Brother DB2-B705-100 User manual

SERVfCE MANUAL
FOR
BROTHER MODEL DB2-B705
-1 00·-200·-400·-500
(
BROTHER INDUSTRIES, LTD.,
NAGOYA, JAPAN .
\
r ----
From the library of: Superior Sewing Machine & Supply LLC

•
PREFACE
Thi s service ma nual is made for the purpo se of ge tting acquai nted with our n ew ly de signed thread
tr imm er se ri es, BROTHER Model 08 2-8705-100 Se ries.
No r ma l troubl es oc cur in your sew ing r oo m will be so lved wi th the kn ow l edge of in st ruction manual
enclosed
wit h th e machine, however, in or der to get much m ore pe rf ec t kno wl edge on this machine,
this
se rvi ce manua l ma y be helpful for your bette r maintenance. We duly h ope that you get fu ll
know l ed ge on t hi s machine by t hi s se rvi ce manual as we ll as in struction man u als and part s cata l og ues.
Incide
nt a ll y, this covers the d es cription on our newly developed BROTHER Needle Positioning Motor,
however, if you u
se wit h ot her br an's , pi ease refer to one pub li shed by tho se manufa cture r.
We sincerely hope th at you wi ll ove r co me the tro ubles which may ar i se in your factory wi th this
pamp hl et.
BROTHER I NDUSTR IES, LTD .
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CONTENTS
1. Features.......................................................................................................................... 1
2. Specifications................................................................................................................... 2
3. Narne of major components.............................................................................................. 3
4. Thread trimming mechanism............................................................................................. 3
5. Construction chart of Brother N. P. Motor .... .. ...... .. ............................................ .. ... .. .. .. ... 8
6. Electric circuits................................................................................................................ 9
7. Setting up the machine ....................... .. ................................................. .. ........................ 13
8. Test running ................................................................................................................... 17
9. Sewing tensions................................................................................................................ 18
10. Adjusting on sewing machine ............................... .. ................................ .. ........................ 20
(1) Adjusting thread trimming mechanism .......................................................................... 20
(2) Adjusting tension releaser .................................................................. .. ........................ 24
(3) Adjusting thread wiper ................................................................................................ 25
(4) Adjusting qichback device............................................................................................ 25
(5) Adjusting presser lifter ................................................................................................ 26
(6) Adjusting synchronizer................................................................................................. 27
11. Adjusting motor ............................................................................................................... 28
12. Maintenance of motor ...................................................................................................... 31
13. Trouble shooting ........................... .. ... .. ......................... .. ...................... .. ........................ 35
(1) In relation with the sewing machine bead..................................................................... 35
(2) In relation with control box and N. P. Motor .... .. .. ..... .. .......... .. .......... .. ................... .. ... 37
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1. Features
(Head)
1.. It ensures high graded sewing conditions and perfect durability at maximum high speed of 4,500
stitches per minute.
2. It is equipped with built-in bobbin winder with compact design and high performance.
3. Belt cover is equipped with as standard accessories, thus it ensures operators' safety.
4. Plunger pump is adopted on this machine, thus it ensures perfect oil return to oil reservoir even
at slow speed operation. This pump can be easily disassembled by the mechaics.
(Thread trimming mechanism)
5. Simple thread trimming mechanism is adopted on this machine, so that it is quite easy adjustment
and maintenance and it also features very safe construction.
6. Stable thread trimming jobs can be obtained because of the thread trimming mechanism driven
by lower shaft.
7. Rotary knife around rotary hook is adopted to do faster trimming jobs and thread tails are
shortened considerably
in co~parison with the conventional machine.
8. All accessories including feed dogs, presser feet and needle plates can be used with this machine
in other words, such parts are common with other lock stitch sewing machines.
9. Built in thread wiper ensures much productivity. (-200)
10. The solenoid reverse mechanism operates with a soft touch and permits even the beginner to sew
backward easily. (Type
400 specifications)
11. The pneumatic thread cutter sewing machine has a presser lifter which can be controlled with a
single pedal operation and thus prevents operator fatigue. (Type
500 specifications)
(N.P. Motor)
12. This motor is newly designed with clutch mechanism on slow speed motor with the speed of
215 r.p.m., thus it ensures faster actions of thread trimming and stopping jobs.
