Philips FW2017 Manuale utente

Service

Services

Service

Table

of

contents

Specification

Warnings

Connection

&

Controls

Wiring

Diagram

Power

Board

Circuit

description

Component

Layout

Circuit

Diagram

(Left

/

Right

channel)

Component

Layout

Circuit

Diagram

(Bass

stage)

Front

Panel

Component

Layout

Circuit

description

Circuit

Diagram

(Supply

part)

Circuit

Diagram

(Control

part)

Component

Layout

Source

Selector

Circuit

diagram

(Volume

part)

Component

Layout

Component

Layout

Circuit

Diagram

(LF

Selector)

CD

Unit

Circuit

Diagram

Component

Layout

Alignment

instructions

Service

Testprogramme

Recorder

Part

Circuit

Diagram

(Digital

part)

Component

Layout

Adjustment

table

Circuit

Diagram

(Analog

part)

Component

Layout

Published

by

Consumer

Electronics

Printed

in

The

Netherlands

°Copyright

reserved

Subject

to

modification

45

-

46

47

-

48

50

-

52

53

-

55

CD

Midi

System

FW2017

Tuner

Adjustment

table

Component

Layout

Circuit

Diagram

Dismantling

of

Set

Exploded

views

Front

part

Tape

Decks

Cabinet

CD

Unit

Mechanical

partslists

Front

part

Cabinet

CD

Unit

Electrical

partslists

CD

Unit

Front

Panel

Recorder

Part

Source

Selector

Tuner

Power

Board

20/21/22/25/30

ce

4

1

WOT

DIGITAL

AUDIO

page

56

57

-

58

59

-

61

62

-

63

65

-

66

69

-

70

72

71

73

-

74

75-77

78

-

80

81

-

84

85

-

86

87

-

89

CLASS

1

LASER

PRODUCT

3122

110

6420

4822

725

23707

PHILIDS

PHILIPS

CS

57

052

Specification

General:

CD

part:

Mains

voltage

:

220V

/

50Hz

for

/20, /22,

/28

Frequency

response

:

20-20.000

Hz

+2

dB)

:

240V

/

50Hz

for

/25,

/30

Output

level

:

2V23dB

230V

/

50Hz

for

/21

Signal

/noise

ratio

:

290

dB

120V

/

60Hz

for

/37

Distortion

>

$1%

at

1

kHz

Channel

difference

:

$2

dB

at1

kHz

Power

consumption

<

150W

at

maximum

output

power

Channel

crosstalk

:

50

dB

max.

<

15W

in

stand

by

De

emphasis

:

Qor

15/50

us

switched

automatically

by

subcode

on

the

disc

Tuner:

Ee

Tuning

range

87,5

-

108

MHz

522

-

1611

kHz

(not

for

/37)

148

-

284

kHz

530

-

1700

kHz

(only

for

/37)

Aerial

input

75

Q

(not

for

/17)

Frame

aerial

Frame

aerial

300

&

(only

for

/17)

4

uV

(2

wV

typ.)

3

mV/m

(1,5

mV/m

typ.)

6

mV/m

(not

guaranteed

above

250

kHz)

[ee

eas

re

Amplifier:

Output

power

:

2x20Wat8Q

0D=0,9%

(from

50

Hz

to

20

kHz)

+

1x

21W

at

42

D=0,9%

(from

30

Hz

to

120

Hz)

Music

power

:

2x

33Wat

8a

+

1x

50Wat

4a

Headphone

:

6,3mm

stereo

jack

1,4V

into

322

D<1%

Power

stage

protection

:

AC,

DC

and

Shortcircuit

Frequency

response

:

Bass

35

Hz

-

150

Hz

+

left

and

right

channel

250

Hz

-

20

kHz

(-3dB)

Tone

control

:

Bass

from

+10

dBto-10dB

+

2dB

at

100

Hz

:

Treble

from

+10

dB

to

-10dB

+

2dB

at

12

kHz

DBB

at

80

Hz

:

+10dB

at

-40dB

Input

sensitivity

:

PHONO

5,5

mV

>

AUX.

300

mV

Output

voltage

:

LINE

400

mV

Recorder

part:

Tape

speed

:

4,76

cm/s

+2%

in

Normal

Speed

:

8,55

cm/s

+12%

in

High

Speed

Wow

&

Flutter

>

©$0,3%

Winding

speed

:

$125

for

C60

cassette

Noise

reduction

system

:

Dolby

B

(Noise

Reduction

factor:

7

dB

typ.)

