Dual 704 User manual

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Dual

Edition

October

1976

704

Service

-Manual

Dual

Gebrüder

Steldinger

•

7742

St.

GeorgenISchwarzwald

Download from www.dual.de

Not for commerical use

Specification

Current

Type

AC

50

—

60

Hz,

without

motor

changeover

Line

voltages

110

—

125

Volt,

220

—

240

Volt

Drive

Electronical

ly-controlled

direct

drive

system

Dual

EDS

900

Power

Consumption

approx.

3.5

Watt

Motor

during

play

<

50

mW

Current

Consumption

with

220

V

50

Hz:

on

start-up

45

mA

with

110

V

60

Hz:

on

start-up

80

mA

during

play

20

mA

during

play

app.

40

mA

Run

-up

Time

(until

nominal

speed

is

reached)

2

-

2.5

sec.

on

33

1/3

rpm

Platter

Non-magnetic,

dynamical

ly-balanced,

detachable,

1.2

kg

300

mm

0

Total

rotating

mass

of

drive

system

(rotor

with

platter)

1.8

kg.

Platter

Speeds

33

1/3

and

45

rpm,

electronically

switchable.

Pitch

Control

For

both

speeds,

adjustable

in

each

case

with

variable

resistor,

range

of

adjustment

10

%

Speed

Check

with

light

stroboscope

for

platter

speed

33

1/3

rpm.

Strobe

markings

for

50

and

60

Hz

provided

on

the

platter

edge.

Sensitivity

of

Light

Stroboscope

for

0.1

%

Speed

Deviation

3

graduations

per

minute

at

50

Hz

3.6

graduations

per

minute

at

60

Hz

Overall

Speed

Variation

(assessed

in

accordance

with

DIN

45

507)

<

±

0.05%

Signal-to-Noise

Ratio

(in

accordance

with

DIN

45500)

Rumble

unweighted

signal-to-noise

ratio

>

46

dB

Rumble

weighted

signal-to-noise

ratio

>

67

dB

Tonearm

Torsion

resistant,

extra

long

tubular

aluminum

tonearm

in

super

flat

universal

four-point

gimbal

suspension,

tonearm

balance

weight

with

double

acting

vibration

damping

(2

anti-resonators).

Effective

Tonearm

Lenght

222

mm

Offset

Angle

26

0

4'

Tangential

Track

Error

Angle

0.16

0

/cm

Tonearm

Bearing

Friction

(related

to

stylus

point)

Vertical

<

0.07

mN

(0.007

g)

Horizontal

<

0.15

mN

(0.015g)

Tracking

Force

0

—30

mN

(0

—

3

grams)

infinitely

variable

with

1

mN

(0.1

g)

cal

ibrations

from

0

to

15

mN

(0

to

1.5

g),

operable

from

2.5

mN

(0.25

g)

stylus

pressure

up.

0

—

3

g

continuously

variable,

with

1/10

calibration

in

the

range

from

0

—

1.5

g,

rel

iable

as

from

0.25

g

tracking

force

Pick

-up

Head

Detachable,

suitable

for

all

pick

-up

cartridges

with

1/2"

mounting

and

a

deadweight

of

4,5

—

10

g

(including

mounting

material)

Adjustable

Overhang

5

mm

Pick

-up

Cartridge

See

separate

data

sheet

Weight

5.4

kg

Dimensions

and

Cutout

Required

refer

to

Installation

Instructions.

2

Dual

Fig.

1

EC

Ec

111

Hz

(33

1/3

Upm)

>7

mV

ss

R2

T

1

p

4,7

k

T1

Cl

47p

R

1

220

k

110/130V

220/240

V

50

—60

Hz.

R3

100

k

f

C4

0,47

µ

R5

470

R4

18k

C6

47

n

T2

II

89

22

k

R

11

22

k

D

1/1

N

4148

D

2/1

N

4148

T3

BC

172

B

BC

172

B

C7

47

n

R6

2k

88

22

k

T4

BC

17213

R

12

22

k

R

10

18k

R

13

100k

C8

4,7

n

R

14

10k

124V±5

R

45

5k

T5

BC

172

B

R

15

100

k

1

1

C9

47

n

R

16

II

6,2

k

T

0,125

A

1

C

52

0/

47

n

110V

..»

220

V

Gl.

