information shown on the display 1 LINE DISPLAY SYSTEM BLOCK CHART pda E LCD panel LCD unit Power supply 1 circuit and motor control m LCD controller circuit driver Contrast SED1278 volume Motor control P C board 4 8 bit MCU M38004M8 lt Message key
39. ould not be less than 1 Q when the foot controller is not inserted Other causes CORRECTION Adjust the mechanism so that the pulley rotates easily Replace the motor Replace the SS VR PCB unit Replace the BT switch Refer to P 50 Replace the motor control unit Replace the motor control unit 29 The motor does not 1 run smoothly or it does not run at a high speed The Pulley is sometimes easy or sometimes difficult to move when it is rotated by hand Accumulated lint or thread under the needle plate Improper tension in motor belt and timing belt Tight gearing of the pattern cam gear and worm gear The rotary shutter is dirty The motor control unit is installed incorrectly It is loose or slanted The voltage between pins 24 and 3 on the SS VR PCB does not stay between 0 and 5 V DC when the power is turned on and the speed adjustor is slid to the maximum Other causes Adjust the mechanism so that the pulley rotates easily Clean inner rotary hook outer rotary hook and feed dog Refer to P 25 Refer to P 27 Clean the rotary shutter Install the motor control unit correctly Replace the SS VR PCB unit Replace the motor control unit 30 Even after the machine is started it stops suddenly The motor control unit is installed incorrectly It is loose or slanted Other causes Install the motor control unit correctly Replace the motor control unit
40. sensor Speed volume m Drive circuit Motor CPU Foot controller 30pins Speed sensor Bobbin winder sw SS Switch Reverse sw 10 TROUBLES AND CHECK POINTS 1 Machine skips stitches 13 2 Fabric does not feed RUM EA MEN EM DEM AMO CAU RENE 13 3 Fabric does not feed straight Edd ROAR RRR RESINA NAE RC 13 4 Upper thread breaks at start se ee 13 5 Upper thread breaks during sewing IPIS DNE EE 13 6 Upper thread breaks during reverse sewing 13 7 Lower thread breaks 18 8 Needle breaks 14 9 Noise ME 14 10 Forward and reverse feedings differ rer ter ate ere errr eer Tore 14 1 1 Improper length of buttonhole legs E ETT 14 12 Improper buttonhole size against button 8126 enne 14 13 Unbalanced patterns PUPPI VIENNE MUNI EE 14 14 Needle hits needle plate when pattern selector dial is turned 14 15 Fabric gathers DAMEN PEINE AME IAE EARN MM REND DRE
41. ss than 0 15 mm ZELDA dez 27 6 POSITION OF ROTARY HOOK STANDARD When pattern dial is set to zigzag stitch zigzag width dial is set to 5 the needle is at the left side and needle raises from its lowest position by 2 75 3 15 mm the pointed end of rotary hook should meet with right side of needle Under this condition clearance between the hook and the needle should be less than 0 1 mm and the hook should not hit the needle ADJUSTMENT 1 2 3 4 5 Set pattern dial to zigzag stitch and zigzag width dial to 5 the needle is at the left side Loosen three screws on lower shaft gear Adjust position of rotary hook When needle raises from its lowest position by 2 75 3 15 mm the pointed end of rotary hook should meet with right side of the needle Tighten three screws Adjust clearance by turning clearance adjusting eccentric screw gg B346 B338 B341 B347 B348 B349 B351 B352 0 1 mm or less 28 7 HEIGHT OF NEEDLE STANDARD When pattern dial is set to the zigzag stitch the zigzag width dial is set to 5 the needle is at the left side and the pointed end of the rotary hook contacts the right side of the needle the clearance between the top of the needle eye and the hook point should be 0 8 1 2 mm ADJUSTMENT Set pattern dial to zigzag stitch and zigzag width dial to 5 the needle is at the left side Set position so that hook point mee
42. t with right side of the needle by turning the pulley Loosen the screw on needle bar holder Adjust height of needle clamp Tighten the screw 2 3 B346 B338 B341 Nas B347 B348 B349 B351 B352 D 0 8 1 2 mm 29 8 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 Adjustthe position of inner rotary hook stopper Face A on inner rotary hook and feed direction should be at right angles 3 Tighten the screw 30 9 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 needle plate should be 0 3 0 8 mm ADJUSTMENT 1 Loosen two screws on the horizontal feed plate Adjust the left and right sides of the feed dog Tighten two screws Turn the pulley to move the feed dog to its initial feed position Loosen the screw on the horizontal feed arm Adjust the arm so the clearance between the feed dog and the needle plate is between 0 3 0 8 mm Tighten the screw Do ROIO i Initial feed dog position e s dE 0 3 0 8 mm
43. ttern dial while needle is in Operate machine correctly the fabric 2 Needle hits inner rotary hook Adjust the position of inner rotary hook stopper Refer to P 30 3 Needle hits needle plate Make sure the correct needle is used Refer to P 27 P 37 4 Bentor blunt needle Change needle 5 Improper clearance between the needle Refer to P 28 and the outer rotary hook 6 Machine feeds while needle is in the Refer to P 25 P 26 fabric 7 Needle flows Refer to P 27 8 Fabric is pulled excessively Guide the fabric 9 Noise 1 Play of worm pattern cam gear Adjust to proper gearing 2 Play of lower shaft Adjust play of the lower shaft 3 Play of upper shaft Adjust play of the upper shaft 4 Noise from rotary hook Clean the race of inner rotary hook and outer rotary hook or replace inner rotary hook 10 Forward and 1 Improper adjustment ofrevers sewing Refer 0 P 46 reverse feedings lever differ 11 Improper length of 1 Improper adjustment Adjust screw buttonhole legs Refer to P 42 12 Improper 1 Improper adjustment of buttonhole Adjust the length of buttonhole buttonhole size length Refer to P 44 against button size 13 Unbalanced 1 Stitch length dial is not set at 4 Operate machine correctly patterns 2 Feed dog is worn out Change the feed dog Refer to P 31 P 32 3 Improper height of feed dog Refer to P 32 4 Improper attachment of feed dog Attach the feed d
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