Pioneer GEX-007(MB)EW User manual

e1rvice

COMPONENT

CAR

STEREO

ELECTRONIC

TUNER

YPIONEER

ORDER

NO.

CRT-517-0

GEX-O0

7

(MB)

ws

GEX=-0077

...::

SPECIFICATIONS

General

Power

source.

...........200005

DC

14.4V

(10.8

—

15.6V

allowable)

Grounding

system..........

epee

iacicctie

Saves’

Sete

ca

ape

wp

tue

aoe

Negative

type

DIMENSIONS.

«6

i

iie

cies

eee

ees

180(W)

x

25(H)

x

137(D)

mm

Maximum

output

level...

1...

0...

cece

eee

eee eee

neue

200mV

OUTPUT

IMPEDANCE

i.

&

sci

ic

die

ees

vee

cece

awe

ele

we

wea

wedwet

1kQ

WOIGIIES

sei

sera

isaar

lor

kb

seek

edeg

seca

ynvddavivd

de

Snssiesind

tdyecerraade

ores

avacrarecove

0.7kg

FM

tuner

FrOQUeNCY

TaNGE

si.

ss6cacaieensa

caw

en

ds

deaee

es

87.5

—

108

MHz

Usable

sensitivity.................00.

12

dBf

(1.1n4V/75Q,

mono)

50

dB

quieting

sensitivity..............

17

dBf

(1.94V/752,

mono)

Signal-to-noise

ratio...

6...

..

0...

cece

eee

70

dB

(IEC-A

network)

DIStOMtIOM

e:s:i5-56

2505860

cane

aires

woe

bm

eae

0.3%

(at

65

dBf,

1kHz,

stereo)

Frequency

response

............0.00000ee

30

—

15,000

Hz

(+3

dB)

Stereo

separation.............0

0c

cee

ee

40

dB

(at

65

dBf,

1kHz)

MW

tuner

FreQUeNCY

TANGE:

0...

ies

eden

ae

de

wae

dea

E

ee

531

—

1,602kHz

Usable

sensitivity................0005

18uV

(25

dB)

(S/N:

20

dB)

SOS

CHVIEY

5

552s

tertae

cies

arenas

Sys

enera

acd

H-eeestoaeaecentuataraduce

50

dB

(+9kHz)

LW

tuner

(EW

model)

Frequency

range

....

1...

cece

e

eee

153

—

281

kHz

Usable

sensitivity.................00.

30uV

(30

dB)

(S/N:

20

dB)

SEIS

CEIVIEY

.

cies.

caring

ogtone:

Ban

dada

arenes

gud

ee

Hee

dames

ee

50

dB

(+9kHz)

Note:

Specifications

and

the

design

are

subject

to

possible

modification

without

notice

due

to

improvements.

PIONEER

ELECTRONIC

CORPORATION

4-1,

Meguro

1-Chome,

Meguro-ku,

Tokyo

153,

Japan

PIONEER

ELECTRONICS

[USA]

INC.

P.O.

Box

1760,

Long

Beach,

California

90801

U.S.A.

TEL:

(B00)

421-1404,

(B00)

237-0424

PIONEER

ELECTRONIC

[EUROPE]

N.V.

Keetbergiaan

1,

2740

Beveren,

Belgium

TEL:

03/775:28-:08

PIONEER

ELECTRONICS

AUSTRALIA

PTY.

LTD.

178-184

Boundary

Road,

Braeside,

Victoria

3195,

Australia

TEL:

[O03]

580-9911

ES

©

JUNE

1985

Printed

in

Japan

(<-]|

=>

Cisley4

CONTENTS

Iie,

‘CONNECTION.

ss

cece

o.vind

Ceti

Neede

eae

gee

1

2.

OPERATION.

é:e-é

sada.

eaicw

ere

dre

aaeaueid

ae

dane

tein

eaniee

2

3:

PARTS

LOCATION

@

ncscasics

oiece

aie

specectos

iad:

Ranlanseaos

wuss

4

4..

DISASSEMBLY

cava

cecceceeeneeew

eer

eeee

ee

5

5.

