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Pfaff 4874 Service Manual

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4874
SERVICE MANUAL

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  • Page 1 4874 SERVICE MANUAL...

  • Page 2: Table Of Contents

    TABLE OF CONTENTS General directions and recommendations Recommendations C.1-2. Mechanical sewing disorders D.1-3. Test program - test of LCD display E.1-2. Test program - tension settings - fine tuning F.1-2. Error code G.1-3. Gauge for the after - sales service Removing back cover Removing front cover 3.a-e.
  • Page 3 TABLE OF CONTENTS 29.a-b. Irregular loop formation on the chain needles (cover hems) Cover hem stitch formation (Narrow & Wide) Triple cover hem stitch formation 32.a-c. Top cover stitch formation (Prog.21~23) 33.a-g. Deco cover stitch formation (Prog.24~30)

  • Page 4: General Directions And Recommendations

    GENERAL DIRECTIONS AND RECOMMENDATIONS Safety For safety reasons, the sewing machine must be disconnected from the mains: - Whenever the machine is left unattended - Whenever preparing the machine for sewing - Whenever servicing - Whenever replacing mechanical or electrical parts or accessories Needles Usually needles of the system 130/705 H may be used.
  • Page 5 RECOMMENDATIONS 1. Never connect the machine to a different voltage than tha t marked on the specification plate. 2. For safety reasons, never perform any repairs on the powe r supply circuit without first removing the mains lead from the machine. 3.

  • Page 6: C.1-2. Mechanical Sewing Disorders

    MECHANICAL SEWING DISORDERS First of all, please refer to the paragraph entitled "maintenance" in the instruction manual, especially when machine does not turn freely by turning the flywheel by hand. If necessary, check and adjust tightness of motor belt. Given below are the most frequent disorders. In most cases, they can be remedied by checking the adjustments in the following order.
  • Page 7 MECHANICAL SEWING DISORDERS 3. Thread breakage Before checking the adjustment, make sure of the good quality of the thread and the needle, the correctness of threading and the smoothness of all the thread passages. Quite often, an injury to thread passage is the cause of thread breakage. If all these points are in order, check the following: - Dull point of needle or bent needle - replace.
  • Page 8 TEST PROGRAM - TEST OF LCD DISPLAY Access to the test program PROG. 1. Switch off the machine. 2. While pressing key "2" and "3" simultaneously, switch on the machine. 3. The matrix pattern turns to "LCD test mode". 4. Press "1", the step motors will rotate to their minimum position and the number "12" will appear on the display.
  • Page 9 TEST PROGRAM - TEST OF LCD DISPLAY 5. Press "1" again, the step motors will rotate to their maximum position and the number "48" will appear on the display. Tension value can be checked and adjusted as a manner shown in the page E1. 6.
  • Page 10 TEST PROGRAM - TEST OF LCD DISPLAY 10. Press "1" again, the display becomes 11. Press "1" again, the display becomes 12.Press "1" again, nothing is displayed 13. Press "1" again, all symbols are displayed 14. Press "1" again, Program version number is displayed Note: It is also possible to proceed with above tests in reverse sequence by pressing key "2"...
  • Page 12 TEST PROGRAM-THREAD TENSION SETTING-DIAL TENSION FINE TUNING Test program for minimum dial tension (step 4 in page D1) and maximum dial tension (step 5 in page D2 ). The following manners are used for the setting of step motors (dial tensions). a) Step 4 The step motors will rotate to its minimum position.
  • Page 13 FINE TUNING OF DIAL TENSION FOR TOP-COVER & DECO-COVER 1. At the indication of Dial Tension Number "4", secure the tension value of thread shouldbe 15 to 20 gr.(with polyester thread #30) 2. If the thread tension is higher than expected( stitch becomes tight.), adjust tensions with fine tuning dial "d"...
  • Page 14 ERROR CODE Error P l a c e i n p r o b l e m P h e n o m e n o n Code Step motor DT-1 Step motor with same number of Error code does not turn. Step motor DT-2 (Example: Error No.3 showed on the display, DT-3 does not Step motor DT-3...
  • Page 15 ERROR CODE C a u s e o f f a i l u r e M e a s u r e Failure of DECO Step motor. Replacing the Step motor. Lead wire of Step motor for D.F. cut off. (burn out) Replacing the lead wire and or the Step motor.

