Pioneer KEX-70 User manual

The

photo

shows

the

model

KEX-73

)

PIONEER

ORDER

NO.

CRT

-

254-0

CASSETTE

CAR

STEREO

WITH

AM/FM

ELECTRONIC

TUNER

KEX=-70

.

CASSETTE

CAR

STEREO

WITH

LW/MW/FM

ELECTRONIC

TUNER

SPECIFICATIONS

General

Power

source..........

DC14.4V

(10.8

~

15.6V

allowable)

Grounding

system

.........

000

cece

ee

eee

Negative

type

Dimensions

(chassis).........

180(W)

x

50(H)

x

150(D)

mm

(Front

face)........

184(W)

x

56(H)

x

31(D)

mm

WIG

a

5:6

ores

owed

Selma

i

ewe

Waid

sR

ehis

a

eva

ee

2.0kg

Tone

controls

(bass)

.........

00.00

ce

eee

+10

dB

(100

Hz)

(treble)

...............005

+

10dB

(10

kHz)

Loudness

contour........

+12

dB

(100

Hz),

+4

dB

(10kHz)

(volume:

—30

dB)

Maximum

outputlevel

...........

0.0.0

.c

cea

eaee

200

mV

Output

impedance.

.........

0...

cc

cece

eee

eae

1kQ

Tape

player

WAPGy

he

ee

var

eele

wees

Compact

cassette

tape

(C-30

~

C-90)

Tape

speed

....

0...

cece

ee

eee

one

4.76

cm/sec.

(+

0.19

cm/sec.

-0.05

cm/sec.)

Fast

forward/rewind

time

.........

Within

120

sec.

for

C-60

Wow

&

flutter.............

No

more

than

0.09%

(WRMS)

Frequency

response......

30

~

20,000

Hz

(+3

dB)

(at

meta!)

30

~

16,000

Hz

(+3

dB)

(at

normal)

Stereo

separation.............

000

c

eee

More

than

40

dB

Signal-to-noise

ratio

........

Dolby

NR

IN:

More

than

63

dB

(IEC-A

network)

Dolby

NR

OUT:

More

than

55

dB

(IEC-A

network)

KEX=73

.

FM

tuner

Frequency

range.

.......

2.

cece

ee

ees

87.5

~

108

MHz

Usable

sensitivity

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

12

dBf

(1.14V/752,

mono)

50

dB

quieting

sensitivity

.......

17

dBf

(1.94V/75Q,

mono)

Alternate

channel

selectivity............

70

dB

(+400

kHz)

Distortion

...............-

0.3%

(at

65

dBf,

1kHz,

stereo)

Frequency

response..............

30

~

15,000

Hz

(+3

dB)

Stereo

separation

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

40

dB

(at

65

dBf,

1kHz)

AM

(MW)

tuner

Frequency

range

........2

cece

aee

531

~

1,602

kHz)

Usable

sensitivity

......

18uV

(25

dB)

(S/N:

20

dB)

(KEX-70)

Usable

sensitivity.

...

.

30yV

(29.5

dB)

(S/N:

20

dB)

(KEX-73)

Selectivity.

........

cc

ccc

cece

ee

eee

50

dB

(+9

kHz)

LW

tuner

(KEX-73)

Frequency

range

..........0e

cece

eee

153 ~

281

kHz

Usable

sensitivity

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

70uV

(37

dB)

(S/N:

20

dB)

SEC.

i

wie ier

mcmesiaawianearass

50

dB

(+9

kHz)

Note:

Specifications

and

the

design

are

subject

to

possible

modification

without

notice

due

to

improvements.

¢

‘Dolby’

and

the

double-D

symbol

are

trademarks

of

Dolby

Laboratories

Licensing

corporation.

¢

Noise

Reduction

System

manufactured

under

license

from

Dolby

Laboratories

Licensing

Corporation.

eee

PIONEER

ELECTRONIC

CORPORATION

4-1,

Meguro

1-Chome,

Meguro-ku,

Tokyo

153,

Japan

PIONEER

ELECTRONICS

OF

AMERICA

1925

€,

Dominguez

St.

Long

Beach;

Calif.

30810

PIONEER

ELECTRONIC

(EUROPE)

N.V.

Luithagen-Haven

9,

2030

Antwerp,

Belgium

PIONEER

ELECTRONICS

AUSTRALIA

PTY.

