Janome MC7700 QCP User manual

SERVICE MANUAL
&
PARTS LIST
MC7700 QCP

SERVICE ACCESS
FACE PLATE AND TOP COVER ............................................................................................................1
BELT COVER..........................................................................................................................................2
MACHINE BASE, BASE COVER AND BED COVER .............................................................................3
FREE-ARM COVER................................................................................................................................4
FRONT COVER ......................................................................................................................................5
REAR COVER ........................................................................................................................................6
MECHANICAL ADJUSTMENT
NEEDLE DROP POSITION ....................................................................................................................7
PRESSER BAR HEIGHT AND ALIGNMENT ................................................................................... 8-10
HOOK TIMING ......................................................................................................................................11
NEEDLE BAR HEIGHT.........................................................................................................................12
CLEARANCE BETWEEN NEEDLE AND ROTARY HOOK ................................................................................... 13
BACKLASH OF HOOK AND LOWER SHAFT GEARS ........................................................................14
FEED DOG HEIGHT.............................................................................................................................15
UPPER THREAD TENSION .................................................................................................................16
THREAD TENSION UNIT REPLACEMENT .........................................................................................17
THREAD TENSION MECHANISM .......................................................................................................18
CIRCUIT BOARD “F” REPLACEMENT ................................................................................................19
CIRCUIT BOARD “A” REPLACEMENT ................................................................................................20
CONNECTOR DIAGRAM .....................................................................................................................21
NEEDLE THREADER PLATE REPLACEMENT ...................................................................................22
THREAD TENSION DRAWING LEVER ...............................................................................................23
UPPER FEED DOG ADJUSTMENT (1) ......................................................................................... 24-25
UPPER FEED DOG HEIGHT ...............................................................................................................26
DRIVING MOTOR.................................................................................................................................27
UPPER SHAFT SHIELD PLATE POSITION.........................................................................................28
CENTER NEEDLE POSITION ADJUSTMENT ....................................................................................29
BUTTONHOLE LEVER POSITION.......................................................................................................30
PRESSER BAR LIFTER SWITCH POSITION......................................................................................31
THREAD CUTTER SENSOR POSITION .............................................................................................32
SWITCHING POWER SUPPLY REPLACEMENT ................................................................................33
SOLENOID POSITION .........................................................................................................................34
STRETCH STITCH FEED BALANCE...................................................................................................35
DIAGNOSIS TEST ......................................................................................................... 36-39
INDEXINDEX
INDEXINDEX
INDEX

1
SERVICE ACCESS (1)
FACE PLATE
TOP COVER
[TO REMOVE]
1. OPEN THE FACE PLATE.
REMOVE THE SETSCREWS (B), (C) AND (D).
RAISE THE CARRYING HANDLE AND REMOVE
THE TOP COVER.
[TO ATTACH]
2FOLLOW THE ABOVE PROCEDURE IN
REVERSE.
[TO REMOVE]
1. REMOVE THE SETSCREWS (A) (2 PCS.)TO
REMOVE THE FACE PLATE.
[TO ATTACH]
FOLLOW THE ABOVE PROCEDURE IN REVERSE.
SETSCREWS (A)
SETSCREW (B)
CARRYING
HANDLE
TOP COVER
SETSCREW (C) SETSCREW (D)
FACE PLATE

2
SERVICE ACCESS (2)
BELT COVER
[TO REMOVE]
1. REMOVE THE SETSCREW (A).
LOOSEN THE SETSCREWS (B) AND (C).
REMOVE THE BELT COVER.
[TO ATTACH]
2. FOLLOWTHE ABOVE PROCEDURE IN REVERSE.
SETSCREW (B)
SETSCREW (A)
BELT COVER
SETSCREW (C)

3
MACHINE BASE
[TO REMOVE]
1. REMOVE THE SETSCREWS (A) (4 PCS.).
REMOVE THE MACHINE BASE.
[TO ATTACH]
2. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
BASE COVER
[TO REMOVE]
1. REMOVE THE SETSCREWS (B) (4 PCS.).
REMOVE THE BASE COVER.
[TO ATTACH]
2. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
BED COVER
[TO REMOVE]
1. REMOVE THE SETSCREWS (C) (2 PCS.).
REMOVE THE BED COVER.
[TO ATTACH]
2. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
SETSCREW (A) MACHINE BASE SETSCREW (A)
SETSCREW (A)
SETSCREW (A)
BASE COVER
SETSCREW (B) SETSCREW (B)
SETSCREW (B) SETSCREW (B)
BED COVER
SETSCREW (C)
SERVICE ACCESS (3)

4
FREE-ARM COVER
[TO REMOVE]
1. REMOVE THE MACHINE BASE AND BED COVER
(SEE PAGE 3).
REMOVE THE NEEDLE PLATE.
2. REMOVE THE SETSCREW (A) AND PIN.
UNLOCK THE HOOK (A) AND (B) FROM THE
INSIDE.
REMOVE THE TAB (A) AND (B) FROM THE HOLES.
SLIDE THE FREE-ARM COVER TO THE LEFT TO
REMOVE THE FREE-ARM COVER.
[TO ATTACH]
3. FOLLOWTHE ABOVE PROCEDURE IN REVERSE.
THE HOOK (B) SHOULD HOLD THETHREAD
CUTTER PLATE.
FREE-ARM COVER
TAB (B)
TAB (A)
PIN
NEEDLE PLATE
SETSCREW (A)
HOOK (B)
HOOK (A)
THREAD
CUTTER
PLATE
SERVICE ACCESS (4)

