JUKI SC-20 Kurzanleitung

aJUKI

SC-20

SC-120

SC-220

SC-320

ENGINEER'S

MANUAL

SC-20

SC-320

No.

1-35-3

1990.7

From the library of: Superior Sewing Machine & Supply LLC

PREFACE

The engineer's manual is written for the technical personnelwho are responsible for the service and maintenance of the

sewing machines. This manual presents detailed explanation

the adjusting procedures, etc. which are not covered by

the INSTRUCTION

MANUAL

intended for the maintenance personneland operators at a garment factory.

It is advisable to use this engineer's manual is combination with the pertinent INSTRUCTION

MANUAL

and PARTS

LIST when servicingthe sewing machines

these models.

OPERATION

PRECAUTIONS

Z Oo

not

put

your

(irsgers

into

the

thread

take-up

cover

while

(he

machine

operating.

During

operation,

careful

not to allow

your

or any

Other person's head or hands to come close to the

handwheel,

bell,

bobbin

winder

motor.

Also, do

not place anything close to them. Doing so may be

dangerous.

i 1_

6. To achieve

security,

sure

that

the

power

supply

earth

wire has

been

connected

before

ope'ating

the

sewing

machine.

1. Keep hands away from (he needle when the

power switch is turned ON or while the machine it

operating.

3. Be sure to

turn

the

power

switch OFF

before

tilling

the

machine

head

removing

the V

belt

S. If

your

machine

provided

with

a belt

cover,

finger

guard

any

other

protectors,

not

operate

your

machine

with

any

them

removed.

7. No

motor

sound

heard

when

the

sewing

machine

not

operating.

So. do

not

forget

turn

the

power

OFF

the

end

work.

From the library of: Superior Sewing Machine & Supply LLC

•'*

*•'

CONTENTS

GENERAL

•

•••••;

•• ^

1-1.

Features • • • . 1

2. OPERATION 3

2-1.

Name

ofpart 3

2-2. Test run ^

2-3.

SC-20

Powerindicatorbox ^

2-4.

SC-120

Control

panel

2-5.

SC-220

Control

panel

2-6. SC-320 Control panel 12

ADJUSTMENT

3-1.

Belt

tension

3-2. Prevention motor vibration (for Ncompany'smotor) 21

3-3. Checkingand correcting the rotational direction of sewingmachine 21

3-4.

Pedal

3-5. Maximum sewing speed 25

3-6.

Auto-lifter

3-7. Howto

reduce

the handlightfrom

flickering

(for

single

phaseonly) 28

FUNCTIONS

4-1. Power supply voltage 29

4-2.

Functions

selection

switches

4-3. Increase

control panel functions 44

44.

Safety circuit 46

4-5. Connectors for standing work 48

4-6. Production control systemand needle-upstop switch functions 50

MAINTENANCE

AND

INSPECTION

5-1. Howto replacethe sensorpotentiometer set 51

5-2.

Memory

battery

charging

monitor LED

(SC-320

only) 53

5-3.

Motor

malfunction

detector

LED

54.

Solenoid

monitor

LED

5-5. How

replace each circuit board 55

5-6. Troubleshooting 64

5-7. Circuit board installment diagrams 75

5-8. Connector connection diagrams 80

5-9. Type

rating plates for SCseries

the PSC unit 81

5-10. Block diagrams 82

From the library of: Superior Sewing Machine & Supply LLC

GENERAL

1-1.

Features

Use

ofan

servomotor

provides

the

following

mqor

advantages:

(1) No noise or vibration while the machine is at rest.

(2)

The

power

consumption

40%

60%

compared

with

the

conventional

power

consumption.

(3)

The

motor

weight

has

been

almost

halved,

permitting

easier

layout

change.

(4)

The

absence

ofa

clutch

(no

brake

case

ofN

company's

motor)

makes

theunit

virtually

maintenance-fiee.

company's

brake

good

for

than10

years

under

normal

operation.)

Unlike the DC servomotor, there is no bmsh.

2) Pedaloperation features

(1) Youcansetthe

maximum

sewing

speed

in400

s.p.m.

stepswith fingertipcontrol according to the type of

operation and your level

proficiency.

(In the conventional unit, the motor pulleyhad to

be changedto alter the maximum

sewing

speed.)

Further, you canget the samespeedat any time.

(2) The

conventional

speed

limit

knobis

also

provided.

