Janome Horizon MC8900 QCP Special Edition User manual

SERVICE MANUAL
&
PARTS LIST
MC8900 QCP

INDEX
CHANGING EXTERNAL PARTS
Face cover...........................................................................................................................................1
Top cover.............................................................................................................................................1
Belt cover ............................................................................................................................................2
Machine base......................................................................................................................................3
Base cover ..........................................................................................................................................3
Bed cover ............................................................................................................................................3
Free arm cover....................................................................................................................................4
Front cover ..........................................................................................................................................5
Rear cover...........................................................................................................................................6
REPLACING ELECTRONIC COMPONENTS
Printed circuit board A.........................................................................................................................7
Printed circuit board F.........................................................................................................................8
Switching power supply unit................................................................................................................9
Driving motor.....................................................................................................................................10
Thread tension unit ...........................................................................................................................11
MECHANICAL ADJUSTMENT
Feed dog height ................................................................................................................................12
Needle drop position .........................................................................................................................13
Presser bar height.............................................................................................................................14
Hook timing .......................................................................................................................................15
Needle bar height..............................................................................................................................16
Clearance between needle and tip of the rotary hook ................................................................ 17-18
Presser bar lifter switch position .......................................................................................................19
Backlash between hook drive gear and lower shaft gear..................................................................20
Upper shaft shield plate position.......................................................................................................21
Upper thread tension.........................................................................................................................22
Needle threader plate........................................................................................................................23
Thread drawing lever.........................................................................................................................24
Upper feed dog (1) ............................................................................................................................25
Upper feed dog (2) ............................................................................................................................26
Upper feed dog (3) ...................................................................................................................... 27-28
Buttonhole lever adjustment..............................................................................................................29
Thread cutter.....................................................................................................................................30
Solenoid position adjustment ............................................................................................................31
Stretch stitch feed balance................................................................................................................32
Needle plate switch ..................................................................................................................... 33-34
DIAGNOSIS TEST................................................................................................................................. 35-37

1
Changing External Parts (1)
Face cover
To remove:
1. Remove the setscrews A.
Remove the face cover.
To attach:
1. Follow the above procedure in reverse.
Setscrew A
Face cover
Top cover
To remove:
1. Raise the carrying handle.
Remove the setscrew B.
Close the carrying handle.
Setscrew B
Top cover
Setscrew C Setscrew D
2. Open the top cover.
Remove the setscrews C and D.
3. Raise the carrying handle and remove the top cover.
To attach:
1. Follow the above procedure in reverse.
Carrying handle

2
Changing External Parts (2)
Belt cover
To remove:
1. Remove the setscrews A.
Setscrew A
2. Loosen the setscrews B and C.
3. Remove the belt cover.
To attach:
1. Follow the above procedure in reverse.
Setscrew B
Setscrew C
Setscrew C
Belt cover

3
Changing External Parts (3)
Machine base
To remove:
1. Remove the setscrews A.
2. Remove the machne base.
To attach:
1. Follow the above procedure in reverse.
Setscrew A
Setscrew A
Setscrew A
Setscrew A
Machine base
Base cover
To remove:
1. Remove the setscrews B.
2. Remove the base cover.
To attach:
1. Follow the above procedure in reverse.
Setscrew B
Setscrew B
Setscrew B
Setscrew B
Base cover
Setscrew C
Setscrew C Bed cover Bed cover
To remove:
1. Remove the setscrews C.
2. Remove the bed cover.
To attach:
1. Follow the above procedure in reverse.

4
Free arm cover
To remove:
1. Remove the machine base and base cover (see page 3).
Press the needle plate release lever to remove the
needle plate.
Needle plate release lever
Needle plate
Changing External Parts (4)
2. Remove the setscrew and pin.
3. Unlock the hook A (inside of the machine base) and B
(edge of the free arm).
4. Slide the free arm cover to the left.
Remove the free arm cover.
To attach:
1. Follow the above procedure in reverse.
Setscrew
Pin Free arm cover
Hook A
Hook B

