Pioneer SX-3800 User Manual

Sefvice

FM

Ouartz

STEREO

Locked

RECEIVER

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MODEL

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This
see
dditional

SX.38OO COMES

Type

KU 120V only

s/G 1

s 1 10V,

KC

service manual is applicable

the additional

service

10V, 120V,

l20V only

service manual

manual

CONTENTS

1. SPECIFICATIONS
FRONT

2,

3. BLOCK DIAGBAM

4.

CIRCUIT DESCRIPTIONS

4.1

4.2 AM Tuner

4.3

4.4

4.5

4.6

4.7

4.8 Protection

DISASSEMBLY....

5.
PARTS

1

DIAL CORD
ADJUSTMENTS

8.
8,1

PANEL FACILITIES

FM

Tuner

Display

EqualizerAmplifier
Tone Control
Power
Power

FM

Circuit

Amplif

Indicator

Circuit

LOCATION

STRINGING

Tuner

Amplifier
ier

IN

22QV,

12OV,

22OY

(ART-519).

. . .

Circuit

FOUR

Volt4e

and

240V

and

24OV

,

to the

lp

VERSIONS

(Switchable)

(Switchabte)

47

DISTINGUISHED

KU type.

-p571.

When repairing

3
5
7

I

o
o

12
12
12
14
14
16
17
19

20

FOLLOWS:

AS

U.S.A. model

U.S. Militarv

General

Canada

When

repairing

8.2

8.3

8.4
EXPLODED

9.

10.

SCHEMATIC
CONNECTION

10. 1

10.2 P.C.

10.3 PartsList

11. PACK|NG....

ADDITIONAL

I.SPEC|F|CAT|ONS

2. CONTRAST

3.

SCHEMATIC

PATTERNS

3. 1

3.2

model

exDort model

model

the

S/G and

the

KC type.

AM Tuner
PowerAmplifier...
FL

Indicator

VIEW

DIAGRAM,

DIAGRAM

Schematic

Board

SE RV ICE

OF MISCELLANEOUS

DIAGRAM,

AND PARTS
Schematic Diagram
Switch Assembly

Remarks

S

olease

Circuit

P.C.

AND PARTS

Diagram

Connection

MANUAL

P.C.

LIST

{AWS.148) 57

please

Wpe,

see the a-

EOARD

Diagram

PARTS

BOARD

LIST

...,...41

.....47

. . . . 48

22
23
24

25

3l
35

46

49

;

t

H

H
H

n

I
H
H
H
H

T

H
H
I

i

t

I

I

e

+

I
I

1.

SPECTFTCATIONS

t

r

t

t

t

t

I
t

t
T

t
t

t
t

Power

Continuous
nel,

Ampl if ier Section

min.,

Hertz

with

Power

at Sohms from

n0 m0re than 0.005% total

nic distortion,

Harmonic

Total

ohms)

I

continuous

watts

30

Intermodulation

continuous

watts

30

Frequency

lnput

Sensitivity/lmpedance

or,rri

Speaker

Distortion

power

rated

per

channel

Distortion

power

rated

per

channel

Response

. . . . .

"-:

:: ::"::'':

Hum

Preamplifier Section
I nput

PHONO
AUX,TAPE

Phono

PHONO

Output

TAPERECI,2

PREAMP

Total

PHONO

AUX,TAPE

Frequency

PHONO

or", iori

Noise

and

(Sensitivity/l

Overload

(

Level/l

OUT

Harmonic Distortion

(REC

Besponse

(RIAA

1*:":

(lHF,

mpedance)

PLAY

1,2 . .

Level

mpedance)

.. ..,.

(Rr_:

-....1V/l

OUT)

PLAY

1,2 . . . . . .

Equalization)

,ro"

i

0utput of 60watts*

per

20Hertz to 20,000

(20

output . .

power

(50

output

power

5 Hertz

Hertz to 20,000

No

output

No more than 0.005%

Hertz : 7,000 Hertz = 4 : 1)

No more than

output

No

to

200,000

(POWER

AMP

1v/50

A,

Hertz,

more than

more

than 0,005%

Hertz
lN)
kilohms

B, A+B

He*z' 8 0hms)

i*

1o

short-circuited,

..

{T.H.D.0.005%,

.. .. . 250mV

kilohms)

50

(20

,';'o^u"'

A network)

115d8

2.5mV/50
150mVl50kilohms

. . .

Hertz)

1,000

150mV

kilohms

Hertz

7Hz

{Volume:

to 20,000

more

No

output}

{10V
No more than
(10V

output)

to 20'000

to

Hertz

8o,0oo

kilohms

Hertz)

than 0.005%

Hertz

chan-

harmo'

0.005%

0.0057o

OA

l!

max.}

0.005%

t0'2dB

aa

]f

Tone Control

BASS .

TREBLE .....

Filter

Contour

Noise

(at

65dBf)

lkHz.

6kHz .

lkHz

6kHz

Ratio. ,

Channel

Response

lnput

.

(Volume

. .

(lHF,

1,2 ..,. . . .

(lH

Ratio

.

-

Selectivity

Ratio, . . . . . . 65dB

Ratio . . . . . . .

.

control set at

+6dB

. .

short-circuited,

F

)

..,..,7ft8

......45d8

...... 35dB

....2}Hzto15kHz1!loe

Subsonic

Loudness

and

Hum

PHONO. .....82d8

AUX,TAPEPLAY

Attenuator.

