Sansui AU-70 Troubleshooting guide

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OPERATING INSTRUCTIONS

&

SERVICE

MANUAL

STEREO CONTROL AMPLIFIER

SANSUI AU-70

SANSUI ELECTRIC COMPANY LIMITED

This amplifier has a maximum output of 50 watts (25W-25W)

and features

an

amazingly low distortion factor of not more

than 0.15% at 20W. A high-quality amplifier with many exci-

ting features, it

is

delivered to you with Sansui's fullest confidence.

This booklet explains the steps necessary for operating and

caring for your new

the

.AU-70. Read

an

the instructions

carefully and retain for future use.

CONTENTS

FEATURES.

.........................................................

3,

4

SPECIFICATIONS ..... ... .....

...

......

...

...

...

.....

...........

. 5

CHARACTERISTICS. ............................................. 6

CONNECTIONS..........................................

..

........

7,

8,

9,

10

SWITCHES AND CONTROLS

........

.

.....

..........

....

.. .. ..

11,

12

OPERATIONS....

................

.. ..

....

.. ..

......................

13,

14

HI

NTS

ON USE

................

..

..............

..

..............

.. 15,

16

SERVICE NOTE

................

..........

......

......

............

17,

18

PAR

TS

LIST

......

......

..

.....

.

...

.

........................

....

.. 19,

20,

21

SCHEMATIC DIAGRAM

..........

........

... .

..........

.

......

.

22

PARTS

LAyOUT

...

..... .

...

... .

............

... ..

.....

..

.....

..... .

23

SUI

STEREO

CONTROL

AMPLIFIER

AU-70

FEATURES

7189A

P.P.

PRODUCES

40W

WITHOUT

PISTORTION

(

MAX

. 0.95%

AT

30

CPS

AND

·0.15%

AT

1,000

CPS

)

The

7189A

power

tubes

operate

in class

AB,P

.

P.

(fixed bias)

Jor

high-fidelity

reproduction.

Their

combined

.

maximum

output

is

limited

to

50 W .

The

amplifier

incorporates

a

multiplex

feedback

circuit

(total

negative

feedback: 26 dB) for

the

first

time

in

this

class of amplifiers in Jilpan.

This

makes

it

extremely

low

in

distortion

over

the whole

frequency

range.

Total

harmonic

dis-

tortion

at

1

kc

is

0.15%.

At

30 cps, a

very

low

frequency

at

which

it is

extremely

difficult · to

minimize

ha

r

monic

distortion,

the

distortion

is

limited to

not

more

than

0.

95%

.

This

is

quite

a

feat

for a

50-watt

amplifier.

Another

remarkable

feature

is

the

damping

factor of 18, a figure

which

is

lower

than

that

of

triode

power

tubes

' coupled

in P.P.

This

is

why

bass

sounds

come

out

with

su

ch

clarity

.

- 3

NFB

USED

IN

ALL

AMPLIFIER

CIRCUITS

,

FROM

PREAMP

TO

POWER

AMPLIFIER

The

low

distortion

of

the

power

amplifier

is

meaningless

if

the

preamplifier

generates

distor-

tions.

Your

AU-70

uses a

three

-

stage

amplifier

circuit

in

its

interm

ediate

or

cpntrol

amplifier-

unlike

conventional

one-stage

control

amplifiers-

and

has

all its circuits in a single

negative

-feed-

back

loop.

These

make

your

AU

-70 free from

noise

and

distortion.

SUPER-PRECISION

TRANSISTOR

PREAMP

-

LIFIER

ELIMINATES

HUM

AND

NOISE

The

exclusive

Sansui

four-transistor

preamplifier,

which

features a

transistor

circuit factor of

4-as

compared

with

conventional

5-1O-al1d

a transistor

noise factor of 2

dB-as

compared

with

conven

-

tional 5 dB, eliminates

hum

and

noise,

the

enemy

of

high

-fidelity

reproduction.

The

amplifier has

a

much

better

SIN

ratio

and

a

gain

three

times

larger

than

vacuum-tube

amplifiers.

EACH

CHANNEL

CAN

BE

OPERATED

IN-

DEPENDENTLY

EQUIPPED

WITH

TONE

DEFEAT

Each

channel

has

independent

tone

contro

ls for

bass

and

treble.

This

makes

fine

adjustment

possible.

Moreover,

each

channel

is

equ

ipped

with

tone

defeat

which

cancels

the

tone

control

circuits.

You

can

easily

obtain

a flat frequency

response

without

causing

any

undulation

in

response

or

redu

ced

gain

in bass

and

treble as in

the

case of

conventional

mechanical

control by

means

of a

tone

volume

knob.

Therefore,

you

can

get

an

accurate,

perfectly flat

response

from

your

AU-70

just

by flipping a switch.

BLEND

CIRCU

IT

PERMIT

CONTINUOUS

S

HIFT

FROM

MONAURAL

.

TO

STEREO

As

you

turn

the

"BLEND"

switch clockwise,

y

our

AU

-70

gradually

shifts from

monaural

to

stereop

honic

repr~duction.

This

feature

enables

you to

get

full

stereophonic

effect by compensa-

ting

program

sour

ces

which

give a, particularly

s

tron

g effect of

th

e conce

rt

ha

lL

EA

S

Y-

TO-

READ

THREE

-

RAN

GE

OUT

P

UT

L

EV

EL

METERS

Each

output

level

meter

can

be switched over to

any of

the

three

scales of 5, 10

and

25 watts.

The

meters not only give

direct

readings

of

both

ch

anne

ls,

but

also indicate

any

lack of

balance

between

the

right

and

left

outputs.

These

prove

very useful

in

balancing

the

outputs

.

THREE

-

DIMEN

S

IONAL

P

ERFORMANCE

POSSIBLE

WITH

CENTER

-

CHANNEL

OUTPUT

TERMINAL

Y~ur

AU

-70

ha

s

an

ou

tput

terminal

for the

center

-channel amplifier.

Connect

it to your

monaural

amplifier to produce a

three-dimensional

effect.