Erase

/

Bias

system

>

AC

80

kHz

RiF-shift

:

service

solution

on

request

Distortion

at

250

nWb/m

:

<3%

Channel

difference

atPB

:

<3dB

Channel

difference

overall

:

<3dB

Channel

separation

>:

$

20

dB

at

1

kHz

Track

separation

:

$50

dB

at

1

kHz

Frequency

response

5.8”

”

typical

value

2)

at

250

nWb/m

CS

57

053

2

1

GENERAL

CHIP

COMPONENT

SOLDER SOLDER

_—

COPPER

TRACK

P.C.B.

SERVICE

PACKAGE

WARNING

All

ICs

and

many

other

semi-conductors

are

susceptible

to

electrostatic

discharges

(ESD).

Careless

handling

during

repair

can

reduce

life

drastically.

When

repairing,

make

sure

that

you

are

connected

with

the

same

potential

as

the

mass

of

the

set

via

a

wrist

wrap

with

resistance.

Keep

components

and

tools

also

at

this

potential.

CF)

ATTENTION

Tous

les

IC

et

beaucoup

d’autres

semi-conducteurs

sont

sensibies

aux

décharges

statiques

(ESD).

Leur

tongévité

pourrait

étre

considérablement

écourtée

par

le

fait

qu'aucune

précaution

n'est

prise

a

leur

manipulation.

Lors

de

réparations,

s'assurer

de

bien

étre

relié

au

méme

potentiel

que

la

masse

de

|'appareil

et

enfiler

!e

bracelet

serti

d'une

résistance

de

sécurité.

Veiller

a

ce

que

les

composants

ainsi

que

les

outils

que

|'on

utilise

soient

également

a

ce

potentiel.

OISMOUNTING

VACUUM

PISTON

SOLDERING

4822

395

10082

e.g.

WELLER

SOLDER

TIP

PT-H7

SOLDERING

IRON

SOLDER

WICK

4822

321

40042

e.g.

A

PAIR

OF

TWEEZERS

+

B

HEATING

4

HEATING

x

SOLDERING

IRON

SOLDER

WICK

CLEANING

PRECAUTIONS

SOLDERING

IRON

HIP

Cc

COMPONENT

(0)

WARNUNG

Alle

ICs

und

viele

andere

Haibleiter

sind

empfindlich

gegen

elektrostatische

Entiadungen

(ESD).

Unsorgfaltige

Behandiung

bei

der

Reparatur

kann

die

Lebensdauer

drastisch

vermindern.

Sorgen

sie

dafiir,

dass

Sie

im

Reparaturfail

Uber

ein

Pulsarmband

mit

Widerstand

mit

dem

Massepotential

des

Gerdtes

verbunden

sind.

haiten

Sie

Bauteile

und

Hilfsmittel

ebenfalls

auf

diesem

Potential.

<>)

MOUNTING

e.g.

A

PAIR

OF

TWEEZERS

iV/p

SOLDER

@0.5-08mm

SOLDERING

PRESSURE

+

SOLDER

@0.5-08mm

SOLOERING

TIME

<3

sec/side

PRESSURE

/

SOLDERING

+

EXAMPLES

i,

ee.

SOLDERING

27

O12C12

CNL)

WAARSCHUWING

Alte

IC's

en

vele

andere

halfgeleiders

zijn

gevoelig

voor

electrostatische

ontladingen

(ESD).

Onzorgvuidig

behandeien

tijdens

reparatie

kan

de

levensduur

drastisch

doen

varminderen.

Zorg

ervoor

dat

u

tijdens

repaatie

via

een

polsband

met

weerstand

verboncien

bent

met

hetzeifde

potentiaal

als

de

massa

van

het

apparaat.

Houd

componenten

en

hulpmiddelen

ook

op

ditzeifde

potentiaal.

C1)

awerrimento

Tutti

IC

e

parecchi

semi-conduteri

sono

sensibili

alle

scariche

statiche

(ESD).

La

loro

longevita

potrebbe

essere

fortemente

ridatta

in

caso

di

non

osservaiiome

della

pits

grande

cauzione

alla

loro

maripolazione.

Durante

le

riparazioni

occorre

quindi

essere

collegato

allo

stesso

potenziakb

che

quello

della

massa

dell’apparecchio

tramit

um

braccialetto

a

resistenza.

Assicurarsi

che

i

componenti

¢

ariche

gli

utensili

con

quali

si

lavora

siano

ancht

a

questo

potenziale.