1

IC

51

—

68

n

D

51

BY

183

300

851

22

k

Transistoren

von

der

Anschlußseite

gesehen

Transistors

as

seen

from

the

connecting

side

Transistors

vus

du

cötä

des

connexions

BC

172

B

BC

252

B

BC

338

BD

135

[3,8V

_C19

C20

20n

20n

I

B

I

C

I

E

C18

ZD

361-1000

p

D7

Spannungen

gemessen

mi

Voltages

measured

with

n

Tensions

mesuräes

avec

jr

Masse

der

Elektronik

ist

Bezugspunkt

für

Messun-

The

gr

,

gen.

Meßgeräte

erdfrei

anschließen,

da

Tonabneh-

for

ma

mermasse

an

+

28

V

liegt.

ment

t

connec

1,2

3

4,

5,

6

8

52

51

1,2

3

4

6,7

9,

10,

11

12

13

14,45

15

16

8

9

52

51

19

20

18

3

)S

900

7R

21

—

2,5k

R

18

1,8k

Drehzahlschalter

Platter

speed

switch

(45

Upm)

Commutateur

de

vitesse

(33

1/3

Upm)

20

/

22

10k

T-

k

I

R23

R19

12k

10

k

I

R17

R25

R26

62k

3k 3k

T6

R

24

8C172BJ

6,2k

D4

1

N

4148

+C

10

—

11.1

R

27

C11

+

C12

—0,47/2

—0,47

bt

T7

BC

252

13

T9

BC

172

13

R

29

1,8

k

T8

BC

252

B

R

30

2,2

M

T

10

BC

1728

R

33

4,7

k

R

31

2,2

M

--

1

7

1

-1

28

3k

R

32

R

46

33

k

R

34

33

k

05

C6

V2

06

C

6

V

2

R

43

1,1

k

8

T

16

BD

135

T

15

BD

135

7

5

R

42

1,1

k

D

-

X

-c

2

T

14

BD

135

R

44

150

R

41

5,6

t

Meßinstrument

(7

—

10

MOhm

Eingangswiderstand)

gegen

Masse

leasuring

instrument

(7

—

10

MOhm

input

resistance)

to

ground

istrument

de

mesure

(7

—

10

MOhm

rösistance

d'entröe)

contre

masse

Dund

of

the

electronics

is

the

reference

point

3surements.

Do

not

connect

measuring

equip-

o

ground

as

the

pick

-up

cartridge

ground

is

ted

to

+

28

V.

T

12

La

masse

de

la

partie

ölectronique

est

point

de

räfö-

rence

pour

les

mesures.

Brancher

les

instruments

de

mesure

sans

mise

ä

la

terre.

La

masse

de

la

platine

est

ä

+

28

V.

R

37

1,8

k

R

38

6.2

k

C

14

100p

R

35

-

220

1

R

36

220

4

1=2›

=== ===

C17

C16

C15

3,3j

3,3u

100/1

Änderungen

vorbehalten

Alterations

reserved

Sous

röserve

de

modifications

Ausgabe

1/April

1976

21,

18,

23,

17,

20, 24,

19,

22,

25

26

27,33

28, 29,

30,31

32

34,46

35

43

44

42

41

39,40

37,38

36

10

11

12

13

14

17

16

15

4

Co

ntents

..,

L

\sw

Page

Specification

2

Circuit

Diagram

3,

4

Dual

EDS

900

Electronic

Direct

Drive

System

6

Description

of

Function

6,

7

Speed

Regulation

7

Mounting

Instructions

for

Dual

EDS

900

8

Replacement

of

motor

electronics

8

Replacement

of

motor

8

Adjustment

of

nominal

speeds

8

Setting

78

rpm

nominal

speed

9

Stroboscope

9

Pitch

control

9

Tonearm

and

Tonearm

suspension

10

Removal

of

tonearm

from

bearing

frame

10

Removal

of

tonearm

assembly

with

tonearm

bearing

10,

11

Replacement

of

spring

housing

11

Adjustment

of

tonearm

suspension

11

Vertical

Tonearm

Control

11

Antiskating

Control

11

,

12

Tonearm

Control

12

Cue

Control

12

Replacement

of

cue

control

assembly

12

Starting

and

Shut-off

13

Muting

Switch

14

Pick

-up

head

not

parallel

to

platter

14

Stylus

slips

out

of

playing

groove

15

Tonearm

soes

not

set

down

or

lowers

onto

record

too

quickly

after

operating

the

cue

control

lever

15

Tonearm

moves

inwards

or

outwards

with

tracking

force

and

antiskating

dials

in

zero

position

15

Motor

does

not

shut

off

when

setting

down

on

tonearm

rest

15

Spare

Parts

16,

19,20

Exploded

Views

17,

18

Audio

Connection

Diagrams

21

Lubricating

Instructions

22

5

Fig.

