JUKI MO-1000 User manual

MO-1000 Series
SERVICE MANUAL
No.00
40138732
2-Needle, 2/3/4-Thread Overlock Sewing Machine

CONTENTS
1SPECIFICATIONS............................................................................ 1
2NAME OF EACH COMPONENT ..................................................... 2
1. Appearance ............................................................................................................... 2
2. Inside of the cover.................................................................................................... 3
3STANDARD ADJUSTMENT / DISASSEMBLY AND ASSEMBLY... 4
1. Removing order of covers....................................................................................... 4
2. Installation of the throat plate ................................................................................. 8
3. Height of the needle bar......................................................................................... 10
4. Position of the feed dog......................................................................................... 12
5. Adjusting the stroke of the sub feed dog............................................................. 14
6. Height of the feed dog............................................................................................ 16
7. Feed dog timing...................................................................................................... 18
8. Position of the balance weights and the cams.................................................... 20
9. Projecting amount of the upper looper ................................................................ 22
10. Radius of the lower looper .................................................................................... 24
11. Adjustment of the loop lift ..................................................................................... 26
12. Timing between upper and lower looper.............................................................. 28
13. Installation of the needle guards .......................................................................... 30
14. Adjusting the looper thread take-up..................................................................... 32
15. Height and lateral position of the presser foot.................................................... 34
16. Adjusting the oating of the disk of the thread tension controller ................... 36
17. Adjusting the tension of the thread tension controller....................................... 38
18. Position of the needle thread take-up thread guide............................................ 40
19. Tension of the belt.................................................................................................. 42
20. Adjusting the needle bar connection guide of the needle threader .................. 44
21. Adjusting the needle threader hook ..................................................................... 46
22. Adjusting the looper threader timing ................................................................... 48
23. Adjusting the pump unit ........................................................................................ 50
24. Position of the lower knife..................................................................................... 52
25. Engagement of the upper knife with the lower knife .......................................... 54

To avoid the risk of re, electric shock, injury to persons or damage to components,
especially keep the following:
• When disassembling, assembling or adjusting the sewing machine, remove the power plug.
• When assembling, be careful about the electrical cord being caught with other components,
damage to the covered parts of the cord or miswiring.
• When replacing the part(s), use the genuine part(s).
WARNING :
26. Adjusting the timing of the upper knife................................................................ 56
27. Adjusting the thread sliding segment .................................................................. 58
28. Adjusting the safety switch ................................................................................... 60
29. Position of the cloth plate...................................................................................... 62
4CIRCUIT DIAGRAM....................................................................... 64
5MAINTENANCE ............................................................................. 66
1. Lubrication.............................................................................................................. 66
2. Grease application ................................................................................................. 66
3. Looper threader...................................................................................................... 66
6TROUBLES AND CORRECTIVE MEASURES ............................. 67