  • Page 16: G.1-3. Gauge For The After - Sales Service

    GAUGE FOR THE AFTER-SALES SERVICE Dimension Gauge No. 10989 4.7mm Height of cloth presser bar 12.0mm Height of needle bar 2.8mm Angular position of lower looper to needle 65.0mm Height of lower looper 6.0mm Angular position of upper looper to needle 1.5mm Chain looper angular position 47.3mm...
  • Page 17 GAUGE FOR THE AFTER-SALES SERVICE Dimension Gauge No. 11684 84.3mm For the adjustment of initial point for Blue & Yellow Decorative Thread Guides 1.2mm and for setting position of the DECO UNIT sensor (Page.23-Fig.1,Page.27b-Fig.6,7,9) 3.5mm For the setting of stitch length unit (setting the both gears(Page.23-Fig.1B&C)) Height of Yellow Decorative Thread Guide from thesurface of needle plate...
  • Page 18 GAUGE FOR THE AFTER-SALES SERVICE Dimension Gauge No. 11691 For the adjustment of setting position of EN-Sensor (measuring the clearance between out side of a projected arc of slit- plate and the bottom of U shaped part of EN-Sensor ) Ref.to Page 22a & b Thickness = 0.2mm Dimension Gauge No.

  • Page 20: Removing Back Cover

    REMOVING BACK COVER 1. Remove mains lead. 2. Remove base plate unit "1" (screws "a"). 3. Remove knobs "b" and screw caps and screws "c". 4. Remove side cover "2". 5. Remove top cover "3" with screws "d". 6. Remove lamp cover "4" with screw "e". 7.

  • Page 21: Removing Front Cover

    REMOVING FRONT COVER 1. Remove mains lead. 2. Remove screws "b", "c" and cover unit 7. 3. Remove snap-on noise cover unit 6. (Spread its sides.) 4. Remove screws "a" (allen screw 2.5mm) and take-up lever noise cover bracket 8. 5.
  • Page 22 REMOVING LCD PRINTED CIRCUIT BOARD 1. Remove: Mains lead 2. Disconnect all connectors from the LCD printed circuit board (connectors wired with 8 step motors, sensors, switches and speed reducer etc.) 3. The details of wiring are available from the page 3b and 3c. SPD DTS DCSW CN11...
  • Page 23 WIRING FOR THE CONNECTORS ON THE LCD CIRCUIT BOARD 3b Secure respective wiring between each connectors and related motors and sensors with wire- harness as shown in the following tables. DCSW DFS DCS Wiring for Sensors Connectors Sensors From DT Sensor P.C.B. Page.3a Page.3a From S.L.
  • Page 24 WIRING FOR CONNECTORS OF MAIN PRINTED CIRCUIT BOARD To SPD (LCD P.C.B.) (CN6) CN12 (CN11) To Speed reducer Fuse Wiring Connectors From Power Supply From Lighting (Lamp) From Transformer (Out-put Side) From Transformer (In-put Side) From Sensor of the EN P.C.B. From Sewing Motor From...
  • Page 26 LCD PRINTED CIRCUIT BOARO FRONT PANEL LCD FUNCTION KEY STEP MOTOR DT1+ DT2+ DISPLAY DT3+ 1~ 6 DT4+ DT5+ 1~ 6 1~ 6 1~ 6 1~ 6 1~ 6 DTS (DT SENSOR P.C.B.) DT1_ORG DT2_ORG DT3_ORG DT4_ORG CN11 FOR MAIN P.C.B. PV (FOR DCM) DT5_ORG SEWING MOTOR OPERATION SIGNAL...
  • Page 27 MAIN PRINTED CIRCUIT BOARD (SPEED ADJUST) EN P.C.B. NP P.C.B. TRNSFORMER FOOT CONTROLLER CN12 LAMP JACK SPEED REDUCER CN11 MAIN SEWING MOTOR MICRO SWITCH FOR FRONT FLAP CN13 FOR LCD P.C.B.
  • Page 28 ANGULAR POSITION OF BALANCE WEIGHTS AND POSITION OF ECCENTRICS Fig.1 Fig.2 Fig.3 Fig.4 Fig.5 Fig.6 Fig.7...
  • Page 29 ANGULAR POSITION OF BALANCE WEIGHTS AND POSITION OF ECCENTRICS 1. Remove: Mains lead - Back - front cover - Machine base. 2. In case of dismantling the lower shaft or if one of the eccentrics is damaged or badly fixed, the positions shown in page 4a, allow resetting the eccentrics approximately. These should be adjusted correctly with each relative adjustment.