FM

Tuner Section

Usable Sensitivity

Ouieting Sensitivity

50dB

MONO
STEREO

Signal-to-Noise

MONO
STEREO

Distortion

MONO l00Hz.

STEREO IOOHz.

Capture
Alternate

400kHz

Stereo Separation

1kHz.
30H2to15kH2.

Frequency

SpuriousResponse
lmageResponseRatio
lFResponseRatio..
AMSuppressionRatio
SubcarrierProduct
SCARejectionRatio
Muting Thteshold
Antenna

tSdB
r',l0dB(10,000H2)

15Hz

(100H2),+3dB

A

11OdB

....-20d8

10.3dBf

16.2dBf

37dBf

83dB

78dB

0.1o/o
a.a7%

0.15%
O.2Yo

0.15%

0.25%

r.odB

... 65dB

.... 90dB

... 55dB

50dB

64dB

....

19.2dBf
300 ohms balanced,
75

(100H2)

(-6dB/oct.)

*40d8

position)

(10,000H2)

network)

{1.8itv)
(3.6sV)

(39pV)

(at

65dBf)

(at

80dBf,

(5pV)

ohms unbalanced.

I

t

I

Eix-3El00

I

AM Tuner
Sensitivity

Selectivity .....30d8

Signal-to-NoiseBatio .... 50dB

lmageResponseRatio
lFResponseRatio..
Antenna

Audio Section
Output

FM(100%Mod.).
AM(3O%Mod.)

Semiconductors

fCs...

FETs.
Transistors

Diodes .......58

Miscellaneous

PowerRequirements

PowerConsumption .

Dimensions

Weight

Section

(lHF,

Ferrite

antenna).

Ext.antenna}

{lHF,

(

(without package)

mpedance)

Level/l

. .....

.......17

.......6

. 300pV/m

. . . 15pV

40dB

...

40dB

....

.... Ferritelooostickantenna

..... 650mVl1

200mV/1kilohms

...,.71

.... ACi20V,60Hz

...

200W(ULl

....506{W}

434{D}mm

19-15116(W)

(H)

x

16.2k9

kilohms

x164{H) x

x6-7/16

17-1116(D)

(351b

in

12oz)

t

r|
r|

t

t
t

;

t

Furnished

Operatinginstructions . . . .

FMT-typeantenna .....

*

Measured Dursuant to
Regulation

NATE:
Specifications
without

Parts

rule

Power

on

and the design subject

notice due to

improvements.

. . . . .

Federal Trade

the

Output Claims

1
I

Commission's

for

Amplif iers,

poisible

to

Tnde

modifications

t
t

t
rl

t
rl

t

il

+

t

T

t
t

r

I

t

2.

TRONT

PANEL

FACILITIES

t

r

t

I
T

r

T

t

POWER

c

Set this
There
the
unpleasant
power

O

Depress
nected

panel.
You
sound
time.

gnlcHrNEss

@

Use
meter
BRIGHT:

DIM:

POWER

CI

This
on
nominal
speaker

orel

@

This

bunnrz

@

This
has
stabilized

switch

will

muting

is

switched

spERrER

the

to the

can depress

from

this

switch

and

the

meter

fluorescent

the

impedance

terminals.

PoINTER

pointer

indicator

been

obtained

by the

SWTTCH

to

ON

to supply

be

a short

circuit

noise

has

that

on

delay

been

is

sometimes generated

and

off

swtrcHEs

switch

corresponding

SPEAKERS

both
pairs

two

terminals

of

these

of

speaker

sELEcroR

to

select

the

frequency

When

bright locations.

At

night

ing

brightness

METER

allows

indicates

LocKED

lights

built-in

displav.

using

the receiver

or in

dark

is

you

to read

display

g

of

ohms

the

broadcasting

tNDtcAToR

up

after

and displays

quartz

power

when

it

actuated

.

to

buttons

rystems

brightness

locations

too high.

out

the rated

tube

when

are

the

optimum

that

the receiving

lock

circuit.

to the

is

set

to ON,

to

suppress

the

speakers

(A

or B)

to listen

at

of the

in

daylight

when

power

speakers

connected

stations.

tuning

receiver.

because

the

when

the

con-

on the rear

to

the

the

same

power

or other

the

exist-

level

with

a

to the

point

state is

TTU

O

,o

@

@

0

c}

tune

STEREO

This

indicator

program

if

SIGNAL

This indicator
during

the

ance

with

The

optimum

number

of indicators

rururruc

When

tuning

point

is indicated

When

the left

knob

slightly

rotate

on,

rnEouENCY

This indicates
With

FM

reception,

of

the display

"AM"

tion,

These

change

changed.

rururruc

Use

this knob

FM

MUTTNG

When

this

in,

the muting
annoying
frequencies
ing

station

fringe

area,

in.

lf

INDICATOR

lights

up

the FM

muting

INDICATOR

lights

in

sequence

tuning

of

an AM

the

strength
tuning

point

light.

tNDtcAToR

in

an FM

indicator

clockwise.

the knob

station,

when

When

slightly

DTSPLAY

the frequency

the

letters

',MHz,'

and

appears

when

on

the

the

KNOB

to

tune

in

to

OFF

SWTTCH

switch

is released

circuit

is

activated

interstation

for

noise-free

is far

set the

there

noise

away

or when

switch

is

broadcasting

a

when

receiving

off

switch

is

released.

from

left

FM

or

broadcast

of

the

signals

is

where

the

optimum

the

center

indicator

has

come

on. rotate

the right

counterclockwise-

which

,,FM.,

on the

left

and

function

broadcasting

and

an

between

reception.

receiving

to

the OFF

indicator

is

tuned.

appear

right.