So, by combining the knob with the function

mentioned in(1)

above,

high-speed

playstrokecan

be provided. This eliminatesthe need for large

pedalingforce to maintain high speed,significantly

reducing operator foot fatigue.

(3) The

speed

acceleration

starting

pointcanbe

adjusted

about 1mm (0.039") by pedal stroke to suit with

each operator.

(4) The minimumspeedfor depressing the front part of

the pedal can be changed(from 200 s.p.m. to 400

s.p.m.).

High-speed'

play

stroke

Pedal

depression

amount

(3)

1mm

(0.039

adjustable

pedal

stroke

/ (4) 400 spm

200

spm

Pedal

depression

amount

Reverse

feedstitchingfeatures

(1)

the

conventional

model,

you

can

select

either

the

mode

which

priority

given

pedaling

for

the

starting

reverse

feed

stitching

orthe

mode

which

the

machine

performs

nonstop

reverse

feed

stitching

a preset speed.

(2)

The

reverse

feed

stitching

speed

has

been

increased

from

1,700

s.p.m.

1,900

s.p.m.

(about

12%

increase).

Furthermore, the

speed

canbe

adjusted

from

1,000

s.p.m.

to 3,500

s.p.m.,

using

the

variable

resistor.

(3)

The

speed

control

circuitry

has

been

improved

prevent

overrun

1-stitch

error

when

the

reverse

feed

stitching speed is changed.

4) Thesoftstart speedhasbeen

increased.

The

soft

start

speed

for

assuring

properly

interlaced

threads

ofa

starting

stitch

has

been

increased

from

200

s.p.m.

to 800 s.p.m.

The

soft

start

speed

now

adjustable

within

range

200

s.p.m.

2,000

s.p.m.,

you

not

have

drop

the speed more than necessary.

- 1 -

From the library of: Superior Sewing Machine & Supply LLC

Enhanced

series

with

easy

upgrading

• '•^ ^ ^

Thecontroller

comes

inthe

SC-20,

SC-120,

SC-220,

SC-320

and

SC-522

series,

andyoucan

easily

upgrade

them

simply

replacing

their

control

panels

(excluding

the

SC-522).

?; > ..

6) A manualcount-downcapabilityhasbeen added.

additional

capability,

the

manual

count-down

capability

has

been

added

the

one-touch

type

reverse

feed

switch

provide

the

control

based

ofa

preset

number

stitches.

Description Applications

Count

back

When the one-touch type reverse feed switch

is pressed,the preset number of stitches is

counted

down.

Sewing pleats

Count

back

Thread

trim

When the one-touch type reverse feed switch

ispressed,the preset number

stitches is

counted

down,

and

threads

are

trimmed.

Replaces the reverse feed

stitching at a seam end.

(This feature is especially useful

in a sewing machine for standing

work

because

the

need

for

operating

the

thread trimmer

switch

eliminated.)

Even

ifa

material

overlap

sewing

startorendis

thick,

the

needle

will

notbe

caught

inthe

thick

overlap.

(After

thread

trimming,

youcanturnthe

handwheel

inthe

reverse

direction

bring

the

needle

barup to its

highestposition.)

8) Aconnectorfor standing workhasbeen

provided

asa standarditem.

9) A

terminal

for connection to a

sewing

control

system

hasbeen

provided.

10)

The

automatic

presser

foot

lifting

capability

can

added

simply

adding

the

auto-lifter

and

transistor

circuit

board.

11)

The

control

panel

very

easy

operate

and

the

slant

panel

surface

makes

easier

see

indication

the

panel.

12)

ensure

easier

operation

the

control

panel,

each

key

has

been

assigned

only

one

function.

13)

You

can

setthe

lifting

duration

ofthe

Auto-lifter

after

thread

trimming

for60

sec.

or ten

minutes.

(For

sewing

machine

for

standing

work,

advisable

set

the

lifting

duration

for

ten

minutes.)

14)

The

output

transistor

has

been

designed

unit

circuit

board

make

ita

common

part.

any

trouble

should occur, the minimum function is assured.

(Example

: If

the

thread

trimmer

transistor

fails,

the

wiper

transistor

will

work

permit

thread

trimming

and

reversefeed stitching.)

15)

The

trouble

checking

feature

for

the

output

system

(output

monitor

LED)

has

been

added

the

conventional

input

system.

This

enables

you

quickly

and

easily

identify

defective

parts.