EQUIPPED

WITH

ADVANCED

,

HIGH-

PERFORMANCE

ACCESSORY

CIRCUITS

Your

AU -70

is

equipped

with

various

advan

ced

access

ory

circuits

such

as loudness control, low

an

d

high

filters,

tape

monitor,

tone

defeat, pre-

sence, blend, speaker switch and

headphone

jack.

- 4 -

SPECIFICATIONS

M

AIN

AMP

LI

FI

ER

:

MAXI

MUM

OUTPUT

:

25W-25

W (

SO

W to

tal)

HARMON

IC

DISTORTION:

Max. 0.15 %

at

20W for 1,

000

Hz

Max . 0.95%

at

20W

for

30

Hz

INTERMODULAT

IO

N

D

IS

TORTION: Max. 0.

85

%

at

20W

, (50 Hz

+

5,50

0 Hz)

FREQUENCY RE

SP

ONSE: 10-

80

,000

Hz

at

±1

dB

OU

TPUT IMPEDAN

CE

: 8

and

16 ohms

G

AIN

AND

SENSITIVITY

:

R

S

T

PHONO: MAG 84 d B (

Ou

tput 2

0W

at

1.1 mV

in

put

)

x-

T

AL

54

dB

(Output 2

0W

at

36mV input)

TAPE: 86 dB (

Ou

tput

2

0W

a t 0 .9mV

in

put)

MIC: 86 dB (

Ou

tp

ut 20 W a t

0.9

mV

in

put)

AUX: (

TA

PE MON)

51

d B (Output 2

0W

a t

50

mV input)

TUNER:

51

dB (O

utput

20W

at

50

mV

in

put)

ESIDUAL

NO

I

SE

:

below

0.25

p.

W

IN

RATIO

52

dB

(

at

T

APE

terminal)

ONE

CONTRO

L:

T

ype

CR

50 Hz +

11

to

- 15 dB

10,

00

0 Hz + 12

to

- 13

dB

E

QUALIZER

:

Ty

pe NF

TAPE:

NART

B (50

p.

s)

PHONO:

RIAA

A

CCESSORY

CI

RCU

I

TS

:

PRESENCE

CO

NTROL: Turno

ver

a t

150

Hz

LOW FILTER: 5

0Hz

- 12.5 dB

HIGH FILTER: 10,

000

Hz -13 .5

dB

LOUDNESS CONTROL

TONE DEFEAT

TAPE MONITOR

HEADPHONE JACK

TAPE RECORDER PLAYBACK CONNECTION (DIN)

TERMINAL

FOR CENT

ER

·

CHANNEL

AMPLIFIER

LEVEL MET

ER

(

FOR

OUTPUT

) Three ra n

ges

of

5,

10

and

2

5W

BLEND CONTROL

VA

CUUM

TUBES

,

TRANSISTORS

AND

DIODES:

7

18

9A X 4, 6AN8 X 2, 12

AX

7 X 3,

OA

-

91

ge

rmanium

dio

de

X 2, 2

5B

-

381

tra

nsis

tor

X

4,

50

-1

B silicon diode

X 2 5W-

0503

silicon dio

de

x l

TOTAL

: 9 tu

bes

a nd 9 di

od

es

PO

WER

SUPPLY

: 117V AC,

50

and

60

Hz:

P

OWER

CONSUMPT

IO

N:

150VA

DI

MENSIONS

: Wi

dt

h 15" /6

/'.

D

epth

12

19

/

32

/1.

Height 519/3/ ' .

W

EIGHT:

30 lbs

- 5 -

~

"I..

CHARACTERISTICS

TONE

CONTROL

CHARACTERITICS

FREQUENCYRESPONSECHARACTE~ST~S

1111 I 1

1111111

NF:

26

dB

LO

AD RESISTANC E:

16

0HMS

20

r-

M~X

M~X

6

-4

II)

~

~

10 2

w

:---....

a;-

0

'"

....

TONE

DEFEAT

~

z 0 w -2

0

......

en

,

"-

Z

.......

A

'"

..."...

~

- 6

~

-10

~

- 8

--

OU

TPUT : I W

-

~

'"

0::

-10

----

OU

TPUT :

20

W

-

20

MIN I

II

1111

-12

1 I I I 11

11

100 I K 10 K 10 100 I K

10K

lOO

K

HIGH

AND

LOW

FILTER

CHARACTERISTICS

HARMONIC

DISTORTION

I I I I I I I I I

10

I J

~Nt~t

t~fE~T

10

-HARMONIC I Ke

;;;-

e

___

DISTORTION 1

00%

'

LOAD

RESISTANCE :

16

0HMS -

0 -

1-

-z _ .-

10

Ke

~

r- 0

w

;::

~

-1

0

HIGH

FILTER

Q:

0 5

0

LOW

FILTER

...

"-

,

"\.

!!?

~

-20

\ c I

I)

Q:

I

:'J

-30 1 .,

--

-

,....

-

100

I K 10 K o I 5

10 15

20 25

I

NPUT

AND

OUTPUT

CHARACTERISTICS

INTER

MODULATION

DISTORTION

I I I I I I I I

10 5

.5

Ke

+50

%LOAD

RES

IS

TANCE

I6

0HMS

25

/'

e

INPUT : MAIN / z

NF

:

26

db

LOAD

Q

RESISTANCE:

16

0HMS

...

10

:5

5

...

-

!!?

II

~

c

...

::::>

1

"-

...

::::>

II 1 5

10

15

20

0

I

/

V

0.

3 I 2

- 6 -

CONNECTIONS

SPEAKER

STEREOPHONIC

REPROD

U

CTION

Connect

(+)

of

th

e rig

ht-hand

s

peaker

to

the

8-

or

16

-ohm

terminal

of

th

e

upp

er R

termin

als

on

the

ba

ck

of

the

amplifier.

Connect

(- ) of

the

rig

ht-hand

speake

r

to

(C) of

the

upp

er R

termin

als.

Connect

(+)

of

the

l

ef

t-

hand

speaker

to

the

8-

or

16-o

hm

termin

al

of

the

lower L

terminal

s

on

th

e

back

of

the

amplifier.

Connect

(-)

of

the

left-hand

spea

ker to (C) of

the

l

owe

r

L

terminal

s.