2

Electronic

Direct

Drive

System

Dual

EDS

900

rotor

axle

resting

surface

for

platter

annular

magnet

coils

return

path

plate

motor

housing-

--

generator

coil

cup

magnet

toothed

dish

return

path

plate

Dual

EDS

900

Electronic

Direct

Drive

System

stop

cam

bearing

cup

end

journal

bearing

The

Dual

EDS

900

electronic

direct

drive

Sy-

stem

is

a

slow-running,

no-commutator

DC

electronic

motor.

The

electro-mechanical

commutation

normally

carried

out

on

DC

mo-

tors

by

the

commutator

is

electronically

controlled

in

the

case

of

the

Dual

EDS

900

by

two

Hall

generators.

These

Hall

genera-

tors

-

dependent

on

the

rotor

position

-

control

via

four

switching

transistors

four

coils

of

the

motor

succesively.

The

cyclic

switching

of

the

field

coils

exerts

rotating

magnetic

field

on

the

eight-pole

annular

magnet

of

the

rotor.

The

field

coils

are

located

in

the

air

gap

between

the

annu-

lar

magnet

and

the

return

path

plate

which

form

the

magnetic

return

path.

The

speed

is

controlled

by

a

frequency

generator

which

is

coupled

to

the

rotor

rigidly.

A

fixed

flat

coil

is

located

in

a

magnetic

circle

which

is

formed

by

a

200

pole

permanent

annular

magnet,

a

toothed

disk

and

a

return

path

cup.

The

toothed

disk

rotates

with

the

rotor

and

generates

a

frequency

in

the

coil

which

is

proportional

to

the

speed.

Any

error

which

might

be

caused

by

eccentricity

between

the

permanent

magnet

and

toothed

disk

is

compensated

thus

generating

a

fre-

quency

of

high

uniformity

which

controls

the

regulating

circuit.

This

frequency

is

transformed

by

a

special

electronic

circuit

into

a

DC

voltage

which

is

proportional

to

speed

(digital/analog

transformation).

The

voltage

thus

generated

is

compared

to

a

highly

stabilized

reference

voltage

and

used

to

control

current

of

the

direct

drive.

plug-in

board

The

unique

design

of

drive

and

control

re-

sults

in

distinct

advantages:

no

pole

sen-

sitivity,

hysteresis,

eddy

current

losses,

and

disturbing

groove

frequencies;

high-

definition

speed

control

without

interfer-

ence,

thus

enabling

a

momentary

control

of

speed

drop.

These

characteristics

guarantee

a

completely

vibration

free

and

uniform

drive

source

for

the

EDS

900.

Description

of

Fumaion

The

four

bifilar

coils

of

the

electronic

mo-

tor

and

the

two

Hall

generators

are

rigidly

connected

to

the

motor

flange.

The

8

pole

annular

magnet

forms

the

rotor

and

also

mo-

ves

the

magnetic

return.

The

four

coils

and

the

two

Hall

generators

are

arranged

between

the

annular

magnet

and

the

magnetic

return.

When

a

north

pole

is

above

the

Hall

genera-

tor

H

1

(Fig.

3

a),

the

base

of

transistor

T

17

becomes

positive

and

the

transistor

conductive

or

low-ohmic.

Current

flows

through

coil

3

which

has

the

effect

of

a

south

pole.

The

north

pole

of

the

annular

magnet

displaced

by

22.5°

from

coil

3

is

attracted.

A

section

of

coil

1

is

also

con-

nected

to

the

collector

of

transistor

T

17,

which,

as

related

to

coil

3

will

be

subject-

ed

to

current

flow

in

counter

direction.

This

section

of

coil

1

has

the

function

of

the

north

pole

and

attracts

the

south

pole

of

the

annular

magnet

displaced

by

22.5

0

.

The

north

pole

of

the

annular

ring

which

was

above

the

Hall

generator

H

1

has

been

rotated

by

22.5°

and

is

now

above

the

Hall

generator

H

2

(Fig.

3

b).

5

Fig.

3

Rotor

a.)

b.)

d.

Sp1

Sp2

Sp3

Sp4

H1

H2

270°

202,5

°

Transistor

T

15

becomes

conductive

and

cur-

rent

flows

through

a

part

of

coil

2,

so

that

a

south

pole

is

formed

while

current

flows

through

a

part

of

coil

4

in

counter

direc-

tion

which

acts

as

north

pole.

