JUKI MB-1800 series Quick start guide

R
Dry-head Type, High-speed, Computer-controlled, Single Thread,
Chainstich Button Sewing Machine
(with Automatic Thread Trimmer and Knot-tying Mechanism)
MB-1800
MB-1800A
ENGINEER’S MANUAL
29345105
No.00

PREFACE
This Engineer’s Manual is written for the technical personnel who are responsible for the service and maintenance
of the machine.
The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel
factory contains operating instructions in detail. And this manual describes “Standard Adjustment”, “Adjustment
Procedures”, “Results of Improper Adjutment”, and other important information which are not covered by the
Instruction Manual. It is advisable to use the revevant Instruction Manual and Parts List together with this
Engineer’s Manual when carrying out the maintenance of these machines.

CONTENTS
1. SPECIFICATIONS...................................................................................................................................1
2. NAME OF EACH COMPONENT.............................................................................................................2
(1) Name of the main unit ................................................................................................................................................. 2
3. OPERATION OF THE SEWING MACHINE ............................................................................................3
(1) Names of the operation panel switches .................................................................................................................... 3
(2) Pattern table ................................................................................................................................................................. 4
(3) How to operate and use the memory switch (User level) ........................................................................................ 5
4. STANDARD ADJUSTMENT ...................................................................................................................6
(1) Height of the needle bar.............................................................................................................................................. 6
(2) Positioning the needle and the looper....................................................................................................................... 6
(3) Timing the travel of the yoke slide............................................................................................................................. 8
(4) Timing of the tension disc No. 2 ................................................................................................................................ 8
(5) Lift and pressure of the button clamp ..................................................................................................................... 10
5. ADJUSTMENT OF THE THREAD TRIMMING MECHANISM ..............................................................10
(1) The mechanism and the name of each component of the thread trimmer .......................................................... 10
(2) Adjusting the position of the moving knife............................................................................................................. 12
(3) Adjusting the height of the thread separating claw of the moving knife ............................................................. 12
6. PROCEDURES IN DISASSEMBLING AND ASSEMBLING ................................................................14
(1) Name of each component ......................................................................................................................................... 14
(2) Disassembling the circuit board .............................................................................................................................. 16
(3) Disassembling the machine arm and bed ............................................................................................................... 18
(4) Disassembling the looper shaft ............................................................................................................................... 20
(5) Disassembling the driving shaft .............................................................................................................................. 22
7. ADJUSTMENT OF THE SENSORS......................................................................................................26
(1) Adjusting the starting sensor................................................................................................................................... 26
(2) Adjusting the presser lifter sensor .......................................................................................................................... 26
(3) Adjusting the feed origin sensor ............................................................................................................................. 28
(4) Adjusting the presser lifter stopper......................................................................................................................... 28
8. HOW TO OPERATE AND USE THE MEMORY SWITCH (SERVICE LEVEL) ....................................30
(1) Memory switch function table .................................................................................................................................. 31
9. HOW TO OPERATE AND USE THE INPUT CHECK MODE FUNCTION ...........................................33
(1) INPUT CHECK CORRESPONDENCE TABLE .......................................................................................................... 34
10. HOW TO OPERATE AND USE THE ALL CLEAR FUNCTION ...........................................................35
11. PARTS TO BE GREASESD..................................................................................................................36
12. ERROR LIST .........................................................................................................................................37
13. CHANGE-OVER OF THE POWER SOURCE VOLTAGE ....................................................................38
14. CAUSE OF TROUBLES AND THE CORRECTIVE MEASURES.........................................................39
(1) Thread trimming troubles and the corrective measures ....................................................................................... 39
(2) Cause of troubles and the corrective measures for MB-1800 ............................................................................... 40
15. CIRCUIT BOARD DIAGRAM ................................................................................................................41
(1) MAIN circuit board..................................................................................................................................................... 41
(2) PWR circuit board ..................................................................................................................................................... 42
(3) PANEL circuit board.................................................................................................................................................. 42
16. BLOCK DIAGRAM 1/2 ..........................................................................................................................43
17. CONNECTION DIAGRAM AND CIRCUIT DIAGRAM ..........................................................................45
(1) Power connection diagram....................................................................................................................................... 45
(2) Sensor connection diagram ..................................................................................................................................... 46
(3) Motor circuit diagram ................................................................................................................................................ 47
(4) Encoder circuit diagram ........................................................................................................................................... 48
(5) Solenoid circuit diagram........................................................................................................................................... 48
18. DRAWING OF THE TABLE ..................................................................................................................49