MONAURAL

REPRODUCTION

When

you

use

an

8-o

hm

sp

ea

ker

sys

tem

for mon-

a

ura

l

reproduction,

co

nn

ect

th

e

upper

and

low

er

16-ohm

speaker

termin

als of

your

amplifier

to

the

(+)

terminal

of

the

speaker.

Conn

ec

t

th

e

upp

er a

nd

lower (C) s

peaker

term

i-

~

0 ,O'

0'

0'

'0'

0'

0

15

~;::..,/-~-~~

P,)\,]

1'-

=~~~

'L'~t::'

L'

.~c

.;.\

~

Q;

O~

Q)

0;

C'

Q;

C e

nals

of

your

amplifier to

the

(- )

termin

al of

the

speaker.

THREE·DIMENSIONAL

STEREO·

PHONIC

REPRODUCTION

Your

AU-70

is equipp

ed

w

ith

a t

er

min

al for a

ce

nter-ch

a

nn

el amplifi

er

so

that

it can

be

used

for

three-dimensional

reproduction.

To

do

this,

connect

th

e

input

terminal

of

a

monaural

amplifier

(Either

a main

or

co

mbination

amplifier

can

be used) to

th

e pin-jack

of

the

ce

nt

e

r-chann

el o

utput

termina

l

at

th

e left

of

the

spea

ker

terminal

b

oa

rd

with

a s

hielded

wire

Th

e ce

nt

er-c

hann

el

mix

es

the

right

a

nd

l

eft

so

und

s

to

produce

the

thre

e-dimensional effect.

Speakers

suitable

tor

the

AU-70

are

20

to

30-cm

coaxial s

peak

ers

and,

for

the

best

mu

sical re

pr

o-

- 7 -

duction,

two

or

three-wa

y

speake

r systems

which

use different

speakers

for

different

fre

qu

ency

ranges.

In

c

hoo

sing

th

e

cabi

net, t

ake

acco

unt

of

ton

al

quality

in ad

dition

to

design.

CAU

TION:

If

you find

th

at

th

e so

und

s

from

both

sp

ea

kers

do

not

mix

well,

but

l

ea

ve a

sort

of

vac

uum

midway

be

tw

een

th

e

spea

kers, you

ca

n conclude

th

at

th

e amplifier and

the

speake

rs

do

not

ma

tch

in

polarity

(phase).

In

such a case, reverse the

(+)

and

(-)

co

nn

ect

ions

of

e

ith

er

spea

ker.

Wh

en

you

use

two

pairs of

spea

kers for stereo-

phonic

re

prod

uction,

mak

e s

ur

e

th

at

the

spea

k

er

output

te

rmina

l

connections

do

not

cause

con

t

act

between

Rand

L a

nd

that

the

terminals

are

con

nected

prop

e

rly

.

If

th

e

connect

ions

are

faulty,

yo

ur

amp

lifier will

not

wo

rk

normally

and m

ay

also

go

o

ut

of

order.

i Pl

ayer

(magnetic)

P

layer

(c

rystal)

RECORD

PLAYER

1.

Connect

th

e o

utp

ut

te

rmi

na

ls to

th

e

"PHONO-

R"

and

"

PHONO-L

"

terminals

(

in

the

case

of

mon

a

ur

al

reprodu

ction, to

eithe

r

of

th

ese

terminals)

on

the

back

of

your

amplifier

with

sh

ield

ed

wires.

2.

Set

the

ca

rt

ri

dge

switch

on

th

e

back

of

your

amp

li

fier to

"MAG"

or

"X

-TAL

"

according

to

the

type

of yo

ur

ca

rtridge.

3.

Connect

the

power-

cord plug

of

the

player

to

the

power

plug r

eceptacle

on

the

back

of

yo

ur

amplifier.

MICROPHONE

Connect

th

e m

ic

r

ophone

to R

or

L of

the

"M

I

C"

te

rminals

on

the

back of yo

ur

amplifier.

When

you use

two

micr

ophones,

connect

olle to

Rand

the

other

to L.

, "

Microphone

8 -

CARTRID

GE

SWITCH

S

et

this

to MAG

or

X·

TAL

dep

end

.

ing on

your

pla

yer

car

tridge

(

ma

gne

tic

or crys

tal

)

,

'.

CONNECTIONS

TUNER

You

can

listen

to

broad

casts eas

il

y

by

c

onnecting

your

amplifier

to

a

tuner

and

MPX

adapt

or.

A)

STEREO

TUNER

Conn

ect

tun

er

output

to the

Rand

L "T

L:N

ER"

te

rmina

ls on the back

of

yo

ur

am

pi

i

fie

r.

8)

MONAURAL

TUNER

Co

nn

ect

tun

er

output

to either R

or

L of the

"Te

NER'

- te

rminal

s

on

the back of yo

ur

amplifier.

C)

FM

MONAURAL

TUNER

AND

FM-M

PX

ADAPTOR.

Con

nect

monaur

al

tu

n

er

outjJut

to

the input

te

rmin

al of the

F:\l-'\lPX

adapt

or a

nc!

connect

R

an

d L

of

t

he

adapt

or o

utput

te

rmin

als to R

AM

/

fM

/

MPX

TU

NER

(SANSUI

TU·70)

and

L, respecti\'ely, ot the "

AUX"

terminals on

th

e back of yo

ur

amplifie

r.

TAPE

RECORDER

1.

SINGLE

-

CONNECTION

TAPE

RECORDER

(

DIN

STANDARD

SPECIFICATION

):

Connect the "

in

,

ld

e-c

onn

ection connec

tor

to t

he

"TAPE-I\E

C ' receptacle on the back of

your

amplifie

r.

2.

PIN

-

JACK

TA

PE

RECORDER

a) Rec

or

d

in

g

Con

nect the

tap

e rel'

or

cie

r i

nput

ternlina

is

to R

and L (R

or

L in th e l'ase of monaural opera-

ti

on) of the

"REC

" te

rmin

als on the back

of

yo

ur

ampli

fie

r \

\'i

th shiel

de

d wires,

b) Pl

aybac

k

e

CENTER

Ii

rI

Q

It

o

16"

eQ

C

•

"CHANOllT

Ii

~

~

G).

fM

TUN

ER

(B)

or

(C)

MPX

ADAPTOR

(C)

9 -

Conn~ct

the

tape

reco

rder

output

termin

al

(

"LINE"

) to

Rand

L (R

or

L in

the

case

of

monaural

operation

)

of

the

"TAPE

MON"

terminal

s

on

the

back

of

y

our

amplifier.

