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Janome 4120QDC, Service Manual And Parts List, Page: 25 / 43

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Janome 4120QDC Service Manual And Parts List Download Page 25

23

CiRCuit boaRd-a (1)

to Remove:

1. remove the front cover. (See pageS 6 – 7)

2. pUll oUt connectorS from the circUit board-a.

3. remove the ScrewS (4pcS.) and the circUit board-a.

to attaCH:

1. follow the above procedUreS in reverSe.

note:

do not diSconnect the connectorS by pUlling on cord. 

to diSconnect, graSp the connector, not the cord.

RePlaCing tHe eleCtRoniC ComPonents

cirUcit board-a

SetScrewS

SetScrew

Summary of Contents for 4120QDC

Page 1: ...SERVICE MANUAL PARTS LIST 4120QDC ...

Page 2: ...tion 10 Adjustment of Hook Timing 11 Adjustment of Needle Bar Height 12 Clearance between Needle and Tip of Rotary Hook 13 Feed Dog Height 14 Top Tension 15 Replacing the Electronic Components Circuit Board A Connection 16 Self diagnostic Test 17 22 Circuit Board A 23 Driving Motor 24 Switching Regulator Unit 25 Adjusting Buttonhole Lever Position 26 Parts List 27 41 ...

Page 3: ...le and thread Use a HA x 11 blue tip needle See mechanical adjustment Needle bar height See mechanical adjustment Ad justment of hook timing See mechanical adjustment Clearance between needle and tip of the rotary hook P 12 P 11 P 13 2 Fabric not moving 1 Incorrect feed dog height 2 Feed dog is in down position 3 Thread on bottom side of fabric is jammed up 4 Feed dog teeth are worn Adjust the pre...

Page 4: ...bbin thread 1 Bobbin holder is incorrectly threaded 2 Too much thread is wound on the bobbin 3 Lint is stuck inside the bobbin holder 4 Thread quality is too low 5 Thread is jamming around the bobbin holder Set the bobbin thread correctly Adjust the position of bobbin winder stopper Clean the bobbin holder Change to a high quality sewing thread Clear out the jamming thread 5 Needle breakes 1 Needl...

Page 5: ... belt tension 4 Not enough oil 5 Upper shaft gear is loose Eliminate the backlash Eliminate the looseness See part removal and replacement driving motor DC motor Oil all moving parts Eliminate the looseness P 24 7 Deformation pattern 1 Inappropriate feed balance 2 Top tension is too strong Adjust the feed balancing screw See mechanical adjustment Top tension P 15 ...

Page 6: ...hanging External Parts Face cover To remove 1 Loosen the setscrew q and lift the face cover to disengage the rib on the inside Remove the face cover w To attach 2 Follow the above procedures in reverse q w ...

Page 7: ...5 Free arm cover To remove 1 Loosen the setscrew q and w Move the free arm cover e to the left Remove the free arm cover To attach Follow the above procedures in reverse Changing External Parts q w e ...

Page 8: ...emove the setscrews B w 6 pcs back cover e 4 Remove the setscrews C r 2 pcs 5 Loosen the setscrew t 6 Disconnect all the connectors from the circuit board A NOTE Do not disconnect the connectors by pulling on cord To disconnect grasp the connector not the cord To attach 7 Follow the above procedures in reverse q w e t Thread tension unit w w r r ...

Page 9: ...7 Changing External Parts Front cover 2 1 Disengage the front cover and rear cover hooks 2 Remove the front cover To attach Follow the above procedures in reverse ...

Page 10: ...e cover and free arm cover See page 4 and 5 2 Remove the setscrews A q 5 pcs 3 Remove the setscrews B w 6 pcs and back cover 4 Remove the setscrews C e 2 pcs Remove the rear cover To attach 5 Follow the above procedures in reverse e w w Back cover q q q Rear cover ...

Page 11: ...the feed dog below the needle plate Place a block 6 mm thick under the presser foot and lower the presser foot lifter w 3 Loosen the setscrew q Raise the presser foot lifter and tighten the setscrew q firmly Attach the needle and face plate NOTE Make sure that the presser foot should be parallel to the feed dog slots e in the needle plate q e Presser foot should be parallel to the feed dog slots w...