5
Changing External Parts (5)
Setscrew A Setscrew A Front cover
To remove:
1. Remove the top cover, belt cover, base cover, machine
base and free arm cover (see pages 1-4).
2. Loosen the setscrews A (inside of the machine base).
Setscrew B
Setscrew C
Setscrew D
3. Loosen the setscrew B (inside of the top cover).
4. Loosen the setscrew C (inside of the face cover).
5. Loosen the setscrew D (inside of the belt cover).
6. Unlock the hooks from the front cover.
Remove the connectors from the circuit board A.
Remove the front cover.
To attach:
1. Follow the above procedure in reverse.
Refer to page 7 for locating connector posts.
Hooks

6
F
Rear cover Rear cover
To remove:
1. Remove the top cover, mahine base, base cover and
free-arm cover (see pages 1, 3 and 4.)
2. Remove the setscrew A.
Changing External Parts (6)
Setscrews A
Setscrews B
Setscrews C
Setscrews C
Rear cover
D E
3. Remove the setscrew B.
4. Remove the setscrews C.
Unlock the rear cover hook from the front cover.
5. Push the indicated points D, E and F away from you
with a screwdriver to remove the rear cover.
To attach:
1. Follow the above procedure in reverse.

7
Slide volume
Printed circuit board L1
(Underside of the arm)
Printed circuit board A connection
Replacing electronic components
Printed circuit board A
NOTE:
Do not disconnect the connectors by pulling on cord.
To disconnect the connectors, grasp the connector, not
the cord.
To remove:
1. Remove the front cover.
2. Grasp the connector directly with your fingers and pull.
Do not pull the lead wire, as this may damage the
contact sleeve inside the connector.
Remove the setscrews and printed circuit board A.
To attach:
1. Follow the above procedure in reverse.
Be sure that the connector post on the printed circuit
board to which it is connected.
Position the connector correctly, then push it straight
down until it locks in place.
Printed circuit board L2
(Underside of the function buttons)
Touch panel
Bobbin winder
switch
Presser foot
lifter support lift
Printed circuit board L2
(Face cove lamp)
M line sensor
BH sensor
Feed motor
Thread cutter
motor
Solenoid 1
Thread tension
release
Phase sensor
Printed circuit board F
Zigzag steping motor
DC motor
Program
Needle plate switch
Drop feed switch
Foot control
Power switch
Setscrew
Setscrews

8
Setscrew
CS rings
Printed circuit board F
To remove:
1. Remove the front cover (see page 5).
2. Disconnect the connectors from the circuit board A
(see page 7).
3. Remove the CS rings.
4. Remove the setscrews, and the circuit board F.
To attach:
1. Follow the above procedure in reverse.
Replacing electronic components
Printed circuit
board F
Setscrew

9
Switching power supply unit
To remove:
1. Remove the belt cover, the top cover and the front
cover (see page 1, 2 and 5).
2. Loosen the setscrew A. Remove the cord guide plate.
3. Disconnect the power supply connector from the
switching power supply unit.
4. Remove the foot control connector from the printed
circuit board A.
5. Remove the setscrews B, and switching power supply.
To attach:
1. Follow the above procedure in reverse.
Replacing electronic components
Switching power
supply connector
Setscrew A
Setscrew B
Foot control
connector
(cord)
Cord guide plate
Setscrew B

10
200 g pressure
5 mm
Setscrew
Setscrew
Driving motor
To remove:
1. Remove the belt cover, the top cover and the front
cover (see pages 1, 2 and 5).
2. Remove the motor belt.
3. Disconnect the driving motor connector from the
printed circuit board A.
4. Remove the setscrews (2 pcs), and the driving motor.
Replacing electronic components
To attach:
1. Attach the driving motor. Tighten the setscrews
temporarily.
2. Adjust the motor belt deflection to about 5 mm by
pressing the middle of the motor belt with your finger
with approximately 200 grams of pressure.
3. Tighten the setscrews securely.
4. Plug the driving motor connector to the printed circuit
board A.
5. Attach the front cover, the top cover and the belt cover.
Motor belt