3. Playing tapes

on

the tape deck

Connect

the

tape

deck

output

terminals

to R

and

L

(R

or

L

in

the

case of

monaural

opera-

tion) of

the

"TAPE

HEAD

"

terminals

on

the

back

of

your

amplifier.

4. Monitoring with a three-head tape

re-

corder

a)

Single-connection

tape

recorder

Connect

the

single-c

onnection

"T

APE-

REC"

receptacle

on

the

amplifier.

b)

Pin

-jack

tape

recorder

Tape-deck

plug

to

the

back

of

your

-

10

-

Connect the tape reco

rder

input

te

rminals

to R

and

L (R

or

L in

the

case

of

monaural

opera-

tion

)

of

th

e "REC" te

rminals

on

the

-

back

of

your

amplifier. Also, c

onnect

the

tape

recorder

o

utput

terminal

"

LINE

" to

Rand

L

(R

or L

in

the

case of

monaural

operation

)

of

the

"

TAPE

MON

"

termin

als

on

the

back

of

your

amplifier.

•

CENTER"

..

Q •

o

I~

Bll

~

"CHANOllT

..

D

~

G).

SWITCHES

AND

CONTROLS

CD

POWER

INDICATOR

T his

lights

up

yvhen

power

is

being

sup-

plied.

It

remains

on

whi

le

the

amplifier

is

in

oper

ation.

@

HEADPHONE

JACK

When

you

want

to avoid

disturbing

others

or

when you use

the

ampl

ifier

as

a

monitor,

co

nnect

h

ead

phon

es to this jack. You

can

still

enjoy

s

tereophonic

reprodu

ction

through

the

h

ea

d

phone

s.

For

thi

s

pur-

pose, you can use any type of

headphones

or

earphones

if

its plug fits

into

the

jack.

But

use dynamic

headphones

designed

for

stereophonic

reproduction,

if

possible.

@

SPEAKER

(

SPEAKER

OFF)

When

you

use

headphones

with

the

head-

phone

jack,

set

this

switch

to

"OFF

" to

cut

off

sound

to

the

speakers

.

This

feature

enables

you

to

enjoy

stereophonic

repro-

duction

without

disturbing

others.

@

PRESENCE

If

the

Tone

Control

al

one

is used

for

bass

com

pensat

ion,

slightly

higher

frequencies

are

compensated

at

the

same

time.

To

avoid

this,

turn

this

switch

"ON"

_

This

sets

the

turnover

at

150 cps,

changing

speaker

damping

and

frequency

re

s

ponse

ch

ara

cteristics

to

compensate

bass.

As

a

resu

lt, all s

ounds

become

impressive

and

you

can

enJoy clear, m

ag

nifice

nt

bas

s.

@

POWER

This

switch

is used f

or

connecting

and

disconnecting

the

power

supply.

Push

the

.

button

for

poweL

Pu

sh it

again

to

shut

it

off_

The

switch

also

activates

and

de

-

activates

the

power

-

supp

ly

plug

recept

acles

on

the

back

of

the

amplifieL

CD

HE"O

PHON

®

POWER

®

@

@

ow

..

TER

-

11

®

OUTPUT

LEVEL

METERS

Th

e

right

and

left

meters

indic

ate

the

out:

put

l

eve

ls of

th

e

right

and

left sp

eake

rs,

re

spectively.

Since

output

is s

hown

se

par

ate

ly for

each

c

hannel

,

the

met

e

rs

provide

easy

balance

adjus

tment.

Besides,

you

ca

n

wat

ch c

hang

es

in

th

e o

utput

of each

channel

dur

i

ng

ope-

ration

.

Each

meter

can

be

set

to

any

of

th

e

thr

ee

range

s of 5, 10

and

25

watts

by

means of

th

e

output-

level

meter

s

witch

on

the

back of the amplifieL

Choose

th

e

a

ppropriat

e

range

according

to

th

e

output

YOU

want. \

'-h

en the

"MODE

"

sw

itch is set

io

R (or L), the

meter

for L (or R)

does

not \york.

(J)

LOUDNESS

\\

-

hen

so

und

\'olume

is

at

a low level,

you

ieel

as

if

bass and

treble

are missing.

In

such a case,

turn

this

switch

"ON

" to

compensate

bass

and

treble.

Th

is will

mak

e you f

ee

l

as

if

you

were

present

at

an

ac

tual concert,

@

LOW

FILTER

(for eliminating

low-frequency

noise)

.

Turn

this

5w

it

ch

"ON

" to reduce

phono

"

motor

and

other

unplea

sa

nt

low-frequency

nOI

ses.

®

HIGH

FILTER

(for eliminat-

ing high-frequency

noise)

Turn

this sw

it

ch

"ON

" to reduce relatively

high-frequen

cy noise, such as

the

sc

ratch

from

rec

orel

s

made

of

poor

mat

erial

or

noise

du

e

to

fluoresce

nt

lamp

s in

th

e

case

of

th

e

tun

er.

@)

TONE

DEFEAT

Turn

this

sw

it

ch "

ON

" to

open

the

tone

co

ntrol

circuit

s_

Then

th

e fre

qu

en

cy

re-

s

pons

e c

ur\'

e of

the

amp

lifier wi

ll

be

co

me

perfectly flat.

,

1

®

TAPE

MONITOR

vVh

en

you

mak

e record

in

gs

with

a

thr

ee

-

he

ad

tape

record

er,

turn

this

sw

itch

"ON"

to use

th

e

am

pI

ifi

er

as

a

mon

itor.

Then

th

e s

ounds

rec

ord

ed on

th

e

tape

are re-

pro

duced while

yo

u

are

reco

rding.

Keep

th

is switch "

ON

"

when

you play

the

t

ape

on

the tap

e

.recorder.

Be s

ure

to k

eep

th

e

~\\"itch

"OFF"

othe

r-

wIse.