LTD.

178-184

Boundary

Road,

Braeside,

Victoria

3195,

Austrailia

E

K

©

APR.

1981

Printed

in

Japan

EX-70/73

CONTENTS

1.

PARTS

LOCATION.........

0.00.

cece

eee eee

ee

1

CAUTION

2.

CIRCUIT

DESCRIPTION..............2.-0--06-

1

When

Handling

IC

PD7004

and

PD2001

3.

ADJUSTMENT

Please

Observe:

3.1

Crystal

OSC

Frequency

Adjustment

..........

17

IC

PD7004

and

PD2001

(IC6

and

IC5

in

the

tuner

control

3.2

FMIF

Adjustment

.................--00-55

18

unit—

KEX-70,

1C5

and

IC4

in

the

tuner

control

unit—

KEX-73)

3.3.

FM

Tracking

Adjustment................--.

19

are

C-MOS

ICs

of

extremely

low

power

consumption

and

very

3.4

FM

MPX

Adjustment

...............-----5

20

high

input

impedance.

Unless

handled

with

special

care,

they

3.5

FM

ARC

Adjustment

...............-2008-

20

could

be

damaged

by

static

electricity

induction.

these

ICs

are

3.6

FM

Scan

(Seek)

Sensitivity

Check

...........

21

supplied

with

a

shorting

cap

(of

aluminium

foil)

attached.

3.7

AM

IF

Adjustment

(KEX-70)..............5-

21

When

soldering

or

performing

other

repair

work,

always

3.8

AM

Tracking

Adjustment

(KEX-70)...........

22

attach

this

cap

as

shown

below.

Remove

the

cap

after

the

3.9

MW/LW

IF

Adjustment

(KEX-73)............

23

repair

has

been

completed.

3.10

MW/LW

Tracking

Adjustment..............

24

Also,

this

type

IC

must

not

be

inserted

in

a

polystyrene

pack-

3.11

AM

(MW)

Scan

(Seek)

Sensitivity

Adjustment

.

25

age

for

storage.

3.12

LW

Scan

(Seek)

Sensitivity

Check

...........

25

3.13

Dolby

NR

Law

Adjustment

..............00-

25

3.14

Dolby

NR

Level

Adjustment.................

25

4.

CONNECTION

DIAGRAM

(KEX-70)...........5-.

29

5.

SCHEMATIC

CIRCUIT

DIAGRAM

(KEX-70)

.......-

33

6.

CONNECTION

DIAGRAM

(KEX-73)...........5--

37

7.

SCHEMATIC

CIRCUIT

DIAGRAM

(KEX-73)

.......

41

8.

CABINET

EXPLODED

VIEW.............--.-05-

45

9.

CHASSIS

EXPLODED

VIEW

...............0055

46

10.

PACKING

METHOD

..........

0.0.0

e

eee

..

49

11.

ELECTRICAL

PARTS

LIST.

...........0..00000-

50

¢

Cassette

Mechanism

Unit

See

the

Service

Manual

CX-118FV

(CRT-199)

when

servicing

the

cassette

mechanism

unit.

The

differences

from

the

CX-118FV

are

shown

below.

Exploded

View

(Top)

Page

26

CX-118FV

KEX-70,

KEX-73

Key

No.

Description

Part

No.

Description

24

Head

CPB-063

Head

Exploded

View

(Bottom)

Page

26

CX-118FV

KEX-70,

KEX-73

Description

Part

No.

Description

Motor

CXM-072

Motor

1.

PARTS

LOCATION

°

FE

IF

Unit

CWE-421

KEX-70O/73

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,

hu-

midity,

etc.

FM

Front

End

Unit

CWB-079

Amp

Unit

CWK-238

Knob

*

CAA-348

(Balance,

Bass)

Switch

Unit

CWS-104

(KEX-70)

CWS-103

(KEX-73)

Knob

%

CAA-349

(Volume,

Treble)

2.

CIRCUIT

DESCRIPTION

PB

Head

Motor

*% %&

CXM-072

Head

* *

CPB-063

Cassette

Mechanism

Assy

CXC-315

Grille

Unit

CXC-331

(KEX-70)

CXC-324

(KEX-73)

Button

%

CAC-347

(Eject)

Button

%

CAC-345

(Clock,

Mono,

Loc.s,

Loud,

70us,

Dolby

NR)

Fig.

