Pioneer SX-550 Service manual

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The following
below.

O

CIRCUIT

DESCRIPTION

locations

in the

text

are

incorrect. Please

perform

the

corrections

shown

Page

Page

Page

o

EACH

Power

MODEL

supply
but instead,
write

in

sx-550/KU

AM

9

phono

9

10

tone control

transformer

it

terminal

tuner

line

1

equalizer

(SX-ssO/KU,

amplifier line

line

10

HG.S)

connected

is

connected

numbers

by

indicated

B

to AF

a terminal

below.

sx-550/HG

amplifier

strip.

t3't
I

Incorrect

dual

metal

-

gdB

assembly

Delete

s'-a

oxide

lead

is not

wire

a lead

color

indications

SX-550/S

Correct

single

carbon

-

10dB

wire

type,

film

and

O

PAGE
Change

50

printed

AC nov

60 Hr

board fuse Fu5

0.5A

to 1.5A.

MWER
8v 50iA

Change

I

I

*ilve-l:

ffi

"T

IND

fuse FuB

1.5A

to 0.8A.

O^ @

,

FUSE

HoLDER

No.

This Service Manual

1.

SPECIFICATIONS

2.

CONNECTION

FRONT PANEL

3.

4.

CIRCUIT DESCRIPTIONS

5.

BLOCK DIAGRAM
LEVEL DIAGRAM

6.

7.

DISASSEMBLY

DIAGRAM

FACILITIES

is applicable only to

CONTENTS

the KC, KU model.

sx-s5C'

4
6
7

I

12
13
14

8.9.DIAL
ADJUSTING PROCEDURES

9.1

9.2 FM

9.3 MPX

9.4 Power

10. PARTS

10.1
1O.2

10.3

10.4 Front

11. EXPLODED

11.1 Exterior

11.2 Part 1
1 1.3

11.4 Part

12.

SCHEMATIC DIAGRAMS.
PARTS

12,1 MiscellaneousParts

12.2 Schematic

12.3 RF

12.4

12.5

CORD

AM

Front Panel
Rear Panel
Top View

Part

AF Amplifier
AF Muting

STRINGING

Section

Section

Section

Amplifier

LOCATION

View

View

View

VIEWS

2 AF As-sembly
3 RF Assembly

LISTS

Diagram

Assembly

Assembly

(ldle

Current)

(AWKO56}
(AWE-072)

P.C.

L ist.

(AWE-072-0)

Assembly

(AWK-056)

(AWM-101)

16

17
18
19

20

21
23
25
27

29
31
33
34

BOARD PATTERNS AND

36
37
40
47
53

13. PACKING
SX-550/KU.

HG.

S Additional Service Manual

55

.

Enclosed Herewith

1.

SPECIFICATIONS

Semiconductors
FETs

........

|Cs..........

Transistors....

Diodes .......

.3

.5
.28
.21

Power Amplifier

Continuous

(Both

channels

Total Harmonic Distortion

Continuous Rated PowerOutput

10 watts

I

Intermodulation Distortion

AUX)
Continuous Rated

10 watts
'I

Damping Factor

(20Hr

I nput Sensitivity/l mpedance

PHONO .

per

8ohms..

per

watt

8 ohms.

per

8ohms..

per

watt

8ohms..

to 20,000H2,8 ohms) .

Section

Power Output

driven). .

channel

channel

. . . . No more than

channel

channel

from 20 Hertz to 20,000

. 20

(20

power

power

output,

(50

PowerOutput

power

power

output_

Mtc....

AUX ...

TAPEPLAYI......

TAPEPLAY2......

PLAY

TAPE

PHONO

Output Level/lmpedance

Overload Level

PHONO

TAPERECl......

TAPE REC 2
TAPE REC 2

SPEAKER
HEADPHONES.

Frequency

PHONO
AUX, TAPE

Tone

Control
BA55 ...
TREBLE.

Loudness

Contour

position)

(DlN

2

.

(DlN

Response

(RIAA

equalization) ....