16) Reliability

The

machine

uses

only

the

components

which

have

passed

our

reliability

test

conducted

each

discrete

component.

17)

are

planning

provide

the

following

options

inthe

future:

Sewing

controlcounter(oflowcost)

18)

The

machine

controller

now

can

applied

the

control

the

ED-1

(cloth

edge

sensor)

(Optional).

- 2 -

From the library of: Superior Sewing Machine & Supply LLC

OPERATION

2-1. Name

part

O Power switch

oControl

box

0Synchronizer

L-shaped

threadstand

PSCbox

0 Max.speed control knob

0Motor

0 Pedal

0One-touch type

reverse

feedswitch

Wiper

0 Stand

levelling

screw(or caster)

0 400 s.p.m.-step speed control knob

0 Connector for standing operation

0 Connector for production control system

- 3

From the library of: Superior Sewing Machine & Supply LLC

O Power switch

Power switch for

the

motor,

PSC and

control

box.

0Control

box

Used

make

settings

for

automatic

reverse

feed

stitching,

the

number

ofstitches forpattern

sewing

orother

sewing conditions.

®Synchronizer

Incorporated

the

machine

pulley,

the

synchronizer

detects

the

needle

position

(up

down)

and

the

se^ymg

speed,

then

sends

resultant

input

signal

to the

main

circuit

board

inthe

PSC

box.

. .

L-shaped

thread

stand

0 PSC box

Comprises

circuitry

control

the

sewing

machine

and

motor,

output

circuitry

operate

the

elements

(thread

trimming

solenoid,

reverse

feed

solenoid,

etc.),

pedal

sensor

detect

pedal

position,

and

power

circuitry

actuate

the

elements.

Max.

speed

controlknob

Allows

analog

adjustment

of the

maximum

sewing

speed

without

changing

themotor

pulley.

0 Motor

Operates

the

machine

high

speed

medium

speed

low

speed

response

toa

signal

received

from

the

PSC

box.

(AnH

company's

motoris

provided

witha

brake.)

0 Pedal

The

front

and

back

parts

ofthe

pedal

are

depressed

control

the

sewing

speed

and

actuate

the

thread

trimmer,

presser

footlifter

(only

fora

version

with

AK-31,

AK-34),

etc.

One-touch

type

reverse

feed

switch

Usedby hand to perform

reverse

feed stitching.

Wiper

Wipes

the

needle

thread

off

the

material

after

thread

trimming

response

toa

wiper

signal

received

from

the

PSC

box.

0 Stand

levelling

screw

(or caster)

Used

perform

adjustment

sothatthe

stand

rests

flatly

onthe

floor

minimize

vibration

during

operation.

0 400 s.p.m.-step speedcontrol knob

This

switch

has

steps

from

1to 16in

order

digitally

setthe

maximum

speed

in400

s.p.m.

steps.

0Connector for standing operation

Used

fora

sewing

machine

designed

for standing operation.

0 Connector for production control system

Usedto connect the machine to a production control system.

- 4 -

From the library of: Superior Sewing Machine & Supply LLC

2-2.

Test

Run

1) Operationwhen the power switchis turned ON

When

the

power

switch

turned

ON,

if the

needle

isnot initsupperstop

position,

the

machine

rotates

untilits €?

needle reaches

the

upper stop position, and then stops with its needle in that position.

the needle is already in its upper stop position when the power switch is turned ON, the sewingmachine stays

stationary.

'-Uf

2)Pedal operation

(1) Thepedalisoperatesin the

foUowing

four steps, (exceptfora

Version

with

AK-31,

AK-34)

©—

High

speed

Low

speed

Stop

Thread

trimming

High

speed

Low

speed

Stop

(neutral)

Thread

trimming

The

sewing

machine runs at low speed when you depress the front part of the pedal.

The

sewing

speed

changes

fromlowto highwhenthe front part of the pedalisfurther

depressed.

(However,if the automatic

reverse

feed stitching switch has been set, the machine willnot mn at high speed

until it completes

reverse

feedstitching.)

When

the pedalis returnedto the neutralposition(stop position),the

machine

will

stop with

needle

down.

When

the backpart of the pedalis depressed, the thread trimmerisactuated and the needlegoesup and

stops in its upper position.

(When

the wiperswitchhasbeenset to ON,the wiperisactuated.)

