Mitsubishi Lt-20 User manual

ate

MITSUBISHI

AUDIO

SYSTEMS

SERVICE

MANUAL

LINEAR

TRACKING

TURNTABLE

MODEL

LT-20

CONTENTS

IDENTIFICATION

AND

OPERATION

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MITSUBISHI

ELECTRIC

SALES

AMERICA,

INC.

3030

East

Victoria

Street

Compton,

California

90221

|

IDENTIFICATION

AND

OPERATION:

Light

emitter

Prism

Main

weight

i

\

'

\

(

!

1

|

i

|

i

1

i

QUARTZ

(Quartz

lock

indicator)

SPEED

(Speed

reset

button)

REPEAT

(Repeat

button)

A

Il

4

Ed

[|

|

i

[|

(

——

=I

Power

on:

turn

the

locking

arm

of

the

arm

rest

in

a

counterclockwise

direction.

Tonearm

becomes

free.

START

<

(Start

button)

SCHEMATIC

REPRESENTATION

OF

LT-20

AUTOMATIC

FUNCTIONS

Stylus-lift

priority:

press

(AV)

to

reverse

stylus

descent.

Stylus

ascent

cannot

be

reversed

before

completion.

Auto

lead-in:

press

the

start

(<4)

button

once

to

commence

audition.

Free

travel:

press

(<4)

and

(

®)

buttons

to

move

the

tone

arm

in

either

direction,

then

(AY

)

to

lower

it.

Auto

return:

the

tone

arm

returns

automatically

at

the

end

of

the

disc.

Return:

if,

while

pressing

()

the

tone

arm

moves

over

the

edge

of

the

disc,

it

will

return

rapidly

to

rest.

Auto

cut:

press

the

stop

{

>)

button

Once

to

interrupt

and

end

disc

audition.

Quick

response:

any

movement

except

lift/cue

of

the

stylus

can

be

interrupted

by

a

new

command.

Free

access

lead-In:

continue

to

press

the

start

(4)

button-and

the

tone

arm

will

travel

on

over

the

disc

until

pressure

is

released.

Press

the

lift/cue

button

(a¥.

}

to

lower

it.

Stylus

protection:

when

there

is

no

disc

on

the

platter,

the

stylus

will

not

descend,

and

the

tone

arm

will

return

to

rest.

Repeat:

pressing

the

repeat

button

turns

the

repeat

function

alternately

on

and

off.

When

on,

the

indicator

lights.

Lift-up

and

cueing:

pressing

the

lift/cue

(4V¥)

button

alternately

lowers

and

raises

the

tone

arm.

Manual

Jead-in:

first

switch

on

the

platter

motor,

then

lift

the

stylus

over

to

the

lead-in

groove.

Manual

lead-out:

lift

the

stylus

and

return

the

tone

arm

to

the

rest

position.

The

platter

will

stop

automatically.

Tracking

force

adjustment

weight

Tone

arm

Arm

rest/POWER

switch

Head

sheli

Platter

mat

STOP

>

(Stop

button)

LIFT/CUE

av

(Arm

lift/cue

button)

SPECIFICATIONS:

1.

PHONO

MOTOR

SECTION

Drive

system

Direct

drive

Motor

Quartz

PLL

DC

servo

motor

Platter

Diameter

304mm

(11-15/16”)

Weight

1.3

kg

(2.9

Ibs)

Material

Aluminum

diecast

33-1/3,

45

rpm

0.025%

(Wrms)

+0.04%

Wp-p,

DIN

45-507

Platter

speed

Wow

and

Flutter

Signal

to

noise

ratio

78

dB

(DIN-B)

65

dB

(IEC-B)

2.

TONEARM

SECTION

Type

Straight

type

universal,

static

balance

220

mm

(8-11/16"’)

171

mm

(6-3/4’’)

Overall

length

Effective

length

|

Tracking

error

Maximum

0.1°

Head

shell

GFRP

6.2

g

Cartridge

weight

range

10—18g

w/head

shell

3.

GENERAL

Power

consumption

14W

Dimensions

424

x

142

x

417

mm

(Wx

H

x

D)

(16-3/4

x

5-5/8

x

16-3/8”’)

Weight

10

kg

(22

Ibs)

Design

and

specifications

are

subject

to

change

without

notice

for

improvement.