@

BALANCE

Th

is

knob

is used to adjust

the

balan

ce of

volume

be

tw

ee

n

the

right

and

left

spea

kers

for

the

best ste

reoph

on

ic

e

ff

ect.

J\

,

1ake

the

adjustment

while

watching

th

e o

utput

l

eve

l

met

ers

and

li

s

tening

to

the

so

und

s of

both

spea

kers

. \\Then

the

amplifier is

adjusted

pr

ope

rly,

yo

u feel as

if

th

e so

und

co

mes

fr

om a

point

midway

between

th

e

two

spea

kers.

@

BLEND

Thi

s

knob

permits

continuous

shift

from

stereo

phoni

c to

monaural

reproduction

.

Turn

it co

unter-clo

c

kwi

se to

brin

g repro-

du

ction closer to

monaural

(

R+L).

For

co

mp

l

ete

mon

aural re

produ

ction,

turn

it

as

far

co

unter-

c

lo

c

kwi

se

as

possible.

Th

e so

und

s of the

righ

t and left sp

ea

kers

beco

me

sepa

rated \"hen you

turn

th

e

knob

cl

oc

kwi

se (R

and

L pe

rform

th

eir respec

tive

functions) .

Th

e best ster

eop

honic effect is

obtained

when you

turn

it

as

far

as possible_

@)

BASS

and

@

TREBLE

for L

Th

ese control the tone of

the

left

spea

ker.

@

BASS

and

®

TREBLE

for R

These

control

the

ton

e of

th

e

right

speaker.

@

®

@

-12

-

@)

VOLUME

Thi

s

knob

is used

to

co

ntrol

th

e

volume

of

the

tuner

, rec

ord

s

and

tap

es.

Turn

it

clockwise for

louder

reprodu

ct

ion.

To

redu

ce

th

e

\'01

ume,

turn

co

un

ter-clockwise.

@

SELECTOR

(input-selector)

TUNER:

For

receiving

bro

a

dca

sts

through

the

tuner.

PHONO:

For

playing reco

rd

s.

MlC:

For

us

in

g a mic

roph

one,

TAPE

HEAD

:

For

playing

tapes

on

th

e

t

ape

c1

eck

(directly

from

the

tape

head).

AUX

:

For

r

epro

du

cing \'oice

input

or

u

si

ng

the

MPX

adaptor.

@

MODE

(Stereophonic/

monaural switch)

Thi

s s

wit

ch is used to shift

from

s

ter

eo-

phoni

c · t6

mon

a

ur

al re

produ

ction

or

vIce

versa

.

STEREO:

Set

the

switch

at

this po

si

tion

for

stereo

reproduction.

Signa

ls f

ed

int

o

A come

out

of

A's

s

peak

er

and

tho

se fed

into

B come

out

of

B

's

sp

ea

ker.

STEREO-

REV

:

Thi

s position, too, is for

stereo

reproclu

ct

ion.

But

signals fed

into

A

come

out

of

B'

s s

peaker

a

nd

tho

se fed

into

B come

out

of

A's s

peak

er.

Choose

this position

when

th

e rig

ht

and

l

eft

are

r

e\'e

rsed

in

r

ep

rodu

ct

ion.

L+ R:

Signals

fed into

Land

H.

are

bl

e

nd

ed

into

one (L+ R)

in

the

amplifier befor

e

th

ey

come

out

se

paratel

y

from

Land

R.

Signals

f

ed

into A

and

13

become

A+B

in

th

e amplifier

and

come

o

ut

of

the

spea

kers

of

A

and

13

in

the

form

of

tb

e

co

mbined

so

und

A+B.

R (Mono R

):

Signals fed into A come

out

of

A's

and

B

's

sp

ea

kers. Use this pos

i-

tion for

reprodu

cing

mono

broad

casts

and

tape

s.

L (Mono L):

Signals

fed

into

B co

me

out

of

A's

and

B's sp

ea

ker

s.

Thi

s position is rarely u

secl

.

OPERATIONS

RECORD

PLAYING

1.

Set

the

"SELECTOR"

switch

at

"

PHONO".

2.

Set

the

"MODE"

sw

it

ch

at

"

STEREO

"

or

"S

T EREO-

REV

"

(at

R

or

L in case of mon-

aura

l

operat

ion

).

3.

Sw

itch on

th

e player, put

on

a record

and

adjust

the

numb

er of

revolutions

as

ne

cessa

ry

before placing

th

e

pickup

on

th

e record.

4.

Balance

the

so

und

s from

both

s

peakers

by

me

ans of

the

"BALANCE"

knob

while

wat

c

hing

the

output

level meters.

.

5.

Adju

st

the

amount

of

sound

by

means

of

the

"VOLUME"

knob.

Other

adjusting

knobs

and

switches

can

be used to

get

the

most

satis-

factory

repreduction

.

When

you play a

monaural

record

on

a

stereo

record player, follow

the

same

procedure

as

for stereo

re

cord

s.

Thi

s will

give

you

better

re

sults.

Catridg

es

are

either

ma

gn

et

ic

or

crystal. Both

can

be used

with

the

AU-70,

but,

if possible,

use a

magnetic

type for

the

highest

fidelity.

If

you feel

that

right

and left

are

r

eve

rsed

when

playing a st

ereo

record,

turn

the

"MODE"

switch to

"STEREO-REV".

To

balance

th

e

sound

s from

both

speakers, play a monaural

record in

the

sa

me

way

as

a stereo record

an

d

adjust

the

"BALANCE"

switch in such a

way

that

you feel

th

at

the sound co

me

s from a

point

midway

between

the

rig

ht

and left speakers.

In

this

case, you can

count

on

th

e

output

l

eve

l

meters

for a

rough

det

er

mina

ti

on of

the

balance.

Also,

make

sure

that

th

e

"BLEND"

knob

is

kept

at

the

point

wh

ere it ca

nnot

be

turn

ed

clockwise

any

further.

When

you supply

power

to

the

player

from

the

power-plu

g receptacle on

th

e back of

your

amplifier,

do

not

fo

rget

th

at

the

player

is

sw

itch-

ed off

when

you

switch

off

th

e

amp

lifier.

BROADCASTS

In

the case of A and B above:

1.

Set

the

"SE

LE

CT OR" switch

at

"TUNER"

.