Page 12: ...0 The clearance between the needle and the edge of the needle hole should be at least 0 2 mm on either side If not adjust as follows 1 Turn the power switch off Remove the face cover See page 4 2 Loosen the hexagonal socket screw 3 x 4 w Adjust the needle drop position by turning the eccentric pin The direction of eccentric pin should be as shown in Fig 1 3 Attach the face cover NOTE Check the hoo...

Page 13: ...wheel toward you to lower the needle at its lowest position 5 Loosen the hexagonal socket screw w 2 pcs 6 Move the needle bar 3 4 mm from the lowest position 7 Turn the lower shaft gear until the tip of hook meets the right side of the needle while holding the handwheel 8 Tighten the hexagonal socket screw w 2 pcs 9 Attach the free arm cover bobbin holder and needle plate Mechanical Adjustment Adj...

Page 14: ...elect the pattern left position Set the zigzag width at 0 4 Turn the handwheel toward you until the tip of hook meets the right side of the needle 5 Loosen the hexagonal socket screw q 6 Move the needle bar to adjust the needle bar height and tighten the hexagonal socket screw q Be careful not to turn the needle bar 7 Attach the bobbin holder needle plate and face cover Mechanical Adjustment Adjus...

Page 15: ... within 0 1 to 0 05 mm at the left and right needle position 5 Tighten the setscrew A 2 pcs 6 Attach the face cover Remove the master needle Attach the bobbin holder and needle pate 7 Check the clearance between the needle and the edge of the needle hole in the needle plate see page 10 The clearance between the needle and the point of hook should be 0 1 to 0 05 mm Clearance between needle and tip ...

Page 16: ...he highest position 3 Remove the free arm cover 4 Loosen the setscrew q and nut w 5 Adjust the feed dog height by turning the adjusting screw e The highest position of the feed dog should be between 0 80 and 0 90 from the surface of the needle plate 6 Tighten the nut w and setscrew q 7 Attach the free arm cover Feed dog height Mechanical Adjustment A B e w q q Presser foot Feed dog 0 80 0 90mm Sur...

Page 17: ...he above limit adjust as follows 1 Set the tension dial 4 2 Remove the cover 3 Lower the presser foot If the top tension is too loose turn the lead screw in the direction A If the top tension is too tight turn the lead screw in the direction B 4 Check the top tension and attach the cover White polyester thread size 50 Pull the thread at the speed of 110 mm sec in the direction of arrow Cover ...

Page 18: ...rcuit board F white w printed circuit board L2 White e PrOGRAM BLACK r Bobbin winding switch Blue t thread cutter motor white y TOUCH PANEL White u FEED MOTOR White i printed circuit board p black o switching regulator BLACK 0 Power switch WHITE 1 DC MOTOR white 2 STITCH WIDTH MOTOR green 3 solenoid thread tension release control Black 4 MICRO SWITCH presser foot lifeter sensor green 5 printed cir...

Page 19: ... to the test you want to perform Enter self diagnostic mode then select the step number of the diagnostic test you require by pressing the reverse stitch button To begin Turn on the switch if any of the following problems occur take the recommended actions in the order they are shown 1 The machine does not respond when the power switch is turned on Check each connector connection Replace the machi...

Page 20: ...s pressed LCD displays F1 when button 4 is pressed LCD displays 03 When the buttonhole lever is pulled buzzer sounds and LCD displays BH symbol BH symbol Bobbin symbol Press buttons 1 4 If the result is correct con dition press the start stop button to proceed the next step If the result is defective condition press the reverse stitch button to proceed the next step Lower the buttonhole lever Move...

Page 21: ...rect condition press the start stop button to proceed the next step If the result is defective condition press the reverse stitch button to proceed the next step LCD displays 06 Turn the handwheel LCD displays stitch width sym bol when the needle bar is at zigzag phase Stitch width symbol Stitch length symbol LCD displays stitch length sym bol when the needle bar is at feed phase LCD displays 07 p...