With

,,kHz..

selector

stations.

FM

broadcast

inside

to

the broadcasting

When

position

station

an FM

through

being

the

the broadcast-

a station

with

stereo

right

in

accord-

received.

maximum

reception

lights

the tuning

comes

on the

left

AM recep.

on

the right.

position

tuned

suppress

and

a

strong

the

in a

then

up.

is

r--

level

signal
you

satisfactorilv

by the
MUTING
tune in. The muting circuit
tuner is receiving AM broadcasts. lf
performed
depressed and a
circuit
indicator

FUNCTTON

{"}

Depress the function
program

before selecting a
sound
FM:
AMr
AUX: Depress

PHONO:

NATE:

Only one

volunnE coNTRoL

@

Use
speakers and
the output

"o."

(}

MUTING

Set this switch to the
audio
volume control if
the

audio output

records

on the

want to receive.

stronger signals.

OFF switch

after the

is

set to

does

air next to a station whose

you

may not be

because the sound will be drowned

ln

cases like this,

to

OFF

does not work when

FM MUTING

station selected, the

mode

not

the OFF

light.

SELECTOR

switch

which corresponds

source. Turn the volume

different function

from

this control to adjust the output level to the

program

one
Depress this
Depress

audio component connected
jacks.

Depress this switch when
on the

jacks.

function

headphones. Turn

level . No

source is

switch

this switch for AM

this switch when

turntable connected

swirch should be deplessed

sound will be heard if

SWITCH

*20d8

output by 20d8.

or tapes.

There

you

this switch when turning down

temporarily and

LOUDNESS SWITCH

When listening to a

down, depress this

control

and treble
When the volume
hear
The loudness
this
treble come through
takes

turned down,

@

Use
right channels.

turned

will be accentuated.

bass

the

deficiency. By depressing this switch, the bass and

on

gRl-Rr\cE

this control to balance the

and treble than when the

switch

punch

a

coNTRoL

First, however, set

performance

is low,

even when the volume control is

human ear

the

is

designed

thus

much

more strongly and the sound

program

able to tune

set the

{depressed

OFF switch has

being

for FM

it

clockwise to

position

is no need to adjust

volume

position)

tuning has been

quartz

and the

control down first

switch

reproduced.
broadcasts.
broadcasts.

listening

playing

to the

at a time.

to attenuate

when

changing over

with the volume

switch

finds

volume is

compensate

to

of

mode switch

the

locked

LOCKED

to the

while

to an

to

the AUX

a record

PHONO

increase

you

set it to

and the bass

harder

it

left

the

in
out
FM

and

the

been

the

the
the

to

high.

for

and

to

MONO. lf
means that
Turn the balance control to the
versely. if
means that
Therefore, turn
adjust. After adjusting. return the mode switch to

the sound appears

the volume

the sound appears

volume of

the

the balance control to the

to

of the

to

the

be louder on the right, it

right

channel

left

and adjust. Con-

louder

be

left

channel

is

on the

is
right

STEREO.

TAPE MONTTOR

@)

Employ for
progress.

1: Playback

the TAPE
Playback

2:,

the

NOTES:

l. 8e

when
When

2.
operate
signat to the T,APE

MODE

G}

Use

this
ances.
STEREO:

MONO:

LOW FILTER

AD

When
can

means that
frequencies
from
Although

intermodulation

BASS

@

When

response in the bass

boosted.

reSponse.

At

the OFF

frequency response is flat.

and

HEADPHONE

€}

Plug
listen
Release
the sound

tape

or monitoring

'l

or

TAPE

2

sure to set the switches

playing

recording

the

tape

SWITCH

switch

Set to this
When set to this
channel
duced

systems.

this switch is

provided

be

you

which

a turntable and other

this

AND

turned clockwise

Turning

position

headphones into this

the

both

through

your

speaker

through

SWTTCHES

playback

jacks.

monitoring of a tape deck

iacks.

records

with tvvo tape decks

monitor

for

monophonically

or

to monitor a

of a tape deck

to

upper

or listening to broadcasts.

2 deck.

selecting

position

signals will

the

simultaneausly. do nat

I switch as this will interrupt

mono or stereo

for

normal

position,

the left

be mixed and repro-

from

recording

connected

connected to

IOFF)

perform.

operations.

and

both

SWITCH

'l

to

set

{or f requencies

can cancel out

is

noise

distortion and damage the speakers.

TREBLE

SHz, a 6dB/oct attenuation

15H2.

the ultra-low

distortion.

of

it can

generated

cannot be

below

noise in

low-pitched

by

forms

heard,

CONTROLS

from

the OFF

and treble

counterclockwise attenuates the

tone control circuit is bypassed

the

range,

position,

respectively,

JACK

jack

stereo headphones.

you

switches

your

headphones only.

if

when

want to

you

listen

higher.

left,

it

higher.

and

in

to

position

the

right

speaker

This

rumble

generate

the

is

want

to

to

H

H

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4.

CIRCUIT

FM

4.1
Front

ganged

equipped L-stage

Clapp circuit local oscillator.

voltage

(variable
system
operation,
diode.

lF Amplifier

filten. The

stitutes
limiting limiter. The IC
stage,an

(PA3001-A),
quadrature
cuits.

ratio, delay characteristics, and other
shows a
the

Multiplex Decoder

(PA4006-A)
functions in
functions of the more

(PA1-001-A)
further

MPX

(see

either
eliminating

distortion.
tures

TUNER

End

FM front

The

tuning capacitor, a dual-gate

controled

capacitance diode).