Safety

regulations

require

that

the

set

be

restored

to

its

original

condition

and

that

parts

which

are

identical

with

those

specified

be

used.

e

Les

normes

de

sécurité

exigent

que

l'appareil

soit

remis

a

|’état

d'origine

et

que

soient

utilisées

les

pieces

de

rechange

identiques

a

celles

spécifiées.

<>)

Le

norme

di

sicurezza

esigono

che

|’apparecchio

venga

rimesso

nelle

condizioni

originali

e

che

siano

utilizzati

pezzi

di

ricambiago

identici

a

quelli

specificati.

GE)

Varning!

Veiligneidsbepalingen

vereisen,

dat

het

apparaat

in

zijnoorspronkelijke

toestand

wordt

teruggebracht

en

dat

onderdeien,

identik

aan

de

gespecificeerde

worden

toegepast.

@

Bei

jeder

Reparatur

sind

die

geltenden

Sicherheitsvorsmré

ften

zu

beachten.

Der

Originalzustand

des

Gerats

darf

nicht

vean

dert

werden

fur

Reparaturen

sind

Original-Ersatzteile

zu

verwenden,

(eS)

Varo!

Avattaessa

ja

suojalukitus

ohitettaessa

olet

aittiina

nakynaattomaille

lasersateilylie.

Ala

katso

sateeseen.

Osynlig

taserstraining

nar

denna

del

ar

6ppnad

och

sparren

ar

urkopplad.

Betrakta

oj

stralen.

CS

57

054

Connection

&

Controls

bh

CS

§7

055

3.5

3.6

CONTROLS,

Fig.

1

1.1

Control

panel

of

DECK

1

(Switch

4822

276

13066)

EJECT:

to

open

the

cassette

compartment.

WIND:

fast

winding

in

the

direction

indicated.

PLAY:

to

start

playback

in

the

direction

indicated.

PAUSE:

to

pause

during

recording/playback.

STOP:

to

stop

recording/playback.

1.2

Control

panel

of

DECK

2

(Switch

4822

276

13066)

WIND:

fast

winding

in

the

direction

indicated.

PLAY:

to

start

playback.

PAUSE:

to

pause

during

play.

EJECT:

to

open

the

cassette

compartment.

STOP:

to

stop

playback.

1.3

Control

panel

of

the

CD

player

(Switch

4822

276

13066)

SKIP:

to

select

the

required

track.

PLAY/PAUSE:

to

start

playback/pause

during

play.

STOP:

to

stop

during

play.

SHUFFLE:

for

playing

ail

tracks

in

a

random

order.

OPEN/CLOSE:

to

open/close

the

CD

tray.

CONTROLS,

Fig.

2

2.1

ON/STAND

BY

button

(Switch

4822

276

13066)

To

switch

on

and

off

(stand

by).

2.2

TAPE

DECKS

-

TUNER

-

COMPACT

DISC

-

TV/AUX

buttons

(Switch

4822

276

13066)

To

switch

on

and/or

select

the

sound

source.

2.3

Control

panei

of

Tuner

and

Cassette

Deck

(Gwitch

4822

276

13066)

RECORDING:

press

(for

at

least

1

second)

to

start

recording.

DIRECTION:

to

select

the

tape

direction

(deck

1).

MODE:

to

select

continuous

playback

or

autoplay

function.

PRESET:

to

select

stored

preset

stations.

SENSOR:

infrared

receiver

for

the

remote

control

unit.

CD

SYNCHRO:

for

synchronous

starting

when

dubbing

a

CD

to

a

cassette

in

deck

1.

A.R.C.S.

(Auto

Rewind

CD

Synchro):

for

first

fast

reverse

and

then

synchronous

starting

when

dubbing

a

CD

to

a

cassette

in

deck

1.

24

VOLUME

(Potmeter

4822

102

10441,

Led

4822

130

81678)

Volume

control

with

indicator

(flashes

when

the

remote

control

unit

is

used

and

is

lit

when

the

unit

is

on

or

in

stand

by

mode).

CONTROLS,

Fig.

3

3.1

TIMER

control

panel

(Switch

4822

276

13066)

3.4

Cassette

deck

function

buttons

(Switch

4822

276

13066)

H.S.D.

(High

Speed

Dubbing):

to

dub

at

high

speed.

DUBBING:

to

dub

at

normal

speed.

CHROME:

selector

button

for

type

of

tape.

DOLBY

NR

button:

to

switch

the

Dolby

NR

(Noise

Reduction)

system

on

and

off.

3.5

Programming

buttons

for

Tuner

and

CD

(Switch

4822

276

13066)

CLEAR:

in

TUNER

mode:

to

erase

the

indicated

preset

station.