CIRCUIT

DESCRIPTION.....5.

2

.scc005¢

e2ewewecaes

6

6.

ADJUSTMENT

.

6.1

FM

IF

Adjustment

..............00

ee

eee eee

13

6.2

FM

MPX

Adjustment................0000

05

13

6.3

FM

Tracking

Adjustment..............00005

14

6.4

AM

Tracking

Adjustment

...............065

15

6.5

AM

Seek

Stop

Sensitivity

AGjUSIMONE:

ces

ccs

wee

egies

dase

ait

omens

15

1.

CONNECTION

e

Before

making

final

connéctions,

make

temporary

connections

then

operate

the

unit

to

check

for

any

connecting

cord

problems.

e

Refer

to

the

respective

Owner’s

Manuals

of

the

units

to

which

this

unit

is

being

connected

for

details

on

correct

connections.

e

Be

sure

to

correctly

connect

the

memory

power

supply

lead

(orange)

and

main

power

supply

lead

(red)

as

specified.

If

the

con-

nections

are

made

incorrectly

or

forgotten,

this

unit

will

make

a

buz-

zing

sound

and

will

not

work

at

all.

7.

SCHEMATIC

CIRCUIT

DIAGRAM

(/EW)..........

21

8.

CONNECTION

DIAGRAM

(/EW)................

24

9.

SCHEMATIC

CIRCUIT

DIAGRAM

(/ES)

..........

27

10.

CONNECTION

DIAGRAM

(/ES)

.............04-

30

V1

EXPLODED!

VIEW

ie

ccc

agenesis

Hanae

erdeanane

iin

e

a's

Based

33

12,

ELECTRICAL

PARTS:

LIST

«2:

cc

cceveeees

exec

ewe

36

13:.

PACKING

METHOD)

2.3.4400c00

5

aban

ee

ane

sx

40

Antenna

cable

Fi

Be

sure

to

use

this

cable

when

the

antenna

jack

and

the

car

antenna

plug

are

from

each

other.

Plug

the

antenna

jack

into

the

car

antenna

plug.

®>Clb

Cassette

deck

or

External

|

CD-Player

with

hae

control

AMP.

CD-R99

(sold

separately)

Remote

Tuning

—

Controller

For

memory

power

supply

(orange)

|

Output

Connect

to

the

positive

terminal

of

°

battery

which

supplys

current

regardless

of

ignition

key

position.

—<—1

For

example,

the

clock

should

be

connected

to

this

connector.

For

main

powe'

I

.

P

PSURR

YY

Connect

the

main

power

supply

only

after

every

other

connection

has

been

made.

This

very

last

connection

is

made

to

the

accessory

connector

leading

from

the

car’s

fuse

unit.

Connect

to

lead

wire

of

relay

for

the

power

auto

antenna.

The

antenna

will

automatically

be

raised

and

lowered

by

turning

the

radio

switch

on

and

off

(Max.

300mA

12V

DC).

Connect

firmly

to

a

metal

part

of

the

car

body.

Improper

grounding

will

cause

noise

to

be

generated.

For

Auto

Antenna

(blue)

For

ground

(black)

Fig.

1

2.

OPERATION

e

Nomenclature

and

Function

=|

>

Cisley

4

@

Preset

Buttons

Tune

12

FM

frequencies

(6

for

FM1

and

6

for

FM2)

and

6

MW

fre-

quencies

with

the

touch

of

a

button.

Frequencies

can

be

preset

freely.

e

6

frequencies

can

be

set

for

MW

and

LW

in

models

equipped

with

LW.

@

Band

Select

Button

Each

press

switches

from

FM1

to

FM2

to

MW

to.

FM1,

etc.

e

Switching

between

FM

and

MW/LW

on

units

equipped

with

LW

is

performed

with

the

band

button.

Switching

between

MW

and

LW

is

accomplished

with

the

tuning

button.

MW

is

531

—

1,602kHz,

while

LW

is

153

—

281

kHz.

©

Seek

Button

Press

to

set

to

the

SEEK

position

(SEEK

illuminates

on

display)

and

use

the

tuning

button

for

seek

tuning.