(refer

These employ 3

a single-stage differential

Performance

PA3001-4.

The recently developed multiplex decoder

Distortion

improved by incorporating a

decoder. The chopper

Fig.

to

DC

to

a constant voltage is applied to the

and Detector

(HA1201)

IC

improvement on

includes an

detector,

marked improvement in comparison to

combines

a single

and

ratings and

4-1)

operates

ground

generation

the

Furthermore,

direct-coupled switching

FRONT ENO

FM

DESCRIPTIONS

end of
RF
oscillator employing a

"Quartz-lock

ICs

in terms of distortion, S/N

AF MUTING IC

to the through circuit, thereby

or

SX-3800 includes

MOS FET-

amplifier, and

This

When the

system") is not in

and 3 dual-element ceramic

of the

(PA3007-A)

the former IF

IF limiter

meter drive, and other cir-

MPX

decoding with muting

IC,

thereby handling the

conventional MPX IC

SIN ratio have been

type switching circuit

by switching the signal

of unwanted

since the

a modified

oscillator

quartz-lock

first

2 stage con-

amplifier current-

in the third

system

amplifier,

parameters,

(PA1002-A).

chopper type

PA4006-A fea-

with the detec-

a 3

is a

vari-cap

IC

IC

noise or

tor, there is no
low frequency end.

Besides the
PA4006-A
ler,

stereo

amplifier,

Composite

and

deterioration

decoder and
incorporates

also
auto selector,

MUT

control

signal

muting

the

VCO killer circuit,

circuit.

dhllL'

InOut

JU1IIIUIJIJUUI

Switchins

Fig.4-1 Chopper type switching

ouartz-Lock

quartz-lock

The
stereo receiver
employing a crystal

the intermediate
voltage by the discriminator
crystal resonator),

frequency being

locked.

control

remain tuned securely

IF
applied
consists of
resonance
tor. The resonance
frequency
at this
being reduced
quency

This extremely stable

system thus

When the

system

to crystal detector

time

increases, the

,is".rc-1q/

system

system

is a frequency servocontrol

resonator.

frequency

resulting

corrected and subsequently

IF

signal

(PA300?-A),

IC

diodes connected

circuit

(10.?MHz),

will be minimal,

equipped

frequency is the same

minimum

to a

.^ I

thL

featured

(iF)

in the

ensures that

for as long as

appears

(see

in

with

which

reactance

means

resulting

level.

in separation

pilot

signal

­|

circuit

in the SX-3800

Any displacement

is detected

(equipped

local oscillator

frequency servo-

tuned frequencies

required.

pin

at

it is amplified

Fig.

parallel

a crystal resona-

the

If
the capacitance

of

at the

circuits,

no.l? of the

4'2)

impedance
in the output
the input

the

cancel-

ivluT

Output

system

DC

as a

with a

and

which

in a series

as the

fre-

in

IF

t
t

H

t

H

H

T

;

;

;

I

H

;

E}

T

T

Fig.4-2

OC AMP

WITH LIMIiER

clRcull

quartz-lock

FM

LPF

sYstem

CRYSTAL

1

r

DTTECIOR

H
I

I

t

rl

T

t

r

t

I

t

I

r

t

I

t
t

rl

l

t

I

(C)

stage
ductance
detection

of tlie
stage reactance
increased,
leaves
stage
of detuning
creased,
detector
teristics, FM
IF

signal

to modulation

axis, And
resonance
will
in

the central
respect
resulting
DC voltage
LPF2
which
in

tlre iocal

oscillator frequency

constant

a

Since
tor is
quencies

r

Limiting

If
overiap
cies
A

DC

(limiter
restricts
tance

A
system

level
quency
This

gate

the
ing

in

Iock

is reduced,

stage

by D2

IF

signal.

resulting

the negative

and C

resulting

output. By

is

if

frequency,

be zero. If,

to the

in

(AC
is

applied

tuned

the

regulated

of

quartz-lock

lhe

with

and

result
amplifier
action

the voltage

diode,

DC

voltage

IC

drops

has been

DC voltage (FM

of

the FET

circuit

(L)

which

If

the input frequency

is

decreased

stage

reactances

in

the respective

in

detection

FIvI

an

will

the

central frequency

however,

frequency,

detector

generation

the

passed

is

filter)

to the variable

oscillator,

frequency).

central frequency

by

extremely

the

Locking

strong

in

considerable
is

by

NFB

thereby limiting

appea$

(PA3007-A)

below

detuned

(fET)

Q2

being

being

turned off.

and

the

reactance

increased,

leaves

in AiVl

portion

a

subsequent

thus

attaining

becomes

signal

be symmetrical

to form

the

adjacent

applied

5pV,

frequency

the detector

there

will

through LPF1

thereby

to

obtain

crystal

high

stability

Range

range

therelore

circuit

at

when

or when

by

muting

via

a Schmitt

turned

resulting

the

and

C stage

detection

of the IF

increase

directions

possible.

is

any

frequency

become

of a DC

a correction

capacitance

a constant

of the

resonator,

is

too

broadcasting

tuning

used

zener

to

the variable

quartz-lock

the

pin

no.L3

the

more

signal)

on, and

of the

in

positive

increase
S-curve

about

is

output

asymmetrical,

(IF

correcting

are

diodes)

antenna

the

than

circuit,

portion

decreases,

reactance

by

D1

which

signal. The

as the

deviation

displacement

voltage.