13. Even the beginner can use this machine with single treadle pedal for inching, sewing, needle up
and down position and thread trimming.
14. Synchronizer is designed with "Lead Switch" and all control circuits are not used with relays, thus
its reliability and durability are very high.
15. Printed Circuit Boards (P.C.B.) are very easy to change and all components are designed to do so,
which ensures easy maintenance.
- 1 -
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Spacifications
DB2-B705-100 DB2-B705-200 DB2-B705-400 DB2-B705-500
Means of thread trimming Electro-magnetic,
rotary knife system thread trimming device.
Means of thread releasing Electro-magnetic solenoid
Thread wiper Nil Equipped
Quick back Nil Nil Solenoid
type Air type
Aut refuter presser foot Nil Nil Nil
Air type
High speed: 4,500 s.p.m.
Sewing speed
Slow speed:
215 r.p.m.
Rotary hook Specially designed hook
"BROTHER" Needle Positioning Motor; or the like.
Motor
MD-931-811 MD-931·812 MD-931-814 MD-931-815
3 phase 400W
(NOTE)
1. Single phase motor is of different specs.
2. Specs. on machine head is referred to the instruction manual of Model DB2-B705.
- 2-
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3. Name of major components
This machine is componed of the following
components.
(1) Head
a. Head
b. Thread trimming mechanism
c. Treadle pedal
d. Tension releaser
e. Synchronizer
f. Thread wiper (Optional parts for -200)
(2) Control box
(3) Needle Positioning Motor
4. Thread trimming mechanism
(1) Construction
As per Fig. 1, there are composed of thread
trimmer clutch
0. Holder fj, Knife 0. Lower
thread finger
G. Holder plate e. Stopper C),
and Solenoid fj.
(2) Procedures
I) At high speed
As per Fig.
2·1, stopper presses down
cam and holder is stationed.
- 3-
Fig. 1
1~1-
Fig. 2·1
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II) At thread trimming signal comes from synchro-
nizer
With your heel, when you presses down the
treadle pedal, synchronizer will order to get
thread trimming signal, solenoid is going to pull
its plunger and stopper, then cam jumps up with
the aid of the spring action. (Fig.
2-2)
III) Holder's rotation
When the cam jumps up, its pin 0 is located in
the same circumference with the projected portion
of clutch
(li), thus holder rotates together with
clutch.
At
that time, solenoid is already disengaged and
stopper is positioned
at its original position and
it contacts with the face of holder. (Fig.
2-3)
N) Just before ending thread trimming
As holder is rotating to the position of afore-
mentioned position ( I
), stopper is climbing up to
cam, thus cam is pressed down. (Fig.
2-4)
-4-
I>"<: I_.
I>< I.
Fig. 2-2
Solenoid OFF
I:>< I ..
Fig. 2-3
Solenoid OFF
0
c><L
r><J"'
Cam begins to press down
Fig. 2-4
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V) At ending thread trimming
Cam gradually pressed down is
out of the
circumference of clutch, then holder stops.
At
that time, the inertia of holder is absorbed
by stopper. (Fig.
2-5)
(3) How to be trimmed upper and lower threads
As per the afore-mentioned procedures, upper and
lower threads
are trimmed as follows:
I )
The hook point gets upper thread
At this time. needle comes up
2.2 mm from
its lowest position, but the signal for thread
timming is given
at its lowest position.
(Fig.
3-1)
II) Knife moves
Signal for thread trimming is given and by
the action of clutch, knife moves with
rotary
hook's rotation. (Fig. 3-2)
- 5 -
Solenoid OFF
1><1 ..
1><:1"'
Fig. 2-5
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III) Knife catches upper thread and lower thread
finger gets lower thread
The point of kinfe comes into upper and lower
threads which is separated by the
rotary hook
and the tringle-shaped loop which is formed by
needle hole of the needle plate, thus the upper
and lower thread is separated. (Fig.
3-3)
At this time, the thread take-up lever is positioned
at a bit higher point from its lowest position,
(upper shaft angle; appr. 330·) and
as per Figs.
3-4 and 3-5, the threads are separated.