1

LevelAdj.

Buffer

Attenuator

Buffer

Balans

Volume

Line

T.

Out

a=}

+

ae

je

He]

FM,AM

re

FM(75kHz

DEV

)400Hz

Volume

ie)

1

Level

Adj

Margin

-1o4

Al

aaa

Tone

Line

T.

J

-2dB

-2

tes

ete

Sh

Out

-23dBs

-20,5d8s

-30

4

AM

(30

%

MOD.)

400Hz

-4

-

Test

Tape

G

507)

(400Hz

200nwb/m)

//

EQ

Amp

4

+40dB

-604

Reh

-7idBs

Lee

Tone

:

Flat

Volume

:

Max

Fig.

2

=>

Cr

4

=

ir

4c}

2.1

TAPE

SECTION

e

Dolby

NR

Circuit

The

Dolby

NR

system

functions

to

reduce

the

amount

of

tape

hiss

and

expand

the

dynamic

range

of

the

high

frequencies.

It

is

able

to

improve

the

S/N

ratio

by

10

dB.

When

the

Dolby

NR

switch

is

at

the

OFF

position,

the

Dolby

NR

circuit

functions

as

a

flat

amplifier,

thereby

allowing

tapes

which

have

not

been

recorded

with

the

Dolby

system

to

be

played

back.

The

Dolby

NR

switch

is

set

to

ON

when

playing

tapes

which

have

been

recorded

with

the

Dolby

NR

system.

REVERSE

©

Equalizer

Amplifier

The

MB3106M

dual-type

IC

is

employed

in

the

equalizer

am-

plifier.

When

the

70us

switch

is

OFF,

Q1

(Lch)

and

Q2

(Rch)

go

OFF

and

the

amplifier

functions

as

a

normal

equalizer

(3180ys

+120us).

2.2

MUTING

CIRCUIT

When

the

switch

is

at

OFF,

+

B

is

applied

to

the

base

of

tran-

sistor

O5

which

then

turns

OFF

since

it

is

a

PNP

type.

Since

the

signal

components

no

longer

pass

through

the

highpass

filter,

the

circuit

functions

as

an

ordinary

flat

amplifier.

When

the

Dolby

NR

switch

is

at

ON,

+

B

is

no

longer

applied

to

the

base

of

transistor

O5

which

then

turns

ON.

+B

is

ap-

plied

to

the

Dolby

NR

indicator

which

lights.

Since

05

is

ON,

the

highpass

filter

is

connected

to

the

output

and

the

Dolby

noise

reduction

effect

is

produced.

OFF

O

|

op

oovey

wR

SWITCH

ON

1

DOLBY

NR

G

tNO.

Fig.

3

When

the

same

switch

is

ON,

Q1

and

Q2

turn

ON,

the

70us

equalization

network

is

added

and

the

amplifier

functions

as

a

CrO2

(Metal)

equalizer

(3180us

+

7Ous),

enabling

the

play-

back

of

CrO2

tapes.

CONNECTOR

Fig.

4

All

the

muting

operations

in

the

KEX-70

(KEX-73)

are

carried

out

by

the

output

section

of

the

amplifier

unit.

A

line

trans-

former

is

used

in

this

section

to

achieve

a

high

common-mode

rejection

ratio

(CMRR).

Muting

itself

is

performed

by

shorting

the

secondary

(output

side)

of

the

line

transformer

with

transistors

Q11

and

Q12.

Muting

is

operational

in

the

following

circumstances:

(a)

Fast

forward

and

rewind

operations

(b)

A.T.S.C.

(Automatic

Tape

Slack

Canceller)

operation

(c)

Scanning

and

seek

operations

(d)

When

the

preset

button

has

been

depressed

(e)

When

the

up/down

button

has

been

depressed

(f)

When

the

reception

band

is

switched

over

(g)

When

the

tuner

goes

OFF

Operations

(a)

and

(b)

A

positive

voltage

is

supplied

from

PD2001

from

mute

input

Y,

and

014

and

Q13

are

turned

on.

When

Q14

and

O13

are

ON,

Q11 and

012

go

ON

and

muting

is

effective.

