Brother International MD-817 Service Manual - Page 51

ITEM

PROBLEM

CHECK

PROBABLE

CAUSE

REMEDY

#14

Needle

(upper)

stops

at

different

places.

•

Is

the

V

-belt

loose?

(YES)

•

Is

there

oil,

grease,

dirt

scratches,

etc.

on

the

syn-

chronizer's

reflecting

sur-

face?

(YES)

(NO)

•

Are

the

speed

and

torque

at

low

speed

OK?

(NO)

(YES)

Insufficient

V

-belt

tension.

Dirt

of

the

synchronizer's

re-

flecting

surface.

Malfunction

of

the

syn-

chronizer.

Malfunction

of

the

control

printed

-circuit

board.

Speed

at

low

speed

is

too

slow.

Operational

malfunction

re-

lated

to

head

thread

trimm-

ing.

Adjust

the

V

-belt

tension.

Clean

the

reflecting

surface.

Replace

the

synchronizer.

Replace

the

control

box.

Adjust

the

VR

TRIM

(LOW).

Adjust.

#15

The

stop

position

of

the

needle

(upper)

is

not

correct.

•

Can

adjustment

be

made

at

the

synchronizer?

(YES)

(NO)

Improper

needle

(upper)

stopping

position.

Reduction

of

motor

brake

force.

Adjust

the

needle

(upper)

stop

position

by

10

—

12mm.

Replace

the

motor.

#16

Thread

wiper

doesn't

function.

•

Switch

OFF

the

power

switch

and

then

measure

the

resistance

of

the

thread

wiper

solenoid.

•

Is

there

5ohms

between

pins

0

and

0

of

the

12

-pin

plug?

(NO)

(YES)

•

Other

than

above.

Malfunction

of

the

thread

wiper

solenoid.

Improper

installation

of

the

thread

wiper

solenoid.

Malfunction

of

the

control

printed

-circuit

board.

Replace

the

thread

wiper

solenoid.

Adjust

the

installation.

Replace

the

control

box.

#17

Thread

wiper

oper-

ation

time

is

too

short.

Improper

installation

of

the

thread

wiper

solenoid.

Correct

the

installation.

#18

Reverser

doesn't

function.

(when

treadle

is

de-

pressed

and

actua-

tor

is

switched

ON)

•

Can

the

reverser

be

oper-

ated

by

the

reverse

lever?

(NO)

•

Switch

OFF

the

power

switch

and

then

measure

the

resistance

of

the

reverse

solenoid.

•

Is

there

about

7ohms

be-

tween

pins

Co

and

e

of

the

12

-pin

plug?

(YES)

•

Measure

the

resistance

of

the

actuator.

Is

there

0ohms

between

pins

0

and

0

of

the

12

-pin

plug

with

the

actuator

switch

ON,

and

cohms

with

the

actuator

switch

OFF?

(NO)

(YES)

Operational

malfunction

re-

lated

to

head

reverse.

Malfunction

of

the

reverse

solenoid.

Malfunction

of

the

actuator.

Malfunction

of

the

control

printed

-circuit

board.

Adjust.

Replace

the

reverse

sole

-

noid.

Replace

the

actuator.

Replace

the

control

box.

-

47

-

Brother International MD-817 Service Manual - Page 51

Brother International MD-817 Manual

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