  • Page 30: A-B. Height And Alignment Of Cloth Presser Bar

    HEIGHT AND ALIGNMENT OF CLOTH PRESSER BAR...
  • Page 31 HEIGHT AND ALIGNMENT OF CLOTH PRESSER BAR 1. Remove: Mains lead. 2. Lift up lever "a" and remove lamp cover. 3. Unscrew screws "b" to remove bracket with lamp holder. 4. Make sure that the shank holder of presser foot is in its highest position. 5.
  • Page 32 HEIGHT AND ORIENTATION OF NEEDLE BAR IN RELATION HEIGHT AND ORIENTATION OF NEEDLE BAR IN RELATION TO THE NEEDLE PLATE HOLES TO THE NEEDLE PLATE HOLES 12mm Fig.1 Fig.2 Fig.3...
  • Page 33 HEIGHT AND ORIENTATION OF NEEDLE BAR IN RELATION TO THE NEEDLE PLATE HOLES 1. Remove: Mains lead - Sewing foot. 2. Insert a new needle (Nm 90) in "R1". 3. With needle bar at its highest position, loosen screw "a" just enough so that needle bar slides with friction.(Fig.1) 4.

  • Page 34: Height-Clearance-Angular Position Of Lower Looper

    HEIGHT-CLEARANCE-ANGULAR POSITION OF LOWER LOOPER 1. Remove: Mains lead. - Sewing foot 2. Make sure that there is no axial play on looper shaft "x". 3. Loosen screw "a", adjust height of lower looper as shown and tighten screw "a". 4.

  • Page 35: Clearance Of Needle Guards

    CLEARANCE OF NEEDLE GUARDS 1. Remove: Mains lead - Needle plate. 2. Insert 2 new needles (Nm 90) in "R1" and "R2" positions. 3. Check height - clearance - angular position of lower looper. 4. Turn the handwheel and bring needle bar in its lowest position. 5.

  • Page 36: A-B. Timing Of Lower Looper

    TIMING OF LOWER LOOPER...
  • Page 37 TIMING OF LOWER LOOPER 1. Remove: Mains lead - Sewing foot. 2. Make sure that there is no axial play on lower looper shaft "a". 3. Insert a new needle (Nm 90) in "R1" and check height and orientation of needle bar (page 6), height and angular position of lower looper (page 7).

  • Page 38: Angular Position Of Upper Looper

    ANGULAR POSITION OF UPPER LOOPER 1. Remove: Mains lead - Machine base. 2. Make sure that there is no axial play neither on the upper looper shaft "a" nor on the 2 pivoting axles "b" and "c". 3. Bring upper looper to its extreme left swing position. 4.

  • Page 39: Clearance And Timing Of Upper Looper To Lower Looper 11

    CLEARANCE AND TIMING OF UPPER LOOPER TO LOWER LOOPER 11 1. Remove: Mains lead - Sewing foot. 2. Check adjustments: - Height and orientation of needle bar (see page 6). - Height - clearnce - angular position of lower looper (see page 7). - Timing of lower looper (see page 9).
  • Page 40 CHAIN LOOPER : ANGULAR POSITION - CLEARANCE - ORBITAL TIMING - CLEARANCE OF CHAIN NEEDLES GUARD 1.5~1.8mm Fig.2 Fig.1 Motion Fig.3 0~0.05mm 1.0mm Fig.4 Fig.5...
  • Page 41 CHAIN LOOPER : ANGULAR POSITION - CLEARANCE - ORBITAL TIMING - CLEARANCE OF CHAIN NEEDLES GUARD 1. Remove: Mains lead - Sewing foot - Machine base - Needle plate. 2. Make sure that there is no axial play on chain looper sha ft "a". If necessary, adjust with stop collar inside shaft "g"...
  • Page 42 CHAIN LOOPER : ANGULAR POSITION - CLEARANCE - ORBITAL TIMING - CLEARANCE OF CHAIN NEEDLES GUARD Fig.6 Fig.7 0.5~1.0mm Fig.8...
  • Page 43 CHAIN LOOPER : ANGULAR POSITION - CLEARANCE - ORBITAL TIMING - CLEARANCE OF CHAIN NEEDLES GUARD 6. Chain looper: Eccentric - Orbital timing. Make sure that there is no axial play on chain looper shaft. If necessary, adjust with stop collar inside shaft "g". Check angular position of chain looper and height and orientation of needle bar.