In

CD

mode:

to

erase

programmed

CD

tracks

from

the

memory.

PROG.:

to

store

preset

stations

and

CD

tracks

in

the

memory.

3.6

CD

control

buttons

for

special

functions

(Gwitch

4822

276

13066)

REPEAT:

to

repeat

all

tracks

or

a

program.

REVIEW:

to

check

a

program.

INTROSCAN:

to

play

the

start

of

all

tracks.

3.7

Sound

controls

(Potmeter

4822

101

21169)

BASS

and

TREBLE:

tone

colour

controls

to

adjust

bass

and

treble.

BALANCE:

balance

control,

to

correct

differences

between

the

left

and

right-hand

channel.

3.8

DSP

buttons

(Switch

4822

276

13066)

With

the

Digital

Sound

Processor,

you

can

select

special

sound

effects.

You

can

choose

from

PRESENCE,

HALL,

STADIUM,

LIVE

and

CONCERT.

Press

CANCEL

DSP

to

switch

off

the

Digital

Sound

Processor.

3.9

DBB

button

(Switch

4822

276

13066)

To

emphasize

bass

tones.

CONNECTIONS,

Fig.

4

4.1

Aerial

connections

AM

(4822

287

40668):

for

the

frame

aerial

supplied

for

long

wave

and

medium

wave

(LW/MW).

Aim

the

aerial

for

optimum

reception.

FM

75

Q

(4822

267

31128)

for

FM

aerial.

You

can

connect

the

auxiliary

aerial

supplied

to

this.

The

use

of

an

FM

outdoor

aerial

or

cable

aerial

is

recommended

for

good

FM

stereo

reception.

4.2

Audio

sockets

(Chinch

socket

4822

267

20373)

AUX:

input

for

connecting

a

record

player

with

a

magneto-dynamic

cartridge,

or

for

a

separate

recorder

(only

for

playback),

a

separate

amplifier

etc.

if

a

record

player

is

connected,

put

button

4.3

(4822

276

13169)

in

the

MD

position

before

switching

on

the

unit,

to

avoid

noises.

If

you

do

not

connect

a

record

player,

always

put

button

4.3

in

the

AUX

position.

TV:

input

for

TV

sound

or

a

video

recorder.

AUDIO:

output

for

connecting

a

separate

recorcler

(only

for

recording),

or

a

separate

amplifier.

TIMER:

to

set

the

start

and

stop

time

when

using

the

timer

function.

For

example,

to

make

a

recording

when

you

are

absent.

TIME:

to

set

the

time.

Then

press

SET

-

or

+

and

finally

TIME

again.

ALARM:

to

set

the

alarm

time.

Then

press

SET

-

or

+

and

finally

ALARM

again.

SET

-

and

+:

to

set

the

time

and

alarm

time.

CANCEL:

12

or

24-hour

setting

(after

pressing

TIME):

to

switch

off

4.3

MD/AUX

switch

(4822

276

13169)

Set

this

switch

to

the

MD

position

when

connecting

a

record

player

with

a

magneto-dynamic

cartridge

to

the

AUX

input

sockets.

If

you

do

not

connect

a

record

player,

always

put

button

4.3

in

the

AUX

position.

Always

switch

the

unit

to

stand

by,

before

operating

the

MD/AUX

the

timer

and

sleep

function.

button

4.3,

to

avoid

undesired

noises.

3.2

PHONES

(Socket

4822

265

20534)

Socket

for

headphones

(impedance

32

-

1,000

ohms).

When

headphones

are

used,

the

loudspeakers

are

switched

off.

4.4

VOLTAGE

SELECTOR

(4822

272

10269

not

on

all

versions)

ff

your

unit

has

a

voltage

selector,

check

that

it

is

set

to

the

local

mains

voltage.

3.3

TUNER

control

panel

(Switch

4822

276

13066)

AUTO

SCAN:

to

scan

stored

preset

stations.

4.5

MAINS

(4822

265

20291)

AUTO

PROGRAM:

to

program

preset

stations

automatically.

Socket

for

the

mains

lead.

BAND:

wavelength

selector

button.

:

TUNING:

tuning

buttons.

46

Loudspeaker

connections

SPEAKERS

8

Q

:

for

the

SATELITE

speakers.

MONO:

to

reduce

noise

when

receiving

weak

stereo

transmitters.

?

par

BASS

4

Q:

for

the

BARITONE

bass

speaker.

