Marantz SM-8 User manual

MARANTZ

DESIGN

AND

SERVICE

Using

superior

design

and

selected

high

grade

components,

MARANTZ

company

has

created

the

ultimate

in

stereo

sound.

MARANTZ

INTERNATIONAL

Only

original

MARANTZ

parts

can

insure

that

your

MARANTZ

product

will

continue

to

perform

to

the

specifications

for

which

it

is

famous.

Parts

for

your

MARANTZ

equipment

are

generally

available

to

our

National

Marantz

Subsidiary

or

Agent.

ORDERING

PARTS:

Parts

can

be

ordered

either

by

mail

or

by

telex.

In

both

cases,

correct

part

number

has

to

be

specified.

The

following

information

must

be

supplied

to

eliminate

delays

in

processing

your

order:

.

Way

of

shipment

Onhwn

.

Complete

address

.

Complete

part

numbers

and

quantities

required

.

Description

of

parts

.

Model

number

for

which

part

is

required

Vestdijk

9

5600

MD_

Eindhoven

The

Netherlands

Phone:

+31/40.758290

.

Signature:

any

order

form

or

telex

must

be

signed

otherwise

such

part

order

will

be

considered

as

null

and

void.

PARTS

ORDERING

Parts

may

be

ordered

at

the

following

addresses:

AUSTRIA

MARANTZ

Hietzinger

Kai

137a

1130

Wien

BELGIUM

SVD

DIVISION

MARANTZ

Industrialaan

1

1720

Groot-Bijgaarden

Beigium

Telex:

24466

CHILE

MARANTZ

DIVISION

OF

PHILIPS

S.A.

AV.

Santa

Maria,

0760

Casilla

2687

Santiago

Telex:

240.239

DENMARK

MARANTZ

Horsvinget

5

2630

Tastrup

NORWAY

MARANTZ

Postboks

7034

Assiden

3007

Drammen

FRANCE

MARANTZ

FRANCE

4

Rue

Bernard

Palissy

92600

Asniéres

France

Telex:

611651

GERMANY

MARANTZ

GERMANY

GmbH

Alexanderstrasse

1

2000

Hamburg

Germany

THE

NETHERLANDS

Elpro

Marantz

Wint

Hontlaan

28

3526

KV

Utrecht

The

Netherlands

Telex:

4748

SWEDEN

MARANTZ

Box

1324

171

25

Solna

FINLAND

MARANTZ

Kuortanegatan

14

00520

Helsingfors

52

GREAT

BRITAIN

MARANTZ

HiFi

U.K.

Ltd

Kingsbridge

House

Padbury

oaks

575-583

Bath

Road

Long

ford

Middlesex

UB7

OEH

Faxnr.:

0753

680

428

GREECE

SHERTON

ELECTRONICS

S.A.

P.O,.Box

21025

Hippocratus

Street

188

Athens

11471

Greece

Telex:

216.795

JAPAN

MARANTZ

JAPAN,

Inc.

35-1,

7-chome,

Sagamiono

Sagamihara-shi,

Kanagawa

Japan

KUWAIT

AL

ALAMIAH

ELECTRONICS

Ussama

Building

Fahd

al

Saleem

Street

P.O.Box

23781

Safat-Kuwait

Telex:

22694

Telefax:

+31/40.75.82.99

Telex:

35000

PHTC

NL

routing

IND

NLMTFAT

ITALY

MARANTZ

ITALIANA

S.P.A.

Via

Chiese,

74

20126

Milano

Italy

SAUDI

ARABIA

AL

ALAMIAH

ELECTRONICS

P.O.Box

5954

University

Street

Riyadh

11432

Saudi

Arabia

Telex:

401530

SOUTH

AFRICA

MARANTZ

DIVISION

OF

PHILIPS

S.A.

Main

Road

Martindale

P.O.

Box.

58088

Newville

21114

South

Africa

SPAIN

Euroservice

S.A.

Bernardo

obrégon,

26

28012

Madrid

faxnr.:

3412

306

198

SWITZERLAND

MARANTZ

Technischer

Service

Duenstrasse

3

3186

Didingen

Switzerland

TURKEY

DOGRUOL

Ltd.

LM.C.

6

Blok

N°6310

Unkapani

Istanbul

Turkey

Telex:

22085

MALTA

CACHIA

&

GALEA

Republic

Street,

68D

Valetta

Telex:

1682

PORTUGAL

MARANTZ

Divisao

philips

S.A.

service

Outurela-carnaxide

2795

LinDA-A-VELHA

Telex:

43906

All

of

the

above

locations

are

fully

equipped

to

take

care

of

your

total

service

needs.