Screws

with

washers(3)

LT-20

|

DISASSEMBLY

INSTRUCTIONS:

1.

Removal

of

Front

Panel

1)

Remove

the

nine

screws

securing

the

bottom

cover.

2)

Remove

the

three

screws

(with

washers)

shown

in

Fig.

1.

3)

The

front

panel

can

now

be

removed.

2.

Removal

of

Tonearm

Ass’y

1)

Detach

the

E-ring

and

coil

spring.

Remove

the

slit

plate

by

lifting

point

@)

slightly

upwards

and

shifting

the

plate

in

the

direction

of

arrow

(Shown

in

Fig.

2).

2)

Loosen

the

wire

holder

on

the

tonearm’s

relay

P.C.B.

3)

Remove

the

two

screws

(4)

securing

the

light

receiving

P.C.B.

that

functions

to

sense

the

tonearm

position.

Take

off

the

P.C.B.

holder,

moving

it

in

the

direction

of

arrow

©.

4)

Unsolder

the

six

lead

wires

(white,

blue,

red,

green

and

two

black

from

left

to

right

in

the

figure)

leading

out

from

the

tonearm

shaft.

5)

Disconnect

CONN-4

of

the

main

P.C.B.

and

separate

it

from

the

other

wires.

6)

After

removing

the

two

screws

@)

,

the

tonearm

ass‘y

can

be

removed

by

moving

it

upwards.

7)

The

tonearm

can

now

be

removed

from

the

arm

base

and

replaced.

NOTES

1.

Except

when

it

is

necessary

to

remove

the

tonearm’s

horizontal

movement

mechanism

©)

and

lead

wires,

them:

as

they

are.

2.

When

attaching

the

P.C.B.

holder

during

re-assembly,

be

careful

not

to

pinch

the

!ead

wires

from

the

tone

arm.

Front-side

are

Fig.

1

P.C.B.

holder

Slit

plate

Screws

@

Wire

holder

Horizontal

movement

mechanism

©

Fig.

2

‘

A

| {

wal

“I

3.

Upon

completion

of

assembly,

twist

the

wires

leading

out:

from

the

tonearm’s

movable

section

to

prevent.

4.

After

replacing

the

tonearm,

be

sure

to

perform

tonearm

adjustments.

ADJUSTMENTS:

1.

Tracking

Force

Adjustment

1)

Set

the

tracking

force

weight

to

the

“0”

position

on

the

tonearm.

;

Tracking

force

weight

Fig.

3

2)

Turn

the

power

switch

ON.

3)

While

lightly

supporting

the

front

of

the

head

shell

rotate

the

adjustment

knob

for

the

main

weight

until

_

zero

balance

is

achieved.

See

Fig.

4

below.

Fig.

4

4)

Return

the

tonearm

to

the

arm

rest.

Adjust

the

tracking

force

weight

to

the

desired

weight.

See

Fig.

5

Set

to

optimum

tracking

weight.

Fig.

5

NOTE:

Adjustments

2, 3,

and

4

should

always

be

done

in

sequence.

2.

Tonearm

Height

Adjustment

1)

Provide

power

to

the

unit.

2)

Turn

the

power

switch

ON.

3)

Loosen

the

arm

height

adjusting

screw,

by

turning

it

counterclockwise.

Then,

after

lifting

the

arm

holder

as

high

as

it

will

go,

secure

it.

4)

Place

a

(30

cm

LP)

record

on

the

platter.

5)

While

maintaining

the

tonearm

in

the

up

position

with

one

hand,

depress

the

<4

(START)

button

with

the

other

to

lower

the

tonearm.

6)

Turn

the

power

switch

OFF.

7)

With

the

set

in

this

condition,

adjust

the

tonearm

so

that

it

becomes

level.

While

holding

the

arm

holder,

position

the

arm

pipe

parallel

to

the

record

surface

and

then

secure

it

in

place

by

turning

the

arm

height

ad-

justing

screw

in

a

clockwise

direction.

See

Fig.

6

and

7

below.

Arm

height

adjustment

screw

Arm

holder

Fig.

6

Fig.

7

Be

sure

to

perform

adjustment

3

(Stylus

Height

Adjust-

ment)

after

completing

the

steps

above.

i

|

'

3.