crystal

wide,

as

is

deglee

is in-

in

charac-

Since

a

central

equal to

DC

level

deviation

This

filter)

voltage

diode

tF

detec-

tuned

obtained.

it

frequen-

difficulties.

a limiter

which

capaci-

range.

of

the IF

input

tuned

r100kHz.

applied

result-

quartz-

the

in-

AM

L

L

the

the

due

the

in

and

the

(i.e.

fre-

will

fre-

to

4.2

AM

TUNER

The

AM
tuning
tains
amplifier,

panel
decoder

minal

(

4,3

Frequency

played
(FL
(a
0 to
which

tion
a buffer

(M54451P)
sion
rFRlied
This

?-segment
on

given
FL
nected
signals

pendent
being
Each

capacitor

a l-stage

The

AM

for

is

adaptor.

is

the converter

emitterf

Frequencies

-

The

An

osc.sr6NAL

ollower)

DISPLAY

in

digital

tube). Each

(see

e)

(with

9

employs

signal

is

the local

(1/8

to

IC

is

according

outline

in

block

tube

a

in

(see

grid

lit

up in

digit

LOCAL

AM

FM LOCAL
OSC.SIGNAL

tuner

detector,

connecting

Display

Fig.

section

plus

an

RF

amplifier,

and AGC

STEREO

CIRCUIT

received

form

the exception

only

OUT

to an

The

signal

output

stage.

by

digit employs

4-3)

to

2 segments

fi'

Fig.4-3

source

amplifier (FET)

where

for

the

responsible

S-digit

to time-shared

-

g

parallel,

Fig.

is

lit

7-segment

during

oscillator.

it

is

subjected

AM

and

frequency

for

display

of

the

composition

diagram

segments

the

D1

4-6)

apptied

for

each

succession

up for

(M5445rP)

rc

lms

L/80

form

(anode)

digit)

sx-gaoo

consists

(HA119Z)

IC

converter,

circuit.

terminal

AM

stereo

appearing

passed

by

the SX-9800

fluorescent

up

display

o

the

(each

-

from

all

of the left

b and

digit

display

both AM

The

signal

to

the
to frequency

for FM)

counter

dynamic

digit

sequential

in Fig.

for

Db

time

to

each

result

the left

during

each

of

a 2-ganged

which

on

via a

indicator

to ?

numerals

c).

and

is

prescalar

before

IC

drive

being

scanning).

pDb009

of

4-b.

each

division pulse

grid

in

hand

con-

2-stage

the rear

broadcast

at this

buffer

are

tube

segments

from

hand

digit

FM

recep-

passed

divi-

being

(pDb0Og).

of

turned

With

digit

con-

(inde-

the

digik

side.

bms

inter-

IF

ter-

dis-

via

IC

the

is

the

I

T

t

FM"aM sELgcrroN

Fig.

4-4

S IGNAL

Frequency

display

FL TUBE

block

a

diagram

a

OIGIT

ORIVER

SEGM€NT

MU

DRIVER

PLE

!TI

XER

I

GND

Fig.4-5

val. Pin
terminal. The
8009s
L
tube brightness
period).
tube
ness

basic signai
division
control signal.

designating
modes employed in the
designated by
levels
mode are

IF
during
characteristics.

system
the
decimal
appear

the TUNING and SIGNAL indicators.

though the segments

are

cuits, the

division

no.? of

for

level

signals, thereby varying

Note

is driven by static drive,

may

be

The

5.12MHz crystal
pulse

Terminals S1 - S4

(H

and

required

ceramic filter stage, 53

FM

Although

is

capable of

FM

band, the L0kHz digit

place)

only as 5 or 0.

The frequency display

static driven by the corresponding drive

pulse

PD5009

time division

H level

varied

used

mode according to the ceramic filter

edd

input

(by

that

by

in the

signal and

reception mode.

varying

L).

The

in

the SX-3800

in

the

is

driven

timing,

is the

brightness

pulse

signals, and to

the degree

varying

since the

changing the

(pin

3 different

coping

locking

FM

(anode)

thereby

the

segment lighting

pov.er

the degree

oscillator

preparation

counter

the

-

nos.3

The

SX-3800

the combination

FL

according to the D3

(see

with IF

54

and

FM

stage

any frequency within

(digit

frequency

tube also incorporates

for these indicators

placing

width is

indicator

grid

voltage.

generates

of

gate

6) are used in
2 reception

Table

IFs

during
offset
being

quartz-lock

in the second

display will

the segments

Block diagram

selector

to

set

200ps

for
FL

of

FL

bright-

of

the

the

time

circuit

1) are

of input

FM

in the
preset

And

cir-

time

al-

PRESETAEL€

OECIMAL COUNTER

22-8lI r

PD5009

of

Inl

lttr-

o,w

ooM

*l-w

,,iw

-'l'*i*iill

t{--

under

indicators
according to the
MHz

MODE

AM L

+

tm3

Fig.4-6

dynamic drive.

indicators are

FM

D1-D5

in

the

s1

H L L 1073

H

H L

5-DIGIT

16

ROM

8C= L

time division

In

addition, the

frequency display

Db

timing,

lit

accordine to

S2

H H

s3

L H

pulse

while the kHz and

the D1 timine.