Page 22: ...e foot control is attached Buzzer sounds when the foot control is deeply depressed Buzzer sounds when the foot control is released LCD displays 09 10 DC motor Buzzer sounds at rightmost or leftmost position LCD displays 10 Buzzer does not sound REMEDY Replace the circuit board A The machine motor does not start The motor stops immediately The motor runs unstable REMEDY Replace the DC motor Replace...

Page 23: ...the result is correct condition press the start stop button to proceed the next step If the result is defective condition press the reverse stitch button to proceed the next step Defective Condition Thread cutter motor does not work the thread cutter symbol does not ap pear when thread cutter is at its initial ized position thread cutter posi tion is not initialized and caution Buzzer sounds REMED...

Page 24: ...21 and fix the defective part The defective part number See page 23 25 Steps and items section Turn the power switch off when the self diagnostic test is finished To display the version of the program Press the touch panel 3 to display the version of the program Turn the power switch on while simultaneously pressing needle up down button and thread cutter button press the needle up down button wit...

Page 25: ...m the circuit board A 3 Remove the screws 4pcs and the circuit board A To attach 1 Follow the above procedures in reverse NOTE Do not disconnect the connectors by pulling on cord To disconnect grasp the connector not the cord Replacing the Electronic Components Cirucit board A Setscrews Setscrew ...

Page 26: ...or belt Tighten them with setscrews 2pcs lightly 2 Move the motor up or down to adjust the motor belt tension The belt should deflect 5 mm when applying 200 grams of load to the middle of the belt Tighten the setscrews 2pcs firmly 3 Attach the rear cover and the front cover Replacing the Electronic Components 200g pressure 5 mm Setscrew DC motor unit Belt Setscrew ...

Page 27: ... the rear cover 2 Remove the setscrews A 3 pcs and the switching regulator 3 Remove the setscrews B 4 pcs To attach 4 Follow the above procedures in reverse Replacing the Electronic Components SWITCHING REGULATOR SETSCREW A SETSCREW A SETSCREW B SETSCREW B SETSCREW A ...

Page 28: ...hen the button hole lever r is lowered Tighten the setscrew To adjust the buttonhole sensor position 4 Attach the buttohole foot R e 5 Lower the buttonhole lever r to its lowest position and open a 1 6 mm gap between the slider and the buttonhole foot 6 Turn the adjusting screw t to the left until the LCD display BH symbol 7 Next turn the adjusting screw to the right until the BH symbol disappears...

Page 29: ...27 4120QDC PARTS LIST KEY PARTS NO NO DESCRIPTION PARTS LIST MODEL 4120QDC ...

Page 30: ...28 4120QDC PARTS LIST 1 2 3 4 4 5 5 6 7 8 8 9 10 10 11 12 13 14 15 16 16 18 19 20 17 21 22 16 27 16 26 25 23 24 28 29 29 2 30 31 ...

Page 31: ...004 808604008 000002105 000101105 808005003 000036005 809023000 000114709 Upper shaft unit Hexagonal socket screw 4x4 Hexagonal socket screw 4x6 Washer FT80 Shaft fixing metal Lower shaft ring Upper shaft shielding plate Spring pin 3x18 Upper shaft gear Spring pin 3x30 Clutch ring Clutch spring Belt wheel Snap ring E 6 Felt Setscrew 4x8 Handwheel Thread take up lever unit Setscrew 4x10 Washer 4 Ti...

Page 32: ...IST 1 2 3 4 5 6 7 8 9 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 15 33 34 35 36 37 38 39 40 41 42 44 44 45 46 48 47 49 50 43 51 52 53 54 54 56 55 57 9 10 58 9 44 11 59 60 60 61 62 65 9 64 63 66 56 67 56 ...

Page 33: ...lever Thread tension release spring Presser foot lifter Snap ring E 5 Presser bar spring adjusting plate Washer 4 Snap ring E 3 Presser bar Presser bar spring Presser bar supporter Hexagonal socket screw 4x8 Needle bar supporter unit Needle bar supporter Threader shaft unit Threader plate unit Threader guard plate Thread retention plate Threader plate Setscrew Nut Threader shaft Spring pin 2x8 Gui...