D11

func-

2.3

DESCRIPTION

OF

DECK

CONTROL

IC

PD2001

The

PD2001

IC

makes

it

possible

to

perform

fast

forwarding,

rewinding

and

direction

change

operation

by

feather-touch

control.

With

every

operation

a

muting

output

signal

is

fed

out

to

the

PD2001

IC

before

the

operation

and

a

pre-muting

circuit

is

in-

serted.

The

KP-707G

is

included

among

the

models

which

employ

the

PD2001

IC

and

a

description

of

its

circuitry

is

given

in

Service

Manual

(CRT-249)

to

which

reference

should

be

made.

Fig.

5

is

used

for

this

particular

description.

When

an

input

is

fed

into

X1

for

changing

from

the

play

to

fast

forward

mode,

a

muting

output

is

first

fed

out

and

about

33ms

later

a

voltage

virtually

equivalent

to

the

VDD

is

fed out

to

both

OF

and

OR.

As

a

result,

the

fast

forward

and

rewind

solenoids

are

at-

tracted

and

the

fast

forward

mode

is

established.

The

time

during

which

both

solenoids

are

attracted

is

about

100ms.

At

KEX-70/73

tions

to

prevent

reverse

current

from

mute

input

Z,

and

the

time

constants

of

the

muting

operation

are

determined

by

R90

and

C57.

Operations

(c)~(f}

A

positive

voltage

is

supplied

from

PD7004

from

mute

input

Z,

and

Q13

and

Q14

are

turned

ON.

When

014

and

Q13

are

ON,

Q11 and

Q12

turn

ON

and

muting

is

effective.

Operation

(g)

When

the

tuner

is

switched

on

(same

for

any

band

position),

a

voltage

(approx.

13V)

is

supplied

from

mute

input

X,

and

C56

is

charged

through

R92

and

D12.

At

this

point,

Q15

re-

mains

in

the

OFF

mode

and

muting

is

not

effective.

Once

the

tuner

is

switched

OFF,

the

voltage

from

the

mute

input

X

is

rapidly

reduced

to

OV.

Q15

is

turned

ON

when

the

charged

C56

discharges.

Once

015

goes

ON,

Q14

and

Q13

both

go

ON,

ultimately

resulting

in

Q11

and

Q12

being

turned

ON

so

that

muting

is

effective.

the

same

time,

input

X11

is

set

to

the

hold

state

by

the

latch

cir-

cuit.

Once

the

time

during

which

the

fast

forward

and

rewind

sole-

noids

are

attracted

has

passed,

the

OF

output

is

set

to

a

high

impedance

and

so

the

fast

forward

solenoid

is

set

to

the

hold

state

with

a

voltage

of

about

2.5V

determined

by

R76,

R77,

R79

and

D14.

Furthermore,

the

OR

output

is

grounded

and

the

rewind

solenoid

is

released

since

no

voltage

is

applied

to

it.

When

an

input

is

fed

into

X3

from

fast

forward

to

rewind),

a

voltage

virtually

equivalent

to

VDD

is

fed

out

to

OR

and

the

mode

is

switched

to

rewinding.

About 100ms

later

the

rewind

solenoid

is

set

to

the

hold

state

by

a

voltage

deter-

mined

by

R76,

R78,

R80

and

D14,

and

overheating

of

the

solenoid

is

prevented.

cn

FF

SOLENOID

Fig.

5

EX-70O/73

Xt

INPUT

X3

INPUT

X!

-————f

hanGaom

_____

Input

latch

hold

|

FF

REW

XI

INPUT

X3-

INPUT

2.4

FUNCTIONS

OF

PD7004

CONTROL

IC

®

PLL

Section

The

PD7004

is

a

control

IC

for

PLL

synthesizer

tuners

de-

veloped

to

enable

FM

reception

at

50

kHz

steps

and

AM

re-

ception

(MW,

LW)

at

9

kHz

steps.

When

some

of

the

pins

of

this

IC

are

connected

via

a

diode

(switch

matrix,

mentioned

later),

a

microprocessor

is

activated

in

line

with

the

program

written

beforehand

into

the

IC

and

scan,

seek,

memory

and

ANTENNA

v7

FM

FRONT

END

UNIT

(CWB-079)

RF

MIX

Circuit

Fig.

7

shows

the

composition

of

the

phase-locked

loop

in

the

FM

mode.