I

H

L

H

H

L

(DlM)

signals

AM

and

section

lF

{MHz)

10.70
't

0.67

450kHz

FIW

are lit

Table

I
I

I
I
I
I

t

I

r|

il

1

i

t

t

10

t

r

sx-g€too

r

t

T

l|

t
t

ll

t
t

f
f

I
I

t
t

t
t

SIGNAL

The

FL

drive
(PA300?-A)

amplified

(HA12010).

IC
comparators
power
to

drive

TUNING

The
tuning
casting
2

detuning
direction
from.
in Fig.

The

station

center
and
feren^tial
and
appearing

{PA3007-A) and
(Q17

more

The
scribes
particular

pin

no.2

lndicator

SX-3800

tube

5-point

signal

and

indicator

the

lndicator

TUNING

indicator

station

direction

in

The

corresponding

4-B

below.

TUNING

has

been

frequency.

turned

Q21

amplifier

being

Q24

at

&

Q1B)

t100kHz.

than

DC

voltage

an

S

curve

broadcasting

serving

obtained

and AIVI

similar

SIGNAL

which

turned

pin
rvhen

Circuit

SIGNAL

indicator

from

tuner

then

applied

This

IC

to

circuit,

indicator.

Circuit

indicator

(which

frequency

indicators

the

station

indicator

tuned

This

is

(resulting

off

le19

on)

no.lB

passed

the

pin

on

when

tuning

frequency,

as

the

Fig.

4-7

indicator

display.

the FM

IC

to

contains

those

b

of

these

consists

lights

properly

is

has

drive

is

to within t100kHz

because

&

e20J

by

the FM

of

the

via

the

station

no.4

reference

consists

The

IF

(HA119?)

the

indicator

pairs

12

employed

pairs

of

up

when

which

been

circuits

activated

in

of

to

are

is

e16
the

detector

being

muting

IF

Schmitt

is

tuned

pAB007_A

and

away

the

level.

signal

system

of voltage

being

tuned)

indicate

tuned

turned

tumed

system

voltage

This

SIGNAL

of

meter

is

first

drive

in

the

used

a center

a broad-

and

the

awav

outlinei

once

the

of

the

on

dif_

off

signal

IC

circuit

away

by

de-

from

on

DC

indicator

an
IC

a

drive

SCHMITT
CIRCUII

(PA30(r/-A

rc

voltage
(Q19

&

tor

switch

When

quency

to

a

higher

be

higher
voltage
voltage
and

the

ing

direction

circuit

)

Fig.

4-8

is

amplified

and

Q20)

circuit

tuning

(or

side

frequency),

than

will

thus

raised,

higher

indicator

TUNING

by

then

(eZZ

&

to

a frequency

tuning

the voltage

that

resulting

frequency

on

be

lowered

pin

also

indicator

the

applied

e2g).

away

in

drive.circuit

differential

to

from

from

no.2.

The

and

e2B

(right

being

polarity

a

the

the

pin

on

e20

the

e1.g

being

hand

turned

amplifier

high

frequency

no.4

collector

collector

tumed

side)

detun-

on.

When.

detec_

fre_

will

on,

I

t

on the
approached from
tuning
voltage
on to light up
detuning

Q23
resulting

off,
will not be lit up,

properly,
equal. Consequently,
turned
ing
since
base voltage,
tuning
charged
on, thereby
cator

4.4 EOUALIZER

with
(HA1201?P).

and

performance
a
dynamic
of 250mV
82dB
within

other hand, the broadcasting

the

to a lower frequency)

away
will be lower,

lower

the

direction indicator. When

is

on, the

in

which means

Once

the broadcasting

the voltages

off, which

direction

is

Q24

indicator

up via

LED.

?his

circuit

newly

This IC is

provide

voltage

gain

margin

(at

2.5mV

t0.2dB

Q24

being

Q24

that the center tuning indicator

means

indicators

tumed

Q25

lighting

a low-noise

an

specifications

(1kHz,

(20H2

off because
will
light up. Furthermore,

R99,

resuiting

AMPLIFIER

is

NFB

an

developed high

openloop

of 35.5d8

or maximum

0.}Abc/o THD),

input,

*

iow frequency

resulting in

frequency

base voltage

tumed on and

frequency

on

q22

that

will be

be turned

up

the

type equalizer

and

gain

IHF-A),

20kHz).

Q22

pin

nos.2

and

Q23

neither

on in

of the

on, and

in

Q26

Quartz

performance

low distortion

of 105d8.

for

this

(at

lkHz),

allowable

and equalization

frequency

(or

side

the

being tumed

(left

either

will

has

& 4 will

will

of the detun-

this case. And

being

Locked

circuit include

S/N

when

pin

no.4

hand

side)

Q22

high,

be

tumed

Q25

been

tuned

both

decreased

the

center

C77

tumed

indi-

amplifier

type,

The main

phono

a

input

level

ratio

or

be
be

is

IC

of

is

4.5 TONE CONTROL AMPLIFIER
This

circuit is an

fier with
iHA12017P).

POWER

4.6
Amplifier

The
amplifier
differential

(Q2),

tor
mirror
The
this

and further

Q1
current from

DC voltage.
drift
voltage

The
arrangement,
constant-current

gain.

age

The
high
speed
switching

"High

The
ington
employing
Emitter
sisting
chip,
parallel

newly developed high

AMPLIFIER

Circuit

basic

is shown in

amplifier comprising

the load

employing
current mirror
stage, which

increase

in

the input

Q2,

Because

in

speed bias

Speed Bias

with

temperature

Q2,

prevented.

is
pre-driver

the

power

bias

servocontrol circuit

operation in

power
arrangement,

an SL

Transistor).

of a number of

each transistor being connected ir"r

via

an emitter resistor. This

NFB

type tone control ampli-

performance

circuit arrangement of the

Fig.