- 5 -

From the library of: Superior Sewing Machine & Supply LLC

(2) In caseof a versionwith AK-31,AK-34

The pedalisoperated in the

following

fivesteps:

High

speed

Low

speed

Stop

Presser

foot

lifting

Thread

trimming

High

speed

Low

speed

Stop

(neutral)

Presser

foot

lifting

Thread

trimming

o The

sewing

machine

startsat low

speed

whenthe front part of the pedalislightly

depressed,

o The

sewing

speed

changes

from

lowto highwhenthe front part of the pedalis further

depressed.

(However,

if the

automatic

reverse

feed

stitching

switch

has

been

set,the

sewing

speed

will

not

change

highuntil

reverse

feed stitching iscompleted.)

When

the pedalis returned to the neutral(stop) position,the

machine

stopswith its needledown,

When

the backpart of the

pedal

islightly

depressed,

the

presser

foot

will

goup.

When

the backpart of the pedalisfurther depressed, the presser foot comesdown,thread trimmeris

actuated, and the machine stops with its needle up.

(If the wiperswitchhas been set to ON, the wiperis actuated.)

Between

the lowandhigh

sewing

speedpositions, the

machine

runsat a speedcorresponding to the pedal

depressionamount. (The speed is infinitely variable.)

o The proper thread trimmingaction willnot be disturbed evenif the pedal is returned to the neutral

position immediatelyafter the machinestarts thread trimming.

At this time, the thread trimmerproperlyoperates

even

if the front part of the pedalisdepressed,

however,

the safetycircuitryisput in operationso that the

machine

will

not mn after thread

trimming

iscompleted.

Therefore, the pedal must be returned to the neutral position once.

2-3.

SC-20

Power

Indicator

Box

1) Power indicator LED

o Lights up when the power switch is turned ON.

o This light stays ON for a while after the power is turned OFF. It is dangerousto carry out maintenance or

adjustment with the PSC box cover open. Be sure that the LED is OFF before starting maintenance such as

part replacement.

SC-

2 0

- 6 -

From the library of: Superior Sewing Machine & Supply LLC

2-4. SC 120 Control panel

1) Control panel

Automatic

reverse stitching (for end) indicator

lamp (LED)

•Lights

when

the

ending

reverse

stitching

switch

ON.

Power indicator lamp (LED)

•

Lights

up whenthe powerswitchisturned ON.

•

Stays

for

while

immediately

after

the

power

switch

turned

OFF.

It is

dangerous

perform

any

maintenance

work

with

the

PSC

box

cover

open.

sure

that

the

lamp

OFF

before

per

forming

maintenance

work

such

parts

replacement.

Switch

for

raising

the

needle.

•

this

switch

turned

when

the

machine

stops

with

its

needle

down,

the

needle

goes

and

stops

its

upper

position.

• By depressing

the

back

part

the

pedal,

the

thread

trimmer

may

actuated.

(Note

that

this

switch

will

invalid

when

the

needle

has

been

moved

down

hand.)

2) Howto use the automatic

reverse

stitchingpatterns

Automatic

reverse

switching

(for

start)

switchO

Stitching

pattern

Automatic

reverse

stitching

(for

end)

switch 0

OFF

m m

Automatic

reverse stitching (for start) indicator

lamp (LED)

•Lights

when

the

starting

reverse

stitching

switch

ON.

Switches

for

setting

the

number

stitches

•

These

are

pushbutton

switches for

setting

the

numbers

stitches

for

steps

and

The

setting

range

from

[+]...

.Increases

the

number

stitches

B . . . .Decreases

the

number

stitches

Automatic

reverse stitching (for start) switch

•

Used

turn

OFF

automatic

reverse

stitching

sewing

start.

•

Each

time

this

switch

pressed,

alternately

turns

OFF.

(This

switch

rendered

invalid

when

the

number

stitches

for

step

has

been

set

"0".)

Automatic

reverse stitching (for end) switch

•

Used

turn

OFF

automatic

reverse

stitching

sewing

end.

•

Each

time

this

switch

pressed,

alternately

turns

OFF.

(This

switch

rendered

invalid

when

the

number

stitches

for

step

has

been

set

"0".)

By combining ON and

OFF

conditions of automatic reverse

stitching (for start) switch O and automatic

reverse

stitching

(for end) switch O , four different stitching patterns are

available.

- 7 -

From the library of: Superior Sewing Machine & Supply LLC

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