JUKI MF-7500 Series User manual

I
ENGLISH
INSTRUCTION MANUAL
MF-7500(D)/UT35

i
CONTENTS
!. SPECIFICATIONS ..........................................................................................................1
@. AT THE BEGINNING......................................................................................................1
#. INSTALLING THE ACCESSORIES ...............................................................................2
1. Installation and setting SC-921...................................................................................................... 2
(1) Installing the SC-921 on the table ( Semi-submerged type ) ....................................................................2
(2) Connecting the cords...................................................................................................................................3
(3) Setting procedure of the machine head .....................................................................................................4
(4) Setting the lower stop position of the needle bar .....................................................................................5
(5) Setting of the auto lifter function ................................................................................................................6
(6) Setting of the pedal stroke...........................................................................................................................6
$. THREADING THE MACHINE HEAD .............................................................................7
%. ADJUSTING THE LOOPER THREAD TRIMMER MECHANISM..................................8
1. Adjusting the looper thread trimmer solenoid ............................................................................. 8
2. Adjusting the Lower knife .............................................................................................................. 9
3. Adjusting the position of clamp pressure adjusting spring ....................................................... 9
4. Adjusting the knife engagement and the knife pressure adjusting spring ............................... 9
5. Adjusting the pressure of clamp spring ....................................................................................... 9
6. Initial position of the looper thread trimmer mechanism.......................................................... 10
7. Adjusting the stopper ................................................................................................................... 10
8. Adjusting the height of the lower knife....................................................................................... 10
9. Adjusting the longitudinal position of the blade point of lower knife.......................................11
10. Adjusting the thread trimmer sensor ...........................................................................................11
^. ADJUSTING THE THREAD RELEASE MECHANISM................................................12
1. Adjusting the disk-rise ................................................................................................................. 12
2. Adjusting the thread release hook .............................................................................................. 12
&. ADJUSTING THE TOP COVERING THREAD TRIMMER MECHANISM....................13
1. Adjusting the engagement of knives .......................................................................................... 13
2. Adjusting the pressure of clamp spring ..................................................................................... 13
3. Adjusting the position of the blade point of moving knife........................................................ 13
*. MAINTENANCE ...........................................................................................................14
1. Cleaning the motor fan ................................................................................................................. 14

– 1 –
Remove xed band 1 for transportation before setting
up the sewing machine.
Model name High-speed, at-bed coverstitch machine Semi-dry head, high-speed, at-bed coverstitch machine
Model MF-7500 series MF-7500D series
Stitch type ISO standard 406, 407, 602, and 605
Example of applica-
tion
Hemming and covering for knits and general knitted fabrics
Sewing speed Max. 6,500 sti/min (at the time of intermittent operation)
V-belt type
Max. 6,000 sti/min (at the time of intermittent operation)
Direct-drive type
Speed of stitch at the delivery:
4,500 sti/min (at the time of intermittent operation)
Max. 5,000 sti/min (at the time of intermittent operation)
V-belt type
Max. 5,000 sti/min (at the time of intermittent operation)
Direct-drive type
Speed of stitch at the delivery:
4,000 sti/min (at the time of intermittent operation)
Needle gauge 3-needle ..... 4.8 mm, 5.6 mm, and 6.4 mm
2-needle ..... 3.2 mm and 4.0 mm
Differential feed ratio 1 : 0.7 to 1 : 2 (stitch length : less than 2.5 mm)
Micro-differential feed adjustment mechanism is provided. (Micro-adjustment)
Stitch length
1.2 mm to 3.6 mm (can be adjusted up to 4.4 mm)
Needle UY128GAS #9S to #14S (standard #10S) UY128GAS #9S to #12S (standard #10S)
Needle bar stroke 31 mm (33 mm when the eccentric pin is changed over)
Dimensions (Height) 451 x (Width) 523 x (Length) 312
Weight 52 kg (With solenoid type thread trimmer) , 46 kg
Lift of presser foot 8 mm (needle gauge : 5.6 mm without top covering), and 5 mm (with top covering)
Micro-lifter mechanism is provided.
Feed adjustment
method
Main feed ............... dial type stitch pitch adjustment method
Differential feed ..... lever adjustment method (micro-adjustment mechanism is provided.)
Looper mechanism Spherical rod drive method
Lubricating system Forced lubrication method by gear pump
Lubricating oil JUKI GENUINE OIL 18
Oil reservoir capacity Oil gauge lower line : 600 cc to upper line : 900 cc
Installation Semi-submerged type
Noise - Equivalent continuous emission sound pressure
level (LpA) at the workstation :
A-weighted value of 76.5 dB; (Includes KpA = 2.5
dB); according to ISO 10821- C.6.2 -ISO 11204
GR2 at 4,500 sti/min.
- Equivalent continuous emission sound pressure
level (LpA) at the workstation :
A-weighted value of 74.0 dB; (Includes KpA = 2.5
dB); according to ISO 10821- C.6.2 -ISO 11204
GR2 at 4,000 sti/min.
!. SPECIFICATIONS
@. AT THE BEGINNING
1