2.

Set

the

"MO

DE

" switch

at

"STE

RE

O"

or

"STEREO-REV"

in

the

case of A

and

at R

or

L (according to

the

cha

nnel

selected) in

the

case of

B.

3.

Tun

e in

with

th

e

tun

er.

4.

Use

other

adjus

ting

knob

s

and

switches

to

get

th

e

mo

st

sa

ti

sfac

tor

y performance.

In

the

case of C

1.

Set

the

"SELECTOR"

s

witch

at

"AUX"

2.

Set

th

e

"MODE"

switch

at

"STEREO"

or

"STEREO-

REV".

3.

Tune

in

with

the

tuner.

4.

Prepare

th

e

FM-MPX

adaptor

for

stereophonic

re

ception.

5.

Use

other

adjusting

knobs

and

switches

to

get

the

most

sa

ti

sfac

tory

performance.

When

you use a

tun

er

or

FM-MPX

receiver, read

th

e

instru

ctions for

th

em carefully.

There

should

be no mistakes in co

nne

ctions

and

operation.

When

you usc o

ur

T U-70, follow

the

instruction

s

for

A.

Wh

en you use

an

FM-tuner

(without

Multiplex)

and

MP·2,

fo

ll

ow

the

instructions

for

C.

USE

A

MICROPHONE

You can use

microphones

with

yo

ur

AU-70

amplifier.

Any

hig

h-imp

e

dan

ce (50 kilo-ohm)

crystal, dynamic or velocity mic

rophone

is accept-

able.

1. Set

th

e

"SELECTOR"

switch

at

"MIC".

2.

Set

th

e

"MO

DE

" sw

itch

at "

STEREO"

(when you use only

one

micro

phone

for

ste

reo-

ph

onic effect)

at

R (when you use

only

one

microphone

for

mo

naural

reproduc

ti

on),

or

at

L+ R (w

hen

you mix

two

different

pro-

-

13

-

gram

sources from

tw

o

mi

c

rophon

es.)

3.

During

stereophoni

c

operation,

you can use

the

"BLEND"

knob

for

mixing

purposes.

4.

Other

adjusting

knob

s

and

switches can be

used for

the

mo

st satisf

ac

tory reproduction.

Remember

that

yo

ur

AU·70

accepts only high-

i

mpedance

micr

ophones. You

canno

t

get

the

best

perform

ance if you use too long micro-

phone

cord,

whi

ch causes \'arious

problems

and

re

du

ces treble. ·

Your

amplifier

ha

s separ

ate

tone'

co

ntr

ols for

right

and

left speaker

s.

You will find this

feature

very

useful

wh

en you use

one

micro-

phone

for

musi

c

and

a

noth

er

for voice.

Furth

er

-

more, it gives added

\,

ersatility to yo

ur

amplifier,

particularly

wh

en you record on

tape

what

is

pic

ked

up

by

microphones.

RECORD

AND

PLAY

TAPES

Your

AU·70

can be sed

with

a

tape

recorder

for

recording

and

pl

aybac

k

and

can also

play

tapes on

th

e

tape

deck.

If

you use a

thre

e

·h

ead

t

ape

re

co

rder

whi

ch

ha

s separ

ate

record

and

playback

heads

, you

can

make

reco

rding

s

while

li

sten

ing to a

repr

oduc

ti

on

of

the

recordings

.

In

oth

er

words, yo

ur

amp

lifier

can

be us

ed

as

a

monitor

which

lets you

know

th

e

quality

of

your

recordin

gs

while

th

ey are

being

made

..

RE

CORDING

Set

th

e'

"SELECTOR

" switch

at

the

prop

er

position

according

to

th

e

program

so

urce

(broad-

cas

tor

record) you

are

going

to record.

2.

Set

"MODE"

switch

at

"STEREO

" (for

s

tereophonic

recording

),

at

R

or

L (for

monaural

recording),

or

at

L+

R (for

monaural

recording

of a

stereophonic

so

ur

ce).

3.

Prepare

the

tape

re

co

rd

er for recording.

4.

Operate

the

recorder

and

amplifier

adjusting

knobs

and

switches properly.

Amplifier

adjusting

knobs

do

not affect

the

level

and

tonal

quality

of recordings,

but

only

control

th

ose

ot

the sound from

th

e spea

ker

s.

Wh

en you

record ' a broadcast

cir

record, you

can

obtain

be

tt

er results by co

nn

ecting

the

tape

. reco

rder

directly to

your

amplifier

in

stead of picking

up

th

e sound from

th

e

spea

kers with micro

phone

s.

PLAYBACK

1.

a) T

ape

deck

Set

the

"SELECTOR"

switch

at

"TAPE".

b)

Tape

recorder

Set

the "

TAPE

MONITOR

" switch

at

"ON".

2.

Set

the

tape

recorder

in

the

play position.

3.

Other

adjusting

kn

obs and switches can

be

used for

th

e most

sa

tisfactory

reproduction.

CAUTION

Wh

en you use a

Tape

Recor

der

, keeping

the

"TAPE

MONITOR

"

sw

itch

at

"ON"

the

"MODE"

switch is n

ot

operative.

If

you

wan

t to use

the

"MODE"

switch,

connect

the

recorder

o

utput

to

the

"AU

X" pin-j

ackso

n

th

e back of your amplifi

er

and

the "

TAPE

MONI-

TOR"

switch at o

ff

.

T

APE

MONI

T

ORING

To

use your

amp

lifi

er

as a

monitor

for a

thr

ee-

head

t

ape

recorder, follow

the

same procedure as

the

one

for

playing

tapes

on

a recorder. Vvhen

yo

u use a recorder,

read

the

instruction

manual

carefully to

avo

id

errors

in

connect

ion

and

oper-

ation.

U

nl

ess you use your

amp

lifier

as

a

tape

mon

i

tor

or

for playing a t

ape

with a

tape

recorder,

be s

ure

to

switch off the "

TAPE

MONITOR

" switch.

Connecting

a

tap

e reco

rder

can

be

done

by

using

either

a single-co

nnection

connector

or

by

pin-jacks.

The

single-connection

plug

conforms

with

German

DIN

standard

specifications.

