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Replacement of the Thread Cutter Unit (new type)

The thread cutter mechanism was modified to improve the performance.
If the thread cutter does not function well, replace the thread cutter unit.  When replacing old type of the thread cutter with
new one, replace also the arm (1) with new type.
Note:  The part number of the arm (1) has been changed from 846153007 to 846233000.

Setscrews (A)

Thread cutter unit (Old  type)

Link unit

Snap ring E-3 (B)

Arm (1) (Old type: 846153007)

Arm (1) (New type: 846233000)

Snap ring E-3 (B)

Link

Snap ring
E-4 (C)

Thread cutter unit (New type)

1. Remove the needle plate. Remove the two set

screws (A) and the thread cutter unit.

2. Remove the snap ring E-3 (B) to release the link.

3. Remove the snap ring E-4 (C) and slide the link to

disengage it from the actuator arm (1).
Rotate the arm to the position shown in the dotted
line and remove it.

4. Place the revised arm (1) on the pin, along with the

spring. Insert the snap ring E-4 (C) between the arm
(1) and the bottom end of the spring.

5. Slide the link back to engage it with the arm (1).

Insert the snap ring E-3 (B).

6. Place the revised thread cutter unit and secure it

with the setscrews (A). Attach the needle plate.

Note:
After replacement, check the position of the thread
cutter switch and thread cutter sliding plate. (Refer to
page s 37 and 26.)

Spring

Summary of Contents for MC6300P

Page 1: ...SERVICE MANUAL MC6300P...

Page 2: ...r plate 23 24 25 26 To adjust thread supply control lever 27 Setting position of thread take up lever 28 To adjust the upper shaft declutch device 29 Setting positions of parts on lower shaft 30 Setti...

Page 3: ...crew A to remove the face plate To attach Attach the face plate with the setscrews A Top cover To remove 1 Remove the setscrews B and C 2 Pull out the connector D of the bobbin winder and remove the t...

Page 4: ...20 cm high Belt cover To remove 1 Remove the setscrews A B and C 2 Remove the belt cover To attach 3 Insert the projections D E and F and tighten the setscrews A B and C Machine base To remove Remove...

Page 5: ...w A Auto hread cutter cover TO REMOVE AUTO THREAD CUTTER COVER To remove Loosen the setscrew A and pull off the auto hread cutter cover To attach Replace the auto thread cutter cover and tighten the s...

Page 6: ...e top cover and belt cover refer to pages 1 and 2 2 Loosen the setscrews A B C and D 3 Pull out the connectors refer to page 10 and remove the front cover To attach 4 Proceed with the above procedure...

Page 7: ...the face plate and top cover refer to page 1 2 Loosen the setscrews A and B Remove the cover D To attach Reverse the above procedure Take care when removing and attaching the cover as the right hand...

Page 8: ...Setscrew C Thread guide D TO REMOVE THE THREAD GUIDE To remove Remove the face plate and tilt the lamp socket E to the left Remove the setscrews A B and C and emove the thread guide D To attach Rever...

Page 9: ...emove the front cover refer to page 4 2 Remove the 4 setscrews A Remove the circuit board A together with the mounting bracket 3 Remove the 2 setscrews D 4 Remove the 2 setscrews B and 2 setscrews C 5...

Page 10: ...D K Setscrew Setscrew Connector of the speed control lever To remove 1 Remove the front cover refer to page 4 2 Pull out the connector of the speed control lever 3 Remove the 8 setscrews To attach Rev...

Page 11: ...or from the circuit board A refer to page 7 3 Remove the 3 setscrews A and 2 CS rings D To attach Reverse the above procedure Make sure that the buttons are placed in the correct places and direction...

Page 12: ...le sensor black 3 pins Circuit board K black 32 pins Presser bar switch black 2 pins Motor for thread tension release red 7 pins Auto thread cutter switch red 2 pins Separation solenoid red 2 pins Bob...