Because

various

countries

have

differing

configuration

requirements,

it

is

necessary

that

you

contact

the

service

facility

in

your

particular

country.

In

the

event

that

there

is

no

service

location

listed

for

your

country,

please,

contact

the

nearest

facility

for

the

necessary

In

case

of

difficulties,

do

not

hesitate

to

contact

the

Technical

Department

at

abovementioned

address.

assistance.

MARANTZ

MODEL

Sm-8

STEREO

POWER

AMPLIFIER

wenan

eran

cul.

INTRODUCTION

This

service

manual

was

prepared

for

use

by

Authorized

Warranty

Staions

and

contains

service

information

for

the

Marantz

Model

Sm-8

Stereo

Power

Amplifier.

Servicing

information

and

voltage

data

included

in

this

manual

are

intended

for

use

by

knowledgeable

and

ex-

perienced

personnel

only.

All

instructions

should

be

read

carefully.

No

attempt

should

be

made

to

proceed

without

a

good

understanding

of

circuitry

operation.

The

parts

list

furnishes

complete

ordering

information.

Most

replacement

parts

should

be

ordered

from

the

Marantz

Company.

However,

a

simple

description

is

included

for

parts

which

can

be

obtained

locally.

1.

SHOCK,

FIRE

HAZARD

SERVICE

TEST

CAUTION:

After

servicing

this

appliance

and

prior

to

returning

to

customer,

measure

the

resistance

between

either

primary

AC

cord

connector

pins

(with

unit

NOT

connected

to

AC

mains

and

its

Power

switch

ON),

and

the

face

or

front

Panel

of

product

and

controls

and

chassis

bottom.

Any

resistance

measurement

less

than

1

Megohms

should

cause

unit

to

be

repaired

or

corrected

before

AC

power

is

applied,

and

verfied

before

return

to

user/customer.

Ref.

UL

Standard

No.

1270.

Para.

66.

3.

D

(Mandatory

Test

after

servicing

Electrical

Appliances,

effective

7-1-83).

2.

FEATURES

@

High

power

—

120W

x

2

of

dynamic

“Marantz”

sound

From

the

line

input,

the

audio

signal

passes

to

the

dual

FETs

in

the

buffer

amp

and

then

to

the

first

stage

which

is

a

differential

amplifier

using

dual

transistors.

One

side

of

this

differential

output

is

phase

inverted,

while

the

output

of

the

buffer

amp

passes

to

a

pure

push-pull

amplifier

which

drives

the

final

output

stage.

The

power

amplifier

stage

uses

newly

developed

super

high

fT

power

transistors

in

parallel

three-stage

Darlington

connection.

This

makes

possible

handling

high

currents

with

sufficient

heat

radiating

capacity.

TABLE

OF

CONTENTS

SECTION

PAGE

INTRODUCTION)

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EQUIPMENT

REQUIRED

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SERVICING

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8.

DIAGRAM

AND

COMPONENT

LOCATIONS

.............0..

0c

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eens

6

8.1.

Voltage

Amp.

Assembly

(P700)

Schematic

Diagram

and

Component

Locations

...........

6000

ee

eee

6

8.2

Speaker

&

Meter

Switch

Assembly

(PSOO)

Schematic

Diagram

and

Component

Locations

.............+5

6

8.3

ASO

Protector-Assembly

(PNOO)

Schematic

Diagram

and

Component

Locations

............05

000008

7

8.4

A-B

Power

Switch

Assembly

(PKOO)

Schematic

Diagram

and

Component

Locations

..............+-+--

7

8.5

Power

Amp.

Assembly

(P600)

Schematic

Diagram

and

Component

Locations

.............0000ee0ee

8

8.6

Output

Network

Assembly

(PWOO)

Schematic

Diagram

and

Component

Locations

..............20005

8

8.7.

Test

Point

Assembly

(PJOO)

Schematic

Diagram

and

Component

Locations

..........0.0.

0000

ee

eee

8

8.8

Meter

&

Supply

Assembly

(PX00)

Schematic

Diagram

and

Component

Locations.............2.0080%

9

8.9

A-B

Detector

Assembly

(PLOO)

Schematic

Diagram

and

Component

Locations

.............00-2e00%

10

8.10

Connection

Assembly

(PP00)

Schematic

Diagram

and

Component

Locations

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

000028088

10

9.