Page 34: ...32 4120QDC PARTS LIST 1 27 2 3 4 5 26 28 29 31 32 33 30 41 34 35 36 37 38 39 42 43 6 7 18 12 17 13 9 8 10 21 19 22 23 24 25 14 16 15 20 11 9 9 9 15 27 38 38 40 44 45 46 47 48 47 49 50 51 52 ...

Page 35: ...8072002 000111304 000103705 Hook race whole unit Hook race unit Hook body unit Bobbin holder stopper unit Setscrew 4x16 Feed base plate unit Setscrew Thread cutter unit Nut 3 2 5 5 Feed fork Feed fork spring Washer Needle plate set plate right Pin Hexagonal socket screw 4x4 Lower shaft bushing Thin head setscrew TP 3x4 Lower shaft unit Lower shaft Upper shaft gear Spring pin 3x18 Washer Shaft fixi...

Page 36: ...34 4120QDC PARTS LIST 6 6 6 7 2 3 5 4 7 1 8 9 10 9 11 15 12 13 14 16 17 19 20 21 22 23 24 25 18 7 26 28 29 30 27 7 33 32 34 7 35 7 31 31 ...

Page 37: ...foot pressure adjustment unit Presser foot pressure adjusting set plate Presser foot pressure dial Adjusting arm 1 Adjusting arm 2 Snap ring E 3 Setscrew 4x8 Needle plate unit Setscrew Hook cover plate Idler unit Idler set plate Idler Snap ring E 6 Setscrew TP 4x8 Bobbin winder unit Bobbin winder set plate Bobbin winder arm unit Snap ring E 5 Clutch lever Setscrew 3x8 B Switch unit Setscrew 2 5x5 ...

Page 38: ...36 4120QDC PARTS LIST 1 5 2 3 4 6 7 8 9 10 11 13 12 12 18 22 12 19 14 15 16 17 10 12 12 17 22 21 23 12 20 24 25 26 ...

Page 39: ...7002 000081119 809024001 830312016 000013800 100517008 Rear cover unit Rear cover Top cover thread guide unit Setscrew 2 6x5 Thread guide unit Snap ring CS 8 Spool pin Arm leg rear Setscrew 4x14 B Bed rubber cushion Carrying handle Setscrew 4x8 Spool holder Face plate unit U S A Face plate unit Australia Continental Europe Face plate unit Canada Face plate Thread cutter unit Setscrew 3x10 B Free a...

Page 40: ...38 4120QDC PARTS LIST 1 2 4 5 7 8 9 10 11 6 11 11 12 13 14 15 16 17 22 23 24 21 18 20 19 25 26 27 28 31 28 32 28 29 30 30 30 3 33 34 35 36 ...

Page 41: ...Front cover Front cover lid Panel 1 Button 1 Panel 2 Slide volume Touch panel unit Touch Panel seat Printed circuit board A unit Setscrew 3x8 B Start stop button Button 2 Printed circuit board F unit Snap ring CS 4 Printed circuit board L unit Lamp holder 2 Bobbin winder stopper Setscrew 4x16 Washer Nut 4 3 7 Rubber foot Setscrew TP 4x12 Adjustable lock nut 4 Bed rubber cushion Setscrew TP 4x6 Set...

Page 42: ...40 4120QDC PARTS LIST 1 2 3 4 5 6 7 8 9 10 11 12 15 16 19 13 14 20 17 21 18 22 23 ...

Page 43: ... unit Standard accessories unit Canada Satin foot F Zipper foot E Blind hem foot G Overedge foot C Bobbin Assorted needle set Screwdriver Lint brush Seam ripper Buttonhole opener Spool holder small Spool holder Spool pin Buttonhole foot R Power supply cord U S A Canada Power supply cord Australia Power supply cord Continental Europe Foot control Stitch chart Stitch chart base Instruction book Engl...

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