Stylus

Height

Adjustment

1)

After

completing

adjustment

of

the

tonearm

height,

turn

on

the

power

switch.

With

the

set

in

the

‘’Play’”’

mode,

depress

the

AW

(LIFT/CUE)

button,

which

will

cause

the

tonearm

to

be

lifted

up.

2)

The

height

obtained

at

this

point

will

be

the

stylus

height.

The

optimum

height

should

be

5

mm

(1/5")

if

it

is

other

then

this

the

Stylus

Height

Adjustment

must

be

made

using

a

hexagon

wrench.”

See

Fig.

8.

Stylus

Record

Surface

5

mm

(1/5*')

_—

Platter

Stylus

Height

Adjustment

Screw.

Hexagon

Wrench

Fig.

8

*

During

adjustment,

use

care

not

to

allow

the

hexagon

wrench

to

fall

into

the

mechanism.

4.

Arm

Rest

Height

Adjustment

Upon

completion

of

Tonearm

and

Stylus

height

adjust-

ments

the

Arm

rest

height

must

be

checked

as

shown

in

Fig.

9.

If

adjustment

is

necessary

follow

the

steps

below.

1)

Loosen

the

arm

rest

height

adjustment

screw

and

move

the

arm

rest

to

the

lowest

position.

2)

Depress

the

B

(STOP)

button

and

return

the

tonearm

to

the

arm

rest.

3)

Depress

the

AV

(LIFT/CUE)

button

and

lift

up

the

tonearm.

At

this

point,

shift

the

tonearm

a

little

towards

the

center

spindle,

and

by

moving

the

arm

rest

vertically,

adjust

it

so

that

there

will

be

a

clearance

of

1

~

2mm

between

the

tonearm

and

the

flat

portion

of

the

arm

rest.

Secure

the

arm

rest

by

tightening

the

arm

rest

height

adjustment

screw.

T-20

'

Arm

rest

height

adjustment

screw

iO

1~

2mm

{0.04-—-0.08’’)

Fig.

9

NOTES

1)

If

the

stylus

height

is

too

low

When

the

tonearm

moves

horizontally,

the

stylus

will

tend

to

come

in

contact

with

the

record

surface

or

platter.

2)

If

the

stylus

height

is

too

high

Adjusted

to

a

height

decidedly

higher

then

the

proper

one,

the

stylus

will

float

at

low

portions

of

a

warped

record.

5.

Adjustment

of

Lead-in

Position

The

cover

label

shown

in

Fig.

10

must

be

taken

off

prior

to

adjusting

the

lead-in

and

rest

position.

Arm

rest

position

adjustment

screw

Lead-in

position

adjustment

screw

Fig.

10

1)

With

a

30

cm

(12”

LP)

record

placed

on

the

platter,

depress

the

<4

(START)

button

and

observe

the

lead-in

to

see

to

which

side

the

stylus

is

off-position.

2)

Turn

the

lead-in

position

adjustment

screw

a

little

using

a

screwdriver.

Depress

the

B®

(STOP)

button

and

return

the

tonearm

to

the

arm

rest.

3)

Depress

the

<4

(START)

button

and

check

the

lead-in,

position

again.

If

it is

still

improper,

repeat

Step

2).

4)

After

adjusting

the

lead-in

position

to

the

optimum

one

with

a

30

cm

record,

repeat

the

same

adjustment

with

a

17

cm

(7”)

record.

NOTES

1)

Care

should

be

used

during

adjustment

as

not

to

damage

the

stylus

as

it

may

set

down

outside

of

the

record

surface.

2)

Be

careful

not

to

set

the

lead-in

position

too

far

inward.

This

may

cause

improper

pick-up

sensing.

6.

Rest

Position

Adjustment

*

When

returning

the

tonearm

to

the

arm

rest,

if

the

arm

does

not

set

properly

into

the

notch

in

the

arm

rest

(hits

either

the

right

or

left

side

of

the

arm

rest

during

descent),

perform

the

following

adjustments.

See

Fig.

11

below.

;

Correct

Fig.

11

1)

Depress

the

<4

(START)

button

to

cause

lead-in

of

the

tonearm.

(Watch

carefully

as

the

tonearm

may

fail

to

perform

proper

lead-in.)