PLAY

(Volume

connector)

(T.H.D.

connector)

. . .

control set at

Hertz

per

watt5

Hertz to 20,000 Hertz, from

output,

Hertz : 7,000 Hertz = 4 :

output,

channel

. . . . . . .

. . . . . .

(8

ohms)

No more than 0.3%

No more than 0.07%

. No more than O.3o/o

No more than 0.07%

No more

than 0.07%

.......... 25

2.5mV/50k ohms

7.5mV/50k
150mV/50k ohms
150mV/50k ohms
150mV/50k
150mV/50k ohms

0.1

7o)

200mV

.... 150mV

....... 150mV

. 30mV/80k ohms

.....

. Low

to 15,00OH2

30Hz

'loHz

.
. .

to 60,000Hzli"dB

+9d8,

...

A,

lmpedance

-10d8
t8dB

-40d8

. . . .

+6dB

(100H2),

+rag

AUX)

Q.07%

from

1,

ohms

ohms

(l

kHz)

B,

A+B

10.3d8

(100H2)
(10kHz)

119kH.1

six-s5C,

Hum

and Noise
PHoNo
AUX

FM

Section

Usable

Sensitivity

50dB

Quieting

Signal

to Noise

Distortion

frequency

Capture

Allernate
Spurious Response

lmage
lF Response
AM
MutingThreshold
Stereo
Subcarrier Product

SCA
Antenna Input

Ratio

Response Ratio

Suppression Ratio...

Separation

Rejection Ratio...

(lHF,

.

TAPEPLAY...

Sensitivity

Ratio at

at 65dBf

.

6kH2......

Response

Ratio

Selectivity

Ratio

...

Ratio

Channel

short-circuited,

MONO

STEREO......

. . . . . MONO

sTEREO...

65dBf .

100H2

I kHz

.

. . .

. . .

. . . . . . MONO

.......

. . .

(1kHz),

40dB

A Network,

rated

power)

........70d8

........90d8

.......

I

20.0dBf

. .

STEREO

MONO........

18.3dBf

. . .

. 39.2dBf

. .

(2.0!v)

l.2dBf

(s.spv)
(4.ssv)

(509V)

. . . . . 70dB

......65dB

O]S%

sTEREO.......03%

MONO........O.15%

STEREO.......0.3%

MONO.........o.4%

STEREO

. 30Hz to

.......O.4%

15,000H2

r3:3dB

...... l.OdB

......60d8

.....75d8

.......65d8

.. 90dB

.......50d8

.......

.....

(30H2

30dB

........40d8

........40d8

300ohms

75

ohms unbalanced

t4dBf

-

balanced

(2.8pV)

15kHz)

AM

Section

Sensitivity

Selectivity
Signal-to-Noise
lmage Response
lF Regoonse
Antenna.

(lHF,

Ferrite antenna)

(lHF,

Ext.

antenna)

Ratio. .

. . .

Ratio

Ratio. . . .. . ..

.. . .

..

Built-in Ferrite

Misceilaneous
Power

Requirements

....

PowerConsumption....

Dimensions

Weight

.......

Furnished
FM

T-type

Operating

Instructions

Without
With

Parts

Antenna

. .

.

. . . .

1 7al8(w)xs-9/16(H)x12-l

package

package

. . . . 65d8

Loopstick

. . . UL; 80W, 185W

. .

Antenna

'l2OY

(max.)

6QHz

csA;l55vA

.148(w)x141(H)x307(D)

. . . . . . . 9.4kg

(20

(23

10.5kg

mm

6(D) in

/1

|b 11 oz)

lb 2 oz)

NOTE:
Specificotio^s
poscible

to

modificotion

improoementg.

ond the design subject to

without notice due

2.

CONNECTION

DIAGRAM

OUTDOOR

FM ANTENNA

.ffi)

75o\LI-l

rall

coax

l

cable I I

'

T-TYPE

FM ANTENNA

3ooa

FM DE.EMPHASIS

r'"-'1

Normaf ly, set this
Be sure

listening to an
emphasis;
NR
TAPE terminals.