It

makes

it easier

to

connect

the

tape

recorder

to

your

amplifier because it

has

a five-pin

plug

for

both

record

and

playback.

When

you

use

your

amplifier

as

a

tape

moritor,

turn

on

the

"TAPE

MONITOR

" switch if

you

want

to

hear

the

sound

you

are

recording.

-

14

-

HINTS

ON

USE

SPEAKER

POLALITY

If

the

phase

(polarity, viz.

+and-)

of

the

right

and

left

speakers

is

not

co

rre

ct, so

unds

at

the

center

of

the

frequen

cy

ran

ge beco

me

weak.

You

will particularly sense

an

attenuation

of bass.

To

ma

ke

s

ure

that

speaker

polarity is all

right

, play

a

monaural

record

on

a

stereo

record playe

r.

If

the

polarity

is

reversed you will

have

the

result

mentioned

above.

In

such a case, reverse the

polarity of

either

speaker.

(Connect

th

e - lead-

wire

to

+.)

When

both

speakers

are

thu

s

made

to

agree

in polarity, you , will feel as

if

the

so

und

comes o

ut

of a single spea

ker

placed

midway

between the

right

and

left speakers.

FUSE

The

amplifier does riot work

when

th

e fuse is

blown.

In

such a case, disconnect

the

power

cord

and

replace

the

fu

se

on

the

back of

the

amplifi

er~

Use

a 3

-ampere

fuse encased in a glass

tube.

Never

risk

the

dang

er of usi

ng

fine wire

or

a fuse of a

larger

capacity as a substitute.

If

the

fuse

has

burnt

out

because

the

amplifier

is

out

of order, locate

th

e

tr

ouble

and

repair

it before

re

pl

ac

ing

the

fuse.

The

fuse , blows if you

use

an

AC

plug receptacle

lar

ge

r

than

the

' specified

·

capacity

(SO

VA

for t

wo)_

HEAT

GENERATED

BY

AMPLI·

FIER

The

top

of

the

amplifier case becomes considerably

hot

after

many

hours

of

continuous

operation_

But

this

should

not

worry

you

because

air

vents

are

provided

on

the

top

and

back

of

the

case.

If

you

place

something

on

the

amplifier

or

put

it in a closed box,

or

keep

its

front

panel facing

Fig. 1

up, it mi

ght

go o

ut

of order.

CONNECTIONS

Wh

en you connect your

amp

lifi

er

to

a

tape

re

corder

or

tun

er,

be

s

ur

e to use an

adequately

thick shielded wires.

If

you use

untwi

sted vinyl

cord like those used for lights, you will suffer

from

hum

.

Furthermore,

do n

ot

,use a

wire

longer

th

an

2 meters

(about

6.5 ft.), bec

ause

the

lon

ger

the

co

nn

ecting

wire

is,

th

e greater the a

ttenuation

of

tr

eble beco

me

s.

For

connection to a

tuner

or

FM

adap

tor, use a

wire

1 to 1.5 m

ete

rs

(about

3.3 to 4.S ft.) long.

When

you use

the

amplifier

f

or

mo

naur

al

reproduction,

it is easier for

operation

to use

th

e

upp

er

R terminal for

connec

tion.

Be

s

ur

e to set

th

e

"MODE"

switch to the

conne

cted

ch

anne

l.

HUM

AND

HOWLING

Wh

en

you

pl

ay a

re

cord or

tap

e, you

may

some-

time

s h

ear

unpleasant

hummin

g or howling.

This

,does not

mean

th

at

y

our

amplifi

er

is defec

ti

ve.

In

mo

st cases,

hummi

ng

or howling

is

a result

of these causes:

If

you

place a r

ecord

player

0

11

or

near

th

e

speaker

box,

th

e vibrations of

th

e spea

ker

cabinet

caused

by

the

sound

waves

from the s

peaker

a

re

tran

s

mitted

to the

player

and

cause howling.

To

prevent

this, keep

the

record

player

away

from

the

speaker

cabin

et

or

put

a thick cus

hion

be-

tween

the

player

and

the

cabinet.

A low, buzzing

sound

wjll also

be

produced if you

do

not

use shielded wires for connection.

If

this

is

not

the

cause, exami

ne

the co

nnections

closely.

Make

sure

that

the

earth

and

live

end~

are

not

reversed so

th

at

the

motor

and

arm

a

re

inade-

quately

grounded.

-

16

-

CONNECT

PERLY

LEADWIRES

Fig

. 2

PRO·

Connect

leadwires properly to

the

s

peaker

an

d

oth

er

input

and

output

termin

al

s.

If

co

nnections

are

loose

or

touch

other

parts, yo

ur

amplifier will

not wo

rk

properly.

Moreover,

it

may

produce

noise.

If

you use

your

amplifier in s

uch

a

way

for a

long

time, it

ma

y eve

ntu

a

ll

y

break

down.

Fin

ally,

read

the

ins

truction

s for yo

ur

tuner

or

tape

recorder

carefully before you co

nnect

it to

yo

ur

amplifier.

LEVEL

METER

SWITCH

Thi

s

is

used to select

th

e most suitable

meter

sensitivity from

th

e

thr

ee

ranges

of 5, 10

and

25

watts.

The

variable

sensitivity is

intended

to

mak

e it easier to

watch

needle movem

en

t.

high:

up

to 5

watts

medium:

up

to 10

watt

s

lo\\':

up

to 25

watts

(maximum

o

utput)

Choose

the

approp

ri

ate

ran

ge

acco

rding

to

volume

l

eve

l you

want.

AC

OUTLET

The

AC

OlJtlets

on

the

back

panel

are

connected

or

disco

nnected

by

the

power

switch

on

the

front

panel.

The

total

capacity

is

SOV

A-30VA

and

another

50VA-

Be

sure

to

lise

them

within

the

limit.

WHERE

TO

BE

PLACED

The

amplifier should be installed to

the

place

as

given

below:

1.

Easy

to

ground;

2.

Floor

not

vibrated;

3.

Not

wet

and

dusty;

4.

Not

exposed to

the

sun;

5.

Well

ventilated.

-

16

-

Fig.

3

SERVICE

NOTE

Symptom

No

power

when

power

switch

is

pushed

on

Probable

Cause

1./

Defective

power

switch

.