2)

Using

a

screwdriver,

slightly

turn

the

arm

rest

position

adjustment

screw.

3)

Depress

the

B®

(STOP)

button

to

return

the

tonearm

to

the

arm

rest.

Confirm

that

the

tonearm

descends:

properly

without

touching

either

the

right

or

left

side

of

the

arm

rest.

If it

does

not

descend

properly

into

the

notch,

adjust

its

position

by

repeating

the

above

ad-

justments.

Upon

completion

of

adjustments,

confirm

proper

lead-in.

If

the

stylus

fails

to

descend

properly

into

the

lead-in

groove,

re-adjust

by

following

the

instructions

given

in

Adjustment

5.

(Adjustment

of

Lead-in

Posi-

tion.)

7-1

Adjustment

of

Horizontal

Tracking

Angle

1)

Remove

the

bottom

cover

of

the

turntable.

2)

Disconnect

the

lead

wire

connected

to

9

of

the

main

P.C.B.

This

will

prevent

platter

rotation.

3)

Disconnect

CONN-4

(5

plug)

from

the

main

P.C.B.

4)

Fig.

13

gives

a

detailed

view

of

CONN-4.

Push

pins

3

and

5

(at

Point

A

shown

in

Fig.

13)

with

a

minus

‘S)

screwdriver

and

remove

the

lead

wire.

To

tonearm

Brown

UO

&

c

Orange

Yellow

Green

Push

with

minus

screwdriver.

Me

A

12345

CONN

-4

Fig.

12

5)

Reconnect

CONN-4

to

the

main

P.C.B.

6)

Connect

the

minus-side

of

an

ammeter

to

3

on

the

body-side

of

CONN-4,

and

the

plus-side

to

the

orange

lead

removed

from

CONN-4.

—

7)

Connect

the

minus-side

of

the

other

ammeter

to

5

on

the

body-side

of

CONN-4

and

the

plus-side

to

the

green

lead

removed

from

CONN-4.

(Range:

0—100uA)

Tester

1

(Ammeter

1)

Red

Orange

\

Green

Tester

2

(Ammeter

2)

Brown

Main

P.C.B.

0

et

sere

Fig.

13

8)

After

turning

on

the

power,

depress

the

<

(START)

button.

The

tonearm

will

be

activated

and

decend

into

the

record’s

lead-in

groove.

The

tonearm

will

not

move

further

due

to

no

platter

rotation

although

the

tracking

servo

will

be

turned

on.

9)

Again

turn

off

the

power

switch.

10)

Disengage

the

drive

belt

for

the

horizontal

drive

motor.

11)

Position

the

tonearm

so

the

space

‘‘A”

and

‘'B”

are

equal

to

each

other

as

shown

in

Fig.

14

below.

Tracking

adjustment

screw

oy

Screwdriver

12)

Read

the

current

indicated

on

both

the

ammeters

connected

in

steps

6)

and

7).

13)

If

the

two

current

indications

are

not

equal

adjust

the

Base

Tracking

Adjustment

screw.

When

these

two

measure-

ments

are

equal

they

should

be

in

the

range

of

8

to

20uA.

;

14)

Disconnect

the

ammeters

and

reinsert

the

lead

wires

Tonearm

vein)

==

&)

var0e

|

B

to

CONN-4.

Reconnect

CONN-4

to

the

main

P.C.B.

7-2

Adjustment

of

Tracking

Servo

Amplifier

1)

The

tracking

servo

amplifier

gain

is

to

be

adjusted

only

after

adjustment

7-1)

has

been

completed.

2)

Connect

a

DC

voltmeter

between

12

of

the

main

P.C.B.

and

ground

(Pin

10).

Adjust

VR101

for

a

reading

of

5.5

volts.

Then

with

the

voltmeter

con-

nected

between

13

and

ground

adjust

VR102

for

5.5

volts

on

the

voltmeter.

After

completing

the

adjustments

apply

lock-tight

to

the

semi-fixed

resistors.

Reconnect

the

lead

wire

to

9

to

restore

platter

operation.

Re-engage

the

drive

belt

to

restore

horizontal

drive

motor

operation.

3

—

4

—

Fig.

14

Voltmeter

f

t

13126

7

CONN

4

9 8

MAIN

P.C.B.

Tracking

Servo

Amplifier

Adjustment

Fig.