_[^*].r _!- _'l*'---t

to

adaptor

:BEEEEE:

it to

set

25rrsec.)

connected

AM ANTENNA

(lndoor

SWlTCH

switch to

"251rs"

FM broadcast

with a Dolby* system

Outdoor)

or

"751ts".

only

between

when

(pre-

the

-

CONVENIENCE

Unswitched
ly used components,
quire

coupled

of

either
Switched

used component

can be

etc.)
leaving the

in the

nent

component

to the

SX-550 switch

the

(3OOW

these

(200W

plugged

power

ON

OUTL

max.l:

power,

outlets.

max.l:
(turntable,

switch

position,

operation.

will be

Less

which

plugged

can be

A

into this

of

power

coupled

frequent'

not re-

do

into

frequen

deck,

tape

By

outlet.

that compo-

supply

with

GROUND

TURNTABLE

CARTRIDGE
TAPE

PLAYER

DECK

TAPE

(Open-reel,

OUTPUT

cassette)

INPUT

TAPE DECK

(Open-reel,

RIGHT

SPEAKER

I

I

DIN TYPE

I

CORD

loureur

cassettel

LEFT

SYSTEMS

A

SPEAKER

LEFT

.m,

ffil

Til

@

RIGHT

SYSTEMS

B

6

FRONT PANEL FACILITIES

3.

SPEAKERS SWTTCH

switch.

OFF:

turning

to eliminate

the

switched

power

Receiver
To select speakers
speaker terminals.
Speakers cut off
used).
Operates speakers
speaker terminals.
To listen simultaneously
systems
terminals.

this

operation,

A combined
selector
POWER
A:

OFF:

B:

A+B:

NOTES:

.

After

to

9 seconds,

operates

c

For

easier

into

(POWER)

ON/OFF

off.

connected to

switch

during

unpleasant
plug

convenience

switch and speaker

connected to the

(headphones

connected to the B

A and B

ON there

which

powgr

is a delay

time the muting

noise.

cord

outlet.

for

system

can be

to

speaker
speaker

of some

circuit

turntable, etc.

FM

STEREO

With

rhe FUNCTION
indicator
ceived.

A

AM/FM

When

tuning

center

FM
stations,
right

of

the

Z

INDICATOR

lights

while

TUNING

in FM

area for

tune

scale.

optimum

for maximum

switch

an FM

METER

stations,

meter

ser to FM,

stereo

broadcast

position

reception.

deflection

the

the

needle

In the

PILOT

STEREO

is

being re-

in

case

of

toward

wnre

the

AM

the

LAMP

t\/N

PHONES f ACK

To listen

into this

WARNING:
Dct
may damage the microphone.

BASS

Controls
with
TREBLE
Turn
toward
quency

through stereo

jack.

plug

not

microphone

a

& TREBLE

for

adjusting

the BASS

control.

controls

the

ranges.

toward

left

control

(MlN)

CONTROLS

headphones,

into

the

tone.

and high

the right

to reduce,

plug

PHONES

the

Adjust low

frequencies

(MAX)

to enhance,

their

firmly

them

jach

as

frequencies

with

respective

you

the

and

fre-

FM

MUTING

Leave

this
suppress
tween

FM
pressed

depress

MODE

NOTE:
Recording
MONO
rate.

SWTTCH

For

stereo
depressed
stereo
sound

signals

from

position

OFF

button

unpleasant

stations.

by this

this

button

undepressed (in

Low-strength

function,

to

(MONO)

playback

for MONO

both

stereophonically

leave

will

be

speaker

moy cause

BUTTON

interstation

so

to

the OFF

position.

this switch

playback,

mixed

to

systems.

with

the MODE

channel

the

ON

noise while

signals

may

pick

up

a weak

undepressed.

left

and right

produce

separation

switch

position)

tuning

also be sup-

monophonic

to

to

be-

station

When

channel

in the

deterio-

.J

sx-s5cl

.EREO
ring

re-

in

the

of

AM

rud

the

I LAMP

lNM

rcNO

TUNING

Select
meter

the

optimum

for

KNOB

desired

LruOMS

station

tuning.

while

observing

FUNCTION

the

AM/FM

FUNCTION

Switch
AM:

FM:

PHONO:

AUX/MIC:

rc

JAcK

high

A

microphone
this

lack.