−1−
1. SPECIFICATIONS
1) Sewing area : X (lateral) direction 10 mm
Y (longitudinal) direction 6.5 mm (0.2 mm pitch)
2) Max. sewing speed : 1,800 rpm
3) Feed motion of button clamp : Intermittent feed (2-shaft drive by stepping motor)
4) Needle bar stroke : 48.6 mm
5) Needle : TQx7, TQx1 (TQx7 #16 at the time of delivery)
6) Button size : 10 to 28 mm
7) Lift of button clamp : Standard 10 mm Max. 14 mm
8) Memory of pattern data : EEP-ROM (32K byte)
9) Enlargement/reduction system : Increase/decrease of stitch length system
10) Limitation of sewing speed : Sewing speed can be optionally limited to 400 to 1,800 rpm with the
up/down key. (Adjustable in 100 rpm unit)
11) Pattern selection function : 1 to 99 patterns can be specified by selecting the pattern Nos.
12) Memory back-up : In case of a power interruption, the pattern being used will be
automatically stored in memory.
13) Sewing machine motor : 100W servo motor (direct-drive)
14) Dimensions of machine head : W : 240 mm L : 550 mm H : 360 mm
15) Mass : 25 kg
16) Power consumption : 150 W
17) Operating temperature range : 5 to 35˚C
18) Operating humidity range : 35 to 85% (no dew condensation)
19) Line voltage : Rated voltage ±10% 50/60 Hz
20) Noise : Workplace - related noise at sewing speed
n= 1,800 min-1 : LPA ≦80 dB(A)
Noise measurement according to DIN 45635-48-B-1.
＊Reduce the max. sewing speed in accordance with the sewing conditions.

−2−
2. NAME OF EACH COMPONENT
(1) Name of the main unit
• Machine head
• Electrical
components
• Operation panel
• Thread stand
• Button tray
• Power switch
• Starting pedal

−3−
3. OPERATION OF THE SEWING MACHINE
(1) Names of the operation panel switches
1Set ready switch
Thisswitch is usedwhen making the sewing
machine from setting status to sewing
possible status.
2Button clamp lifting switch
This switch performs up/down of the button
clamp.
3Stitch shape selection LED
4Stitch shape selection switch
This switch is used when changing the stitch
shape.
5＋/ Forward switch
This switch increases the set value or performs
traveling forward when confirming the feed.
6−/ Backward switch
Thisswitch decreases the set valueor performs
travelingbackward when confirmingthe feed.
7Item selection switch
This switch is used when selecting the item
desired to be changed.
8Item selection LED
9Reset switch
This switch returns the various set values
to the original status or performs release
when an error occurs.
!0 Display section A