–1 –
No. Items Description
1 Model name 2-Needle, 2/3/4-Thread Overlock Sewing Machine (with differential feed
adjusting)
2 Stitch choice 2 needles, 4 thread overlock
2 needles, 3 thread overlock
1 needle, 3 thread overlock
1 needle, 2 thread overlock
3 Sewing speed Up to 1,500 sti/min Rating 1,350±150 sti/min
4 Needle gauge Overlocking: 2.2 mm
5 Overedge width 2 needles, 4 thread: 5.0 to 9.0 mm
1 needle, 3 thread (right hand needle): 3.0 to 7.0 mm
1 needle, 3 thread (left hand needle): 5.0 to 9.0 mm
Roll hemming: 2.0 mm
Knife width 2.5 to 6.5 mm
6 Thread sliding segment (*1) It is in synchronism with the lower knife from scale marks "2.5" to "5" of
the knife adjusting knob.
The amount of travel of the thread sliding segment can be nely adjust-
ed with the MTC knob.
7 Stitch length 1.0 to 4.0 mm (Standard 2.5 mm)
8 Differential feed 1：0.7 to 2
9 Needle bar stroke 29.4 mm
10 Presser foot height 4.8 mm to 5.0 mm
11 Feed dog height 1.3 mm (This side end of the sub feed dog P = 2.5 mm; differential feed
ratio: 1:1)
12 Needle system (Japan) ORGAN needle HA×1 # 11 (Standard) to # 14
Needle system (Overseas) SCHMETZ (130/705H 15X1H) # 80
13 Number of needles Max. 2
14 Number of threads to be used Max. 4
15 Needle threader Operated by the manual lever
16 Looper threader Automatic threading by the air pump
17 Air pump Piston pump driven by the motor
Motor: DC 12V
18 Liquid crystal display (*2) Display section: 63.0 mm (W) × 17.5 mm (H)
19 Power switch Rocker switch
20 Light LED 5V x 2
21 Motor 100V : 100 to 120W
110/120V : 100 to 120W
220 to 240V : 100 to 130W
22 Foot control No-heat method (semi-conductor control type)
23 Driving system Timing belt drive
24 Machine size 330 mm (W) × 280 mm (D) × 310 mm (H)
25 Machine weight 9 kg
1SPECIFICATIONS
M/ML
ML
* 1: Only for ML type
* 2: Only for M/ML types

–2 –
Open thread guide
Thread guide support
Retractable support rod
■View with looper cover open
Lower looper thread tension dial
Upper looper thread tension dial
Right needle thread tension dial
Left needle thread tension dial
Thread take-up cover
Main Power/Light switch
Thread stand
Stitch length adjustment dial
Differential feed adjustment dial
Front cover
Cloth plate
Handwheel
Machine socket
Looper cover with built in
knife guard
Looper cover opening indent
Thread cutter
Presser foot lifter
Stitch plate
Needle clamp
Upper knife
Presser foot
Automatic needle threader
LCD screen *1
Top cover
Spool holder pin
Anti - vibration cone
Foam pad
Upper knife changeover knob
Overlocking width
adjusting knob *2
Upper looper
Lower looper
Threading hole
Lower knife
Upper knife xing screw
Cutting width adjusting dial
Selection lever for overlocking
or roll hemming
Air-control pushbutton
Threading changeover
lever
2NAME OF EACH COMPONENT
Presser foot pressure
regulating knob
Caution: Be sure to turn off the power switch
before opening the looper cover.
1. Appearance
M/ML
ML
* 1: Only for ML type
* 2: Only for M/ML types

–3 –
Safety switch
Looper threading
mechanism
Knife
Needle threading mechanism
Microprocessor PCB *1 Power PCB
Air pump motor
Motor
2. Inside of the cover
ML
Safety switch
Front face
Rear face

–4 –
1. Removing order of covers
1-1. The top cover
○ Pushing the arrowed section in the gure by both
hands (i.e., removing the projections of the front
cover from the holes in the top cover), draw this
side upward.
○If it is not easy to detach the rear projection from
the corresponding hole, detach it with a screw-
driver or the like.
In the case the rear projection cannot be easily
removed since its left side comes in contact with
the presser spring regulating knob, detach the
presser spring regulator knob rst. Then, the rear
projection will be detached smoothly.
1-2. The looper cover
○Loosen and remove the set-
screws 1.
3
STANDARD ADJUSTMENT / DISASSEMBLY AND ASSEMBLY
Draw upward
Push
Push
Screwdriver or
the like
Projection
Hole
Presser foot pressure
regulating knob
1

–5 –
1-3. The base plate
If the sewing machine is tilted away from you, the sewing machine
will not be stabilized since the rear cover has a rounded surface.
It is recommended to place the sewing machine with the cloth plate
down on the table.
○Loosen and remove the setscrews 1.
○ The projections of the base plate are tted in the holes in the
front and rear covers. Push up the base plate to remove the
projections from the holes.
1-4. The rear cover
○Raise the presser bar lifting lever.
○Loosen and remove the setscrews 1.
○Remove the rear cover.
Caution: If you remove the rear cover forcibly
by moving it to the right and left, the
claws between the rear cover and the
front cover can break.
1
Raise the presser
bar lifting lever.
1
Push the
base plate

