Brother International MD-817 Service Manual - Page 18

ADJUSTMENT

:;

M

DC

Servomotor

Rotating

direction

of

machine

O

About

13mm

*

Lower

the

machine

head

and

then

mount

the

belt

on

the

motor

pulley

and

the

ma-

chine

pulley.

*

The

belt

fits

the

machine

pulley

and

the

motor

pulley

as

shipped.

However,

the

belt

tension

may

loosen

in

time;

check

the

belt

tension.

*

The

machine

rotates

counterclockwise

as

seen

from

the

pulley

side.

*

Adjust

the

belt

0

by

loosening

the

set

screw

0

and

turning

the

nut

so

that

it

gives

about

13mm

when

pressed

by

hand.

2

Needle

_position

detector

(synchronizer)

Model

DB2-B798

*

Take

off

the

synchronizer

cover

for

adjustment.

The

synchronizer

detects

the

needle

with

two

sensors

and

controls

the

needle

down

signal

and

the

thread

trimming

signal

with

one

sensor.

Needle

down

stop

position

4

18-22mm

5mm

Needle

up

stop

position

For

medium

materials

9-11

mm

For

thick

materials

10-12mm

ce)

Model

B798

22-26mm

7.5mm

11-14mm

*

When

adjusting

each

sensor,

do

not

fail

to

turn

off

the

power

switch.

Position

adjustment

for

needle

down

signal

*

Turn

the

machine

pulley

and

set

the

needle

5mm

up

from

the

bottom

to

align

the

lower

end

of

the

magnet

0

with

the

upper

end

of

the

thread

trimming

needle

down

sensor

0.

(As

for

the

model

8747

•

B748,

adjust

the

needle

7mm

up

from

the

bottom

and

as

for

the

model

B798,

7.5mm.)

When

the

lower

end

of

the

magnet

does

not

coincide

with

the

upper

end

of

the

thread

trimming

needle

down

sensor

0,

loosen

the

screw

0

and

move

the

thread

trimming

needle

down

sensor

for

adjustment.

When

the

thread

trimming

needle

down

sensor

O

is

moved

in

the

rotating

direction,

the

needle

bar

comes

up.

And

when

in

the

reverse

direction,

the

needle

bar

comes

down.

Turn

on

the

power

switch

and

stop

the

machine

at

the

needle

down

stop

position

so

that

the

distance

between

the

top

of

the

needle

plate

and

the

lower

end

of

the

needle

clamp

screw

is

18

22mm.

(As

for

the

model

8798,

the

distance

is

22

—

26mm.)

Position

adjustment

for

needle

up

signal

*

Stop

the

machine

at

the

needle

up

stop

position.

The

needle

point

stops

9

—

11mm

away

from

the

top

of

the

needle

plate

for

thin

and

medium

materials,

and

10

—

12mm

for

thick

materials.

(As

for

the

model

B798,

the

needle

point

stops

11

—

14mm

away.)

When

the

needle

point

does

not

stop

properly,

loosen

the

screw

0

and

move

the

needle

up

stop

sensor

0

for

adjustment.

When

the

needle

up

stop

sensor

0

is

moved

in

the

rotating

direction,

the

needle

bar

comes

down.

And

when

in

the

reverse

direction,

the

needle

bar

comes

up.

*

Tighten

the

screws

0

and

0

to

a

torque

of

6

-

10kg-cm.

-

14

-

Brother International MD-817 Service Manual - Page 18

Adjustment

Page 18 highlights