15

INTERNAL

DIAGRAMS

AND

PINOUT

OF

INTEGRATED

CIRCUITS:

MSA117RS

HORIZONTAL

DRIVE

I.C.

SERVO

V

Ref

INPUT

-B

OUT

2

COMP

2

GND

2

TC4011BP

TC9142P

x'tal

5.52960

MHz

XT

Ni

Nz

CPouT

33/45

STOROBO

LD

Voo

GND

@)

—

a

— —

Qe

ab

ope

20"

2?

Frequency

Divider

AFC

B-bit

D/A

Converter

AFC

Frequency

Control

DC

Output

Lock

Range

Sensing

Circuit

I i t

de

ae

APC

aes

ane

Bit

D/A

Converter

(7)

APC

Phase

Control

Frequency

Divider

coats

]

De

Outsut

l

—e

ee

EE

—

a

©

yest

mm

LT-20

BA6109

VERTICAL

DRIVE

I.C.

INPUT/OUTPUT

TRUTH

TABLE

FIN

|

R

IN

|Vout!

|Vout

2

H

Lb

L

OPEN|OPEN

Vz}

Vout!

Vec2

Vout2

Vz2

O3

O2

O08

OlO

Og

Vec

|

O7

6K

VR

O

4

dhe

30K

1,

FIN

O5

IK

GND

O11

1K

RINO6

oe

INFORMATION

ON

LOGIC

IC

(MSM-5831RS)

1.

Circuit

Construction

S-CEAD-

INO

tke

‘OLEAD

IN

P>2Zorest

Control

circuit

Input

circuit

[__f>!8

ostow

{>+Dorepear-

ino.

{>Lorrt

prive

>_>

osteo

-

ino.

RECORD

SIZE

O

2.

and

Function

1

(S-LEAD-IN):

L

when

tonearm

is

on

a

record,

otherwise

H.

2

(S-END):

Becomes

L

when

tonearm

is

moving

inwards

on

a

record

and

reaches

the

end

groove,

otherwise

H.

3

(S-REST):

L

when

at

arm

rest,

otherwise

H.

4

(UP):

L

when

tonearm

is

being

tifted

or

moving

horizontally,

otherwise

H.

5

(DOWN):

L

when

tonearm

is

at

arm

rest

or

on

a

record,

otherwise

H.

6

(REPEAT):

Ordinarily

H.

When

L

is

fed

into

this

pin,

the

tonearm

continues

the

repeat

operation.

To

release,

feed

in

L

once

more

or

make

11

(STOP)

L.

7

(33/45):

Used

when

selecting

platter

speed

manually.

Making

this

L

causes

speed

to

change

from

33-1/3

rpm

to

45

rpm

or

vice

versa.

9

(START),

10

(LIFT/CUE),

11

(STOP):

When

START

becomes

L,

the

tonearm

moves

inwards;

when

STOP

becomes

L,

the

tonearm

moves

outwards.

When

LIFT/CUE

becomes

L,

the

tonearm

is

lifted

or

lowered.

Note

that,

while

the

tonearm

is

being

lifted,

making

this

L

produces

no

change,

but

if

L

is

fed

in

during

sthe

lowering

process,

it

changes

back

to

upwards.

—10—

12

(CLK):

By

connecting

an

external

resistor/condensor

combina-

tion

to

the

input,

a

reference

clock

pulse

is

generated

internally.

13

(RESET):

A

resistor/condensor

combination

is

connected

to

the

input.

Immediately

after

switching

on

the

power,

the

RESET

input

becomes

L,

blocking

automatic

move-

ment

of

the

tonearm.

14

(Vss):

Connects

to

ground.

15(RECORD

SIZE):

L

indicates

30

cm

LP,

H

indicates

17

cm

EP.

16

(SPEED-IND):

L

indicates

33-1/3

rpm,

H

indicates

45

rpm.

Can

be

changed

freely

by

making

7

(33/45)

L.

17

(T/T-DRIVE):

When

9

(START)

becomes

L,

this

becomes

H

and

the

platter

rotates.

When

record

play

is

finished

and

the

returns

to

arm

rest

position,

this

becomes

L

and

platter

rotation

stops.

18

(SLOW):

To

move

the

tonearm

horizontally

while

on

a

record,

this

output

becomes

L

and

the

horizontal

motion

speed

is

low.