4-9. The first

PNP

circuit of which is

NPN

an
provides push-pull

serues to cancel

gain.

circuit absorbs

prevents

and

Q1

stage

load

source

bias voltage

stage

servocontrol circuit. The high

Servocontrol Circuit").

(Q13

stage

the last

RET

The RET

twin transistor

outflorv of base

the

follows

drift of the center

(Q4,

circuit of which

(Q6)

the

-

(Super

smail

any temperature

Qb)

resulting a high volt-

is supplied

power

is

Q16)

stage

is a kind

transistors

IC

power

stage is a

twin transis-

a current

(Q3).

operation in

even harmonics

generation

is a Darlington

provides
stage

a 2-stage Dari-

is

SEPP circuit

Linearit5' Ring

of

on a single

of a

point

employs

by the

non-

(refer

to

IC

con-

provides

t
t

H

H
H

t

a

I

t

n

i

td

Fig.

4-9

Power

+

I

i

;

+

I

amplifier

+

I

r

sx-3aclo

I
I

r

r
r

T

r

T

T

I

f,

F

t
I

t

F

excellent high
ble

lo those
more, becanse
circuit
is
hor,vever,

extremely wide
+

High

active region
mr-rm
circuit

tortion and
Operating Principle

SI)PP
is
a fixed
ancl
X
When

this
side is increased,
ends

voitage
However,
is

Z

resulting in

creases

same
X and
across
polver

lined
to the
while
fhe
(Q3

sequently,
sisting of

Q4,
previous

rent, the base
to

due to the

Furthermore,
follower

ir-r

possibie

'I'he

circuit

60W, 101-lz

Speed

By

operating the

idle current,

prevents

Since

idle current flows

porver

appliecl,

amount

Y

sen'ing as a bias). The voltages

Z,

and

the

circuit,

RB1

of

across

practically

Y

anrl

'I'he

high

the

amount

Z,

poinls

stage from being

This

high speed

Fig.

in

crrcuit,

Q3

collector

and

Q4)

and

circuil

With

R1

same level

the

lvitli R3

frequency

of a small-signal

lhere is

the lorv-frecluency

dorvn

by the input

features

to ZOkHz, THD

Bias

Servocontrol Circuit

(no

reduces heaf loss.

stages

DC level

the

(w'itir

Z

and
positve

porver

the

and the

also heing

point
the

since

constant, the voltage

(PNP power

PNP

the

speed bias

voltage

as the

thereby cancelling

Z

4-11. lVhen

Q1

and

Q4

and
at this time may

rvith

,tr

VR1.

the

junctions

PN

this circuit
shown in
D1

and

of

signal) by

Qf

characteristics

transistor.

no time clonstant

region,

(DC

DC

to

coupling

polver

power

possible

the high speed

generation

the

(see

and Y at this

portion

voltage across

stage bias) will

power

across

voltage

Y,

and

bias servocontrol

and

u'ill

base

power

ensuring

and

Q1

on an AC

may

as the

inputs

capacitor).

described

frequency

0.005Va,

stage

cut-off)

through

Fig.

4-10)

is shifted by D

voltage

the

time will be equal.

of a signal is applied to

stage current

voltage (Vn1)

increased,

X and Z being

stage

servocontrol

points

increase

the voltage

preventing

and

cut off.

there is no

are almost

Q2

be on.

of both

Fig.

a simple shift in DC

emitter resistance.

The

of these

be disregarded. Con-

stage bias circuit con-

formed

is equivalent
4-10.

a constant

point

Z

basis

be considered

compara-

Further-

NFB

in the

amplification

will be

above

only within

and with mini-

bias servocontrol

of switching

normal class

when

across

resulting in

points

being

X

by

may be

(level

cut off,

provide

range

Bdl).

across

on

across

be decreased,

cut

and

across

circuit
signal applied

voitage

Q3,

flow of cur-

fluctuations

(60W

dis-

no signal

and VR

points

points

NPN

the

across both

increased.

X and

points

off.

circuit in-

Y

by the

points

decrease

PNP

the

is out-

cut off,

across

transistors

D3,

and

to the

brought

level.

emitter-

an

the

by

X

the

When
creased
plied
of this emitter-follower
follower voltage
more or less equal to that
is,
produced
applied

forms
bias voltage

same amount

Z

is increased

above

applied.
across
age

B

Y

the idle current
stage
decrease
the signal,
rnanner,
from

In
circuit
signals

the voltage

by tl're

to

this circuit,

the voltage increase across

at

R3.

across the base and collector

part

of the

applied to

that the voltage across

voltage

the

Consequently,

points

across

off

being cut
other words,

from

Fig. 4-'l 0 Normal

Fig.

X

points

(noting

in current).

Q3

thereby

acts to

being

PRE-

ORIVER

PFE.