EXPLODED

VIEW

AND

PARTS

LIST

.....

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(ELECTRICAL

PARTS

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11.

TECHNICAL

SPECIFICATIONS

.......

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12.

SCHEMATIC

DIAGRAM

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24

Masts

@

Class

A

—

Class

AB

automatic

switching

circuit

3.

P.W

BOARDS

Quarter

A

allows

the

main

amplifier

to

operate

as

a

pure

class

A

amplifier

for

outputs

of

up

to

30W,

which

is

a

quarter

of

the

rated

output

120W

at

8Q,

at

the

switch

to

class

AB

for

outputs

larger

than

30W.

The

transition

from

class

A

to

class

AB

or

vice

versa

is

carried

out

by

switching

the

bias

current

and

the

power

supply

voltage.

As

can

be

seen

from

the

circuit

diagram

the

chassis

of

Mode

Sm-8

consists

of

the

following

units.

Each

unit

mounted

or

a

printed

circuit

board

is

descrided

within

the

square

enclosed

by

a

bold

dotted

line

on

the

circuit

diagram.

The

automatic

switching

circuit

monitors

the

input

volt-

1.

PowerAmp.

.......

mounted

on

P.W.

Board

P60C

age

of

the

main

amplifier

and

the

output

current

of

the

2.

Voltage

Amp.

.....-

mounted

on

P.W.

Board

P70C

speaker

in

order

to

detect

output

transitions.

Note

that

3.

Test

Point.........

mounted

on

P.W.

Board

PJOC

the

use

of

a

phase

correction

circuit

inside

the

detector

4.

A-B

Power

Switch.

..

.

mounted

on

P.W.

Board

PKOC

prevents

waveforms

including

those

with

a

steep

rising

5.

A-B

Detector.......

mounted

on

P.W.

Board

PLOC

edge

from

being

distorted.

The

automatic

switching

6.

ASO

Protector

......

mounted

on

P.W.

Board

PNOC

circuit

can

be

easily

used

for

amplifier

configurations

7.

Connection

........

mounted

on

P.W.

Board

PPOC

uniquely

designed

by

Marantz

by

merely

connecting

the

8.

Speaker

&

input

of

the

detector

to

the

signal

system.

Meter

Switch

.......

mounted

on

P.W.

Board

PSOC

9.

Output

Network.....

mounted

on

P.W.

Board

PWOC

10.

Meter

&

Supply

.....

mounted

on

P.W.

Board

PXOC

@

Large-sized

peak

power

meter

of

the

logarithmic

com-

pressed

type

Large-sized

power

meters

that

are

suitable

for

high

quality

power

amplifiers

are

available.

This

power

meter

can

be

used

to

check

the

output

level

and

the

balance

between

the

right

and

left

channels.

It

operates

by

detecting

signal

peaks,

but

it

displays

rms

values

which

directly

represent

the

outputs

of

the

amplifier

to

an

8Q

load.

In

addition,

since

a

circuit

generating

logarithmic

com-

pressed

displayes

is

used,

outputs

of

small

to

large

quantities

can

be

monitored

without

changing

the

range.

This

power

meter

can

also

be

used

as a

peak

holder

by

setting

appropriate

switches

on

the

panel.

@

Protective

circuit

which

does

not

degrade

tone

quality

The

overload

protective

circuit

detects

both

overvoltage

and

overcurrent

conditions,

while

in

the

area

of

safe

operation

(A.S.O.)

does

not

degrade

the

operation

of

the

drive

transistors.

The

protective

circuit

has

adaptable

characteristics

so

that

its

operation

does

not

interfere

with

the

program

and

its

operation

is

always

constant.

e

Plus

The

power

output

circuit

is

equipped

with

high

efficiency

heat

sinks

to

cool

the

power

transistors,

thus

providing

continuous

high

output

power.

4.

TEST

EQUIPMENT

REQUIRED

FOR

SERVICING

This

table

lists

the

test

equipment

required

for

servicing

the

Model

Sm-8

Stereo

Power

Amplifier.

Distortion

Analyzer

Distortion

measurements

Audio

Oscillator

AC

VTVM

Oscilloscope

Sinewave

and

squarewave

signal

source

Voltage

measurements

(AC)

Waveform

analysis

and

trouble

shooting

and

ASO

alignment

|

Circuit

Tester

DC

VTVM

Trouble

shooting

Voltage

measurements

(DC)

AC

Wattmeter

Line

Voltmeter

Variable

Autotransformer

(0

~

140V

AC,

10A)

Monitors

primary

power

to

amplifier

Monitors

potential

of

primary

power

to

amplifier

Adjust

level

of

primery

power

to

amplifier

Shorting

Plug

5.