At

H

level,

the

motion

speed

is

high.

19

(REPEAT-IND):

When

6

(REPEAT)

is

L

in

the

repeat

mode,

this

becomes

L.

20

(V.M-UP),

21

(V.M-DOWN),

22

(H.M-OUT),

23

(H.M-

TN):

When

the

tonearm

is

at

rest

position

or

on

a

record

and

thus

5

(DOWN)

is

L,

at

first

20

(V.M-UP)

becomes

L

and

the

tonearm

moves

up,

causing

5

(DOWN)

to

become

H.

At

that

time

4

(UP)

is

L,

and

when

the

tonearm

stops

at

the

upper

limit,

the

horizontal

motion

starts.

When

the

tonearm

moves

inwards,

23

(H.M-IN)

is

L,

when

it

moves

outwards,

22

(H.M-OUT)

is

L.

When

the

tonearm

has

moved

to

the

pre-set

horizontal

Position

and

is

being

lowered,

21

(V.M-DOWN)

becomes

L.

Thus,

of

these

4

signals

during

tonearm

movement,

there

is

always

one

which

becomes

L,

but

never

two

or

more

simultaneously.

27

(REST):

Same

as

output

of

3

(S-REST).

28

(Vpp):

Supply

voltage

INPUT.

LT-20

WIRING

DIAGRAM:

OUTPUT

:

e

CAM

DOWN

CAM

UP

$103

$102

YEL

RELAY

P.C.B

(Pattern

Side)

Praca

th

REST

POSITION

SENSING

Sol

MUTING

SWITCH

ee

ey

re

LT-20

GND

REFLECTOR

LIGHT

EMITTER

P.C.B

VERTICAL

MOTOR

ll

RED,

BLK

SIZE

SENSING

S110

P.C.B

:

POWER

SWITCH

¥

$109

oF

:

GND

:

GND

-

MOTOR

P.C.B

(Pattern

Side)

~

|

=

Qa

z

2

:

One

CONN-4

RED

CONN-2

CONN-3

ale]

lg

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loo

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ae

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[STOP

|

;

START

LIFT/CUE

REPEAT]

[SPEED]

QUARTZ

et

RED,

BLK

AC

[20V

60Hz

LA

HORIZONTAL

MOTOR

TU

id

RED,

BLK

POWER

SUPPLY

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P.C.B

(Parts

Side)

=

QUARTZ

LAMP

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@)

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BLK

TRANSFORMER

—12—

PRINTED

CIRCUIT

BOARDS

MAIN

P.C

BOARD

RIZ5

QU5

owe

-RIZ2

4a

RIOZ..

R106.

DD

MOTOR

P.C

BOARD

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33/45:

a

POWER

SUPPLY

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—14—

key

pi

Secisbedd

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hoe

we

vey

sree:

SCHEMATIC

DIAGRAM:

DISC

SIZE

SENSING

CIRCUIT

Qio3

83

3

2Scl74l

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3

3S

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103

BA6IO9

098765432

LT-20

QUARTZ

SERVO

CIRCUIT

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786M

VERTICAL

DRIVE

RIB

Lak

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ras)

SIZE

LIGHT

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POSITION

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LIGHT

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RECEPTION

END

LIGHT

RECEPTION

NC

NO

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pte}

sir

{velo

0

4)

c

NC

NOpen

®

LEAD-IN

POSITION

if

SENSING

238

END

SENSING

CONTROL

CIRCUIT

MSM

5831RS

C108

0.01

OOWN|

MIOl

I

HORIZONTAL

|

DRIVE

MOTOR

>

MSAII7RS

MSA

(Kk)

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CIRCUIT

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45

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[REPEAT]

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WHT

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(SPEED)

,

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(Sram

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Cera

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|

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2x

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POWER

SUPPLY

FOR

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DRIVE

Quis

Qi20

2SB549

2SD330

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CPIN

par

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EMITTER

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QUARTZ

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INDICATOR

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9)

Lalo6

=Lalo7

—

CONN-4ey

TONE

ARM

MUTING

|

“----+

CONSTANT

VOLTAGE

Ql22

ciz0

RISO

IK

ciat

2200

35V

POWER

SUPPLY

2SD330

2SB549

=e

ye,

WW.