Page 13: ...l socket screw A 4 Attach the face plate Hole of needle plate 0 2mm or more 0 2mm or more A B Hexagonal socket screw A Threader lever TO ADJUST NEEDLE DROP POSITION When the straight stitch is selecte...

Page 14: ...ear C 7 Move the needle bar between 3 25mm and 3 55mm from the lowest position 8 Turn the lower shaft gear C until the tip of the hook meets the right side of the needle 9 Tighten the hexagonal socket...

Page 15: ...eedle bar Fix the arm thread guide and face plate guide 9 Attach the arm thread guide face plate bobbin holder needel plate A and presser foot Needle plate A Bobbin holder B Point of hook Hook race Ne...

Page 16: ...orter B to the original position and adjust the clearance between the needle and the tip of the rotary hook J by using Adjustment II Adjustment II 1 Remove the machine base refer to page 2 2 Turn the...

Page 17: ...ittle turn the lower shaft bushing in direction B 5 Tighten the hexagonal socket screw D 6 Attach the needle needle plate and bobbin holder 7 Attach the machine base NOTE After adjusting the backlash...

Page 18: ...cket screw A Adjust the direction and height of the presser bar 3 Attach the face plate TO ADJUST DIRECTION OF PRESSER BAR AND ITS HEIGHT When the presser foot is lifted the distance between the surfa...

Page 19: ...og is not parallel to the surface of the needle plate at its highest position make the adjustment as follows For this adjustment a hexagonal socket screw I part No 000111108 is required 1 Insert a hex...

Page 20: ...A B C and D on page 4 it is not necessary to remove the connectors 2 Remove the face plate 3 Remove the setscrews A and B Remove the thread guide cover C 4 Loosen the hexagonal socket screw D 5 Remove...

Page 21: ...and thread guide refer to pages 1 and 6 2 Loosen the setscrew A 3 Adjust the opening by turning the eccentric pin 4 Tighten the setscrew A TO ADJUST TENSION RELEASE MECHANISM 1 When the presser bar li...

Page 22: ...n the tension release gear C counter clockwise until it stops 4 Check the opening It should be 0 8mm E If the opening is not wide enough loosen the setscrews A and B Tighten the setscrew B slightly Mo...

Page 23: ...he dial B To loosen the tension turn it counter clockwise To tighten the tension turn it clockwise 5 Push in the tension dial A aligning the 4 with the setting mark C TO ADJUST UPPER THREAD TENSION Th...

Page 24: ...Loosen the setscrew D and turn the stopper E in the direction of A if the amount of thread is not enough B if the amount of thread is too much 2 Tighten the setscrew D TO ADJUST BOBBIN WINDER The amo...

Page 25: ...holder 2 Pull out the threader plate unit A To attach 3 Push the threader plate unit A up to snap it with the pin B as shown in Fig I 4 Attach the foot holder To adjust the position of the threader pl...

Page 26: ...w type 1 Remove the needle plate Remove the two set screws A and the thread cutter unit 2 Remove the snap ring E 3 B to release the link 3 Remove the snap ring E 4 C and slide the link to disengage it...

Page 27: ...g arm 1 Tighten the 2 setscrews A then tighten the setscrew D To check the auto thread cutter Set the needle bar at the lowest position Insert the pin C into the groove of the cutter driving cam by pu...

Page 28: ...D at the rightmost position 2 Loosen the setscrew C and turn the cam A to set the the left end of the sliding plate D is in line with the right side of the second feed dog from the right Tighten the...

Page 29: ...the needle plate 2 Turn the hand wheel toward you until the thread supply control lever comes to its lowest position Check the distance between the upper surface of the bobbin holder and the thread s...

Page 30: ...k C Setscrew B long Thread take up lever E Insert the needle bar crank into the take up crank C so that the flat part of the needle bar crank D faces the setscrew B Then tighten the setscrew B SETTING...

Page 31: ...s leveled the take up crank D should be at the angle of 12 3 degrees B Play on the declutch piece To reduce the play of the declutch piece loosen the setscrews F and G While pushing the upper shaft de...