–6 –
1-5. The front cover
○ Turn the pulley to retract the looper to the position indicated in the gure A.
Caution: Be sure to retract the looper without exceptions. Be aware that the 2/3 thread changeover
lever can break if the looper is not retracted.
○Remove two connectors 1(CN3 and CN4) of LED lamp from the power PCB. Cut the cable clip band.
○Loosen and remove the setscrews 2.
○Remove looper threading lever screw 3to remove the lever.
○Remove the setscrews 4and 5.
○While keeping needle threader shaft 6held pressed, remove
it from the left side of the cover.
○Remove the looper threading section.
【ML type】
Caution: At this time, be aware that LCD panel cable 7is
connected to the PCB on the right side.
23
7
6
1
5
4
A
Rear side of the
sewing machine
Cable clip band
Push
Avoid interference
with Front Cover

–7 –
1-6. Looper cover guide
○Loosen and remove the setscrews 1.
○Remove the cover with the knife changeover lever
aligned with the position of notch on the cover.
1-7. The cloth plate cover
○Open the cloth plate. Remove three screws 2to
remove safety switch 1.
○Loosen and remove the setscrews 3.
○Remove the cloth plate.
3
1
2
1
1

–8 –
2. Installation of the throat plate
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
Standard adjustment

3
2
1
1
Lower knife
(C)
1.4 mm
（B）
(A)
Parallel
4
Thread sliding
segment lever
ON
+ 0.6
- 0.2
Thread sliding
segment lever
OFF

–9 –
Adjustment Procedure Results of Improper Adjustment
Checking items:
1Throat plate
2Setscrew
3Feed dog
4Thread sliding segment
* Check that all needles are laterally equidistant with respect to the
throat plate slot (A).
* Check that the distance between the needle center and the front edge
of the throat plate slot is 1.4 mm (B).
* Check to be sure that the lower knife (right end face) is positioned
between the left end and center (C) of the marker dot on throat plate
1when the lower knife adjustment knob is set at the scale mark 1.
Or, check to be sure that the lower knife (right end face) is spaced 2.5
mm away from the right needle.
How to perform adjustment:
○Set the thread sliding segment lever in the OFF position.
○Loosen setscrew 2. Carry out the adjustment by moving throat plate
1as described below:
a) The feed dog 3teeth are parallel to the slots in the throat plate 1.
b) The needles are spaced equidistantly with respect to the slots in
the throat plate (A).
c) The distance between the needle center and the front edge of the
throat plate 1slot is 1.4 mm (B).
○Retighten the setscrews 2.
○After the completion of the adjustment, set the thread sliding segment
lever in the ON position to check the parallelism between the throat
plate and thread sliding segment 4. If they are not in parallel to each
other, carry out adjustment referring to "27. Adjusting the thread
sliding segment".
If the feed dog comes in contact
with the throat plate, abnormal
noise or breakage can be caused.
If the thread sliding segment is
improperly positioned, stitching
failures such that the material is
caught or thread breaks can be
caused.
+ 0.6
- 0.2
+ 0.6
- 0.2

–10 –
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
Standard adjustment
3. Height of the needle bar
1
2
(A) 11.16 ± 0.15 mm
Flat surface
(C)
(B)
(C)
(D)
(E)
(F)