:

TC4011BP

BA6IOS

Ol2~O1s

ISR34-100

connection

of

Transistor

and

IC’

2SA999

2SC2320

Tc9l42P

MSAH7RS

RO4

100K

Q05

fav

Q06

hav

5

288561

a

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}0,0V~12,8V

(*}

g

=<

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evew.

———

a

Lev

gl

x

Oe

383

oT

:

{

1o.0v~

no.

ev)

3

re

RO

750

10

Sov

cos

10

50v

cor

0.047

<

CO9

0.22

SOV

L7

s

1¢

28

MSM5831IRS

4.

Ay

and

LS

RIO

680

4

L3

SIGNAL

FLOW

>:

....Tonearm

lifting

p>

.-..-Tonearm’s

horizontal

internal

movement

Ye

Stopping

of

tonearm’s

horizontal

internal

movement

(Lead-in

position

sensing)

>...

.

Starting

of

tonearm

lowering

cA.....Starting

of

tonearm

lifting

(End

sensing)

movies

Tonearm’s

horizontal

external

movement

NOTES:

|

1.

Units

of

capacitors

and

resistors

Ca

avcd

No

symbol

:

uF

P-symbol

:

pF

Riticte

ad

No

symbol

:

2

K-symbol

:kQ

M-symbol

:MQ

2.

Unspecified

diodes

are

all

1S2473VE

and

unspecified

transistors

25C2320.

3.

As

for

voltages,

those

for

the

phono

motor

section

are

those

measured

during

33-1/3

r.p.m,

rotation,

while

others

have

been

measured

with

the

tonearm

at

the

rest

position.

All

measurements

were

taken

with

a

digital

voltmeter

having

an

input

impedance

of

1

MQ.

=

marked

components

are

those

that

are

critical

for

the

con-

tinued

safety

and

performance

of

this

unit.

Replace

only

with

components

of

the

exact

type

as

specified.

5.

Component

values

and

design

subject

to

change

without

notice

for

improvement.

EXPLODED

VIEW:

PARTS

LIST:

Parts

No.

Description

No.

Parts

No.

Description

+

i

1

M07527690

Dust

Cover

63

Spring

2

MO07527127

Hinge

64

Holder

3

M07543622

Platter

Sheet-Assy

65

MO7179660

Switch-Micro

(POWER)

4

M07543620

Platter

66

Clamper

5

MO07137605

Refelector

(Emitter)

67

Cover-Bottom

6

Holder

68

M07550190

Leg

7

M07543600

Tonearm-Assy

(with

weight-assy)

69

Nut

M14

8

M07527635

Weight-Assy

70

Shield-Plate

9

Base

71

Spring

10

Knob

72

Spring

11

MO7527753

Arm

Lifter

73

Spring

12

Shaft

74

Shaft

13

M07543616

Head

Shell-Assy

75

Holder

14

M07543225

Ornament

76

P.C.B.-Ass’y

15

Hinge-Holder

77

Tapping-Screw

16

M07527445

Clamper

78

Screw-Metal

17

M07527446

Clamper

79

Tapping-Screw

18

M07461440

Power

Cord

80

Tapping-Screw

19

M07527446

Output

Cord

81

Tapping-Screw

20

M07527618

Arm

Rest-Assy

82

Screw-Metal

21

Cabinet

83

Tapping-Screw

22

Cover

84

Screw-Bind

23

M07543100

Panel-Assy

85

Tapping-Screw

100

&—79

24

Holder

86

Tapping-Screw

25

PCB-Assy

87

26

M07527210

Knob

88

Screw-Metal

27

PCB-Assy

89

Screw-Bind

28

M07543550

Motor

(786M)

90

Screw-Bind

29

Holder

91

Screw-Bind

30

Terminal

92

Screw-Bind

31

Holder

93

Screw-Bind

32

M07543500

Power

Transformer

94

Screw-Bind

33

Gum-Bush

95

Screw-Bind

34

Washer

96

Screw-PC

35

Clamper

97

Washer

36

PCB-Assy

98

Washer

37

PCB-Assy

(Logic)

99

Washer

38

Metal

Coller

E-ring

39

Base

E-ring

40

Clamper

E-ring

41

M04165646

Gear

(Vertical)

E-ring

42

M07527645

Gear

(Horizontal)