5

6

CS

57

056

WIRING

DIAGRAM

PR-DECK

_

REV,OECK

it

0

i

1

BROWN

GREY

8002

BLUE

|

oeAnce

|

ORANGE

ARINSTRANSFORNER

1010

BROW

BROWN

ALTE

B260(FOR/17

ONLY?

RED

ALL

PCBS

SHOKN

FROM

THE

COMPONENT

SIDE

@——

SOLDER POINT.

HANDSOLOERED

CS

57

057

VERSION

B

SLACK

3009

8015

PCBL

TUNER

HERA

C3

1001

CO-DECK

HERIPHONE

POWER

BOARD

The

output

stage

is

switched

on

via

the

voltages

+STBY

and

-STBY.

These

voltages

are

derived

from

the

voltages

+VCC1

and

-VCC1,

respectively,

and

can

be

switched

off

via

the

astable

monoflop

(TS7287,

7290).

This

astable

monoflop

has

the

task

of

switching

off

the

output

stage

in

the

event

of

a

fault

(short-circuit

or

DC

at

the

output).

if

a

brief

fault

occurs,

then

the

output

stage

will

be

switched

off

for

around

4-5

seconds

(charging

time

of

C2276

via

R3288).

In

the

case

of

prolonged

DC

voltage

at

the

output,

TS7287

will

operate

as

a

switch

(see

faults

+/-

DC

at

the

output)

and

switch

off

the

output

stage

for

the

duration

of

the

fault.

Without

fault

is

the

state

of

the

monoflop

whereby

TS7290

is

conducting

and

is

blocking

transistor

7287

via

R3291.

As

a

result,

the

collector

of

TS7287

is

HIGH

(approx.

+11V).

Via

R3286

the

base

of

TS7280

also

becomes

HIGH

and

switches

the

latter

through.

This

causes

TS7279

and

7282

to

block.

Transistors

7278

and

7283

are

conducting

and

switch

through

the

voltages

+STBY

and

-STBY

respectively.

Faults:

+DC

at

the

output:

Via

D6287

a

positive

voltage

arrives

at

the

base

of

TS7287,

causing

the

collector

of

TS7287

to

become

LOW.

TS7280

blocks.

Via

the

potential

divider

R3279/R3281

a

voltage

of

approx.

1V

presents

itself

at

R3281.

The

result

is

that

a

voltage

of

approx.

0.7V

lies

on

the

base

of

7S7279

and

the

emitter

of

TS7282

respectively.

The

transistors

switch

through

and

thus

block

TS7278

and

7283.

The

voltages

+STBY

and

-STBY

are

not

switched

through

and

the

output

stage

is

not

operative.

-DC

at

the

output:

Via

D6290

a

negative

voltage

arrives

at

the

base

of

TS7290,

causing

it

to

block.

At

the

collector

of

TS7290

there

now

reside

around

+20V.

TS7287

is

switched

through

via

R3291,

causing

the

collector

of

TS7287

to

become

LOW.

TS7280

blocks

and

switches

the

unit

to

standby.

+/-DC

pulse:

Normally,

there

are

around

3V

DC

at

C2276.

If

TS7287

is

now

brought

into

conductance

by

a

pulse

(+DC

across

D6287,

-DC

across

D6290/TS7290),

then

the

end

of

the

elco,

which

had

previously

been

charged

to

+11V,

is

suddenly

on

earth.

As

the

other

end

of

the

elco

was

around

3V

more

negative,

a

negative

voltage

now

lies

at

the

base

of

TS7290

and

blocks

it.

Consequently,

around

+20V

reside

at

the

collector

of

TS7290.

The

+voltage

arrives

at

the

base

of

TS7287

via

the

potential

divider

R38291/

R3274+3249

and

keeps

it

in

conductance.

Meanwhile

C2276

is

charged

via

R3288.

After

4-5

seconds

the

voltage

at

C2276

has

risen

so

far

that

transistor

7290

is

switched

through

again

via

R3289,

causing

transistor

7287

to

be

blocked

again

via

R3291.

Short-circult

at

the

output:

The

principle

on

which

the

circuit

operates

is

explained

only

on

the

basis

of

the

right-hand

channel

and

is

of

course

also

valid

for

the

left-hand

channel

and

the

bass

channel.

in

normal

operation,

with

every

positive

half

wave

via

the

feedback

the

base

of

TS7308

becomes

more

positive

than

the

emitter.

The

transistor

remains

blocked.

D6302

prevents

switching

through

during

the

negative

haif

wa-

ve.

If

during

the

short-circuit

at

the

output

the

si-

gnal

being

fed

back

falls

away,

in

the

case

of

the

positive

half

wave

the

emitter

becomes

more

positive

than

the

base.

