JUKI MF-7700D Series Quick start guide

40084333
No.E386-00
ENGINEER’S MANUAL
Semi-dry head, Flat-bed Top and Bottom Coverstitch Machine
MF-7700D Series
®

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 Adjustment", and other important information which are not covered by the
Instruction Manual.
It is advisable to use the relevant Instruction Manual and Parts List together with this Engineer’s Manual as well as
the MF-7700, SC-500, and SC-510 Series Manuals when carrying out the maintenance of these machines.
In addition, for the motor for the sewing machine with thread trimmer, refer to the separate Instruction Manual or
Engineer’s Manual for the motor. And for the control panel, refer to the Instruction Manual for the control panel.
This manual gives the "Standard Adjustment" on the former page under which the most basic adjustment value is
described, and on the latter page "Results of ImproperAdjustment" under which stitching errors and troubles arising
from mechanical failures are described together with the "Adjustment Procedures".

CONTENTS
1. SPECIFICATIONS................................................................................................... 1
2. CONFIGURATION OF THE MACHINE COMPONENTS........................................ 2
3. MODEL NUMBERING SYSTEM ............................................................................ 3
(1) MF-7700D Series . ................................................................................................................... 3
(2) MF-7700D Series Thread trimmer.......................................................................................... 4
4. MOTOR PULLEY AND BELT ................................................................................. 5
5. STANDARD ADJUSTMENT ................................................................................... 6
(1) Threading the machine head . ............................................................................................... 6
(2) Adjusting the rocking thread take-up ................................................................................... 8
(3) Adjusting the position of the needle thread guide rod ..................................................... 10
(4) Adjusting the position of the thread receiver .................................................................... 12
(5) Adjusting the position of the spreader thread guide and spreader thread take-up....... 14
(6) Adjusting the spreader......................................................................................................... 16
(7) Adjusting the timing relation between the looper and needle bar................................... 20
(8) Returning amount of the looper .......................................................................................... 22
(9) Height of the needle ............................................................................................................. 24
(10)Locus and longitudinal motion of the looper..................................................................... 26
(11) Adjusting the needle guard ................................................................................................. 28
(12)Installing cover of the looper and needle guard after adjusting ...................................... 32
(13)Adjusting the feed dog......................................................................................................... 34
(14)Adjusting the feed relation .................................................................................................. 40
(15)Adjusting the presser foot ................................................................................................... 42
(16)Adjusting the micro-lifter ..................................................................................................... 44
(17)Adjusting the looper thread cam......................................................................................... 46
(18)With regard to lubrication .................................................................................................... 48
(19)Setting for functions of SC-500 ........................................................................................... 52
(20)Adjusting and setting SC-510.............................................................................................. 54
(21) MF-7700D/MF-7800D How to use the timing gauge .......................................................... 58
6. E10/MD10.............................................................................................................. 59
(1) Specifications (E10).............................................................................................................. 59
(2) Specifications (MD10) .......................................................................................................... 59
(3) Adjusting the needle guard ................................................................................................. 60
(4) Adjustment of knife .............................................................................................................. 62
(5) Presser adjustments ............................................................................................................ 66
(6) Method of lubrication ........................................................................................................... 68
(7) Adjustment of the amount of feeding ................................................................................. 70
(8) Adjustments for heavy material sewing ............................................................................. 72
(9) Mounting position of the eccentric cam............................................................................. 74