During

seek

tuning,

the

FM

fre-

quency

changes

in

50kHz

steps,

while

MW

changes

at

9kHz

steps.

e

LWchanges

at

9kHz

steps

in

models

equipped

with

LW.

@

Local

Station

Button

Use

this

button

to

change

the

seek

threshold

level

of

the

seek

function.

Normally,

this

button

is

kept

in

the

OFF

position.

At

night,

when

radio

signal

conditions

are

favorable,

very

weak

signals

are

often

detected

and

sought

out

by

the

seek

function.

Pressing

this

button

(Note:

LOC.

will

illuminate

on

the

display)

will

raise

the

seek

threshold

level

to

eli-

minate

this

problem.

@

Preset-Scan

Button

Press

to

tune

each

stored

frequency

for

5

seconds

in

the

order

of

the

preset

button

numbers.

Press

once

again

to

cancel

the

preset-scan

function

and

to

stay

at

a

certain

frequency.

©

Reading

the

Displays

@

Band

Indicator

Changes

in

the

order

of

F1

>

F2

>

M

with

each

press

of

the

band

select

button.

F1,

F2

and

M

stand

for

FM1,

FM2

and

MW

respectively.

e

For

models

equipped

with

LW,

switching

between

MW

and

LW

is

accomplished

with

the

tuning

button.

@

FM

Stereo

Indicator

Lights

when

an

FM

stereo

broadcast

is

tuned

in.

©

Seek

Indicator

Lights

when

the

seek

button

is

pressed.

@

Local

Station

Indicator

Lights

when

local

station

button

is

pressed.

@

Channel

Number

Indicator

Corresponding

channel

number

lights

when

preset

button

is

pressed.

©

Frequency

Indicator

Fig.

2

@

Display

@

Power

Switch

Press

to

switch

power

ON

and

OFF.

(The

cassette

deck

takes

priority

over

the

tuner,

so

switch

the

cassette

deck

OFF

when

in

use.)

©

Stereo/Monaural

Button

Switches

an

FM

broadcast

between

stereo

and

monaural.

Usually

this

button

is

kept

in

the

raised,

stereo

position

(red

MO

on

button

not

lit).

In

this

setting,

stereo

broadcasts

will

cause

the

stereo

indicator

on

the

display

to

light,

and

full

stereo

effect

can

be

enjoyed.

Automatic

Recep-

tion

Control

(ARC)

ensures

constant

optimal

tone

quality.

If

excessive

noise

is

present,

pressing

this

button

(red

MO

on

button

lit)

allows

monaural

reception

for

less

noise

and

better

listening.

©

Memory

Button

@

Tuning

Button

When

the

seek

button

is

in

the

OFF

position,

each

press

of

the

(+)

side

of

this

button

increases

the

FM

frequency

in

25kHz

steps

or

MW

in

9kHz

steps.

Each

press

of

the

(—)

side

decreases

the

frequencies

by

their

respective

steps.

Holding

down

either

side

of

the

button

causes

the

frequencies

to

change

at

high

speed.

e

LWchanges

at

1kHz

steps

on

models

equipped

with

LW.

e

Tuning

in

Broadcasts

3)

|

oe

TUNE

1.

Press

the

power

switch

@

to

turn

power

ON,

and

the

band

together

with

the

frequency

will

appear

on

the

display

@.

2.

Select

a

band

using

the

band

select

button

©.

e

For

models

equipped

with

LW,

use

the

tuning

button

@

to

select

either

MW

or

LW.

3.

Select

a

frequency

using

seek,

manual

or

one

of

the

other

tuning

methods.

4.

Adjust

the

volume,

balance,

bass

and

treble

to

the

desired

levels

using

the

controls

on

the

cassette

deck

or

CD

player

(with

control

amplifier).

Seek

Tuning

With

the

seek

button

©

in

the

ON

position,

the

frequency

increases

when

the

(+)

side

of

the

tuning

button

@

is

pressed

and

decreases

when

the

(—)

side

is

pressed.

At

this

time,

the

broad-

cast

is

automatically

tuned

in.