The

VCO

(CWB-079

local

oscillator)

frequency,

fvco,

is

amplified

by

04

of

CWB-079

up

to

the

level

the

1/20-

fixed

divider

.PB552C

IC8

can

divide

it,

and

the

prescaler

out-

put

signal

of

IC8

enters

10

of

PD7004.

The

signal

is

then

fed

into

the

programmable

divider

which

is

microprocessor-controlled

inside

PD7004

and

the

frequency

of

the

signal

is

divided

by

the

required

ratio.

A

frequency

of

4.5

MHz,

whcih

serves

as

the

PD7004

clock

pulse

(funda-

mental

frequency

that

drives

the

microprocessor),

is

gener-

ated

by

crystal

oscillator

X1,

this

is

divided

down

(1/1800)

to

2.5

kHz

to

form

the

reference

frequency

of

the

phase

com-

7

©

Loop

Filter

O

&|

1C8uPBS552C

lea

Programabie

-

Bi

Fig.

6

other

control

operations

are

performed

by

the

28-pin

C-MOS

LSI.

This

is

combined

with

the

IR2403

(IC7)

driver

IC

for

the

display

LED

to

configure

the

PLL

synthesizer

tuner.

The PLL

synthesizer

tuner

is

now

described

centering

on

the

circuitry

operations

of

the

KEX-70/E

(Tuner

Control

Unit:

CWE-070,

FE

IF

Unit:

CWE-421).

To

IF

Amp

,

Detector

Q42,

041

Data

Out

aq

t/20i*SS

Y

Fig.

7

parator

whose

phase

is

then

digitally

compared

with

that

of

the

frequency-divided

signal,

and

the

pulse

centering

at

2.5

kHz

is

fed

out

from

12

via

the

charge

pump.

The

fre-

quency

deviation

is

converted

into

shifting

voltage

from

a

cer-

tain

DC

center

voltage.

When

the

frequency

is

higher

than

the

optimum,

positive

pulses

appear

at

the

output

and

the

more

it

deviates,

the

wider

pulse-width

and

vise

versa.

This

output

is

then

fed

into

the

loop

filter

(active

filter

com-

posed

of

041

and

42),

the

charging

and

discharging

of

C93

and

C94

are

used,

a

DC

voltage

is

formed

and

this

is

applied

to

6

of

CWE-421

as

the

tuning

voltage.

The

oscillation

fre-

quency

of

the

CWB-079’s

local

oscillator

is

fixed

and

the

phase-locked

loop

is

then

completed.

This

mode

is

now

locked

and

the

tuning

voltage—between

approx.

3.0V

and

8.8V—is

made

constant.

The

ANT,

RF

and

VCO

circuits

are

all

controlled,

the

reception

frequency

is

determined

and

this

is

held.

The

above

can

be

expressed

as

follows:

(fvco/20)/N

=

fr

=

2.5

kHz

fvco=

Nx

20x

fr

=

Nx50

kHz

This

means

that

every

time

the

programmable

divider

N

counts,

the

reception

frequency

changes

in

a

50

kHz

step.

in

the

AM

mode

the

CWM-070

IC1

local

oscillator

output

is

amplified

by

O4,

it

enters

11

of

PD7002,

its

frequency

is

di-

*

PD7004

Specifications

FM

KEX-70/73

vided

down

by

the

programmable

divider

to

fr

=

9

kHz,

phase

comparison

is

performed

as

with

FM,

a

pulse

with

a

frequency

of

9

kHz

as

the

reference

is

fed

out

from

13,

a

DC

voltage

is

formed

by

the

Q43

and

044

loop

filter,

this

is

supplied

to

the

ANT,

RF

and

OSC

block

of

the

AM

tuning

circuit,

the

oscilla-

tion

frequency

is

fixed

and

locked.

The

AM

tuning

voltage

range

from

0.9V

to

8.8V,

with

the

result

that

the

frequencies

vary

within

a

531

kHz

to

1602

kHz

range.

The

for

the

AM

mode

is:

fvco

=

Nxfr

The

fr

serves

as

the

channel

spaces

(9

kHz)

and

tuning

is

per-

formed

in

9

kHz

steps.

This

completes

the

description

of

the

PLL

section.