Shade-Plate

43

M07469639

Motor

Holder

44

Cover

Holder

45

Holder

46

M07527646

Gear

(UP-DOWN)

47

M04165621

Gear

(Horizontal-Big)

48

M04162628

Belt

49

Holder

50

Pulley

51

Holder

52

M07543670

Wire

53

Cover

54

Pulley

55

Holder

56

PCB-Assy

57

Holder

58

Holder

59

Metal

Colter

60

Holder

61

M04165459

Switch-Micro

—

(Rest)

M07297450

Switch-Micro

(CAM

UP,

DOWN)

—-7-

—18—

Parts

No.

Description

Diodes

M07060320

M07543325

M075433

26

M07543326

M07297320

M070603

20

M07060320

MO07151322

MO7171322

M07391320

M070603

20

M07452323

1S2473VE

182473VE

SR535D

$G235D

SP254FS

SP254F5

182473VE

MZ318

MZ310

1SR34-100

182473VE

5.1E3

MO07297343

M0743

7343

MO07527343

M07527344

M07508310

TC4011BP

MSM-5831RS

BA6109

MSA117RS

TC9142P

1

Transistors

M07137303

M07137307

M07390304

MO07137307

M07390304

MO7137303

M07137303

M07390303

M07137303

M07390303

M07230307

M07390303

M07061304

M07390303

M07061304

M07390303

PH101

28C1741

2SA999

28C1741

2SA999

PH101

2SC2320

28C2320

PH101

28€2320

28C2320

28C€2320

28C2320

2SB549

28C2320

28D330

28C2320

28D330

28C2320

28C€2320

NOTE:

A

and

=

marks

components

which

have

special

characteristics

to

maintain

the

safety

performance

of

this

unit.

When

replacing

any

of

these

parts,

be

sure

to

use

only

the

specified

parts.

Parts

No.

Description

M07390303

M0

7390303

M07390303

M07215304

M07390303

M07508308

M07390303

28C2320

28€2320

28C2320

28B561

2SB561

28C2320

288544

2$C2320

28C2320

Electrica!

Parts

M07374251

MO07374251

M07297250

M04165459

M07297450

MO07445660

M07445660

MO07445660

M07445660

M071

79660

M07445661

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

12V

0.05A

Lamp

5V

0.06A

Lamp

5V

0.06A

Micro

Switch

Micro

Switch

Micro

Switch

Push

Switch

Push

Switch

Push

Switch

Push

Switch

Push

Switch

Micro

Switch

Slide

Switch

M07543410

(Position)

(END)

(Lock)

(Tracking)

(Reflector)

(REST)

(CAM

UP)

(CAM

DOWN)

(REPEAT)

(SPEED)

(START)

(LIFT/CUE)

(STOP)

(POWER)

(MUTING)

Semi

Fixed

(B220K)

Semi

Fixed

(B220K)

Packing

M07543900

MO7527910

M07543910

MO07527930

M07527778

M04165726

M04165725

M07543940

MO07543945

MO7191603

MO7462012

M07297013

Packing

Box

Cushion

Mold

Cushion

Packing

Bag

Screw-Metal

Shade

(EP)

Shade

(LP)

Warranty

Card

Adaptor

45

rpm

Stylus

Gauge

H-Wrench

(DUST

COVER)

M3

x

30

Instruction

Booklet

LT-20

PACKING

INSTRUCTIONS:

After

loosening

the

screw

at

the

left

move

the

arm

base

to

the

left

and

secure

it.

_

Assembly

screw

Securing

of

transformer

:

for

transport

Caution

label

Washer

Minimum

arm

base

height

P-bind

screw

Caution

label

Adhesive

tape

(Front

surface)

Locking

of

tonearm

ass'y

Fold

and

fit

on

top

of

both

sides

of

dust

cover.

203

Platter

Main

weight

Nx

\

pe

S

Wa

Head

shell

Place

Platter

underneath

rubber

Mat.

Adhesive

tape

ad

eae

;

LT-20-US

MITSUBISHI

ELECTRIC

SALES

AMERICA,

INC.

SM-1001

3030

East

Victoria

Street,

Compton,

California

90221,

U.S.A.

PRINTED

IN

JAPAN

481

Mitsubishi LT-20 User manual

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