In case of sooner or
later timing, it affects on
separation of upper and lower threads, then it
causes error of thread trimming.
- 6-
.. ")
Fig. 3-4
Fig. 3-5
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N) Upper and lower threads are trimmed
As per the above procedure, the upper and
lower threads which are caught by knife
holder are timmed by the sharp edge of knife
gradually expanded by their own shape.
At this time, the position of thread take-up
lever is up highest. Due to the shape of the
knife, not so as to be pulled the upper thread
with excessive tension, the tension releaser
is
functioned to release the upper thread without
any resistance.
The threads which were caught by knife and
holder are very much affected on the length
of threads out of needle eye and bobbin case,
and finally on the formation of the first stitch
at the beginning of the next stitch. (Fig. 3-6)
(4) Tension releaser
In case that the signal for thread trimming is
given, the tension release solenoid 0 is functioned,
pulled tension release lever
f), pushed tension
release bar 8 with the intermediate action of
connecting
bar 0 and plate 8 and opened tension
discs
(t.
In case that the signal for needle up position is
given the tension release solenoid is off, thus
tension discs
are closed. (Fig. 4)
(5) Thread wiper
In case that the signal for needle up position is
given, with the interval of 10-lOOms, the thread
wiper solenoid 0 is
on, thus thread wiper 0 is
functioned with the intermediate action of lever
0 and grooved link O·
In case that the thread wiper solenoid is off,
thread wiper returns to its original position with
the aid of spring. (Fig.
5)
- 7-
I>;=~=='
~--......._
Fig. 3-6
Fig. 4
Fig. 5
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(6) Quickback mechanism
When the backtack button is pushed, reverse sole-
noid 0 (Type
400) or reverse cylinder (Type 500)
operates to lower reverse handle 8 via lever f)
and connecting link C). The machine sews back-
ward
as long as the backtack button is kept
pushed.
When the backtack button is released, a reset
spring moves it back to its original position so
that the machine sews forward again. (Fig. 6)
(7) Automatic presser lifter (Type 500)
When the power is switched on, the air pressure
inside presser lifter cylinder 0 increases to move
the piston, which drives knee lifter 8 via piston
operating link
f) to push up push rod 8 and the
presser foot. (Fig.
7)
When the treadle top plate is slightly stepped on,
the air pressure inside presser Iifter cylinden 0
decreases to lower the presser foot.
- 8-
. ---------------
Fcg. 6
Fcg. 7
--........
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5. Construction chart of Brother N.P. Motor
0 Synchronizer
f) Needle up position
8 Needle down position
0 Thread trimming
0 Slow speed motor
0 Main motor
-9-
f) Clutch lever
0 Brake
0 Clutch
tii) Switch for thread trimming
CD Treadle pedal
Fig. 8
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6. Electric circuits
-100,
-200,
-400 Type
-l
8
0 ll.C
=±
0
-
,\,C
12\' 0 • 12\'. 24\'
-
ll.C
• 12\"
AC
27V SV
12\'
~--
I
____ j
11.1"
Fig. 9
- 10-
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I -500 Type I
- 11 -
~
~-
D.C
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0. Electric source SW
f). Pilot lamp
@). Transformer
8. P. C. B. for electric source
e. 9P plug
0. Wiper coil
8. Tension releaser coil
0. Trimmer coil
C). Main motor
tli). Mark
G). Fuse
(8. 7P plug
tl). Slow speed motor
tl. 3P plug
Cl. Wiper SW
(D. Logic circuit
$. Brake coil
C]!). Clutch coil
(1 ) Switching on
fl). 4P plug
•· 6P plug
fD. Needle up
t». Needle down
fj. Trimming
fJ. Safety SW
fl). 3P plug
fi. Micro SW for high speed
tj. Micro SW for trimming
fi. Control box
@). Stands for bushings for control box
.:I!). Transformer
i). P.C.B. for electric source
e. 6P plug
1). Back SW
@). Back coil
6). 2P plug
~. Foot pedal SW
In case that you may switch on, whatever position of synchronizer may be, the brake is functioned
not to move the sewing machine. This is so-called safety guard.
In case you will find that the needle is not positioned to be
up the kighest, you may press the
treadle pedal
on its rear end, thus needle comes up and stops.