– 2 –
1) Install right and left support plates 1 and two rubber seats 2 of the respective support plates.
2) Install control box mounting plate 3 on the control box with four screws 4.
3) Install the parts assembled in Step 2) on the underside of support plates 1 with four screws 5.
4) Install support plates 1 and the control box on the table with mounting bolts asm. 6 supplied with the unit. At
this time, insert the nuts and washers supplied with the unit as illustrated in Figure A so that the support plates
and the control box are securely xed.
5) Install the control box (or the one equipped with a small sized motor unit) on the table. Then, install the sewing
machine head on the table. (Refer to the Instruction Manual for the sewing machine.)
6) Install the mounting plate 9 on the CP-18 panel 7 with four tapping screws 8 supplied with the unit.
At this time, take care not to allow the cable to be caught under the mounting bracket.
7) Install CP-18 panel 7 on the table with wood screw !0.
(1) Installing the SC-921 on the table ( Semi-submerged type )
#. INSTALLING THE ACCESSORIES
1. Installation and setting SC-921
7
6
1
2
4
2
3
5
!0
8
9
!0
6
Hexagonal nut
Spring
washer
Convex
washer
Fig. A

– 3 –
1) Pass cords 1 of the thread trimming solenoid,
reverse-stitching solenoid, etc. and the cord from
the motor through hole A in the table to route them
down under the machine table.
2) Loosen screw B in cover 2 with a screwdriver to
open the cover.
3) Connect 14P code 3 coming
from the machine head to con-
nector 6 (CN36).
4) Insert 3P cord 9 coming from
the machine head into connec-
tor !0 (CN42).
5) Insert presser foot lifter cord 2P
4 into connector 7 (CN37).
6) Connect connector 5 coming
from the motor to connector 8
(CN30) on the circuit board.
Be sure to securely insert the respective connectors after checking the inserting directions since all con-
nectors have the inserting directions. (When using a type with lock, insert the connectors until they go to
the lock.) The sewing machine is not actuated unless the connectors are inserted properly. In addition, not
only the problem of error warning or the like occurs, but also the sewing machine and the control box are
damaged.
The connector for the operation panel is provided.
Paying attention to the orientation of the connector !5,
connect it to connector (CN38) !6 located on the circuit
board. After the insertion, securely lock the connectors
to prevent them from coming off easily.
(2) Connecting the cords
7) Insert pedal sensor cable !1 into connector !2 (CN34).
8) Insert motor fan cord !3 into connector !4.
[Connecting the connector for the operation panel]
Be sure to turn OFF the power before connect-
ing the connector.
!5
!6
7
4
5
8
3
6
9
!2!0
!1
!3
!4
2
B
1A