  • Page 44: Chain Looper Thread Take Up Rotary Cam

    CHAIN LOOPER THREAD TAKE UP ROTARY CAM 1. Timing adjustment for chain looper thread take up rotary Cam "C": When the small hole "D" on "C"adjoins at the surface of chain looper thread guide plate "A", the needle "L2" in its downward movement must be positioned as shown in Fig. 1. 2.

  • Page 45: Height Of Feed Dog

    HEIGHT OF FEED DOG 1. Remove: Mains lead - Sewing foot - Needles and rear cover 2. Set stitch length at "0.6" and differential feed at "1". 3. Turn the handwheel and bring feed dogs to their highest position. 4. Loosen screw "a". 5.

  • Page 46: A-B. Moving Cutter And Vertical Feed Timing

    MOVING CUTTER AND VERTICAL FEED TIMING 0.5mm Fig.1 Fig.2 Fig.3 Fig.4...
  • Page 47 MOVING CUTTER AND VERTICAL FEED TIMING Caution: The eccentric "7" is used for feed and moving cutter timing. See page 4. 1. Remove: Mains lead - Sewing foot - Machine base. 2. Check height and orientation of needle bar - height of feed dog. See page 6&14. 3.
  • Page 48 HORIZONTAL FEED TIMING AGAINST CHAINSTITCH NEEDLE Fig.1 Fig.2 Fig.3 Fig.4...
  • Page 49 HORIZONTAL FEED TIMING AGAINST CHAINSTITCH NEEDLE 16b Note: It is essential to precisely check and adjust this timing. This adjustment avoids bending the chain needle(s) when sewing through maximum thickness of materials. 1. Remove: Mains lead - Machine base 2. Check adjustment height of feed dog and vertical feed timing. (See page 14 and 15a,b) 3.

  • Page 50: Adjustment For Differential Feed Unit Operated With Stepping Motor

    ADJUSTMENT FOR DIFFERENTIAL FEED UNIT OPERATED WITH STEPPING MOTOR 1. Loosen set screws "1" and "2" for D.F. step motor gear "C" .(Fig.1) 2. Insert Gauge pin "A" (No.11685) into two holes on the both gears "C " and "D"of D.F. stepping motor.

  • Page 51: Position Of Fixed Cutter And Cutting Width Dial Setting 18

    POSITION OF FIXED CUTTER AND CUTTING WIDTH DIAL SETTING 18 1. Remove: Mains lead - Sewing foot - Needles. 2. Disengage moving cutter. 3. Basic position: Turn dial "a" to bring indicator to position mark "1/4~1/8" and check if clearance of 0.2~0.3mm is obtained between fixed blade "b" and needle plate edge. 4.

  • Page 52: Position Of Loopers Threads Take Up Lever

    POSITION OF LOOPERS THREADS TAKE UP LEVER 1. Remove: Mains lead and loopers threads take up lever cover unit "6"on page 2. 2. Turn the handwheel and bring upper looper thread take up lever "a" in its highest position. 3. Check and make sure that the distance between thread take up lever guide and inside of the machine base is at 47.3 mm.

  • Page 53: Position Of The Stitch Width Finger

    POSITION OF THE STITCH WIDTH FINGER 1. Remove: Mains lead. 2. Check and make sure that the stitch width finger (=instant rolled hem device) is flush with the needle plate, that the distance between the needle plate tongue and front section of stitch width finger is at 0.5 to 1mm.

  • Page 54: Lateral And Front Covers Safety Device

    LATERAL AND FRONT COVERS SAFETY DEVICE The device is built in order to switch off the machine as soon as one (or both) of the covers is opened. In case that machine is still switch off by the device with both covers closed: check if switch clicks ON and OFF when opening / closing covers.

  • Page 56: A-B. Adjustment Of Setting Position For En-Sensor And Slit-Plate

    ADJUSTMENT OF SETTING POSITION FOR EN-SENSOR & SLIT-PLATE In order to secure the proper position of EN-Sensor (Fig.2, "f",Page22b) and the related Slit- plate (Fig.2, "d", Page22b), take a following manner for this adjustment : 1. Adjustment of setting position for EN-Sensor 1-1.
  • Page 57 ADJUSTMENT OF SETTING POSITION FOR EN-SENSOR & SLIT-PLATE 0.2mm No.11691(thickness gauge) No.11692 No.800703(PIN) Fig.2 Fig.3 No.11692 Fig.1...