TS7308

is

con-

ducting.

D6308

is

for

a

positive

pulse

in

the

conducting

direction.

Via

R3274

this

positive

pulse

reaches

the

base

of

TS7287

and

swit-

ches

the

latter

through.

The

astable

monoflop

switches

off

the

output

stage,

as

described

under

fault

+/-DC

pulse,

for

4-5

seconds.

Due

to

threshold

voltages

(7308,

6308,

7287),

this

short-circuit

interruption

will

only

operate

from

around

1.4Veff

at

the

output

of

IC7322.

7322

Feedback

Fig.

1

9

Gs)

Current

limitation:

If

the

emitter

current

through

TS7304

increases,

the

voltage

at

R3312

will

also

increase.

Via

the

potential

divider

R3316/3314

the

latter

also

reaches

the

Bcsssa

7316

base

of

TS7318.

Once

the

threshold

level

oo

is

reached,

TS7318

switches

through.

|

BDTS638

Consequently,

the

base

of

TS7304

beco-

nee

mes

more

negative

than

the

emitter

and

blocks.

B8CS48B

33290

22arR

Fig.

2

Signal

path:

The

circuit

shown

in

Fig.

3

corresponds

in

principle

with

the

circuit

in

the

manual,

but

components

which

are

not

|

absolutely

essential

to

its

basic

understanding

have

been

omitted.

The

transistors

7310

and

7316

are

to

be

considered

as

switches

rather

than

am-

sce’

plifier

elements.

The

power

supply

is

switched

on

and

off

via

the

+STBY

and

-STBY

voltages

respectively.

If

the

preamplifier

(IC7322)

is

modulated,

a

current

flows

across

its

load

resistor

(3340),

which

in

first

approximation

is

calculated

from:

Signai

iin

4

SPEAKER

é

u,*V,

ee

eo

tu

R,

aoT638

Vy=

voltage

amplification

of

1C7322

Ug=

voltage

between

2

and

3

Ra=

R3340

3312

A186

This

current

must

be

supplied

from

the

-vecs

power

supply

and

causes

an

AC

voltage

drop

at

resistors

3324

and

3320

which

modulates

the

output-stage

transistors.

Fig.

3

Mute:

The

preamplifier

is

muted.

If

the

base

of

TS7320

is

HIGH,

it

switches

through

and

short-circuits

the

input

signal

of

the

preamplifier

(7322).

Muting

occurs

when:

a)

the

astable

monoflop

is

active

(to

avoid

plops

when

switching

off

the

output

stage).

b)

the

headphones

are

connected

(base

of

TS7284

goes

to

LOW

via

connector

1256.

TS7284

biocks.

The

collector

is

HIGH,

so

the

base

of

TS7320

is

also

HIGH.)

c)

During

the

various

switching

operations

(source

selector)

a

MUTE

signal

(LOW

active)

is

supplied

via

8

of

1251,

so

that

the

base

of

TS7284

goes

to

LOW.

10

CS

57

058

SCHEDA

DI

ALIMENTAZIONE

Lo

stadio

di

uscita

viene

attivato

dalle

tensioni

+STBY

e

-STBY.

Queste

sono

ottenute

rispettivamente

dalle

tensioni

+VCC1

e

-VCC1

e

possono

essere

interrotte

attraverso

il

Monoflop

astabile

(TS7287,

7290).

Quest’ultimo

ha

il

compito

di

disattivare

lo

stadio

di

uscita

in

caso

di

guasto

(cortocircuito

o

corrente

continua

in

uscita).

Se

la

disfunzione

é

di

breve

durata,

lo

stadio

di

uscita

viene

disattivato

per

circa

4-5

secondi

(Tempo

di

carica

di

C2276

attraverso

R3288).

Se

la

corrente

continua

permane

sull’uscita,

il

TS7287

funziona

come

un

interruttore

(Vedere

“Guasti,

+

/-CC

in

uscita")

e

disattiva

lo

stadio

di

uscita

per

tutta

la

durata

del

guasto.

Assenza

di

guasto

@

la

condizione

del

Monoflop

astabile,

e

consente

di

azionare

il

TS7290

e

disattivare

il

transistor

7286

attraverso

I’R3291.

In

tal

mado,

il

collettore

di

TS7287

passa

a

livello

alto

(ca.

+11V).

Attraverso

R3286,

passa

a

livello

alto

anche

la

base

di

TS7280,

attivando

quest’ultimo.

Di

conseguenza,

TS7279

e

7282

si

bloccano.

|

transistor

7278

e

7283

diventano

conduttori

e

inseriscono

nel

ciruito

le

tensioni

+STBY

e

-STBY.

