Janome MC9900 User manual

SERVICE MANUAL
&
PARTS LIST
MC9900

INDEX
CHANGING EXTERNAL PARTS
Face cover...........................................................................................................................................1
Belt cover ............................................................................................................................................1
Top cover.............................................................................................................................................2
Base plate ...........................................................................................................................................3
Base cover ..........................................................................................................................................3
Bed cover ............................................................................................................................................4
Free arm cover................................................................................................................................ 4-5
Front cover ..........................................................................................................................................6
Rear cover...........................................................................................................................................7
REPLACING ELECTRONIC COMPONENTS
Printed circuit board A.........................................................................................................................8
Printed circuit board F.........................................................................................................................9
Printed circuit board B (USB board)....................................................................................................9
Switching power supply unit..............................................................................................................10
Driving motor.....................................................................................................................................11
Thread tension unit ...........................................................................................................................12
MECHANICAL ADJUSTMENT
Feed dog height ................................................................................................................................13
Clearance between needle and tip of the rotary hook ................................................................ 14-15
Backlash between hook drive gear and lower shaft gear..................................................................16
Needle drop position .........................................................................................................................17
Hook timing .......................................................................................................................................18
Needle bar height..............................................................................................................................19
Upper shaft shield plate position.......................................................................................................20
Upper thread tension.........................................................................................................................21
Tension release mechanism..............................................................................................................22
Needle threader plate........................................................................................................................23
Thread drawing lever.........................................................................................................................24
Buttonhole lever adjustment..............................................................................................................25
Presser bar lifter switch position .......................................................................................................26
Embroidery foot height......................................................................................................................27
Embroidery foot detecting sensor adjustment...................................................................................28
Presser foot lifter switch adjustment..................................................................................................29
Knee lifter..........................................................................................................................................30
Thread cutter.....................................................................................................................................31
Remaining bobbin threader sensor...................................................................................................32
Needle plate sensor .................................................................................................................... 33-34
Bobbin winder ...................................................................................................................................35
Stretch stitch feed balance................................................................................................................36
Y-carriage play adjustment................................................................................................................37
Adjusting X and Y sensors (simple adjustment)................................................................................38
Cloth guide start position ..................................................................................................................39

1
Setscrews
Face cover
Changing External Parts (1)
Face cover
To remove:
1. Remove the setscrews (2 pcs.).
Remove the face cover.
To attach:
1. Follow the above procedure in reverse.
Belt cover
To remove:
1. Remove the cap and setscrew A.
2. Loosen the setscrews B and C.
Remove the belt cover.
To attach:
1. Follow the above procedure in reverse.
Setscrew A
Belt cover
Cap
Setscrew B
Belt cover
Setscrew C
Belt cover
Base plate

2
Flange plate
Mark A
Spring
Mark A
Spring
Fig. 2
Changing External Parts (2)
Top cover
To remove:
1. Raise the carrying handle and remove the setscrew A.
2. Open the top cover. Pull out the flange plate from the
bobbin winder spindle (see fig. 2).
3. Remove the setscrew B and C.
3. Open the face cover. Close the top cover.
Raise the carrying handle and remove the top cover.
To attach:
1. Follow the above procedure in reverse.
To attach the flange plate, align the spring and mark A
of the flange plate, and push the flange plate down
until it snaps to the machine (see fig 4).
Setscrew A
Carrying
handle
Top cover
Face cover
Bobbin winder
Fig. 1
Fig. 3
Fig. 4
Setscrew B Setscrew C

3
Setscrews
Changing External Parts (3)
Base plate
To remove:
1. Remove the setscrews (x 4).
2. Remove the base plate.
To attach:
1. Follow the above procedure in reverse.
Base plate
Fig. 1
Rail cover
Setscrews
SetscrewsBase cover
Fig. 2
Base cover
To remove:
1. Slide the rail cover in the direciton of arrow to remove
the rail cover (see fig 1).
2. Remove the setscrews (X4) (see fig 2).
Remove the base cover.
To attach:
1. Follow the above procedure in reverse.