– 4 –
For the operation panel other than CP-18, refer to the Instruction Manual for the operation panel to be used
for the setting procedure of the machine head.
1) Call function setting No. 95.
(3) Setting procedure of the machine head
Type of machine head Model name
F75 MF-7500/UT35
MF-7500/UT37
F75d MF-7500D/UT35
MF-7500D/UT37
2) The type of machine head can be
selected by pressing switch 3 (
switch 4).
* Refer to the
"MACHINE HEAD LIST"
on the separate sheet or the Instruc-
tion Manual for the machine head of
your sewing machine for the type of
the machine head.
3) After selecting the type of machine
head, by pressing switch 1 (
switch 2), the step proceeds to
96 or 94, and the display automati-
cally changes to the contents of the
setting corresponding with the type
of machine head.
4
321
4
321
4
321

– 5 –
Call function setting No. 122. Check to
be sure that the lower stop position of
the needle bar is as shown in Fig. 1. If
not, adjust the lower stop position of the
needle bar properly using function setting
No. 122. (Adjustment can be made within
the range of ±15°).
(4) Setting the lower stop position of the needle bar
4
321
Fig. 1

– 6 –
(5) Setting of the auto lifter function
WARNING :
When the solenoid is used with the air drive setting, the solenoid may be burned out. So, do not mistake
the setting.
When the auto-lifter device (AK) is attached, this function makes the function of auto-lifter work.
1) Turn ON the power switch with
switch 3 held pressed.
2) "FL ON" is displayed on indicators A
and B with a blip to make the auto
lifter function effective.
3) Turn OFF the power switch, and turn
ON the power switch again to return
to the normal mode.
4) Repeat the operation 1) to 3), and
LED display is turned to "FL OFF".
Then, the function of auto-lifter does
not work.
FL ON : Auto-lifter device becomes effective. Selection of the auto-lifter device of solenoid drive (+33V) or of
air drive (+24V) can be performed with switch 4.
(Changeover is performed to drive power +33V or +24V of CN37.)
FL OFF : Auto-lifter function does not work. (Similarly, the presser foot is not automatically lifted when pro- (Similarly, the presser foot is not automatically lifted when pro-
grammed stitching is completed.)
1. To perform re-turning ON of the power, be sure to perform after the time of one second or more has
passed.
(If ON / OFF operation of the power is performed quickly, setting may be not changed over well.)
2. Auto-lifter is not actuated unless this function is properly selected.
3. When “FL ON” is selected without installing the auto-lifter device, starting is momentarily delayed at
the start of sewing. In addition, be sure to select “FL OFF” when the auto-lifter is not installed since the
touch-back switch may not work.
4
3
21
AB
Solenoid drive display (+33V) Air drive display (+24V)
: Pedal stroke of thread trimming start
: Lifting start position of pedal presser lifter
g
g
(6) Setting of the pedal stroke
When using the top covering thread, per-
form the setting below.
¡ Set so that thread trimming operation
can be performed before using the
auto-lifter.
¡ Set the lifting start position of the
pedal presser lifter of the function set-
ting No. 41 to " / " and the
pedal stroke of the thread trimming
start of the function setting No. 43 to "
/ " respectively.
Occurrence of stitch skipping,
thread trimming failure, or stitch
trouble may be caused unless
the setting is changed. So, be
careful.

– 7 –
Thread the machine head according to the following threading illustrations.
* For the adjustment procedure other than the above, refer to the Instruction Manual for MF-7500.
When the thread tension located in the face plate section is used for the machine with automatic
thread trimmer, the length of needle thread remaining on the needle is shortened and slip-off of the
thread at the start of sewing may occur.
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. If threading is wrong,
stitch skipping, thread breakage, needle breakage or irregular stitches will be caused. So, be careful.
$. THREADING THE MACHINE HEAD
1
2
1 2

– 8 –
%. ADJUSTING THE LOOPER THREAD TRIMMER MECHANISM
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.
17.5 ± 0.5 mm
3
1
2
@1
@0
!9
18 mm
1. Adjusting the looper thread
trimmer solenoid
1) Stroke of looper thread trimmer solenoid 3 is 17.5
± 0.5 mm. When adjusting the stroke, loosen set-
screw 2 of collar 1 and move collar 1 to the right
or left to adjust.
2) After adjusting the stroke, loosen screw @0 from the
lower side, and move collar !9 to the left and right
to adjust so that the distance between rubber cush-
ion @1 and UT base is 18 mm.