The

rotation

of

the

rotor

through

22.5

0

moves

the

subse-

quent

south

pole

of

the

annular

magnet

on

the

Hall

generator

H

1

(Fig.

3

c).

Transistor

T

16

becomes

conductive,

coil

1

is

the

south

pole

and

coil

3

forms

a

northpole.

By

a

fur-

ther

rotation

through

22.5°

the

south

pole

moves

via

Hall

generator

H

2,

which

controls

Transistor

T

14

(Fig.

3

d).

Coil

2

becomes

the

north

pole,

coil

4

the

south

pole.

Speed

Regulation

The

rotor

rotates

with

a

toothed

disk

having

200

teeth.

A

magnetic

tape

is

cemented

round

the

motor

flange.

On

one

side

the

tape

has

200

north

poles

on

the

other

side

200

south

poles.

The

north

poles

are

arranged

directly

opposite

the

rotor

center.

A

coil

is

mounted

in

the

vicinity

of

the

magnetic

tape

and

the

toothed

disk.

A

changing

magnetic

field

is

produced

by

the

rotating

toothed

disk.

This

magnetic

field

induces

in

the

coil

a

voltage

with

the

corresponding

frequency.

This

fre-

quency

is

111

Hz

at

a

rotational

speed

of

33.3

rpm.

135°

67,5

°

22,5°

0

The

pulses

produced

by

induction

are

lead

to

the

input

amplifier

consisting

of

tran-

sistor

T

1

and

T

2.

The

signal

across

emit-

ter

and

collector

of

transistor

T

2

is

lead

to

the

frequency

doubler.

The

doubled

pul-

ses

are

applied

to

transistor

5

(via

capa-

citor

C

8)

which,

together

with

transistor

T

6,

works

am

a

mono

flop.

The

rectangular

pulses

thus

gained

are

integrated

via

re-

sistors

R

23,

R

25,

R

26

and

capacitors

C

10,

C

11,

C

12

and

produce

a

base

voltage

of

transistor

T

9.

The

pulse/pause

ratio

of

the

monoflop

can

be

varied

by

controls

R

45

(basic

setting

monoflop),

R

20

(coarse

speed

control

45

rpm),

R

22

(coarse

speed

control

33

rpm)

and

R

21

(fine

speed

adjustment).

As

a

result

also

the

potential

across

the

base

of

transistor

T

9

changes

after

inte-

gration

T

9

and

T

10

take

the

form

of

a

dif-

ferential

amplifier

which

controls

-

via

the

collector

of

transistor

T

9

-

the

base

of

T

7

which,

together

with

T

8

also

takes

the

form

of

a

differential

amplifier.

The

ampli-

fied

control

voltage

is

lead

from

the

col-

lector

of

transistor

T

8

to

the

base

of

T

12

via

resistor

R

37.

The

transistor

T

12

and

T

13,

which

are

connected

am

an

emitter

fol-

lower,

control

the

current

for

the

four

switching

transistors.

The

maximum

starting

current

is

controlled

by

R

40

via

transistor

T

11.

7

Mounting

Instructions

for

Dual

EDS

900

For

repair

of

the

Dual

EDS

900

special

tools

4.

Pull

off

motor

electronic

system

from

and

measuring

means

are

required.

Work

on

motor

(18)

carefully.

the

motor

or

motor

electronic

system

should,

therefore,

only

be

carried

out

by

an

autho-

rized

Dual

service

station.

Expenses

arising

from

unauthorized

interference

will

be

char-

5.

6.

Fix

replacement

motor

electronic

system

on

motor

(18).

Solder

connecting

cables

(see

connection

ged

to

the

conisgnor.

diagram

Fig.

6).

7.

Slide

cover

over

power

pack

and

fix

it

by

means

of

machine

screws

(117).

Removal

8.

Slide

cover

(175)

over

motor

electronic

1.

Extract

unit

plug

from

power

line.

Lift

system

(172)

and

fix

it

by

means

of

off

platter

(4).

Bring

unit

into

head

position.

Remove

machine

screws

(174)

and

washers

(173).

Lift

off

cover

(175).

9.

machine

screws

(174).

With

the

unit

in

normal

position

connect

it

to

power

line.

Switch

on

unit

and

2.

Remove

machine

screws

(117)

and

cover

of

check

power

consumption

on

operation:

power

pack

(123).

220

V/50

Hz

approx.

20

mA

3.

Unsolder

leads

for

operating

voltage

on

110

V/60

Hz

approx.