−4−
(2) Pattern table
Three same sewing sizes and numbers of stitches for each stitch shape have been stored in pattern Nos. 1 to
51 at the time of delivery.
By selecting sewing size and number of stitches from the table below, the stitch shape can be changed to the
three different kinds of patterns of the same stitch shape and be stored in memory.
Pattern No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
4-holed
( , crossover stitch : with)
4-holed
( , crossover stitch : without)
4-holed
( X, crossover stitch : with)
4-holed
( X, crossover stitch : without)
4-holed
( Z, crossover stitch : with)
2-holed (crosswise)
2-holed (lengthwise)
4-holed
( , crossover stitch : with)
4-holed
( , crossover stitch : without)
3-holed ( )
3-holed ( )
3-holed ( )
3-holed ( )
2-holed
(crosswise) label attaching
Wrapped-around
(crosswize size : 4 mm)
Wrapped-around
(crosswise size : 5 mm)
Wrapped-around
(crosswise size : 6 mm)
Initial value
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
10.0
2.6
2.6
2.6
Range
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.0 to 6.5
2.6, 2.8, 3.0
2.6, 2.8, 3.0
2.6, 2.8, 3.0
2.6, 2.8, 3.0
6.0, 8.0, 10.0
0.0 to 6.5
0.0 to 6.5
0.0 to 6.5
Unit
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
2.0
0.2
0.2
0.2
Initial value
15
16
15
16
15
8
8
15
16
17
17
17
17
5
16
16
16
Range
15, 19, 23, 27
16, 20, 24, 28
15, 19, 23, 27
16, 20, 24, 28
15, 19, 23, 27
8, 10, 12, 14
8, 10, 12, 14
15, 19, 23, 27
16, 20, 24, 28
17, 23
17, 23
17, 23
17, 23
5, 7
6, 10, 16
6, 10, 16
6, 10, 16
Stich size (mm) Number of stitches
Stich shape

−5−
(3) How to operate and use the memory switch (User level)
1) The speed up to 3rd stitch can be set so that the sewing speed at the start of sewing is controlled and the
stitch is stabilized.
2) Effective/ineffective of the knot-tying functon can be selected.
3) Operating/non operating of the wiper can be selected.
In case the wiper is installed and set to the non-operating setting, when the pattern without crossover
thread is selected, the wiper works only when the crossover thread is trimmed, and it does not work after
thread trimming at the time of completion of sewing.
In case of the pattern with crossover thread as well, the wiper does not work after thread trimming at the
time of completion of sewing with this setting.
In case of the setting of operating the wiper, the wiper always works at the time of thread trimming.
1Starting of the memory switches In the state that ＋/−switches 2are simultaneously
pressed, turn ON the power, and the memory switches
are in the state of setting.
At this time, “ ” is displayed in display section A 3 .
Press set ready switch 5and all 5 stitch shape
selection LEDs 9flash on and off. This state means
that the memory switches are being inputted.
2Setting procedure of the memory switches
There are the memory switches 1 to 8.
Switch N0. “ ” is displayed in the display section A 3and item selection LED !0 of the pattern No.
lights up. In this state, press item selection switch 4, and the memory switch No. and the description
are alternately displayed in display section A 3.
In the state that the memory switch No. is displayed, press the ＋switch 8and the memory switch No.
increases by one.
When the description of the memory switch is displayed, item selection LED !0 of the pattern No. goes
off.
When setting is completed, turn OFF the power. Return ON the power to return to the normal setting state.
Remarks
400 to 1,800 rpm
400 to 1,800 rpm
400 to 1,800 rpm
400 to 1,800 rpm
400 to 1,800 rpm
400 to 1,800 rpm
Switch No.
1
2
3
4
5
6
7
8
Description
Speed of 1st stitch of soft start
Speed of 2nd stitch of soft start
Speed of 3rd stitch of soft start
Speed of 1st stitch after trimming crossover thread
Speed of 2nd stitch after trimming crossover thread
Speed of 3rd stitch after trimming crossover thread
Knot-tying function 0 : Ineffective 1 : Effective
Wiper operation 0 : Non operating 1 : Operating
Initial setting
18＊100 [rpm]
18＊100 [rpm]
18＊100 [rpm]
18＊100 [rpm]
18＊100 [rpm]
18＊100 [rpm]
1 (Operating)
0 (Non operating)
Setting range
4 to 18
4 to 18
4 to 18
4 to 18
4 to 18
4 to 18
0.1
0.1
1
2
3
4
5
6
7
8
9
!0