Manual

Tuning

With

the

seek

button

@

in

the

OFF

position,

tuning

is

performed

pressing

the

(+)

side

and

(—)

side

of

the

tuning

button

@.

©

For

normal

seek

tuning

on

models

equipped

with

LW,

the

frequency

changes

at

9kHz

steps

in

the

range

of

155

—

281

kHz.

Manual

tuning

is

used

to

tune

in

the

frequency

of

153kHz.

Once

153kHz

is

tuned,

switching

to

seek

tuning

allows

advancement

of

the

frequency

changes

at

9kHz

steps

in

the

range

of

153—279kHz.

When

1,602

kHz

is

reached

in

MW,

tuning

wraps

around

to

155kHz

in

LW.

2

i=]

—>

Cisley4

e

Presetting

Frequencies

.

Press

the

band

select

button

@

until

either

FM

or

MW

is

selected.

For

models

equipped

with

LW,

use

the

tuning

button

@

to

select

either

MW

or

LW.

.

Use

either

seek

tuning

or

manual

tuning

to

tune

in

the

desired

frequency.

.

Pressing

the

memory

button

@

will

cause

a

preset

number

to

blink

on

the

display

for

5

seconds.

Press

one

of

the

preset

buttons

@

during

this

period.

At

this

time,

the

channel

number

of

the

button

pressed

will

be

shown

on

the

display

@.

.

The

preceding

operation

presets

a

single

frequency

to

a

single

button.

Set

the

other

5

buttons

by

repeating

steps

(2)

and

(3).

=]

—>

Caley.

3.

PARTS

LOCATION

NOTE:

e

For

your

Parts

Stock

Control,

the

fast

moving

items

are

indicated

with

the

marks

*

&

and.

*%

%&:

GENERALLY

MOVES

FASTER

THAN

x.

This

classification

shall

be

adjusted

by

each

distributor

because

it

depends

on

model

number,

temperature,

humidity,

etc.

DIN

Connector

Cord

CDK-112

Cord Cord

CDK-368

CDK-308

FM

Front

End

CWB-172

Buzzer

CPV-031

Grille

Assy

CXD-882

(GEX-007

(MB))

CXD-762

(GEX-007)

Fig.

6

|

>

Cele

p 4

4.

DISASSEMBLY

e

Removing

the

case

1.

Remove

three

screws.

Fig.

7

©

Removing

the

grille

switch

assembly

1.

Lift

the

connector

up

in

the

direction

indicated

by

the

arrow

(1),

and

disconnect

the

flexible

PCB.

2.

Remove

two

screws.

Flexible

PCB

at

Grille

Switch

Assy

SS

Oo

re

Fig.

8

©

Removing

the

switch

unit

1.

Remove

the

four

screws

labeled

A.

2.

Open

the

stopper

connected

to

the

holder,

and

remove

the

.

switch

unit.

©

Removing

the

holder

1.

Remove

the

three

screws

labeled

B.

Grille

Assy

Fig.

9

<j]

Caley,

5.

CIRCUIT

DESCRIPTION

e

Block

Diagram

TUNER

P.C.

BOARD

ANTENNAG)

om

—

=

=z

=x

>

PAOOI4

CERAMIC

PAOOI3

PAOOI4

NOLSE

LA3376P

PA2014

FM

FRONT

END

FILTER

IF/DETECTOR

BUFFER

FILTER

SUPPRESSOR

MPX

DECODER

DIODE

SWITCH

ISOLATOR

L-ch

a

ee

eee

>I

‘

,

eet

CwB-172

co

|

AM

tl

BT

+B

5

8

7

g

LOW-PASS

=

2 2

Se

|

a

HIGH

PASS

eee

—

-

10

5

!

%

Cri

12

13

R-ch

i

[

OFF+B

ai

a

4

(O-

«)

@)

LOCAL

MONO

SWITCH

EM TV

SWLTCH

Q28

Q27

a9

RF

AMP

MIXER

IF

AMP

AM

DETECTOR

5:

4

-£)

pa

=

—-

nam

a

>t

LOCAL

MUTE

SWITCH

ANT

CONTROL

SWITCH

T6

Q28

17

Qs

CERAMIC CERAMIC

SQ

Q26

FILTER

INVERTER

l

Qs

_

MW/LW

SWITCH

AUTO

ANT.