ADJUSTMENT

PROCEDURES

1.

Class

B

idting

adjustment

a)

Apply

a

sine

wave

signal

of

1

to

2

VRMS

to

JL14

from

an

audio

oscillator

in

order

to

forcibly

make

it

Operate

as

a

class

B

amplifier.

b)

Adjust

RL43

and

RL44

so

as

to

give

DC

voltage

of

7

mV

at

the

JJO1-02

and

JJ03-04

test

points.

NOTE:

Carry

out

the

adjustment

one

minute

after

the

switch

is

turned

on.

After

the

set

is

stabilized,

the

voltage

should

be

27

mV

(50

mA).

2.

Class

A

idling

adjustment

a)

Disconnect

the

input

to

JL14.

b)

Adjust

RL39

and

RL40

so

as

to

give

DC

voltage

of

440

mV

at

the

JJO1-02

and

JJ03-04

test

points.

NOTE:

Carry

out

the

adjustment

one

minute

after

the

input

to

JL14

is

disconnected.

The

class

B

ad-

justment

must

be

done

first.

After

the

unit

is

stabilized,

the

voltage

should

be

370

mV

(655

mA).

3.

Comparator

balance

adjustment

a)

Connect

a

trigger

oscilloscope

to

JL14.

b)

Set

the

load

of

the

device

to

OPEN,

apply

a

signal

with

a

frequency

of

1

kHz

and

increase

it

gradually.

c)

While

observing

the

output

waveform

of

the

unit

and

pulses

at

JL14,

adjust

RL31

so

as

to

generate

two

pulses

per

output

waveform

period.

Shorts

amplifier

input

to

eliminate

noise

pickup

rae

acs

Output

waveform

+5V

|

JL14

T.P

Ov

4.

Switching

level

adjustment

a)

Connect

a

trigger

oscilloscope

to

JL14.

b)

Set

the

load

of

the

unit

to

OPEN

and

apply

a

signal

having

a

frequency

of

1

kHz

to

the

L

channel.

c)

With

the

output

set

to

15.5V,

adjust

RLOQ

so

as

to

generate

pulses

at

JL14.

d)

Apply

a

signal

to

the

R

channel

and,

similarly,

adjust

RL10.

5.

Power

meter

adjustment

a)

Set

the

load

of

the

unit

to

8Q,

apply

a

signal

having

a

frequency

of

1

kHz

and

increase

the

input

signal

to

30.9V.

b)

Adjust

the

following

so

as

to

give

a

reading

of

120V

on

the

meter.

For

the

L

channel,

adjust

R

X05.

For

the

R

channel,

adjust

RX06.

6.

VOLTAGE

CONVERSION

7.

BLOCK

DIAGRAM

@

EUROPEAN

MODEL

ONLY

OUTLET

BEFORE

CONVERTING

VOLTAGE.

™N

nd

OOOO

S

>

To

convert

the

unit

to

a

different

power

source

voltage,

oS

oe

a

is

change

the

position

as

illustrated

in

the

drawing

below.

7

CAUTION

=5

fy.

3

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=

DISCONNECT

POWER

SUPPLY

CORD

FROM

AC

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VOLTAGE

uo

ES

ea

1

a

we

-—2

<=

D

SELECTOR

oo

oa

3

1

<

oo

2a

=

'

{

t

!

t

x

|

oad

=z

Lon

'

=

'

=

©

{

[we

co

{

wey

a

!

—

oa

|

_——_—

Note

on

safety:

Symbol!

A\

Fire

or

electrical

shock

hazard.

Only

orignal

parts

should

be

used

to

replace

any

part

marked

with

symbol

A

.

Any

other

component

substitution

(other

than

original

type),

may

increase

risk

of

fire

or

electrical

shock

hazard.

8.

DIAGRAM

AND

COMPONENT

LOCATIONS

330

0729

R739

2s

(-1.69V)

(-2.08V)

7h

€65.6V)

R749

12k

8.1

Voltage

Amp.