11
Replacing electronic components
Thread tension unit
Setscrew A Thread tension unit
To remove:
1. Remove the belt cover and the top cover (see pagesf 1
and 2).
2. Remove the front cover (see page 5).
3. Disconnect the Solenoid 1 thread tension release
connector from the printed circuit board A (see page 7).
4. Remove the setscrews A and B.
Remove the thread tension unit.
To attach:
1. Follow the above procedure in reverse.
2. Check the upper thread tension (see page 22).
Setscrew B

12
Mechanical adjustment
Nut
Setscrew A Adjusting screw B
Presser foot
0.80 – 0.90 mm
Surface of
needle plate
Feed dog
Hexagonal socket screw I
Setscrew D
Threaded hole C
Feed dog height
When the foot pressure dial is at “7” and the presser foot A is lowered, the highest position of the feed dog should be 0.80
to 0.90 mm from the surface of the needle plate.
Adjusting screw B Threaded hole C
Setscrew A
Setscrew D
Adjustment 1:
1. Turn the power switch on. Adjust the stitch length at
maximum length.
Turn the power switch off.
2. Remove the bed cover and base cover.
3. Set the pressure adjusting dial at “7” with the presser
foot lowered.
4. Turn the handwheel toward you to raise the feed dog
at its highest position.
5. Loosen the setscrew A.
6. Loosen the nut.
Adjust the feed dog height to 0.85 mm by turning the
adjusting screw B.
7. Tighten the nut and setscrew A.
8. Attach the bed cover.
Adjustment 2:
If the feed dog 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 4x6 I,
part no. 000111108 is required.
1. Insert a hexagonal socket screw I, part no. 000111108
into the threaded hole (C) until it stops.
2. Turn the setscrew D clockwise to loosen it.
3. Turn the hexagonal socket screw I until the feed dog
is parallel with the surface of the needle plate.
4. Tighten the setscrew D.
5. Remove the hexagonal socket screw I.
6. Attach the bed cover and base cover.

13
To adjust:
1. Attach the needle #14.
2. Turn the power switch ON. Select straight stitch.
Check that the needle drop position is centered
when the drop position is set at "4.5", and the
clearance between the side of the needle and the
needle hole is 0.2 mm or more when the needle
position is set at "0.0" and "9.0" (see fig. 1).
If this is not the case, adjust as follows;
3. Lower the needle threader until the hexagonal socket
screw shows up (see fig. 3).
Loosen the hexagonal socket screw. Turn the
eccentric pin to adjust the needle drop position.
The direction of eccentric pin should be as shown as
fig. 2.
4. Tighten the hexagonal socket screw.
Check the hook timing and the needle bar height after
this adjustment (see page 15 and 16).
Mechanical adjustment
Needle drop position
When the straight stitch is selected, the needle should be positioned in the center of the needle plate hole.
When the needle drop position is set at "0.0" and "9.0", the clearance between the side of the needle and the needle
hole should be 0.2 mm or more.
Hexagonal
socket screw
Eccentric pin
Needle hole
0.2 mm or more0.2 mm or more
A = B
Hexagonal
socket screw
Eccentric pin
Needle threader
Needle threader
“9.0”
“0.0”
Needle drop position "4.5"
Fig. 1
Fig. 2
Fig. 3

14
Should be
pararell
Mechanical adjustment
Presser bar height
The clearance between the presser foot and the surface of the needle plate should be 6 mm when the presser foot is
raised.
The presser foot (zigzag foot A) should be pararell to the slot of the feed dog teeth when attached.
Zigzag foot A
6 mm
Zigzag foot (A)
Slot
Setscrew
To adjust:
1. Attach the zigzag foot (A).
2. Drop the feed dogs.
3. Raise the presser foot with the presser foot lifter.
4. Open the face cover.
Loosen the setscrew on the presser bar suporter to
adjust the presser foot direction as illustrated so the slot
for the feed dog teeth and the zigzag foot should be
pararell.
5. Place the 6 mm spacer (block) between the presser foot
and the needle plate. Tighten the setscrew while
depressing the foot against the spacer.
Needle plate
Presser foot bar supporter