Guasti:

+CC

in

uscita:

-CC

in

uscita:

Impulso

+/-CC:

e

Attraverso

D6287

giunge

una

tensione

positiva

alla

base

di

TS7287.

In

tal

modo,

il

collettore

di

TS7287

passa

a

livello

basso.

TS7280

si

blocca.

Attraverso

il

ripartitore

di

tensione

R3279/R3281

si

ottiene

in

corrispondenza

di

R3281

una

tensione

di

circa

1V.

Di

conseguenza,

sulla

base

di

TS7279

o

sull’emettitore

del

TS7282

@

presente

una

tensione

di

circa

0,7V.

|

transistor

si

attivano

e

bloccano

cos

TS7278

e

7283.

Le

tensioni

+STBY

e

-

STBY

non

entrano

nel

circuito

e

lo

stadio

di

uscita

non

funziona.

Attraverso

D6290

giunge

una

tensione

negativa

alla

base

di

TS7290.

In

tal

modo,

quest’ultimo

si

blocca.

In

corrispondenza

del

collettore

di

TS7290

sono

presenti

ora

circa

+

20V.

TS7287

viene

attivato

attraverso

{'R3291.

In

tal

mado,

il

collettore

di

TS7287

passa

a

livello

basso.

TS7280

si

blocca

e

predispone

la

macchina

in

Stand-by.

Di

norma,

in

corrispondenza

di

C2276

sono

presenti

circa

3Vcc.

Se

ora,

attraverso

un

impulso

(+CC

attraverso

D6287,

-CC

attraverso

D6290/TS7290)

TS7287

diventa

un

conduttore,

|’uscita

del

condensatore

elettrolitico,

in

cui

erano

prima

presenti

+11V,

va

improwisamente

a

massa.

Sull’altra

uscita

del

consensatore

elettrolitico

erano

presenti

circa

-3V,

ed

era

presente

una

tensione

negativa

sulla

base

del

TS7290,

tramite

la

quale

questo

viene

bloccato.

In

tat-modo,

sono

presenti

circa

+20V

in

corrispondenza

del

collettore

TS7290.

Attraverso

il

ripartitore

di

tensione

R3291

/R3274+3249,

la

tensione

positiva

perviene

alla

base

del

TS7287

e

la

tiene

sotto

tensione.

Nel

frattempo,

C2276

viene

caricato

attraverso

|’R3288.

Dopo

4-5

secondi,

la

tensione

in

corrispondenza

di

C2276

é

salita

a

tal

punto

che,

il

transistor

7290

viene

nuovamente

riattivato

attraverso

I’R3289.

Di

conseguenza,

il

transistor

7287

viene

nuovamente

bloccato

attraverso

|’R3291.

Cortocircuito

in

uscita:

La

funzione

principale

del

circuito

é

chiarita

solo

facendo

riferimento

al

canale

destro

e,

naturalmente,

vale

anche

per

il

canale

sinistro

e

per

quello

dei

bassl.

Feedback

In

condizioni

normali,

a

ogni

semionda

positiva,

la

base

del

TS7308

diventa,

attraverso

la

retroazione

(feedback),

pil

positiva

dell’emetti-

tore.

ll

transistor

rimane

bloccato.

D6302

impe-

disce

I’attivazione

durante

la

semionda

negati-

3340

100R

va.

Se

ora,

per

un

cortocircuito

in

uscita,

il

segnale

di

reazione

viene

soppresso,

!’emettitore

di-

venta,

in

corrispondenza

della

semionda

posi-

Sc

tiva,

pi

positivo

della

base.

TS7308

si

attiva.

D6308

si

trova

nella

posizione

di

passaggio

per

un

impulso

positivo.

Quest’ultimo

raggiunge,

attraverso

1’R3274,

la

base

del

TS7287

e

attiva

7322

3354

7308

BCS558B

Fig.

1

quest'’ultimo.

|!

Monoflop

astabile

disattiva

lo

stadio

di

uscita,

come

nel

caso

dell’errore

per

impulso

+

/-CC

per

4-5

secondi.

Sulla

base

delle

tensioni

di

soglia

(7308,

6308,

7287)

questa

interruzione

per

cortocircuito

funziona

solo

a

partire

da

1.4Veff

in

corrispondenza

di

1C7322.

9@)

Limitatore

di

corrente:

B8CS58eB

7316

7318

BCS48B

3320

220R

Fig.