QiO~

Ql4

=|

AN6540

8.5V

REGULATOR

POWER

SW

FM/AM

+B

SWITCH

;

wick

Ics

00

|__

ID

Q27,

Q29,

Q30

qd]

PLL

CONTROL

|

FM/AM

MUTE

Ema

IN

sD

KEY

TOUCH

SOUND

CONTROL

8

:

LOOP

FLLTER

FM-IN

£01,2

‘

|

=

Q22,

Q23

SWITCH

UNIT

(1/2)

1c?

ZS

—

PD4052A

:

E

POWER

1i~6

15

BACK

UP

34-52

DIS

PLAY

aK

Hl

I

|

e

xt

|

21~24

—_—

—

sid

REMOTE

CONT.

DRLVER

MONO

IPOWER

2

REMOTE

CONTROL

° =

KEY

BOARD

F2——

-

is

WV

||

JACK

|

i

|

@-

S-

=

SWITCH

UNIT

(2/2)

Fig.

10

=]

—>

ieler4

@

Operation

of

FM

Section

IF

PNS

LEVEL

]

DETECTOR

|

MUTE

MPX

HIGH

CUT

CONTROL

SEPARATION

:

CONTROL

Reh

PNS

1C_

20!

PAOOI3

OR

|

LEVEL

circuit

|

peTeCToR

|

MUTE

ARC

Mark

Ill

MPX

1C

203

PAOOIS

Leh

HIGH

CUT

|

SEPARATI

on}

CONTROL

|

CONTROL

Reh

ARC

Mark

V

The

high-cut

and

separation,

which

were

controlled

by

the

input

signal

strength

level

in

the

ARC

Mark

III,

can

also

be

controlled

by

the

noise

level

in

the

ARC

Mark

V.

Therefore

noise

in

strong

signal

areas,

impossible

to

suppress

before,

can

now

be

suppressed

adequately.

Noise

Detector

Circuit

Co-using

the

PNS

HIGH

PASS

FILTER,

this

operates

by

detecting

the

components

above

100

kHz

in

the

wave

detector

output.

The

HPF

output

is

amplified

to

a

sufficient

level,

rectified,

phase

reversed

and

then

DC

converted.

1.

Front

end

section

inemaaiadi

i

Amp

Block

Gain |/dB

MIX

Gain

10dB

=

IF

Amp

Gain

|18dB

13dB

Cerami

21dB

ATT

ANT

RF

Amp

RF

|

Balun

—-

Mixer

|

.

Filter:

IFT

|

IF

Amp

Filter

IF

Amp

Filter

Tune

Volt

The

RF

signal

from

the

antenna

passes

through

an

atten-

uator

constructed

as

a

band-pass

filter

and

is

sent

to

the

pi-

shaped

matching

circuit,

where

high-end

spurious

response

is

improved.

The

signal

then

goes

to

the

RF

amp.

The

RF

amp

employs

a

MOS

FET

capable

of

handling

a

wide

dynamic

range.

The

output

from

the

RF

amp

passes

through

a

parallel

resonance

circuit,

is

converted

to

a

balanced

signal

from

an

unbalanced

by

a

balun

circuit

and

then

goes

to

the

mixer

stage.

This

is

a

J-FET

single

balance

ARC

Mark

V

Fig.

11

Input

Level

35

dBuV

Switch

The

noise

level

ceases

to

control

the

high-cut

and

separation

when

the

input

level

drops

below

35

dBuV,

and

control

of

these

is

carried

out

entirely

by

the

input

signai

strength

level.

This

is

the

same

as

in

the

Mark

III.

This

function

operates

in

this

manner

because

the

noise

level

control

will

always

output

a

signal

when

the

signal

strength

is

below

35

dBuV,

and

signal

strength

control

is

sufficient

for

medium-

weak

input

signal

areas.

Fig.