SWITCH

for

selecting

impedance

with a

desired

For AM

For FM stereo
receives
monophonic

indicator

in stereo.
To operate

PHONO

For listening

(cartridge
etc.)
set to this

phone.

Note,

the component

in,

iacks

program

broadcast

monophonically during

broadcasts.

lights

a turntable

iacks.

tape

connected

position

when the

cannot

(approx.

standard

be

source.

reception.

reception.

up when

to an

player,

to the

microphone

used.

50k-ohms)

plug

the broadcast

audio component

TV sound
AUX

using the

when

connected

can be

Automatically

FM

The STEREO

is

connected

jacks.

is

to the

dynamic

connected

to

tuner,

Also

micro-

plugged

AUX

tYPe

to

on) to
ng be­)e sup­rtation

. When

hannel

phonic

in

the

eterio-

VOLUME

Clockwise
headphones.

LOUDNESS

Depress
frequency
the listening
for
treble.

BALANCE

Control

right
center
clockwise

CONTROL

rotation increases

BUTTON

this button

response

level,

hearing characteristics

CONTROL

for adjusting

speakers

increases

or

rotation

volume

listening

when

human

of the

and the

headphones.

right

depressed

by emphasizing

volume

channel

increases

left

from

at low

ear varies

position

balance

Clockwise

channel

between

volume,

volume.

speakers

volume.

according
compensates

bass

the

left

rotation

while

from

counter-

or

The

to

and

and

TAPE

MONITOR

these switches

Set
follows:
1

. For

. .

progress
iacks

2

NO?ES:
o

a

in 1 above,

. As

. .

TAPE

jack

Leaue both

when

tion
The signat
switch

pressed

When record.ing

not operates

do
will interrupt

playback

with a tape

(REC

&

jacks

2

(DlN

type).

of these

using tape

not

from

will be

interrupted

position.

.the signal

(1

in the

or for

PLAY).

(REC

the source selected

with
the

&.2)

with

buttons

two

TAPE

deck

a tape

&

BUTTONS

(depressed)

ON

monitoring

connected

deck connected

PLAY)

oTTAPE

the

in

as the sound

dechs

if switches

tape dechs
MONITOR
to the

.position

of a recording

TAPE'1

to the

to the

REC/PLAY

undepressed'

by the

are

simultaheously,

I

TAPE

source.

FUNCTION

left in the

button as

2 dech.

as

in

posi-

d'e'

this

a

4.

CIRCUIT

DESCRIPTIONS

TUNER

FM

A
used

FET
with
the
tage
The
and

provides
Local

value

lF

Composed
one IC (HA1137).
IC
(quadrature
circuits.

Multiplex

The
require
stabilized
contains
switching
matic
switching
signal provides

!t_91
MUTING

signal passes
through

and
tor

SECTION

Front

End

frequency

with

possesses

a

transistor,

input

Amplifier

and

crosstalk

output.

tuning

in

terms

local

oscillator

its

excellent

stable

oscillator

capacitor

of

contains

Demodulator

(HA1156W)

IC

a

tuning

switching

a

double

system

stereo-mono

transistor

"t

input

switch

an amplifier

linear

a single

high

of noise.

voltage

to

and

two

detector),

automatic

sigrrals

through

canceller

3-gang

stage FET

input

and

allows

circuit, plus

is a variation

temperature

frequency

passed

is

the

mixer

Detector

dual

The HAl1BT

a limiter

used

coil

balanced

demodulator

selector
controlled

below

OFF).

the

transistor

element

amplifier,

muting,

in

and

in

signal

monophonic

the
The
de-emphasis

that

combines

produce

to

variable

impedance

simple

a significant

even

this

addition

generator

differential

circuit

circuit.

by

stereo

capacitor

RF

amplifier.