– 9 –
1) The looper thread is held by clamp pressure ad-
justing spring !2 after thread trimming.
2) Holding pressure of the looper thread can be ad-
justed by turning screw 8.
3) When screw 8 is turned clockwise, the holding
pressure is increased and turned counterclockwise,
the pressure is decreased.
4) Make the holding pressure as low as possible
within the range of holding the looper thread.
1) Loosen screws 7 and 8, and adjust the position
of upper knife !0 so that the engagement of the up-
per knife !0 with the lower knife 4 is 0.5 mm when
lower knife 4 moves to the extreme right.
2) At the same time, adjust so that a clearance of 0.5
to 1 mm is provided between knife pressure adjust-
ing spring !1 and clamp pressure adjusting spring
!2.
3) After the adjustment, tighten screws 7.
1) Set lower knife 4 and lower knife holder 5 with
setscrews 6 at the position of the illustration.
2. Adjusting the Lower knife
3. Adjusting the position of clamp
pressure adjusting spring
1) Loosen screws 9.
2) Adjust so that a clearance of 2.5 ± 0.5 mm is pro-
vided between the top end of clamp pressure ad-
justing spring !2 and the top end of lower knife 4
when the lower knife 4 is brought to the rightmost
position.
3) After the adjustment, tighten screws 9.
4. Adjusting the knife engagement
and the knife pressure adjusting
spring
5. Adjusting the pressure of
clamp spring
4
5
6
65.5 mm
0.5 mm
4
8
!0
79
!1
!2
2.5 ± 0.5 mm
Clearance of 0.5 to 1 mm
!2
!1
4

– 10 –
Center of needle
bar
22 ± 0.5 mm
4
0.3 to 1 mm
!2
!3
0 to 0.1 mm
!3
4
!4
When the needle bar advances from its upper dead
point by 15º, the clearance of 0 to 0.1 mm has to be
provided between the under surface of lower knife 4
and the top surface of looper !3.
8. Adjusting the height of the
lower knife
When the lower knife 4 is located at its leftmost posi-
tion, the top end of the lower knife 4 has to be spaced
22 ± 0.5 mm from the center of needle bar.
6. Initial position of the looper
thread trimmer mechanism
Adjust the position of stopper !4 so that a clearance of
0.3 to 1 mm is provided between looper !3 and clamp
pressure adjusting spring !2 when the counter knife is
located at its leftmost position (forward end).
7. Adjusting the stopper
Perform the work with the needle bar at the
highest position when actuating the thread
trimmer mechanism by hand.

– 11 –
5
!5
!8
!7
!6
9. Adjusting the longitudinal
position of the blade point of
lower knife
Perform the work with the needle bar at the
highest position when actuating the thread
trimmer mechanism by hand.
The safety switch is installed so that the sewing ma-
chine does not start unless the looper thread trimmer
device returns to its home position.
1) Loosen setscrews !6.
2) Adjust switch plate !7 so that LED of thread trim-
mer sensor !8 lights up in the state that the thread
trimmer device is fully returned to its home posi-
tion.
3) Tighten setscrews !6.
Perform the work with the needle bar at the
highest position when actuating the thread
trimmer mechanism by hand.
10. Adjusting the thread trimmer
sensor
4
Blade point of lower knife is in the
center of thickness of looper.
!3
1) Advance the needle bar by 15º from its upper dead
point.
2) Adjust so that the blade point of lower knife 4 is
placed at the center of thickness of the looper !3
when the lower knife 4 is projected until its top
end is aligned with the end face of the looper !3.
3) Loosen nut !5, move lower knife holder 5 to and
fro, and adjust the position of the blade point of
lower knife 4.
4) After the adjustment, tighten nut !5.