15
3.70 to 4.00 mm
Lowest needle position
Needle #14
Bobbin holder
Setscrews A
Hook Tip of hook
Hook
Mechanical adjustment
Hook timing
The amount of ascending travel of the needle bar from its lowest position to the position (Needle drop position 0.0)
where the tip of the rotary hook exactly meets the right side of the needle should be 3.70 to 4.00 mm
Tip of hook meets the
right side of the needle
(Needle drop position 0.0) To adjust:
1. Remove the bed cover (see page 3).
2. Attach the needle #14.
3. Turn the power switch ON. Select straight stitch.
Set the needle drop position at "0.0".
* Do not turn the switch OFF.
4. Remove the presser foot, the needle plate and the
bobbin holder. (see page 4)
* Cover the needle plate with the fabric to prevent
damaging the needle plate when removing.
5. Turn the handwheel toward you to lower the needle at
its lowest position.
6. Loosen the setscrew of the lower shaft gear.
7. Turn the handwheel toward you to raise the needle bar
further 3.85 mm from its lowest position.
8. Turn the lower shaft gear until the tip of ratary hook
meets with the right side of the needle.
Tighten the setscrews of the lower shaft gear.
* Check the needle bar height after this adjustment.
Lower gear

16
1. Attach the needle #14.
2. Turn the power switch ON. Select straight stitch.
Set the needle drop position at "0.0".
* Do not turn the switch OFF.
3. Remove the presser foot, the needle plate and the
bobbin holder. (see page 4)
* Cover the needle plate with the fabric to prevent
damaging the needle plate when removing.
4. Turn the handwheel toward you until the tip of hook
meets the right side of the needle.
5. Loosen the hexagonal socket screw.
6. Move the needle bar to adjust the the needle bar
height.
Tighten the hexagonal socket screw.
Be careful not to turn the needle bar.
7. Attach the bobbin holder, needle plate.
Hexagonal socket screw
Needle setting groove
Tip of hook
Needle bar
Mechanical adjustment
Needle bar height
The distance between the upper edge of the needle eye and the hook race should be in the range of 1.6 to 2.0 mm
when the tip of the hook meets right side of the needle in the needle drop position "0.0" as the needle ascends from its
lowest position.
1.6 to 2.0 mm
Upper edge of the needle eye
Needle #14
Hook
Tip of hook meets the
right side of the needle
(Needle drop position 0.0)
Hook race
Hook
Bobbin holder

17
Master needle
Tip of hook
-0.1 to +0.05 mm
Master needle
Left needle position Right needle position
Mechanical adjustment
Clearance between needle and tip of the rotary hook
The clearance between the needle and the point of hook should be -0.1 to +0.05 mm.
1. Remove the top cover (see page 2).
2. Remove the presser foot, the needle plate and the
bobbin holder. (see page 4)
* Cover the needle plate with the fabric to prevent
damaging the needle plate when removing.
3. Attach the master needle.
4. Turn the power switch ON.
Select the zigzag stitch pattern 9.
Adjust the stitch width at its maximum (9.0).
Needle plate hole
Setscrew
Needle bar
supporter
Center
Adjustment 1
Clearances must be
even
A
B
5. Turn the handwheel toward you. Adjust the clearance
between the needle and the tip of the rotary hook, by
moving the needle bar supporter in the direction
of arrow, to adjust the clearance between the needle
and tip of hook.
6. Check the clearances A and B between the needle
and the edge of needle plate hole. If the clearances
are not even, follow the procedure in the next page.

18
Setscrew C
Setscrew B
Setscrew A
Hook base plate
Adjustment 2
1. Remove the bed cover (see page 3).
2. Turn the power switch ON, and select the zigzag stitch
pattern 9.
Adjust the stitch width at its maximum (9.0).
3. Remove the presser foot, needle plate and bobbin
holder.
4. Loosen the setscrews A and B.
Loosen the setscrew C just enough to move the hook
base plate.
5. Turn the handwheel toward you.
Adjust the clearance between the needle and the tip
of the rotary hook by moving the hook base plate up
or down between -0.1and +0.05 mm at the both left
and right needle position.
6. Tighten the setscrews A, B and C.
7. Check the backlash between the lower shaft gear and
the hook drive gear. If the backlash is too great or the
engagement of the gears is too tight, adjust the
backlash (see page 20).
* Check the hook adjustment and needle bar height
after this adjustment (see page 15 and 16)