5
[TO REMOVE]
1. REMOVE THE TOP COVER, MACHINE BASE, BASE
COVER AND FREE-ARM COVER (SEE PAGES 1, 3
AND 4).
2. LOOSEN THE SETSCREWS (A), (B), (C), AND (D).
UNLOCK THE REAR COVER HOOKS (E) FROM
THE FRONT COVER.
REMOVE THE CONNECTORS FROMTHE CIRCUIT
BOARD A (SEE PAGE 20).
REMOVE THE FRONT COVER.
[TO ATTACH]
3. FOLLOW THE ABOVE PROCEDURE IN REVERSE.
FRONT COVER
SETSCREW (A)
HOOK (E)
SETSCREW (B)
SETSCREW (C)
SETSCREW (D)
HOOK (E)
HOOK (E) HOOK (E)
SERVICE ACCESS (5)

6
[TO REMOVE]
1. REMOVE THETOP COVER, MACHINE BASE, BASE
COVER AND FREE-ARM COVER (SEE PAGES 1, 3
AND 4).
2. REMOVE THE SETSCREWS (A) (6 PCS.).
UNLOCK THE REAR COVER HOOK FROMTHE
FRONT COVER.
REMOVE THE REAR COVER.
[TO ATTACH]
3. FOLLOWTHE ABOVE PROCEDURE IN REVERSE.
REAR COVER
SETSCREWS (A)
SETSCREWS (A)
SETSCREWS (A)
REAR COVER
SERVICE ACCESS (6)

7
MECHANICAL ADJUSTMENT
NEEDLE DROP POSITION
WHEN THE STRAIGHT STITCH IS SELECTED,THE NEEDLE SHOULD BE AT THE CENTER OF THE HOLE OF
THE NEEDLE PLATE.WHEN THE MAXIMUM ZIGZAG WIDTH (7.0) IS SELECTED, THE DISTANCE BETWEEN THE
NEEDLE AND THE EDGE OFTHE HOLE OF THE NEEDLE PLATE AT THE RIGHT AND LEFT NEEDLE
POSITIONS SHOULD BE 0.2 mmOR MORE AS SHOWN IN FIG. 2.
HEXAGONAL
SOCKET SCREW (A)
ECCENTRIC PIN (B)
THREADER
LEVER
FIG. 1.
1. OPEN THE FACE PLATE.
CHECK THE NEEDLE DROP POSITION ON THE
STITCH PATTERN ( ) AND ZIGZAG STITCH ( )
WITH MAXIMUM WIDTH.
2. LOOSEN THE HEXAGONAL SOCKET SCREW (A)
JUST ENOUGH TO TURNTHE ECCENTRIC PIN (B).
ADJUST THE NEEDLE DROP POSITION BY
TURNING THE ECCENTRIC PIN.THE DIRECTION
OF THE ECCENTRIC PIN (B) SHOULD BE AS
SHOWN IN FIG. 1.
3. TIGHTEN THE HEXAGONAL SOCKET SCREW (A).
CHECK THE CENTER NEEDLE POSITION SENSOR.
(SEE PAGE 29)
4. CLOSE THE FACE PLATE.
HOLE OF NEEDLE PLATE
0.2 mm OR
MORE
0.2 mm OR
MORE
A=B
FIG. 2

8
SETSCREW E SETSCREW B
PRESSER BAR HEIGHT AND ALIGNMENT (1)
WHEN THE PRESSER FOOT IS LIFTED, THE DISTANCE BETWEEN THE SURFACE OF THE NEEDLE PLATE AND
THE BOTTOM OF THE ZIGZAG FOOT SHOULD BE 6 MM.
SETSCREW (A)
LED LAMP
NEEDLE BAR
SUPPORTER
SPRING
1. ATTACHTHE ZIGZAG FOOT A.
ADJUST THE PRESSER FOOT PRESSURE DIAL
TO “7”.
REMOVE THE TOP COVER.
(SEE PAGE 1)
2. RAISE THE PRESSER FOOT LIFTER.
3. LOWERTHE FEED DOG.
4. REMOVE THE NEEDLE BAR SUPPORTER
SPRING.
5. REMOVE THE SETSCREW (A) AND REMOVE THE
LED LAMP.
6. REMOVE THE SETSCREWS (B), (C) AND (D).
REMOVE THE CARRYING HANDLE
SUPPORTER.
7. REMOVE THE SETSCREWS (E), (F) AND (G).
REMOVE THE FRONT BRACKET.
SETSCREW (D)
SETSCREW (C)
SETSCREW (G) SETSCREW (F)
CARRYING
HANDLE
SUPPORTER
FRONT
BRACKET
MECHANICAL ADJUSTMENT