coupling

of

a Clapp

compensation

without

through

base.

ceramic

is

a high

FM

and meter

section

and

An

the FM

muting

demodulator

circuit,

carrier

the

F ig. 1

The

compared

with

advan-

circuit

AFC.

a low

filters

to

circuit,

reproduc­level

demodula_

and

density

detector

drive

does

not

pLL

a

amplifier

an auto_
extemal

muting

(FM

then

filter

is

it

Tuner

Section

AM

Tuner

Composed
element

is

employed
tween
other
amplifier
the

PHONO
IC

right
and

the
tion

*21

-1s

MICROPHONE
A

provided

fier.
when
amplified
both

switch
microphone.

the

stage

mixer

(TA7136P1)

channels.

tolerances

equalizer

within

single

A

a

the

is

of a

ceramic

itself

followed

EOUALIZER

0.3dB

transistor

in

addition

selector

plug

microphone

left

set

single IC

filter.

with

one

antenna

tuning

is

not

by

is

used

Tolerances

!1Vo

elements,

from

Fig.2

CIRCUIT

switch

is

inserted

and

right

to

the

the local

metal

PHONO

(HA11BS)

A 2-gar,:rg

stage

and RF

tuned

a 2-stage IF

AMPLI FIER

with independent

leading

30Hz

amplifier

to

the

cuts

into

signal

channels.

AUX position

variable

providing

amplifier

oscillator.

but

feeds

amplifier.

!2Vo

styrole capacitors

oxide

resistors

to

to 15kHz.

Equalizer

(monophonic)

phono

the

AUX

the

is

then

The FUNCTION

and

capacitor

tuning

and
The

direcfly

left

comprise

RIAA

an

equalizer

jack

jack.

MIC

supplied

when

using

dual

be_
the
RF

to

and

devia-

is

ampli_

iniut

ihe

to

a

Fig. 3 Microphone Circuit

When
potential

ON

and C2 is immediately
interval
constant

power

the

instantly

is extremely

even if

oN.

amP.0UT

Control

Power

amp. I N

switch

becomes

brief,

power

the

Pornt

Q4

Since

time

point

becomes

remains

is set to OFF,

-

16V.

discharged.

muting

the

switch is again set to

B

C

this

TONE CONTROL

A

CR network tone control circuit

which each

attenuator
tor and a resistor.
decrease the
quency
quency
constant
to
are

+9dB

AF
When

of

stage for compensation. The control ranges

this

+8dB

to

MUTING

the

point

relative levels

sounds. Since relative control over the

response by the attenuator results

loss,

an amplifier

-8dB

to

-gdB

for the lows

Fig.4

AMPLIFIER

power

Fig.

C in
Rb time constant,
potential

C2

& Rg time constant and normally reaches

Q3
from which

CL & Rl

at

this time

becomes OFF when

time

time constant and normally

circuit consists of a capaci-

These function

of

(Q1

for the highs

(at

Tone Control

switch is set to ON, the

5 instantly rises

and

becomes

Q4

gradually

point

point A potential

approximately 8V from R1 & R2.
operate when
muting
power

interval

supply is

point A potential

(T)

extends from the time the

set to

ON

to when

is

employed
increase and

to

low

and

&

is used

Q2)

(at

10kHz) and

100H2).

YR1:TREBLE

VRz:

BA55

due to

OFF.

increases with

B is below

rises with the

FET

is

above 0V.

point A poten-

in

fre-

high

fre-

in a

prior

CONTfuL

CONJROL

potential

C3 &

Point

the

-19V.

-15.4V,

reaches

Q1 & Q2

The

tial reaches 0V. This interval is set f.or 6 - 7
seconds.

Conlrol amp. OUT

Powef

amo. lN

F

ig. 5

AF

Muting

OFF

POWER

Fis.