40

mA

line

transformer

(124).

Unsolder

connec-

ting

leads

on

fine

speed

control

(197)

and

knob

(242).

Attention:

Da

not

unsolder

cable

on

motor

(172).

Fig.

4

0

Check

nominal

speeds.

If

necessary,

read-

just

as

described

below.

Replacement

of

Motor

1.

Extract

unit

plug

from

power

line.

Remove

platter

(4).

2.

With

the

unit

in

head

position

remove

machine

screws

(174)

and

washers

(173).

Pull

off

motor

electronic

board

(172)

together

with

cover

(175)

carefully

from

the

motor

(18).

3.

With

the

unit

in

normal

position

remove

the

three

machine

screws

(19).

Remove

motor

(18).

Loosen

machine

screw

(z)

and

remove

set

spring

(20).

4.

Mount

set

spring

(20)

on

the

replacement

motor.

Place

motor

(18)

on

installation

plate

(23)

and

mount

it

with

machine

screws

(19).

5.

With

the

unit

in

head

position

the

motor

electronic

system

(172)

with

cover

(175)

to

the

motor

(18)

and

secure

it

with

washers

(173)

and

machine

screws

(174).

6. 6.

With

the

unit

in

normal

position

con-

nect

it

to

the

power

line

Switch

on

unit

and

check

power

consumption

when

opera-

ting:

220

V/50

Hz

approx.

20

mA

110

V/60

Hz

approx.

40

mA

Check

nominal

speeds.

If

necessary,

read-

just

am

described

below.

Setti

ng

nominal

speeds

With

knob

(44)

bring

the

fine

speed

control

(242/R

21)

into

center

position.

With

con-

trols

(R

22)

and

(R

20)

on

the

motor

elec-

tronic

system

adjust

nominal

speeds.

Control

(R

22)

is

used

for

33

1/3

rpm,

R

20

for

45

rpm

(refer

to

Fig.

6).

Check

with

strobe

disk.

8

*A,

Changeover

to

78

rpm

nominal

speed

Fig.

5

Stroboscope

Instead

of

45

rpm

the

Dual

704

can

be

chang-

ed

to

a

nominal

speed

of

78

rpm.

To

change

the

speed

bring

the

fine

speed

control

(242/R

21)

in

center

position

using

knob

(44).

Using

control

R

20

on

the

motor

electronics

board

(172)

adjust

for

78

rpm

(refer

to

Fig.

6).

Check

with

strobe

disk.

Stroboscope

Accurate

setting

of

the

platter

speeds

33

1

/

3

and

45

rpm

can

be

checked

during

play

with

the

aid

of

the

stroboscope.

When

the

platter

(4)

is

rotating

at

exactly

33

1/3

or

45

rpm

the

lines

of

the

strobos-

cope

appear

to

stand

still.

If

the

lines

move

in

the

direction

of

rotation

of

the

platter,

the

platter

speed

is

too

high.

If

the

lines

move

backwards,

the

platter

is

rotating

more

slowly

than

the

nominal

speed.

Adjustment

of

platter

speeds

33

1/3

and

45

rpm

is

carried

out

separately

with

the

"pitch"

controls

(44).

Strobe

markings

are

provided

on

the

outer

edge

of

the

platter

for

50

and

60

Hz

line

frequencies.

To

replace

glow

lamp

(103)

remove

machine

screws

(105)

and

remove

strobe

cover

(104).

lt

can

happen

that

the

stroboscope

lines

appear

to

move

slightly

although

the

exact

speed

setting

with

stroboscope

stationary

has

not

been

altered.

This

apparent

contra-

diction

is

explained

by

the

fact

that

the

electronic

central

drive

motor

operates

fully

independently

of

line

frequency

whilst

the

only

relatively

accurate

line

frequency

of

the

PC

current

supply

is

used

for

speed

measurement

with

the

light

stroboscope.

The

constantly

detectable

fluctuations

of

line

frequency

by

+

2

%

(according

to

the

infor-

mation

of

the

electricity

supply

companies)

brief

frequency

fluctuations

up

to

1

%

arm

possible

-

only

effect

the

stroboscope

in-

dication

and

can

cause

the

lines

to

"wander"

although

the

platter

speed

is

as

constant

and

absolutely

accurate

as

before.

Pitch

Contml

Each

of

the

two

standard

speeds

33

1/3

and

45

rpm

(78

rpm)

can

be

varied

by

about

10

%.