12

type

mixer

which

can

accommodate

a

wide

dynamic

range.

One

of

the

IF

signals

from

the

mixer

passes

through

the

IF

amp

and

ceramic

filters.

Another

IF

signal

goes

to

the

AGC

amp.

This

AGC

amp

can

operate

even

in

the

presence

of

interference

signals.

The

AGC

amp

output

is

fed

back

to

the

RF

attenuator

circuit,

forming

a

wide

loop

AGC.

The

AGC

circuit

operates

at

antenna

input

levels

above

65

+5

GB.

2.

IF

detector

section

A

single-tuning

quadrature

detection

is

performed

by

IC

PA0013

using

IF

amp

and

T1

to

obtain

an

audio

fre-

quency

output.

3.

PNS

section

This

is

a

pulse

noise

canceller

using

IC

PAO014

and

CR

composite

part

CR1

which

comprises

filters.

4.

Multiplexer

section

Stereo

multiplexing

is

performed

by

IC

LA3376P.

This

IC

does

not

operate

the

stereo

circuit

in

the

absence

of

cur-

rent

flowing

through

the

stereo

indicator

terminal

(Pin

10).

5.

Muting

of

weak

incoming

signals

IC

PAOO13

develops

a

DC

voltage

at

6

when

the

input

is

weak

or

detuned.

When

this

voltage

is

applied

to

5

through

the

filter

consisting

of

capacitors

and

resistors,

the

attenuator

goes

into

operation.

The

on/off

(AUTO/MONO)

of

this

weak

input

signal

muting

is

con-

trolled.

The

stop

signal

for

the

seek

operation

uses

a

voltage

developed

at

6.

(During

broadcast

reception,

the

voltage

is

at

OV).

®

Operation

of

AM

Section

IC

HA12434

used

in

this

unit

is

designed

for

electronic

tuning

and

provided

with

the

output

circuit

of

the

stop

signals

for

seeking

and

VCO

buffer.

Its

feature

includes

a

wide-band

AGC.

1.

RF

amplifier

section

This

section

performs

a

single-tuning

2-stage

RF

amplifi-

cation.

The

first

stage

is

a

narrow-band

amplifier

section

consisting

of

Q9

and

its

load,

i.e.,

resonance

circuit

(inductance

of

T2,

and

capacitance

of

varicap

diode

D8-1,

C51).

The

second

stage

is

a

section

consisting

of

RF

amplifier

1

inside

the

IC

and

its

load,

or

resonance

circuit

(inductance

of

174,

and

capacitance

of

D8-2,

C54).

15

is

not

only

a

terminal

lead

to

which

the

load

of

RF

amp

1

is

connected,

but

also

an

input

termi-

nal

of

the

mixer

input.

2.

VCO

section

The

VCO

(voltage-controlled

oscillator)

oscillates

at

its

resonant

frequency

by

the

feedback

circuit

from

12

to

13

and

the

resonant

circuit

connected

to

13.

The

resonant

frequency

is

determined

by

the

induc-

tance

of

L6

and

the

composite

capacitance

of

Ca,

and

D8-2.

Ca

is

a

padding

capacitor

connected

in

series

with

capaci-

tance-varying

varicap

diode

D8-3,

and

Ca

is

a

capacitor

connected

in

parallel

with

varicap

diode

depending

on

its

grade.

All

this

contributes

to

better

tracking

with

the

RF

stage.

6.

Local

station

seeking

While

seeking

strong

signal

stations,

the

gain

of

the

front

end

is

decreased

by

making

the

voltage

at

AGC

terminal

in

the

front

end

4.5V

by

Q1.

7.

Separation

control,

high

frequency

control.

8

of

IC3

(LA3376P)

functions

as

the

separation

con-

trol

(SNC)

pin,

and

pins

7

function

as

the

high-cut

control

(HCC)

pins.

SNC

and

HCC

are

controlled

by

the

control

voltage

from

17

of

1C1

(PA0013).

The

control

voltage

can

be

varied

by

adjusting

semi-fixed

volume

VR1,

connected

to

20

of

IC1.