– 12 –
1) Loosen setscrew 2 in adjustment cam 1, turn
adjustment cam 1 and disk-rise plate 3 moves up
or down.
2) Adjust the clearance between the click section of
disk-rise plate 3 and thread tension disk 4 to 0.2
to 0.5 mm, and tighten setscrew 2.
3) If the click section of disk-rise plate 3 comes in
contact with thread tension disk 4, sewing trouble
will be caused. So, be careful.
When the thread remaining length at the start
of sewing is short, stitch skipping or slip-off of
thread from needle eyelet at the start of sew-
ing is apt to occur.
^. ADJUSTING THE THREAD RELEASE MECHANISM
1. Adjusting the disk-rise
2. Adjusting the thread release
hook
1) Loosen setscrew 5. Adjust so that the top end of
tension release rod 6 is spaced 35 ± 1 mm from
the top end of take-up thread guide 7. Then,
tighten setscrew 5.
2) Loosen setscrew 9, move the position of thread
release hook 8 up or down, and the thread
remaining length at the start of sewing can be ad-
justed.
• When the position of thread release hook 8is
raised, the thread remaining length at the start
of sewing is decreased and when it is lowered,
the thread remaining length at the start of sew-
ing is increased.
• If stitch skipping occurs at the beginning of
sewing when using non-elastic thread, properly
adjust the remaining length of top-covering
thread at the start of sewing using setscrew !0
and minimize the remaining length of looper
thread at the start of sewing using screw !1.
*A
Clearance between click and disk is 0.2 to 0.5 mm.
(5 places)
1
2
3
4
5
6
7
8
9
*A
!0
!1
35 ± 1mm
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.

– 13 –
Make sure that the moving knife does not
interfere with other components such as
presser, needle, spreader, etc. within the work-
ing range of moving knife 2.
&. ADJUSTING THE TOP COVERING THREAD TRIMMER MECHANISM
1. Adjusting the engagement of
knives
1) Adjust so that the engagement of xed knife 1
with moving knife 2 is 0.5 mm.
2) When adjusting the engagement, loosen setscrews
4 and move knife holder 5 up or down to adjust.
2. Adjusting the pressure of
clamp spring
1) Top covering thread is held with clamp spring 3
after thread trimming.
2) Holding pressure can be adjusted by loosening nut
6 and turning screw 7.
3) Holding pressure is increased when tightening
screw 7 and it is decreased when loosening screw
7.
4) After the adjustment, tighten nut 6.
5) Make the holding pressure as low as possible
within the range of holding the top covering thread.
3. Adjusting the position of the
blade point of moving knife
1) Bring the needle bar to its highest position.
2) When hinge screw 8 is lowered, moving knife 2
lowers together.
3) Adjust so that the hook of moving knife 2 enters
the recess in the top face of spreader 9 to be
brought to the position where the moving knife
catches the top covering thread when moving
knife 2 is brought to the lowermost position. Then,
tighten screws !0, !1 and !2.
Adjust the moving knife vertically so that a clear-
ance of 0.5 mm is provided between the recess
section of spreader 9 and the moving knife, and
laterally so that the moving knife 2 is brought to
the center of the width of recess in spreader, as
illustrated in Figure A.
4) Screws !2 are for adjusting vertical position of the
knife, screws !0 for adjusting lateral position of
the knife, and screws !1 for adjusting angle of the
knife.
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.
!2
!0
!1
0.5 mm
1
4
5
6
7
8
3
2
0.5 mm
Fig. A
2
9
2
9

– 14 –
*. MAINTENANCE
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. Cleaning the motor fan
1
2
3
Open the motor cover 1 and remove the screws 2.
Clean up the periphery of the motor fan 3 and the mo-
tor cover 1.
After the completion of cleaning, re-install the motor fan
3 and the motor cover 1.