Mw

LW

Reception

frequency

87.5~%108

MHz

153281

kHz

_

53111602

kHz

Channel

space

50

kHz

UP/DOWN

1

kHz

9kHz

SCAN,

SEEK

9

kHz

IF

offset

10.700

MHz

468

kHz

468

kHz

Phase

comparison

reference

frequency

2.5

kHz

9

kHz

1

kHz

Input

frequency

4.91~5.935

MHz

9992070

kHz

621~749

kHz

Prescaler

1/20

externally

mounted

Programmable

counter

frequency-

division

ratio

N

UP/DOWN

129

Number

of

channels

411

120

SCAN

SEEK

15

FM

FRONT

END

UNIT

19642374

Tuning

Volt

Loop

D.P.C

Filter

Charge

Pump

Frequency

Divider

|/I800

4.5MHz

Xtal

OSC

Timer

Frequency

Divider

For

instance,

when

the

reception

frequency

is

87.5

MHz,

the

local

oscillator

frequency

is

98.2

MHz,

a

local

oscillator

volt-

age

of

about

200

mVrms

(560

mVp-p)

is

fed

out

from

5

of

Front

End

CWB-079,

and

this

enters

prescaler

IC8.

The

mini-

mum

acceptable

level

of

this

IC

is

150

mVp-p

and

frequency

division

is

not

performed

at

lower

levels.

The

maximum

level

is

1Vp-p.

When

the

above

frequency

is

divided

(1/20),

the

result

is

4.910

MHz

and

this

becomes

2.5

kHz

when

divided

down

(1/1964)

by

the

programmable

divider

(N

=

1964).

This

matches

the

reference

frequency

and

phase

comparison

be-

Counter

Cc

aod

Local

OSC

Programable

Divider

5

N

1964

~

2374

Down

Scan

CH

Counter

Seek

Call

|

controtiee

Key

Matrix

Senser

None

111~230

621749

OSC

Out

C3

|,

wPB552C

1/20

66-f

3)

Display

Circuit

RAM

Memory

Fig.

8

comes

possible.

After

digital

phase

compazison,

the

signal

enters

the

loop

filter

via

the

charge

pump

to

become

a

DC

voltage.

When

the

manual

UP

key

is

depressed

once,

D1/K1

are

shorted

by

the

diode

and

when

this

is

sensed

by

the

K2

pin,

the

up

counter

inside

the

IC

counts

up,

and

one

is

added

to

the

programmable

divider

N

to

make

1965,

thereby

the

fre-

quency

steps

up

for

one

channel

on

the

frequency

scale

to

tune

into

87.55

MHz.

EX-7O/73

In

the

SCAN

mode,

the

up-counter

counts

up

one

by

one

with

the

D3/K2

matrix,

single

units

are

added

in

succession

to

the

programmable

divider

N

starting

at

1964

and

both

the

re-

ception

frequency

and

the

display

are

changed.

When

certain

frequencies

are

received,

a

squelch

signal

from

the

tuner

enters

the

control

unit,

transistor

032

is

turned

on,

the

D6/K2

matrix

is

energized

and

the

scanning

operation

is

stopped.

In

this

case,

scanning

is

automatically

started

with

the

PD7004

microprocessor

after

5

seconds.

To

stop

this

opera-

tion,

the

SCAN

key

is

depressed

again.

When

the

SEEK

key

is

depressed

during

the

scanning

operation,

the

mode

is

set

to

“seek’’

and,

just

as

with

scanning,

single

units

are

added

in

succession

to

the

programmable

divider

N.

Once

the

squelch

signal

is

sensed,

the

operation

is

stopped

just

as

with

scan-

ning,

and

this

remains

terminated.

MW

operations

are

the

same

as

those

for

FM

but the

LW

operations

are

slightly

different.

The

MW

frequency

band

ranges

from

531

kHz

to

1602

kHz—a

span

which

can

be

divided

by

9

(multiples

of

9).

This

means

that

if

the

reference

frequency

is

made

9

kHz,

the

same

opera-

tion

as

with

FM

can

be

induced

simply

by

stepping

up

or

down

in

single

units

the

programmable

divider

N.

However,

the

LW

frequency

band

ranges

from

155

kHz

to

281

kHz—a

span

which

cannot

be

divided

by

9—

thereby

making

it

necessary

to

make

the

phase

comparison

reference

frequency

1kHz.