(2) Pressing pedal on front end
By pressing the treadle pedal lightly, micro-switch is engaged, then the sewing machine runs slowly
at 215 r.p.m., by the slow speed motor.
By pressing the treadle pedal further, the clutch contacts high speed motor, then, the sewing machine
runs fast.
(3) Needle down position
In case that you may put the treadle pedal to be a neutral position, the micro-switch is disengaged,
the sewing machine runs slowly by the slow speed motor and stops
at needle down position.
(4) Thred trimming, thread wiping and needle up position
After the needle down position, in case you may press the rear end of the treadle pedal, the sewing
machine runs slowly by the slow speed motor, thread trimming and tension releasing mechanisms are
functioned, then the sewing machine stops
at the needle up position, and thread wiper is functioned.
In this case, please
take note that you may fail to trim the threads if you press the treadle pedal so
quickly. Also, when the sewing machine stops
at the needle up position, even though you may press
the
rear end of the treadle pedal, the sewing machine does not run nor thread trimming •may be
functioned.
(5) Thread trimming, non-thread wiping and needle up position
In case that you would like to do the sewing jobs without thread wiping, switch off the thread wiper
switch on the control box.
- 12-
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7. Setting up the machine
Setting the h ead . oil reservoir. thread stand on table is exactly same as i\ lodel DB2-8705's. T h erefore,
refer the i nstruction ma nual for l\l ode l 082-8705.
(NOTE)
Do not hold the synchronizer in case you hold the sewing machine head.
(1) Motor pulley and V-belt
M otor pulley
115 mm 105mm 100 111111 95mm 90 mm
--
4.050 T 3.850
50 liz High speed 4,550 4.300 3.650
L
--
---
Slow speed 215 200
190 180 1
70
r--·
-
f-
-t--
95mm 90 mm 85mm
80 mm
75m m
60 IIz High spee d 4. 550
I 4.300 4.100 3.850 3.550
-
Slow speed 215 200 190 180 1 65
V-belt: 42 inches for 60 liz
.J3 in ches for 50 I-1 z
(2) Motor pulley change
Ir you wish to chan ge the motor pu ll ey, p lease take note the followings (Fig. 11)
(I) Rem ove pu ll ey cover 0 and change the pull ey f) .
(2) f aste n sec urely th e nut ~ -
(3) Get the prop er tension of V-bell. (See the
instruction manual
of Model D82-8705).
If
the tension is too loose, the stop po-
sition is not accurate.
(4) In case you may change the position of
the
motor. loosen three bolts 0 and ro-
tate bracket fj so that clutch lever 0
and pu ll rod 0 is right angle.
(NOTE)
The pulley to be used with this motor
is recommended to use with BROTHER
K pulley, although the commonly sold
pulleys are a~plicable.
- 13 -
0 0
I
85mm ~
I 3,450
-
1 60
Fig. 11
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(3) Connection of wires
I ) Put the plugs out of sewing machine head
and synchronizer into the table top hole
O·
The wire out of synchronizer should be fixed
with wire supporter
f) on the belt cover.
Connect the plugs 8 comes from control
box
8. (Figs. 12, 13)
II) To prevent the static electricity, connect the
earth wire C) out of table hinge to the
bracket of motor.
III) Pass the plugs through the hole in the table
and connect them to the plug sockets leading
from control box C), safety device
ct. valve
box 0 and treadle 8). (Fig.
13, Fig. 14)
(A) plug for Types 100, 200, 400, 500
(B) plug for Types 100, 200, 400, 500
(C) plug for Type 400
(D) plug for Type 500
(E) plug for Type 500
(F) plug for Types 100, 200, 400, 500
·- 14-
Fig. 12
Fig. 13
Fig. 14
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Ill) To connect the air tube to the connector, first
disconnect
nut 8 and sleeve 0 and then fit
them
over the tube end as shown in the figure.
Insert
the tube end in to the socket, tighten
the nul \\'ith your fingers,
and then turn the
nut once or twice with a spanner so the tube
cannot be removed when pu ll ed by hand.