SNC

and

HCC

are

controlled

by

the

input

signal

strength

level.

How-

ever,

these

are

also

controlled

by

the

noise

detector

level

from

IC2

(PA0014,

PNS),

unless

the

input

signal

strength

is

below

35

dBuV.

The

noise

detector

output

from

7

of

CR1

is

input

to

16

of

IC1.

The

noise

detector

control

of

the

high-cut

and

separation

will

switch

on

above

35

dBuV.

8.

Mono/stereo

When

the

Mono

switch

is

turned

on,

pin10

of

IC3

(LA3376P)

will

be

opened,

the

stereo

indicator

will

go

out,

and

the

output

will

switch

to

monaural.

5

(MUTE

DRIVE

PIN)

of

IC1

(PA0013)

will

also

be

grounded,

disengaging

the

level

mute.

3.

Mixer

section

The

VCO

output

frequency

from

the

VCO

section

and

the

input

signal

from

RF

amp

1

are

mixed

together

at

the

mixer

section

to

produce

the

IF

component

(450

kHz).

4.

IF

section

The

intermediate

frequency

section

consists

of

the

IF

filter

(450

kHz)

by

T6

and

CF2,

the

IF

amp

1

and

the

IF

filter

by

T7.

8

is

not

only

a

load

connecting

terminal

of

the

IF

amp

but

also

an

input

terminal

of

detector

circuit

1.

5.

Detector

section

8

is

connected

to

the

detector

and

provides

an

output

to

5,

audio

output.

This

output

contains

both

audio

frequency

component

(AC)

and

DC

com-

ponent.

6.

AGC

section

(AGC

by

the

reception

frequency)

The

DC

component

of

the

detector

output

at

5

is

de-

tected

by

AGC

amp

1

at

1

by

passing

it

through

the

filter

consisting

of

R55

and

C73.

The

AGC

starts

operat-

ing

at

an

input

level

close

to

the

maximum

sensitivity.

The

output

of

AGC

amp

1

is

connected

to

AGC

amp

2,

and

controls

the

gain

of

RF

amp

1.

The

AGC

voltage

is

developed

at

3

through

AGC

amp

3,

and

current

flows

through

D5

and

D6,

lower-

ing

the

impedance.

As

a

result,

attenuation

is

effected.

When

Q7

turns

on

and

the

load

impedance

of

the

drain

i-]—>

eisley,

of

QQ

is

lowered,

attenuation

is

effected.

These

attenua-

tions

due

to

the

decrease

in

impedance

enable

AGC

operation.

The

input

level

to

develop

a

voltage

at

3

is

about

55

dBuV

during

reception

of

MW

999

kHz.

Thanks

to

the

AGC

operation

mentioned

above,

the

output

variation

characteristics

against

input

variation

are

broader

than

the

conventional

AM

characteristics.

7.

AGC

section

(wide-band

AGC)

OUTPUT

Characteristics

of

(dB)

conventional

circuits

The

wide-band

AGC

is

to

control

the

gain

of

the

RF

0

amplifier

section

when

the

input

RF

level

at

16

is

high.

This

is

intended

to

prevent

interference

due

to

the

-10

saturations

of

RF

amp

Q9,

RF

amp

1

in

the

IC,

etc.

Caused

by

a

large

input

other

than

the

reception

fre-

-20

:

—_

=

INPUT

10

20

30

40

50

60

(dBpVv)

quency.

Operation

is

as

follows:

A

DC

voltage

corresponding

Fig.

13

to

the

level

of

the

input

RF

is

developed

at

2

by

amplifying

and

detecting

the

RF

signal

from

16

by

RF

and

2

and

detector

3

respectively.

This

is

delayed

by

the

time

constant

of

C75

and

the

gain

of

this

portion

is

determined

by

R58.

By

applying

this

DC

voltage

to

AGC

amp

2,

the

AGC

at

RF

amp

1

and

AGC

at

Q7,

D5

and

D6

are

effected.

Characteristics

of

this

unit

circuit

8.

Stop

signal

The

stop

signal

for

seek

operation

is

produced

by

extract-

ing

the

IF

signal

from

the

secondary

winding

of

T7

and

adjusting

its

level

by

VR5.