–11 –
Adjustment Procedure Results of Improper Adjustment
Checking items:
1Right hand needle
2Throat plate
* Check that the distance between the throat plate surface and the OL
right hand needle point with the needle bar at the highest point of its
stroke is 11.16 ± 0.15 mm (A) when using needle system 130/705H.
ORGAN NEEDLE HA×1 (130/705H) #11 setting
SCHMETZ NEEDLE (130/705H 15×1H) #80 setting
How to perform adjustment:
○Remove screw (E) of the needle threader to remove needle threader
unit (F).
○Loosen the setscrew (B) of the needle bar connection (C) slightly.
(The needle bar should not slip down. If the needle bar slips off, refer
to the orientation of the needle bar connection.)
○Allow the needle bar (D) to reach its highest position.
○Move needle bar (D) up and down by hand to adjust dimension (A) is
obtained.
○Retighten the setscrew (B).
○After the completion of the adjustment, adjust the needle threader.
Refer to "20. Adjusting the needle bar connection guide of the
needle threader" and "21. Adjusting the needle threader hook".
Orientation of needle bar connection (C)
○ The needle bar connection should be placed with its at surface up.
If the height of the needle bar dif-
fers from the standard adjustment,
stitching failures such as stitch
skipping and thread fraying can be
caused.
If the orientation of the needle bar
connection is wrong, the needle
bar connection can interfere with
the needle bar bushing, disabling
rotation of the sewing machine.
( )

–12 –
Standard adjustment
3
(A) Equidistant clearance
(E)
2
1
Interference should be prevented
(C)
(B)
(D)
4. Position of the feed dog
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
1 mm
(When the feed
amount is maximized/
differential feed ratio:
0.7/ closest point)

–13 –
Adjustment Procedure Results of Improper Adjustment
Checking items:
1Main feed dog
2Sub feed dog
3Throat plate
* Check that the feed dog and the slot in the throat plate 3are parallel
with each other, that the clearances on the right and left side of the
feed dog are equal (A).
* Maximize the feed amount (scale mark: 4). In this state, check to be
sure that the main feed dog 1is at the most retracted position and
main feed dog 1does not interfere with throat plate 3(B).
* Check at the most-advanced position in max. main feed and min. sub-
feed the clearance between the main feed dog 1and the sub-feed
dog 2is 1 mm (C).
How to perform adjustment:
○Maximize the feed amount (scale mark: 4). Move main feed dog 1to
the most retracted position.
○Loosen the setscrews (D) of the main feed dog 1.
○Move main feed dog 1to adjust so that it does not interfere with
throat plate 3.
○Retighten the setscrews (D).
○Maximize the feed amount (scale mark: 4). Adjust the differential feed
ratio to 0.7. Bring main feed dog 1and sub feed dog 2to the posi-
tion where they are closest to each other.
○Loosen the setscrews of the sub-feed dog (E).
○At the most-advanced position in max. main feed and min. sub-feed,
move the sub-feed dog back and forth, to perform adjustment so that
the clearance between the main feed dog 1and the sub-feed dog 2
is to be 1 mm (C).
○Retighten the setscrews (E).
If the clearances on the right side
and left side of the feed dog are
not equal, the feed dog can inter-
fere with the throat plate. In addi-
tion, irregular feed and wrinkles on
the material can be caused.

–14 –
Standard adjustment
5. Adjusting the stroke of the sub feed dog
3
2
1
(C)
(B)
(A) (A’)
12
(A)
(A’)
3
Same line
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.

–15 –
Adjustment Procedure Results of Improper Adjustment
Checking items:
1Main feed dog
2Sub feed dog
3Throat plate
* Adjust the stitch length to 4 mm.
* Set the differential feed ratio at "N".
* Turn the handwheel to move the feed dog up and down. Measure the
clearance provided between main feed dog 1and sub feed dog 2
when the tip of feed dog teeth is aligned with the top surface of throat
plate 3both in the ascending and descending operations. The differ-
ence between these two measurement values (A - A') has to be 0 ± 0.1
mm.
How to perform adjustment:
○Loosen the setscrew (B) of the eccentric stud (C).
○Turn the eccentric stud (C) to perform adjustment.
○Retighten the setscrew (B).
If the difference in the aforemen-
tioned clearances deviates from
the standard adjustment, the stitch
length in the actual sewing will dif-
fer from the indicated stitch length
shown on the knob.

–16 –
Standard adjustment
1
6. Height of the feed dog
(A) 1.3 mm
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
(B)
(C)