ORIVER

4-1 1

High

across

positive portion

gain

And

power

(by positive portion

level

Z cancels

and

Z

and

without

that there

and

Q4

preventing

off.

the high speed

prevent

applied to the

speed bias servocontrol

points

it becomes

(Q1).

practically

is

of

the R3 voltage is

stage

will be in

Q3

when no signal

the increase

Y,

cutting the

For

the negative

are operated

"poler

any

power

stage bias circuit

X and Z is

of the signal

the input

Since

the input

points

of

bias circuit. So

excess by
points

of

the decrease

thereby

actually

NPN

the

bias servocontrol

stage cut-off"

polyer

in-

ap-

signal

the emitter-

voltage

1-,

a

(that

signal

X and Z)

the voltage

which

QB

the
the

X

and

the signal)

is being

in

voltage
in

volt-

maintaining

power

PNP

is a slight

portions

in

the same

power

stage.

circuit

of

stage

is

F

F

IJ

POWER

4.7

t

]NDICATOR CIRCUIT

('tA73t8P)

ic

rN

s16NAL

The
fluorescent
thermionic emissions
celerated
segmental
This tube is used to indicate
other

An

Fig.

in
pin

no.6

tains
peak

The dynamic

40dB to obtain a

by

The

tube are driven by
channel)
amplifiers. These amplifiers
levels,
separately as the
these
power
will

light

o*-l

SX-3800

into the
anodes, resulting

symbols.

outline of

4-12.

(

a detector

hold circuit

output

equipped

so each amplifier

amplifiers apply

indicator

up in turn as

output

indicator

fluorescent

FL

the

The

output

of the

)

range of

IC

circuit, conpressor

for both

"peak

pou'er

the

rvith 12

input level increases.

segmetrts, each

power

(FL

tube

from the

in the emission

tube drive

circuit sj"tnal is applied to

(TA?318f

left

the

signal
held"

indicator

HA12010 ICs

are biased at increasing

lvill

voltages

the

the input level rises.

t/?

HOLO

OC AMP

F/LAMENT

Fig.

4-12

indicators feature

tube).

numerals, letters,

segments of

pairs

commence

In

this tube,

cathode are ac-

substance

circuit is shown

-A).

and right

is thus contracted
DC voltage.

of

to the output

successive segment

of the

of

IC

The

(40d8),

channels.

tire

(one

for each

differential

to

operate

And

light.

&

Power

and

con-

and

FL

since

indicator

circuit

PROTECTION

4.8
purpose

The

speakers

output circuit is
the following cases:

L.

2. Upon detection

3. Upon detection of a

Muting

On and Off

supply is
time constant

If
be
through R8

Q4
muting

abruptly decay, and
resiclual component of
rapidly
upon
restore

and the

During
power

short circuit in the
caused by component failure or accident.

Operation when

With

reference

turned on,

there is

off, and the timing capacitor C1 charges

condr,rcts,

on the

When

the

discharge,

the relay will become de-energized and

mnting.

"transient

the

supply is turned on and off.

of the

no input

and R6, and thus

tire

power

polver

CIRCUIT

this circuit is to

of
power

amplifiers.

automatically

operations"

of an overload,

ioad.

voltage

DC

Power

Fig.

to

Q3

(DC)

relay

amplifier

supply is

Q3

Q4

4-13 when the

turns off due

*81

circuit is

on

Qb

operates, and the output

will conduct
+81.

cease to conduct, rvhere-

will

L€VE L
SHIF I

OFFSET

COM.

PENSAIOR

protect

The relay in

opened

Supply is Turned

and

Q4

will be

turned

As a result, C1

in

any of

lvhen

caused by

in the output

porver

*81

to

very

sma11.).

they will

Q6,

turns

removed.

off,

owing

on.

-81

\Vhen

to the

the
the

the

(l'he

up

rvill
rvill

t
t

H

r|

I

t

t
t

t

a

I

H

I

t

H

I

14

I

t

I

J

r

six-gaoo

F
T

r

r

T

T

T

Overload

The

load (RL)

base

connected
so if
If

RL falls
on,
quence,
deenergized,
open.

DC Voltage

The
ler
Any
the
emitter
turns
is

negative,

As

conseqnence,

become

circuit

Detector

overload

in one

and

emitter

to

RL

decreases,

thereby

Q4

output

and

Q5

DC

voltages

porver

amplifier,

and

on.

C1

Q6

de-energized,

to open.

detector

side
of

the

opposite

Q1

below a prescribed

C1 will

will

turr

thus

causing

Detector

circuit

base

via

appearing

base.

Q5

will rapidly

turns

Q4

circuit

of a Wheatstone

a sensing

corners

will

become

rapidly

on and

is

a low-pass

it
If

on.

will

discharge.

the relay

the

connected

the

wil]

be applied

the voltage

discharge.
C1 will
turn

on

thus

causing

incorporates

bridge.

transistor (e1)

of

the

bridge,

forward

value,

output

to

filter

output

is

rapidly

and

If

the relay

biased.

will

e1

As

conse-

will

become

circuit

the

e6

(Rg,

circuit

to

the

positive,

the

voltage

discharge.

the

ourpur

the

The

are

turn

to

emit-

C2).

of

e6

eb

will

F

ig.

4-

1 3

Protection

circu

ir

I
I

t

T
T

I

I

I

I
I

I

15

DISASSEMBLY

5.

Bonnet

Remove

bonnet
Bottom

Remove

bottom

Panel

Front

Remove

knobs.

from

Q

Case

the

case.

Plate

the

plate.

the

Remove

front

the

two

fifteen

all

the

Panel.

screws

screws

control

screws

two

each

ot

O

to

O

knobs except

and

@

of the

side

detach

two

the

push

nuts

Bonnet

i

I

t

l|

case

I
t

I

$\

A\

s\$

f\,.\

Front

panel

Bottom

t
t

plate

l

I

t

I

I

T

to

I

t