¢

Charge

Pump

and

Loop

Filter

P07004

Comparator

The

phases

of

the

reference

frequency

and

the

VCO

fre-

quency

divided

by

the

prescaler

and

programmable

divider

are

compared

by

the

digital

phase

comparator.

Since

the

output

pulse

cannot

be

connected

directly

to

the

active

filter.

The

PD

‘output

is

fed

out

of

the

complimentary

switching

circuit

(charge

pump}

which

consists

of

a

n-channel

MOS

FET

anda

p-channel

MOS

FET.

The

charge

pump

is

characterized

by

3

modes:

(1)

When

the

p-channel

is

OFF

and

n-channel

ON

(2)

When

the

p-channel

is

ON

and

n-channel

OFF

(3)

When

the

unit

is

floating

with

both

p-

and

n-channels

OFF

However,

there

is

currently

a

movement

to

make

the

fre-

quency

allotment

of

LW

broadcasting

station

multiples

of 9,

and

reception

frequency

band

will

span

153

kHz

to

279

kHz.

In

order

to

cope

with

this

change,

the

PD7004

allows

the

fre-

quency

scale

from

153

kHz

to

281

kHz

to

be

scanned

either

up

or

down

in

1

kHz

steps

during

the

manual

UP/

DOWN

tuning

operation,

and

it

allows

a

jump

to

be

made

at

one

end

of

the

band

to

the

other

end.

Example

of

UP

operation:

279

kHz

>

280

kHz

>

281

kHz

153

kHz>

154

kHz

Example

of

DOWN

operation:

155

kHz

>

154

kHz->

153

kHz

>

281

kHz

>

280

kHz

During

the

SCAN/SEEK

tuning

operation,

the

frequency

scale

is

moved

up

in

9

kHz

steps

from

the

starting

frequency

and

when

the

uppermost

frequency

limit

of

281

kHz

is

ex-

ceeded,

the

scale

is

moved

up

again

in

9

kHz

steps

from

the

lowermost

frequency

of

155

kHz.

Example

1

of

SCAN/SEEK

operation:

263

kHz

>

272

kHz

>

281

kHz

155

kHz

>

164

kHz

Example

2

of

SCAN/SEEK

operation:

295

kHz

>

268

kHz

>

277

kHz

>

155

kHz

>

164

kHz

The

maximum

frequency

switchable

by

a

C-MOS

IC

is

about

7.2

MHz.

This

means

that

the

FM

local

oscillator

signal

fre-

quency

cannot

be

divided

directly

and

that

a

prescaler

is

re-

quired

to

divide

the

frequency

down

to

about

5

MHz

previ-

ously.

Fig.

9

A

plus

pulse

and

a

minus

pulse

are

fed

out

onto

the

DC

voitage.

In

mode

(7),

Q41

and

Q42

turn

OFF

when

the

minus

pulse

is

fed

out

and

the

042

collector

voltage

rises.

Next,

C93

and

C94

charge,

the

tuning

voltage

increases

and

the

reception

fre-

quency

moves

up

the

scale.

In

mode

(2),

Q41

and

Q42

turn

ON

when

the

plus

pulse

is

fed

out,

and

the

042

collector

voltage

falls.

As

a

result,

the

recep-

tion

frequency

moves

down

the

scale.

Mode

(3)

signifies

that

the

loop

is

locked.

However,

the

out-

put

pulses

are

such

that

the

above

three

modes

are

repeated

all

the

time

even

when

the

loop

is

locked,

and

the

locked

loop

state

is

maintained.

*

Display

Control Section

A

dynamic

lighting

system

is

adopted

for

the

PD7004

display

with

the

LEDs

being

lighted

in

synchronization

with

the

D1

through

D6

(PD7004

28

through

23)

digit

signals.

A

sweep

is

performed

in

a

period

of

about

3

msec.

The

digit

signals,

used

to

indicate

the

digits

(D1

=

1st

digit;

D2:

2nd

digit),

are

fed

out

from

PD7004.

The

LEDs

employed

for

dis-

playing

the

numbers

are

composed

of

7

segments

and,

with

the

addition

of

the

dot

[.],

the

8-segment

output

is

fed

out

from

the

|C,

the

required

segments

of

the

LED

for

lighting

are

synchronized

with

the

digit

output

and

segment

output

and

turned

on,

in

each

case

at

a

period

speed

of

3

msec,

with

a

sweep

being

performed

from

the

highest

digit

to

the

lowest

digit.