The

variable

speed

control

(242/R

21)

loca-

ted

in

the

voltage

divider

is

adjusted

by

turning

the

pitch

control

knob

(44).

By

this

means

the

differential

amplifier

is

altered

and

the

motor

speed

accordingly.

44

Fig.

6

A

R20

522

Ee5-

H

r

J

Fernre.er

IR

21/

r

IZ=r

'

cle

;Kiew.

Eheallulm.

Fig.

7

Power

Supply

Board

(component

side)

Gl

immlampe

Gl

im

tamp

Lornpe

ci

effluves

Netztransformator

Mains

transformer

Transformateur

de

riseau

0

48

.

--ER

52/7,781-6

0_51

B/185/T00

11-

3

IZ07,r

e

111

---

N

1

151/2281-811

T125

mA

0

220

110V

cr

220V/

50-600z

9

Fig.

8

Tonearm-Tonearm

Suspension

31

29

183

24

Tonearm-Tonearm

Suspension

69

48

26

68

51

59

61

36

52

38

The

feather-light,

extremely

torsion

resi-

stent

all-metal

tonearm

is

suspended

in

a

gimbal.

Suspension

is

by

means

of

4

hardened

and

precision

polished

steel

points

which

rest

in

precision

ball

bearings.

Tonearm

bearing

friction

is

thus

reduced

to

a

mini-

mum.

Bearing

Bearing

friction

friction

vertical

horizontal

▪

0.007

p

▪

0.015

p

as

related

to

stylus

point.

As

a

result,

it

ensures

most

favourable

pick

-up

conditions.

Before

adjusting

the

pick

-up

force

to

suit

the

built-in

pick

-up

cartridge

the

tonearm

is

balanced

with

the

scale

set

to

zero.

Coarse

adjustment

is

car-

ried

out

by

moving

the

weight

with

the

stem

(49),

the

subsequent

fine

adjustment

by

tur-

ning

the

weight.

The

balance

weight

is

de-

signed

such

that

pick

-up

cartridges

having

a

deadweight

of

4.5

-

10

g

can

be

balanced.

lt

takes

the

form

of

a

anti-resonator

thus

absorbing

the

vibration

energy

in

the

range

Fig.

9

36

56

57

38

201

128

207

211

37

42

205

49

of

tonearm

and

chassis

resonance.

For

this

purpose,

the

inner

part

weight

is

matched

to

the

tonearm

resonance

and

thus

acts

as

anti-resonator

by

means

of

antiphase

vibra-

tion.

The

outer

part

of

the

balance

weight

taking

the

form

of

a

higher

balanced

anti-

resonator

prevents

transmission

of

partially

occurring

chassis

resonance

to

the

tonearm.

The

tracking

force

is

adjusted

by

turning

the

graduated

spring

housing

(59)

incorpo-

rating

a

coil

spring.

The

scale

has

markings

for

a

range

of

adjustment

from

0

to

30

mN

(0

to

3

p)

which

permit

accurate

adjustment

of

the

tracking

force.

One

graduation

in

the

range

of

2

-

15

mN

(0.2

-

1.5

p)

corresponds

to

1

mN

(0.1

p),

in

the

range

of

15

-

30

mN

(1.5

-

3

p)

to

2.5

mN

(0.25

p).

Removal

of

tonearm

assembly

with

tonearm

bearing

1.

Secure

unit

in

repair

jig.

Remove

weight

(49)

undo

fixing

screw

(52).

Set

tracking

force

scale

(59)

to

zero.

2.

Move

unit

into

head

position.

Remove

screening

plate

(150).

Unsolder

tonearm

on

muting

switch

(149).

3.

Move

unit

into

normal

position.

Turn

both

mounting

screws

-

SW

4.5

-

(55)

counter-

clockwise

to

the

stop

of

the

bearing

fra-

me

(51).

Attention:

Observe

the

bayonet

mounting.

Slide

tonearm

(48)

rearwards

and

remove

it

upwards

from

the

bear-

ing

frame.

For

installation

proceed

in

the

reverse

order.

Removal

of

tonearm

from

bearing

frame

Proceed

as

follows:

1.

Secure

unit

in

repair

jig.

Set

graduated

spring

housing

(58)

to

zero.

Arrest

tone

-

arm

(48).

Remove

weight

(49).

2.

Loosen

tension

layer

(63)

and

bring

tone

-

arm

(48)

in

its

highest

position

using

knob

(65).

Fasten

tension

layer

(63).

Bring

knurled

ring

(68)

in

position

"3".

10