7. MF-7724DU10D60 (4 needles)............................................................................. 77
(1) Specifications . ..................................................................................................................... 77
(2) Needle .................................................................................................................................... 77
(3) Standard adjustments .......................................................................................................... 78
1) Needle mounting.............................................................................................................................78
2) Threading the machine head .........................................................................................................80
3) Adjusting the rocking thread take-up ...........................................................................................82
4) Adjusting the position of the needle thread guide rod ...............................................................84
5) Adjusting the rocking thread take-up thread receiver ................................................................86
6) Adjusting the looper.......................................................................................................................88
7) Adjusting the height of the needle................................................................................................88
8) Adjusting the rear needle guard....................................................................................................90
9) Adjusting the looper thread cam...................................................................................................90
10)Installing position of the spreader ................................................................................................92
8. UT31 ...................................................................................................................... 94
(1) Installation of SC-500 ........................................................................................................... 94
(2) Change of the setting ........................................................................................................... 96
(3) Adjusting the synchronizer ................................................................................................. 98
(4) Installation of SC-510 ......................................................................................................... 100
(5) Adjusting the looper thread trimmer mechanism............................................................ 106
9. UT33 .................................................................................................................... 120
(1) Installation of SC-500 ......................................................................................................... 120
(2) Installation of SC-510 ......................................................................................................... 122
(3) Piping of the thread trimmer device ................................................................................. 124
(4) Adjusting the looper thread trimmer mechanism............................................................ 126
(5) Adjusting the top covering thread trimmer mechanism ................................................. 130
(6) Adjusting the air-blow wiper.............................................................................................. 132
10.TC13 (Tape cutter) ............................................................................................. 134
(1) Specifications ..................................................................................................................... 134
(2) Adjustment of knife ............................................................................................................ 136
(3) TC13C .................................................................................................................................. 140
11. OTHER CAUTIONS ............................................................................................ 146
(1) MF-7700D dry section......................................................................................................... 146
(2) Application of appropriate grease .................................................................................... 146
(3) Adhesives application spots ............................................................................................. 148
12.TROUBLES AND CORRECTIVE MEASURES .................................................. 149
13.DRAWING OF TABLE......................................................................................... 163
(1) Semi-Submerged Type ....................................................................................................... 163
(2) For MF-7700D/E10 (Semi-Submerged Type) .................................................................... 164

– 1 –
1. SPECIFICATIONS
No. Item Specifications
1Model name Semi-dry head, flat-bed top and bottom coverstitch machine
2Model MF-7700D series
3Stitch type ISO standard 406, 407, 602, 605 and 607
Hemming, covering, and elastic tape attachment for knits and gen-
eral knitted fabrics
5Max. sewing speed 4,000 sti/min (at the time of intermittent operation)
3-needle...........5.6 mm and 6.4 mm 4-needle.................... 6.0 mm
2-needle...........4.0 mm
1 : 0.7 to 1 : 2 (stitch length : less than 2.5 mm)
7 Differential feed ratio Micro-differential feed adjustment mechanism is provided.
(Micro-adjustment)
8 Stitch length 1.2 mm to 3.6 mm (can be adjusted up to 4.4 mm)
UY128GAS #9S to #12S (standard #10S)
(Nm65 to Nm80, standard Nm70)
10 Needle bar stroke 31mm
11 Dimensions Height: 451 mm, Width: 515 mm, Length: 265 mm
12 Weight 46kg, 49kg (with UT33), 52kg (with UT31)
5 mm (with top covering)
8 mm (without top covering)
Main feed ................ dial type stitch pitch adjustment method
14 Feed adjustment method Differential feed....... lever adjustment method (micro-adjustment
mechanism is provided.)
15 Looper mechanism Spherical rod drive method
16 Lubricating system Forced lubrication method by gear pump
17 Lubricating oil JUKI MACHINE OIL 18 (Equivalent to ISO VG18)
18 Oil reservoir capacity Oil gauge lower line : 600 cm3to upper line : 900 cm3
19 Installation Semi-submerged type
20 Micro-lifter Provided as standard
21 Provided as standard
22 Cartridge oil filter Provided as standard
Needle tip, needle thread sili-
cone tank
4Example of application
13 Lift of presser foot
6Needle gauge
9Needle

– 2 –
2. CONFIGURATION OF THE MACHINE COMPONENTS
Presser spring regulator Oil gauge Rocking thread take-up
Needle bar thread take-up cover Feed regulating knob Front cover
Oil circulation identification window Eye guard cover Slide cover
Oil hole cap Throat plate Needle bar thread take-up
Micro-lifter Needle tip silicon oil lubricating unit thread receiver
Needle thread silicon Differential lock nut Rocking thread take-up
oil lubricating unit Micro-adjustment knob thread guide
Thread guide No. 1 Finger guard Silicon container thread guide
Upper pulley Thread trimming knife Belt cover
Thread tension nut Rocking thread take-up receiver