−6−
(1) Height of the needle bar
The upper engraved line of the two engraved lines for TQx1 and TQx7 should be aligned with the bottom of
the lower bushing when the needle bar is at its lowest position.
4. STANDARD ADJUSTMENT
(2) Positioning the needle and the looper
1) Looper timing
When the needle bar is ascending from its lowest
position and the lower engraved line on the needle
bar is aligned with the bottom of the lower bushing,
the looper’s blade point should coincide with the
center of the needle.
(When the needle bar is ascending.)
2) Clearance between the needle and looper
The clearance is 0.05 to 0.1 mm when the looper’s
blade point coincides with the center of the needle.
3) Clearance between the needle guide and needle
The clearance between the needle guide and
needle is 0.05 to 0.1 mm when the needle bar is at
its lowest position.
Height of the needle bar
For TQx1
For TQx1
Engraved line
(upper engraved line)
Lower
bushing
Looper timing
Lower bushing
Engraved line
Looper’s blade
point coincides
with center of
needle.
Clearance between needle and looper
0.05 to 0.1 mm
Looper’s blade point
Clearance between needle guide and looper
Needle guide
0.05 to 0.1 mm
Screw
1
2
3
4
1
2
3
4
Standard Adjustment

−7−
™If the needle bar is too high, skipped
stitches will be produced.
If the needle bar is too low, the needle
will come in contact with the looper.
1) Adjusting the looper timing
™Loosen the two screws3in the looper and cam sleeve
and adjust in the rotating direction of the looper and
cam sleeve so that the looper’s blade point aligns with
the center of the needle when the lower engraved line
of the needle bar is aligned with the bottom of the lower
bushing. Then tighten the screws 3.
2) Clearance between the needle and looper
Loosen two screws 4in the looper support ring and adjust
in the longitudinal position of the looper when the looper’s
blade point is aligned with the center of the needle. Then
tighten the screws 4.
3) Clearance between the needle guide and needle
Loosen the screw 2in the needle guide 1and adjust in
the longitudinal position of the needle guide 1so that the
clearance between the needle guide 1and needle should
become 0.05 to 0.1 mm when the needle bar is at its lowest
position. Then tighten the screw 2.
™If the clearance between the needle
and looper is too excessive, it is likely
to produce skipped stitches. If the
clearance is too small, in accordance
with the material used, the needle will
come in contact with the looper
resulting in needle breakage and
looper’s blade point breakage.
™For thick materials and overlapped
sections, adjust the clearance between
the needle guide and needle so that
the needle guide touches the needle
by 0.1 to 0.2 mm.
1) Slightly loosen knob 1and turn cover 2in the direction
of the arrow and you will find hand pulley 3.
2) Turn the hand pulley by hand, loosen setscrew 4in the
needle bar thread-take up lever and adjust so that the
upper engraved line of the two engraved lines on the
needle bar aligns with the bottom of the lower bushing
when the needle bar is at its lowest position.
Adjustment Procedures Results of Improper Adjustment

−8−
(3) Timing the travel of the yoke slide
1) Crosswise travel timing of the yoke slide
The height of the descending needle bar is 53 to 58
mm when the yoke slide advances and begins to
travel from the right to the left (TQx7).
(In case of TQx1, 43 to 48 mm)
2) Lengthwise travel timing of the yoke slide
The yoke slide should go back immediately after
the blade point of the looper has passed the thread
triangle. And, it is good for the looper to go back
like a slant line of the movement of the triangle.
3) Lengthwise positioning of the yoke slide
Position the yoke slide so that the blade point of
the looper passes through the center of the thread
triangle.
(Use a 4-hole button, 9 or 10 stitches for positioning.)
(4) Timing of the tension disc No. 2
The tension disc No. 2 should float when the height of ascending needle bar becomes 54 to 57 mm.
(In case of TQx1, 44 to 47 mm)
Needle bar
53 to 58 mm
Advances and begins to
travel from right to left.
It is good for
the looper to
go back like
a slant line.
Yoke slide
(Begins to travel from right to left.)
Blade point of looper
54 to 57 mm
Begins to float
Screw driver
Needle bar
Standard Adjustment