  • Page 58: Adjustment For Stitch Length Unit Operated With Step Motor

    ADJUSTMENT FOR STITCH LENGTH UNIT OPERATED WITH STEP MOTOR 1. Loosen the two set screws "D" (Fig.2). One of the set screw located behind a drawing (Fig.2)and lower position. 2. Insert guage pin "A" (Fig.1 N0.11684) into the both hole on the gear "B" and "C" (Fig.1) for the step motor.

  • Page 59: Timing Adjustment For Top Cover Triangle Thread Guide And Top Cover Hook

    TIMING ADJUSTMENT FOR TOP COVER TRIANGLE THREAD GUIDE AND TOP COVER HOOK 1. Set the program any one of No. 21-23 and power supply should be turned off. Top Cover Hook Top Cover Triangle 2. Turn the hand wheel, so that the both "B"...

  • Page 60: Adjustment Of Threads Take Up Lever For Top Cover And Deco Cover

    ADJUSTMENT OF THREAD TAKE UP LEVER FOR TOP COVER AND DECO-COVER. In order to obtain good stitching result especially for the Top-Cover and DECO-Cover, main- tain well Thread take up lever "A". For this purpose, check the distance of both "a" and "b" and if both are not equal, adjust the shape of Thread take up lever(A) by hand work with bending it in the directionof arrow ) upto resulting to have equal distance at the "a"...

  • Page 61: Installing Of Deco Unit

    INSTALLING OF DECO UNIT Install DECO UNIT on to the position as shown Fig.1, with following manner: 1) Prepare preassembled DECO UNIT with Blue and Yellow Decorative Thread Guide and Gauge No.11687. 2) Before putting the guage on the needle plate, turn the handwheel in the normal direction until the "L2"...

  • Page 62: A-B. Adjustment For Deco Unit

    ADJUSTMENT FOR DECO-UNIT(ADJUSTMENT OF INITIAL POINT FOR BLUE & YELLOW DECORATIVE THREAD GUIDES When the undermentioned parts of DECO unit replaced and or the initial point of both (Blue and Yellow ) Decorative Thread Guides shows incorrect position, it is required to make an adjustment of the initial point for the both Decorative Thread Guides with following manner: Name of parts 1.
  • Page 63 ADJUSTMENT FOR DECO-UNIT(ADJUSTMENT OF INITIAL POINT FOR BLUE & YELLOW DECORATIVE THREAD GUIDES) 1.5 mm Fig.5 Fig.4 84.3mm 84.3mm Fig.6 No.11684 Fig.7 Fig.9 Fig.8...

  • Page 64: Cover Hem Stitch Being Pulled

    COVER HEM STITCH BEING PULLED 1. If "L0 or L1" needle thread is being pulled to the right (Fig.1), then check the following points: 2. Insert new needles (Nm 90) . 3. Check and make sure that needles are correctly inserted into the needle clamp. 4.
  • Page 66 IRREGULAR LOOP FORMATION ON THE CHAIN NEEDLES (COVER HEMS) Fig.1 Blue Green Blue Green Blue Green L0/L1 Fig.2 Fig.3 Fig.4 Blue Green Blue Green L0/L1 Fig.5 Fig.6...
  • Page 67 IRREGULAR LOOP FORMATION ON THE CHAIN NEEDLES (COVER HEMS) 29b When the chain needles are in down position and going upstroke, the needles should pass behind the loops. See cover hem stitch formation on page 30 and 31. However, it is possible that some irregular loops will appear on the chain needle threads.

  • Page 68: Cover Hem Stitch Formation (Narrow & Wide

    COVER HEM STITCH FORMATION (NARROW & WIDE) Needles rise to form loops. Chain looper Needles go down into the thread triangle, start its motion from right to left. and chain looper is moving to the right. Chain looper pass into neelde thread loops. Chain looper is releasing needle thread loops.

  • Page 69: Triple Cover Hem Stitch Formation

    TRIPLE COVER HEM STITCH FORMATION Needles rise to form loops. Chain looper Needles go down into the thread triangle, start its motion from right to left. and chain looper is moving to the right. Chain looper pass into neelde thread loops. Chain looper is releasing needle thread loops.

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