This

signal

is

connected

via

450

kHz

filter

CF3

from

7

to

IF

amp

2

to

detector

2.

This

output

appears

at

6

and

become

OV

during

reception.

9.

Local

station/distant

station

seek

During

local

station

seek,

Q8

turns

on,

whereby

C43

is

grounded.

The

impedance

of

C43

allows

attenuation

in

the

antenna

system.

@®

Frequency

Synthesizer

Section

(FM)

During

FM

reception,

a

combination

of

synthesizer

control

IC7

(the

frequency

dividing

ratio

is

controlled

to

1/64

or

1/66

by

IC7)

allow

the

slower

counter

method.

The

FM

VCO

is

frequency-divided

to

a

ratio

of

1/64

or

1/66

by

prescaler

IC7.

An

output

of

4.5

MHz

(X2)

which

becomes

a

clock

pulse

Antenna

Synthesizer

Control

IC

(|

0

Q22,

23

VCO

FREQUENCY

for

IC7

is

divided

into

1/360

by

the

reference

frequency

eM

TUNING

divider

to

produce

12.5

kHz

(all

this

is

processed

inside

VOLTAGE

Loop

Filter

1C7).

Since

the

reception

frequency

is

87.5

~

108.0

MHz

and

the

intermediate

frequency

(IF)

is

10.7

MHz,

the

oe

aids

oscillator

frequency

of

VCO

will

be

98.2

~

118.7

MHz.

Fig.

14

As

the

overall

frequency

division

ratio

is

7856

~

9496,

the

output

of

the

programmable

counter

inside

IC7

will

be

12.5

kHz.

This

output

is

compared

in

phase

with

a

reference

frequency

of

12.5

kHz

by

the

phase

detector

in

IC7,

and

is

output

to

12

of

IC7.

The

loop

filter

consisting

of

Q22

and

Q23

converts

the

signal

into

a

DC

voltage

signal

which

in

turn

controls

the

tuning

circuit

in

the

front

end

section

as

a

tuning

voltage.

10

=]

—>

ela

4

@

Frequency

Synthesizer

Section

(MW)

The

MW

section

employes

a

direct

frequency

dividing

ehenne

rn

nae

Tuner

Hees

method.

So

that

the

reception

frequency

is

incremented

in

9

kHz,

the

frequency

of

the

phase

comparator

is

9

kHz.

This

is

produced

by

dividing

4.5

MHz

(the

output

of

X2),

a

clock

frequency

of

IC7,

to

1/500.

Since

the

reception

frequency

range

is

531

~

1,602

kHz

and

the

intermediate

frequency

is

selected

at

450

kHz,

the

frequency

of

the

local

oscillator

(VCO)

will

be

981

~

2,052

kHz.

wT

orace

This

output

is

output

from

12

of

IC5

and

enters

Loop

Filter

0

9

of

IC7.

x2

If

the

frequency

dividing

ratio

of

the.programmable

counter

in

IC7

is

set

to

109

~

228,

the

output

will

be

9

kHz.

This

frequency

is

compared

in

phase

with

a

reference

frequency

of

9

kHz

by

the

phase

comparator

and

is

output

from

12

of

IC7.

The

signal

is

converted

into

a

DC

voltage

signal

by

the

loop

filter

consisting

of

Q22

and

Q23,

which

in

turn

controls

the

tuning

circuit

as

a

tuning

voltage.

@

The

Functions

of

Control

IC

(PD4052A)

PD4052A

is

a

52-pin

flat

package

C-MOS

LSI

which

controls

25kHz

incremental

tuning

for

FM,

9kHz

incremental

tuning

for

AM.

This

PLL

type

frequency

synthesizer

tuner

control

IC

makes

possible

7-segment

digital

display.

Since

this

IC

employs

a

static

method

for

the

display

driver,

the

per-

formance

of

the

receiver

is

improved.

KEY

BOARD

MUT

ING

CIRCUIT

Fig.

16

11

Pioneer GEX-007(MB)EW User manual

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