−9−
™For adjusting the timing of the travel of the yoke slide,
align the engraved marks of the loop positioning finger
cam and the triangle loop positionig finger cam with the
engraved mark of the cam and looper sleeve after
completing the adjustment of looper so that the engraved
marks are on a straight line. Then temporarily tighten the
screw.
1) Adjust the crosswise travel timing of the yoke slide in the
rotational direction of the triangle loop positioning finger
cam.
When the timing is higher than 58 mm (48 mm), adjust
the timing in the rotational direction of the cam.
And when it is lower than 53 mm (43 mm), adjust in the
reverse rotational direction.
The center of the cam is aligned with the center of the
yoke slide support in the longitudinal position of the cam.
2) Adjust the lengthwise travel timing of the yoke slide in the
rotational direction of the loop positioning finger cam.
For the triangle movement of the yoke slide, it is good for
the yoke slide to go back in a slant line. When the yoke
slide goes back like a swollen line, adjust the cam in the
reverse rotational direction, and when it goes back like a
hollow line inside, adjust the cam in the rotational direction.
3) Adjust the longitudinal position of the yoke slide by moving
the loop positioning finger cam in the lengthwise direction.
™If the triangle loop positioning finger
cam begins to travel too late, thread
breakage, thread remaining, baloon
stitch, and insufficient tightness of
stitches will result. On the contrary, if
it begins to move too early, the needle
will come in contact with the yoke slide.
™If the loop positioning finger cam
begins to go back too early, the retreat
of the yoke slide will become like a
swollen line and the looper will hook
the thread twice.
™On the other hand, if it begins to retreat
too late, its retreat will become like a
hollow line and the needle will come in
contact with the yoke slide.
™If the longitudinal position of the yoke
slide is improper, the looper will hook
the thread twice or the needle will come
in contact with the yoke slide.
™Loosen the adjusting nut of the tension post No. 2 and
insert a screwdriver into the tension post No. 2 to adjust
the timing.
The timing of the start of floating is when the thread
tension is lost after passing the thread through the thread
tension No. 2, holding it with fingers and turning the
handwheel by ha
™If the thread tension is released too
early, thread remaining and/or poor
tightness of stitches will result.
On the other hand, if the timing of
thread tension release is too late,
thread will break.
Looper
Engraved points
Triangle loop
positioning
finger cam Cam and looper sleeve
Loop positioning finger cam Yoko slide retreats
like a swollen line.
Yoko slide retreats
like a hollow line.
Screw driver
Timing of start of floating
is when thread tenshon is
lost at the time of needle
bar ascending.
Nut
Adjustment Procedures Results of Improper Adjustment

−10 −
(5) Lift and pressure of the button clamp
1) Lift of the button clamp
AStandard : 12 mm
Max. : 9 mm
2) Pressure of the button clamp
Adjust the position of the pressure adjusting nut to
4 to 5 mm.
4 to 5 mm
5. ADJUSTMENT OF THE THREAD TRIMMING MECHANISM
(1) The mechanism and the name of each component of the thread trimmer
Throat plate
Presser lifter solenoid
Thread trimming arm
Thread trimming lever
Presser lifter sensor
Presser lifter link
Presser lifter lever
1
2
3
A
1
2
Standard Adjustment