The

above

process

is

explained

using

Fig.

10

D1

through

D6

are

active

at

‘’L”

and

S1

through

S8

are

active

at

’H’’.

If

the

description

is

simplified

and

confined

to

one

LED,

then,

as

in

Fig.

10,

the

LED

lights

only

when

the

digit

output

is

‘“L”

and

the

segment

output

is

‘““H.”

+5.8v

Q22~

Q27

On

Display

Sn

es

jy

be

Fig.

10

4

=>

Cy

48

Va

5c}

More

specifically

in

the

above

figure

when

digit

output

Dn

(iC

output)

is

‘’L,’’

the

Q23~Q27

Darlington

pnp

transistors

turn

ON

and

when

the

segment

output

Sn

is

‘’H,””

IR2403

and

Q37

turn

ON,

segment

1

of

the

LED

lights.

For

instance,

when

the

first

digit

output

goes

to

‘‘L’”’,

and

segments

(2)

and

(3)

go

to

“HU

a

"is

indicated

and

lighting

is

repeated

as

in

Fig.

12

at

a

speed

of

3

msec.

Distributing

a

signal

to

multiple

digit

lines

by

turns

is

called

dynamic

lighting.

In

the

dynamic

system,

much

fewer

IC

pins

are

used

than

with

the

static

lighting

system

where

each

of

the

segments

is

lighted

with

a

DC

voltage.

However,

the

dynamic

signal

which

causes

the

lighting

is

a

5Vp-p

square

wave

and

so

care

must

be

taken

lest

it

should

not

interfere

RF

and

power

supply

circuit.

The

frequency,

clock,

band

and

channels

are

indicated

by

the

above

method.

ea

__

vdeo

ee

es

ies

(aeons

=

J

ras

Ee

EX-70O/73

e

Switch

Matrix

PD7004

q

Ne

Ae

CH3/8

All

the

functions

of

the

KEX-70/E

including

scanning,

seek,

memory

and

band

(display)

selection

are

controlled

by

the

PD7004

by

sensing

its

D1~D6

display

signals

at

the

22

through

19

or

key

sensing

inputs

k1

through

K4.

When

changing

over

to

AM

(MW),

for

example,

D5

and

K2

¢

Scan

Operation

When

the

SCAN

key

is

depressed

with

the

radio

on

at

the

FM

1

position

(with

Q30

and

Q28

ON),

PD7004

is

set

to

the

SCAN

mode

and

the

frequency

division

ratio

N

of

the

programmable

divider

increases

one

step

at

a

time

during

a

fixed

time

period.

Due

to

the

phase-locked

loop

configuration

the

tuning

voltage

also

rises

and

the

reception

frequency

moves

up

the

fre-

quency

scale.

The

absence

or

presence

of

broadcasting

sta-

tions

is

identified

by

PD7004

which

judges

whether

or

not

032

has

turned

ON

with

every

1-step

change,

and

N

is

stopped

Y

FM

Front

End

CwB-079

fas

tne

IF

Amp

TA7302P

Stop

Signal

Circuit

Q5,Q6,Q7,

a8

IF

Amp/FM

Detector

Noise

Suppressor

PA4007

Fig.

13

are

not

connected

unless

Q13

is

turned

ON.

Q28

connects

D4

and

K1

and

unless

this

turns

ON,

the

radio

does

not

come

on

and

the

frequency

is

not

displayed.

The

nine

diodes,

D27

~

D34

and

D41,

are

designed

to

safe-

guard

against

malfunctions

caused

when

the

touch-type

switches

are

depressed

twice.

from

changing.

In

other

words,

the

scanning

operation

can

be

stopped

by

turning

Q32

ON

when

a

station

has

been

picked

up.

11

of

the

PA4007

IC,

serving

as

the

open

collector

output,

is

set

to

the

open

state

when

a

station

is

tuned

in,

and

032

turns

ON.

When

no

station

is

tuned

in,

it

is

shorted,

and

032

goes

OFF.

It

is

set

to

the

hold

state

when

032

goes

ON

during

the

seek

and

scan

operations

by

virtually

the

same

operation.

The

procedure

is

the

same

for

AM

reception.

MPX

Decoder

LA3370

AF

Out

PO07004

Fig.

14

Pioneer KEX-70 User manual

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