2

Percorso

del

segnale:

7304

BOT63B

Con

l’aumentare

della

corrente

dell’e-

Mettitore

attraverso

1S7304,

aumenta

anche

la

tensione

presente

su

R3312.

Quest'ultima,

raggiunge,

attraverso

il

ripartitore

di

tensione

R3316

/

3314

la

base

del

1S7318.

Se

si

raggiunge

il

Aiea

valore

di

soglia,

TS7318

viene

attivato.

In

tal

modo,

la

base

di

TS7304

diventa

pil

negativa

dell’emettitore

e

si

blocca.

ll

circuito

illustrato

nella

Fig.3

corrisponde

in

linea

di

massima

a

quello

riportato

nel

manuale;

tuttavia,

alcuni

componenti,

non

necessari

per

una

comprensione

generale,

sono

stati

tralasciati.

|

transistor

7310

e

7316

non

vanno

con-

siderati

come

amplificatori

bensi

come

interruttori.

Attraverso

le

tensioni

+STBY

e

-STBY

l'alimentazione

viene

fornita/interrotta.

Se

ora

il

preamplificatore

(IC7322)

viene

modulato,

attraverso

la

sua

_

resistenza

(8340)

passa

una

corrente,

che

in

prima

approssimazione

viene

calcolata

con

la

seguente

formula:

Vy

=

Amplificazione

di

corrente

di

IC7322

Us

=

Tensione

tra

i

2

e

3

Ra

=

R3340

Questa

corrente

deve

essere

fornita

dall’alimentatore

e

provoca

in

corrispon-

denza

delle

resistenze

3324

e

3320

una

caduta

della

tensione

di

commutazione,

che

modula

i

transistor

dello

stadio

di

uscita.

*vcc1

+STBY

Feedback

Stgnal

itn

oH

3354

peel

-STBY

4

-vcec1

Fig.

3

Esclusione:

|

preamplificatore

viene

commutato

silenziosamente.

Se

la

base

di

TS7320

@

a

liviilo

alto,

essa

attiva

quest’ultimo

e

interrompe

il.segnale

di

ingresso

del

preamplificatore

(7322).

Viene

silenziata

nei

seguenti

casi:

a)

il

Monoflop

astabile

@

attivo

(Per

evitare

Plop

alla

disattivazione

dello

stadio

di

uscita).

b) Le

cuffie

sono

inserite

(la

base

del

TS7284

viene

portato

a

livello

basso

dal

spina

1256.

TS7284

si

blocca.

II

collettore

é

a

livello

alto

e

di

conseguenza

anche

la

base

diTS$7320).

c)

Durante

i

vari

processi

di

commutazione

(Source

Selector)

viene

trasmesso

un

je@gnale

MUTE

(attivo

a

livello

basso)

attraverso

il

8

del

1251.

In

tal

modo

la

base

del

TS7284

passa

a

livello

basso.

10a)

CS

57

062

3356

C11

3385»

FL

6254

GIS

6289

Ci4

=

6308

«G3

6364

Ell

7280

O15

7304

0026

810

1270

09

2250

GIS

2261

F

9

2270

F

4

2304

CS

2379

«F

4

2396

G12

3257

H12

3302

C9

3329

«13

88

7313

613

7322

GJ

7368

811

esd

05

1271

F

3

2251

GIE

2262

6

3

2271

B15

2307

C6

2380

F

4

2399.

Fl2

3261

G15

3307

C7

3330

C9

336C

Cll

3387,

FLl

6257

O16

6290

014

6309

£12

§365

Ell

7282

C15

7305

C13

7314

88

7360

811

7369

(O11

1251

E16

1272

O10

2253

«G14

2263

«=F

7

2272

«C15

2308

CS

2384

F12

3250

GIS

3264

€

4

3308

C6

3339

=F

6

3364

C2

3388

F13

6261

616

6301

F 7

6310

£9

6380

Eil

7283

B1S

7306

«C9

TAS

Cl2

7361

810

7370

«G4

1253

G14

1273,

F

4

2254

GIS

2264

67

2273)

O14

2343

F

6

2387

E14

3251

GIS

3265

04

3311

Ci2

.

3340

F 3

3365

C10

5250

|

FS

6262

F13

6302

F

3

6311

E12

6381

Fil

7284

(O15

7307

G&

7316

C8

7362

«(Cll

7381

FI2

tes4

H10

1274

013

2255

G14

2265

G8

2275

O14

2344

F

3

2388

E14

3252

«01S

3272

«C15

3312

C8

34S

G6

3369

C10

s25t

F 6

6263

F13

6303

013

6312

—

9

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