Page 32: ...e lower shaft are as shown below The setting angle of the parts A B and C is the same as D Belt wheel Spring pin D Shield plate Feed cam C Cam B Lower shaft gear Pin Feed lifting cam Cam A X X view Y...

Page 33: ...wheel D Spring pin E SETTING POSITIONS OF UPPER AND LOWER SHAFTS When the setting mark A on the cam B is exactly at the top the spring pin E is vertically straight and the setting mark C on the belt...

Page 34: ...from the circuit board A 4 Remove the 2 setscrews A and pull out the driving motor To attach 5 Tighten the 2 setscrews A slightly 6 djust the belt tension and tighten the 2 etscrews A firmly Correct...

Page 35: ...s If it is not pressed within 3 seconds the machine will return to default setting mode Press the stitch length button 2 Turn the balance wheel toward you slowly with your hand until the needle comes...

Page 36: ...le lever C 3 Loosen the setscrew A and move the buttonhole lever guide B until the LED shows L Tighten the setscrew A 4 Attach the buttonhole foot R and lower the buttonhole lever 5 Adjust the clearan...

Page 37: ...easurement is more than 38mm B If the measurement is less than 32mm When the stitch lenght adjusting button is pressed the adjusting screw F comes to the adjusting position Turn the adjusting screw th...

Page 38: ...s button The LED show FL in one second then UP 3 Remove the face plate and top cover plate refer to page 1 4 When the presser bar is lifted or lowered the ELD shows UP or dn respectively If not loosen...

Page 39: ...zag width minus button within 3 seconds 2 Press the stitch length plus button twice The LED shows cL in one second then oF 3 Remove the machine base and auto thread cutter cover refer to pages 2 and 3...

Page 40: ...ws D Adjust the distance to 5mm 3 Tighten the 2 set screws D 4 Attach the belt cover TO ADJUST POSITION OF SOLENOID FOR UPPER SHAFT DECLUTCH DEVICE The distance between the upper surface of the yoke A...

Page 41: ...page 2 2 Loosen the 2 setscrews D and adjust the distance to 2 5 mm C by moving the setting plate E 3 Tighten the 2 setscrews D 4 Attach the machine base TO ADJUST POSITION OF SOLENOID FOR AUTO THREA...

Page 42: ...between the yoke A and the snap ring on the plunger B should be 3mm C Setscrews D Yoke A 3 mm C Plunger B 1 Remove the machine base refer to page 2 2 Loosen the 2 setscrews D and adjust the distance t...

Page 43: ...and raise the presser bar lifter 7 Set the needle bar at the highest position Before using the diagnosis device Check or replace the following part s if nothing happens when the power switch is turned...

Page 44: ...3 Auto lock button F4 Reverse button Codes of buttons on the circuit board K 01 Bobbin winder button 02 Twin needle button 04 Memory button 05 Stitch length button 06 Zigzag width minus button 07 Zigz...

Page 45: ...dn Press the clear button to proceed to the next step By pressing the stitch length minus button you can return to the previous step 3 Switch Bobbin winder switch Presser bar lifter switch Auto threa...

Page 46: ...e clear button to proceed to the next step Correct condition Turn the hand wheel away from you and read the figure if it shows between 414 and 420 Press the clear button to proceed to the next step 4...

Page 47: ...r button to proceed to the next step Correct condition Press the buttons which correspond to the solenoids 1 Auto thread cutter solenoid Set the needle bar at the lowest position Press the correspondi...

Page 48: ...epping motor Press the Clear button to proceed to the next step Correct condition 1 When the presser bar is lowered and the foot control is depressed the driving motor runs 2 When the bobbin winding b...

Page 49: ...g the up down needle position button and lock stitch button at the same time turn the power switch on Press the stitch 16 button twice within 3 seconds If not pressed within 3 seconds machine will be...

Page 50: ...Check if the setscrew on the lower shaft ring is in line with the projection of the feed lifting cam The setscrew B should be at the position as shown 3 The clearance between the feed lifting cam and...

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