2.

Defective

line

cord

.

Replace

.

Replace

.

What

to

Do

3.

Loose

contact

betwe

en

plug

and

socket

or

R

eco

ndition

or

re

pla

ce .

defective

plug

.

4.

Blown

fuse.

Replace

.

Power

indicator

is

lit

when

power

switch

is

pushed

on.

but;

A.

the

unit

does

not

work

at

all. 1.

Def

e

ctive

tube.

2.

Abnormal

voltage

in

tubes

and

o

ther

parts

.

B .

PNONO

and

TAPE

does

not

fu

nction.

1.

Defective

head

amplifier

(

transistor

section

).

2.

Defective

selector

switch.

3.

Loose

contact

or

short

-

circuit

between

input

terminal

and

pin

-

jack

.

4.

Defective

record

pla

ye

r.

tape

recorder.

or

others.

connected

to

the

unit.

5.

Defective

coupling

condenser

.

C.

Weak

sound

on

AUX

. 1.

Abnormal

voltage

in

power

circuit

and

PHONO

and

TAPE

.

other

parts.

A.

Normal

voltage

at

'

eve

ry

part

1.

Defective

fixed

resistance

.

but

weak

sound

on

AUX

2.

Short

-c

ircuit

in

ou

tput

transformer.

3.

Discharged

capacitor.

4.

Aged

tube

.

5.

Defecti

ve

slide

switch

or

selector

switch

.

I

,

If

again

blown

after

replacing.

check

power

transformer

(

T,

) &

path

condenser

(Cs,)

in

power

circuit

for

short-circuit.

Check

V

,

~

V

9

and

silicon

diodes.

Check

voltage

in

tube

and

other

parts

and

replace.

if

necessary

. If

voltage

is

OK.

check

AUX

input

circuit

and

hereafter.

Rep

l

ace

transistor

head

amplifier

unit.

Replace

or

repair

S2'20

and

/

or

S2e. S

2f

Replace

or

repair.

Replace

.

Re

plac

e

C,

and

/

or

Cs.

Check

and

repair

.

Check

R

,,~

R

,s

.

R

66~

R"

and

Compound

part

CRS01. CRS02.

Check

C

2

'

~

C

Z

"

C

a6

and

Ca,

tubular

electro

-

ly tic

capacitor

C2, . C

26

.

C.

o.

C"

.

--

-------------------+----------------

-------

------

~------------------------

--

---

I

B.

Normal

voltage

at

every

part

1.

Defective

selector

switch

.

but

weak

sound

on

PHONO

and

TAPE

. 2.

Abnormal

input

circuit

:

between

input

terminal

defective

shielded

wire

.

loose

contact

and

pin

·

jack:

3.

Defecti

ve

record

pla

y

er

.

tape

recorder

or

others.

connected

to

the

unit

.

4.

Defecti

ve

coupling

condenser.

5.

Discharged

by

pass

condenser.

-

17

-

Replace

or

repair

S

2"

S

20.

S

2e

. Sz

f.

S".

and

S

JO

Repla

ce

or r

epa

ir.

Replace

Check

C,. Cz•

C,.

C6• C,.

and

Cs.

Check

Cs.

C,.

C9•

and

C

'O

.

Symptom

A .

Distorted

so

und

on

AUX.

B.

Distorted

sound

on

PHO

NO

and

TAPE.

A .

Hum

on

AUX

.

Probable

Cause

What

to

Do

1.

Aged

tube

.

Check

V

,~

V

9

'

2.

Short

-c

ircuit

In

output

transformer

.

Check

and

repair

T z

and

T 3

3.

Defecti

ve

loudspeaker.

Replace

.

4.

Defective

record

pla

y

er.

adapto

r

or

others.

Replace

connected

to

the

unit.

l.

Defecti

ve

record

pla

ye

r.

tape

rec

order

or

Replace

.

o

th

e

rs

.

connected

to

the

unit.

2.

De

fecti

ve

tubular

elect

r

oly

tic

capacito

r.

3. Di

scon

ne

c

tion

at

fixed

resistance

.

l.

Electrol

ytic

capacit

or

di

scharged

.

2. D

efec

t

ive

tube.

Replac

e

C,

and

/

or

C2.

Chec

h

R

2

,

~

R

az

.

R•. R ,a. R

...

R

15

• R

'6

. R

17

• R'B.

R'

9.

R

zo

. R2,

and

R

22

.

Check

Ca

,.

C66

~

C'

3

.

C76~C77'

Check

V,

~

V

9.

3.

Def

ective

record

pla

ye

r.

ada

pt

or or

others.

R

ep

lac

e.

connected

to

the

unit.

4.

Hum

balancer

not

properl

y a

dj

uste

d.

Check

VR

.. a

nd

VR

".

5. Dis

connected

NF

r

esistor.

Ch

eck

RS2

and

Rs3.

B .

Hum

on

PHONO

and

TAPE.

l.

D

efec

tive

shielded

wire

and

/

or

wrong

con-

Replace

a

nd

connect

correctly

nection

of

record

pla

ye

r.

tape

reco

rder

or

others

.

2.

Audio

system

and

shielded

wire

induced

from

outside

.

3.

Residual

hum

of

audio

sys

tem

co

nnected

to

the

unit.

A .

Noise

on

AUX

and

TUNER

. 1.

Fix

ed

resistor

badly

connected

or

touched

by a

nother

part

.

Keep

prop

er dis

tance

between

audio

system

and

inductor.

Replace

or

repair.

.

2.

Capacitor

nearly

short-

cir

cui

ted

or

touched

Check

C'6. C

S7

• C60 • C6, .

by

another

part.

3.

Primar

y coil

of

output

transformer

nearly

Check

T z

and

T

a.

dis

co

nnected.

4.

Defecti

ve

tube

. Check

V,

~

V

9.

B .

Noise

on

RHONO

and

T A

PE

.

1.

Fixed

resistor

defective

or

ne

a

rly

discon-

Check

R

7~

R

a2

nected.

2.

Defecti

ve

capacitor.

Check

C

,~ClO

3.

Noise

or

bad

connection

of

audio

system

Replace

or

repair

connected

to

the

unit.

---

18

-