(Fig. 18)
(5) Air pressure (Type 500)
(1) Keep air pressure at 5kg em~ ±0.5kg cm2•
It can be regulated with the valve box reduc-
ing \·alve. If the air pressure is too low,
loosen hexagonal nut 0 and turn knob f)
clockwise. If the air pressure is too high, turn
the knob counterclockwise, operate the back-
tack button or the treadle to lower the air
pressure, and then increase the air pressure
again. After its regulation. tighten the hexago-
nal nul to fix the knob . (Fig. 19)
(2) If water co ll ects inside bottle @. stop the
compressor to lower the air pressure and then
push up drain cock 0 and discharge the water.
- 16 -
\ -
3 - 5 mm
Fog . 18
Fog . 19
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8. Test running
Remove the needle from needle bar.
It is vitally important for you to make sure each procedure and take the following step.
If you will find out any troubles, look into the trouble shooting in this service manual and take proper step.
(1) Switch on and make sure whether pilot lamp is put on, then switch off. At that time, the direction of
motor should be examined.
(NOTE)
1.
If you will find out that the sewing machine rotation is reverise, either two of three wires
should be changed.
2. This BROTHER Needle Postioning
Motor is not featured to get reverse rotation by merely
changing
the position of the plug located in the motor body similar to BROTHER Clutch Mo-
tor. If you change the position of the plug, motor does not run. Connect the plug with con-
nector matching red markings.
3. Green coloured
wire is earth wire which should be grounded.
4. Do not switch on while you are pressing the treadle pedal. Pedal should be neutral position.
(2) Make sure whether slow speed motor runs smoothly pressing the treadle pedal lightly.
(3) Make sure whether the sewing machine stops at the needle down position, when the pedal is positioned
at the neutral after pressing the pedal at the front.
(4) Make sure whether the sewing machine stops at the needle up position after knife's rotation, when the
pedal is pressed
at the rear.
(5) After making sure all the above procedures, put the needle and start sewing.
(Treadle Pedal)
Its operation and function is as per Fig. 13.
(NOTE)
1.
Switch on and after recognition of the
motor running with a few second inter-
val, you may take the steps.
2. Do not set the wires on moving parts.
3. Switch off without fail to check the
sewing machine as well as the motor
for adjustment and repair.
4. Do not disconnect the plugs while
switching on.
5. Do not pull the wire to disconnect the
plugs or terminals.
- 17-
0
•
0. Lower presser foot.
f). Low-speed sewing
@). High-speed sewing
G). Neutral (Machine stops with needle
down; presser foot is raised).
0. Thread cut and removed; machine
stops
with needle up. Fig. 20
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9. Sewing tensions
(1 ) Pre-tension
When the threads are trimmed, the upper
tension assembly is released, then the pre-
tension is the only tension
on the upper
thread.
If you may get the stronger the
tension
on it, the shorter the upper thread
out of the needle eye after thread trimming
is done, and vice versa.
To adjust the tension,
the thread-off, skip stitching
at the beginning
and thread tail on the top of material can
be eliminated.
The standard length of thread after trimming
is about
30-35 mm. (Fig. 21-1)
(2) Upper tension
Upper tension is almost same as Model DB2-
B705, however, take note the followings be-
cause of the thread trimming mechanism.
I )
On the synthetic threads, if you will
loosen the tension, you may encounter
the thread breakage
at the beginning.
(Fig.
22-2)
II) Make sure the upper thread is given out
of thread stand without much resistance.
(After thread trimming, there causes
thread-off
at the beginning because of
short upper thread out of the needle eye.)
III) In case of skip stitches, the upper thread
cannot be trimmed although the lower
thread can
be trimmed.
N) In order to avoid the skip stitch and
upper thread-off
at the beginning, select
the following parts with much attention.
(Fig.
23)
a) Needle plate;
The smaller the hole ©. the better.
b) Presser foot;
The smaller on the points® & @,
the better. But, the thicker thread
over #50, use the standard presser
foot.
c) Rotary hook ;
Special hook.
"BROTHER" hook for Model B705-
100 Series.
d) Feed dog;
Standard feed dogs can be used.
But, the thicker feed dog cannot be
recommended because the knife may
hit the feed dog in case of too thick
feed dog.
Fig. 21-1
Fig. 22-2
Fig. 23
18 -
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