– 3 –
123456789101112 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
MF77 D / / –
3 to 6 Model code
7722 2-needle top & bottom covering stitch
7723 3-needle top & bottom covering stitch
7724 4-needle top & bottom covering stitch
15 to 23 Device and attachment
Blank Not provided
TC13 Solenoid type tape cutter
MD10 Mechanical metering device
*When device or attachment is one, delete slash
(/) of 14th digit.
26 Specification Code for Destination
AStandard
GFor China (domestic China)
HFor Turkey
12 to 13 Needle gauge
40 4.0mm
56 5.6mm
60 6.0mm
64 6.4mm
Application code
Application Description
For universal Lapseam, Covering,
Hemming
C10 For collarette For regular binder
E10 Elastic tape attachment With right hook knife
8 to 10
U10
11 Tongue shape of throat plate
BStandard
DD-type
* Selection of 56 and 64 is prohibited for 2-needle type.
*For the triple needle type, the selection of 40 only is possible for the U10.
* Applicable only to 60 for 4-needle type
24 TC control voltage division
A220 to 440V
B100 to 240V
CSC-510
27 Accessory Specification Code
A
G
*Selected only for TC unit attachment type
3. MODEL NUMBERING SYSTEM
(1) MF-7700D Series
Semi-dry head, flat-bed top and bottom coverstitch machine
Applicable model : MF-7700D Series
Standard (Foreign language manuals in Japanese, English,
Chinese, German, French, Italy, Turkey, and Spanish)
Chinese (available only in China) (2-language manual in
English and Chinese)

– 4 –
12345678910111213141516171819202122
MF77 D –
3 to 6 Model code
7723 3-needle top & bottom covering stitch
14 to 18 Device and attachment
UT31 Solenoid type vertical thread trimmer unit
UT33 Pneumatic type vertical thread trimmer unit
UT33A Pneumatic type vertical thread trimmer unit (ASTAS)
19 Specification Code for Destination
AStandard
GFor China (domestic China)
HFor Turkey
12 to 13 Needle gauge
56 5.6mm
64 6.4mm
Application code
Application Description
For universal Lapseam, Covering,
Hemming
8 to 10
U10
11 Tongue shape of throat plate
BStandard
DD-type
(2) MF-7700D Series Thread trimmer
Semi-dry head, flat-bed top and bottom coverstitch machine
Applicable model : MF-7700D Series Thread trimmer
22 Control box and motor classification
BSC-500/M50
CSC-510/M51
21 Accessory Specification Code
A
G
Standard(Foreign languagemanuals in Japanese,English,
Chinese, German, French, Italy, Turkey, and Spanish)
Chinese (available only in China) (2-language manual in
English and Chinese)

– 5 –
4. MOTOR PULLEY AND BELT
MF-7700D Series
50Hz 60Hz
(sti/min) Pulley size (mm) Belt size (inch) Pulley size (mm) Belt size (inch)
3,500 ø80 M-34 ø65 M-33
4,000 ø90 M-35 ø75 M-34
1 . The table shows the numbers when a 3-phase 2-pole 400 W clutch motor (1/2 HP) is used.
2 . The commercially-available motor pulley near to the counted value is designated since the outside diameter of
the commercially-available motor pulley counts by 5 mm.
3 . When you use a new sewing machine, use the machine at a speed of 4,000 sti/min or less for the first 200 hours
(approximately one month). A good result can be obtained in terms of the durability.
(Caution) 1. Use a motor pulley which is adaptable to this sewing machine.
2. This sewing machine will exceed its max. revolutions and max. sewing speed, finally leading
to the occurrence of malfunction, unless the adaptable motor pulley is used.
Sewing speed of the
machine

– 6 –
(Caution) In case of threading for standard seams, rocking thread take-up thread guide is not used.
2. Threading for soft seams
(1) Do not pass needle thread through needle bar thread take-up .
(2) When soft seams are required, change the threading of needle thread and slide the position of looper thread
cam eyelet.
(3) Do not pass needle thread through needle bar thread take-up . Pass the thread from rocking thread
take-up to rocking thread take-up thread guide .
(4) Other points are same as those of "1. Threading for standard seam".
E
In case of soft seams
Engraved marker line Left Right
5. STANDARD ADJUSTMENT
(1) Threading the machine head
A
Broken lines Awhen stretcher thread is used
C
B
D
When covering thread is
excessively loosened = B
When covering thread is
excessively loosened even
after passing B= C
When covering thread is
excessively tense = D
When using more
stretchable thread When using less
stretchable thread
Standard Adjustment
(Caution) In case of the soft seams, rocking thread take-up
thread guide is used.
1. Threading for standard seam