−11 −
1) The knife moves in accordance with the lifting of the button
clamp. Therefore, the length of the remaining thread on
the wrong side of a fabric depends upon the height of the
button clamp at which the thread is trimmed.
For the adjustment, insert something of 10 mm thick into
section Aand make a state that button clamp jaw levers
1are lifted .
Loosen screw 2and tighten screw 2to fix the button
clamp in the state that lifting hook 3is pressed to the
lower side.
2) Make adjustment by turning the pressure adjusting nut 1 .
™Increasing the lifting amount of the
button clamp will increase the length
of the remaining thread. Especially in
case of MB-372, thread tightness
becomes strong at the end of sewing
resultingin thread breakage and thread
slip-off.
™If the lifting amount of the button clamp
is too low, the length of the remaining
thread will become short resulting in
thread slip-off.
™If the pressure of the button clamp is
too low, the thread end at the start of
sewing will come out on the wrong side
of the fabric unevenly by 10 to 20 mm.
Adjustment Procedures Results of Improper Adjustment

−12 −
(2) Adjusting the position of the moving knife
Adjust the position so that the distance between the thread trimming connecting plat (front) and the edge of
the slot in the throat plate should be 12 to 13 mm when the button clamp is at its highest position.
(3) Adjusting the height of the thread separating claw of the moving knife
Make adjustment so that the clearance between the thread separating claw 1and the looper 2should
become 0.5 to 0.7 mm.
0.5 to 0.7 mm
Top end of thread separation nail
1
2
3
4
5
6
7
8
9
1
2
Standard Adjustment

−13 −
1) Remove cover 1with setscrew 2.
2) In order to place thread trimming connecting plate A 9to
the most advanced position, lift the presser lifter lever to
such an extent that roller 4and hook 5of presser lifter
lever 3come in contact with each other and insert spanner
6as shown in the figure on the left.
3) Insert gauge 7into the end face of the throat plate groove,
loosen screws 8, make the top end of thread trimming
connecting plate A 9come in contact with gauge 7, and
tighten screws 8.
™If the thread separating claw is too high,
the claw may fail to separate the thread
on the needle from that on a fabric. As
a result, thread may not be trimmed,
or the both threads are trimmed
together, causing thread slippage from
the needle in the subsequent stitching
start.
™If this dimension is excessively large,
the thread trimming timing is delayed
and the remaining thread on the wrong
side of cloth is lengthened.
If the dimension is excessively small,
the thread trimming timing becomes too
early, thread trimming failure such as
poor tightness of stitche (easily frayed)
at the last stitch, simultaneous thread
trimming of two threads due to the
failure of thread separation, no thread
trimming, etc. is apt to occur.
™Make adjustment by bending the thread separating claw
1.
Adjustment Procedures Results of Improper Adjustment

−14 −
6. PROCEDURES IN DISASSEMBLING AND ASSEMBLING
(1) Name of each component
Feed needle bearing
Needle bar upper bushing
Needle bar clamp
Needle bar lower bushing
Yoke slide
Triangle loop positioning finger cam
Loop
positioning
finger cam
Needle bearing
Thrust bearing
Rocking rod fulcrum shaft
Screw gear
Crank rod hinge screw
Crank rod
Procedures in disassembling and assembling

−15 −
Cautions in disassembling Cautions in assembling

−16 −
(2) Disassembling the circuit board
1) Cover components
2) Circuit board components
Control box cover
Side cover
POWER circuit boardMAIN circuit board
POWER circuit board
Setscrew 1
MAIN circuit board
Setscrew 3
Circuit board installing plate
Collar
Setscrew 3
Setscrew 2
Procedures in disassembling and assembling

−17 −
Disassembling and assembling of the circuit board
Disassembling
1) Remove the control box cover and the side cover.
Remove all connectors connected to the circuit board.
2) Loosen setscrews 1by 2 to 3 mm.
3) Remove setscrews 2, hold the circuit board installing plate
by hand and draw it out in the direction of the arrow and
you can remove the circuit board in the state that it is
connected to the circuit board installing plate.
4) Remove 8 setscrews 3, and MAIN circuit board and
POWER circuit board can be removed.
Assembling
1) Assemble in the order of MAIN circuit
board, collar, circuit board installing
plate, collar and POWER circuit board.
Cautions in disassembling Cautions in assembling