Assembly

(P700)

Schematic

Diagram

and

Component

Locations

8.3

ASO

Protector

Assembly

(PNO0)

BrOG

VOLTAGE

ANE

LASSY.

a

Schematic

Diagram

and

Component

Locations

me

moe’

R74)

R782

4a.7k

4.7K

330

47k

|

(63.4V)

R785

33k

|

(630v)

Or"

own

cr

109780

0]

|

C67)

(2.08V)

20

P

t

Q709

S

Q713

‘E

|

3

4

le

75

ike

|

oy

am

eatin

hes

K

a7i9

C74.0V)

(620V)

CK)

R248

|

5

—O

om

O

©

ae)

©

O

~O

O

|

[oy

R738S

R742

(eD.BY,

|

4.7K

S

330

(F)

ONLY

220/100V

0718

_|

[e775

+,,100/80Vv

G3.5v)

cex00l

(¥

C777_0.001

aval

K)

R779,\.

47k

ve

167)

(2.08V)

O77)

A

KC)

aria

=p

Q710

OH

:

777

KH

:

PS

ee

x

D>

a8

‘NO

8

C4077

ey

ee

&

Or73

‘aidan

(ov)

9779

7)

c779

1000p

Q716

61.69V)

R732

A

m3

ed

J

708

UN

0720

Rr

eu)

R735

C143)

4.7K

(63.0V),

K)

R744

740

Ul

i

663.3)

656)

C7I2

0.47/00V

R

|

Q722

2/2

PSOO

8.5

Power

Amp.

Assembly

(P600)

Schematic

Diagram

and

Component

Locations

8.6

Output

Network

ilariall

wisbbeas

Schematic

Diagram

and

pompuren

Locations

|

P60O0

POWER

AMP

and

PROTECTOR

|

R6EIZ

47

wy

Kk

saa

iy

R607

|

REO!

Q603

C60!

27k

270p

623

0.047

rR

O

Oo

A

..

é

5

On

So

os

=

O

rae

O

3

5

Oo

a

5

O

A

5

O

2°

|

rf

JOS

9)

(Sw)

R626

R644

wze|

f°

cer

sas

(WQ61

9636

|

ee

(43.50)

R646

We

K)

raw

Visine

47k

er,

5s?

Q6i8

L___

3

or

A

We

y

a

nett

3

S080)

(-L46V)

2

|

jeosow

an

:

CE05UN-270V)

(-0.79V)

Q620

TT

\

oe

Bore

art

oe

2

iw

oe

R

"Sens

anmeestectonseonr

cc

ene

sreamestrit

onetime

aeenteaner

enn

22.0)

Q640

Q624

&

%&

ret

6

ov

tes”

os

8.8

Meter

&

Supply

Assembly

re:

Schematic

ee

and

Component

Locations

220780v

|

[COV

5s

leech

€74.0V)

2

[|

|

Olvliolz

ee

HO

00

OO

eee

OD

L

[

BS

of

O~

t

=

x

5

rr)

Yo

x

5S

8.7

Test

Point

Assembly

(PJ00)

Schematic

Diagram

and

Component

Locations

JJO1

JJO2

9.

EXPLODED

VIEW

AND

PARTS

LIST

8.9

A-B

Detector

Assembly

(PLO0)

Schematic

Diagram

and

Component

Locations

@

[C01-99]

Front

Panel

0058

7)

-“@

Be

Ge

QLO3-1/4

021B

,

@(U):

for

U.S.A

e

(E):

for

Europe

e(F):

for

Japan

PART

NO.

DESCRIPTION

222H063400

Front

Panel

Assembly

222H063010

Escutcheon,

Front

Panel

2461063030

Escutcheon,

Pocket

Frame

2144160020

Bracket

222H063020

Escutcheon,

Pocket

Panel

51060305A9

|

P.H.M.

Screw

P3

x5

2461271010

Holder

51042610A0

F.H.M.

Screw

F2.6

x

10

53112603A0

|

Hexagon

Nut

M2.6

51100204E0

B.H.M.

Screw

B2x4

1143259010

Bushing,

Holder

2978259110

Bushing,

Push

Switch

201H158010

|

Window,

Meter

2461063420

Pocket

Cover

Assembly

2144063410

Pocket

Cover

Assembly

2461063050

Escutcheon,

Pocket

Cover

2461253010

Handle

2461253210

Handle

2461254010

2461254020

53110303E9

Hexagon

Nut

2461107020

Sheet

][]

P

ABH

NNN

|

oa

oo

oa

a

[|=

RPRANNNA

DY

BW

ean

a

—"-

PEPNNNAHND

awa

wa

51500308Z0

F.H.

Tapped

Screw

F3

x

6

51280308Z0

B.H.

Tapped

Screw

B3

x

8

10

Marantz SM-8 User manual

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