6

POWER

Composed
direct

Open
NFB
are
adequate

Q1
back is

power
the

AMPLI FIER

coupled

gain

amount

provided

stability even

form

a differential

applied from

stage to

junction

CIRCUIT

of differential first stage,

pure.complementary

at lkHz is

approximately 80dB and

is approximately

with this

circuit in

with the NFB

OCL

50d8.

order to

disconnected.

amplifier: IIOVo d.c. feed-

the base of

point

is always

the

junction

Ql

point

so the

potential

maintained

all stages

circuit.

R3

and R4

obtain

of the

at

of

the

same level.

B

AmPlifier

Fig.7

Power

sx-55cl

POWER
High

required

SUPPLY

stability (ripple

in

minimized

in

Fig.

the

its
Q3

output

emitter.

8,

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sx-55cl

DIAGRAM

LEVEL
(

dBv)

60

50
40
30
20
10

0

-10

-20

-30

-40

-50

(

AUX

150mV)

(

MIC

7.5mV

(

PH0N0

2.5mV)

(80

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cr)

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FREOUENCY:

lV
lkHz

-60

t5

7. D'SASSEMBLY

REMOVE

Side

board

shown in figure. When reinstalling,

space
panel.

does not occur between them and front

BOARDS

SIDE

can be removed

by taking out 4 screws

observe

NS

that

REMOVE

Take

out

2 screws

TOP PLATE

shown

in figure

to remove.

six-E'5Ct

REMOVE

Take
ward

REMOVE FRONT PANEL

Use
screw
push
TION
left
and remove.

BOTTOM

out 8 screws

to remove.

allen hex wrench

and remove knob.

buttons),

and SPEAKERS

and right

PLATE

shown in

remove

then

screws

to

switches. Take

(2

loosen

Pull

off all

shaft nuts

screws)

figure

tuning knob set-

pull

and

knobs

of

out upper

of front

rear-

2

-c

-*+g;{:':i';:-*

8

I
I

(except

FUNC-

panel

)

)/4

":(

,:,"LW

DIAL

8.

1. Tie

end

2.

Close tuning

3.

Pass

cord

half

turn

pulley

4.

Wind cord

3

turns

5.

Wind 3 turns
so

that

6. Turn

TUNING

needle

7.

With

tuning

dial

needle

8.

Apply

CAUTION:

Do not touch
Handle
and
of needle.

lacquer

dial

finger-prints

CORD

of cord

A-dial

around

the

moves smoothly.

needle

to inner

capacitor

through

around

dial

pulley,

needle-B-C-dial

clockwise

dial

shaft,

around

cord

is

under

dial

knob

capacitor

to starting

to tied ends

dial

needle

with

only by the

cannot

be removed

(as

STRINGING

stud

blades

pulley

then

shaft-D-dial

viewed

then route

pulley

tension.

and

blades

point

(left

of cord.

the

hand.

molded

of

fully.

confirm

fully

from

pulley.

dial

opening,

pa.ss

in

Fom rear

to

and tie

closed,

edge

portion.

metallic

make

the

pulley.

pulley

to

that

of scale).

Smudges

a

route:

panel)

D.

spring

dial

move

portion

Dial

pulley

Dial

\

shaft

needle

rO)

''z-'

B

ADJUSTING

9.

sx-Ei='Cl

PROCEDURES

9.1 AM

1. Through

2.

I

,l

o.

SECTION

a lk ohm
signal
Set for 400H2

Connect

jack
Set FUNCTION switch

Set
A
Adjust
Set AM SG and
C

generator

AC VM

(L

or R).

AM SG and SX-550

(60OkHz).

T6 for

(1,400kH2).

resistor, connect an

to the

at

30dB and 30%

maximum indication

SX-550 dial indication

AM antenna terminal.

modulation.

(Voltmeter)

to AM

dial indication

to TAPE

position.

AM

REC

point

to

on AC VM.

to

Doint

7. Adjust
VM.

8.

Again set
point

9. Adjust bar
tion

10.

Return AM SG and

point

11.

Adjust TC5 for
VM,

12.

Repeat steps 4-11
AC VM indications

TC4 for

AM SG and

A.

on AC

C.

VM.

maximum indication

SX-550 dial indication

antenna

core for

SX-550

maximum

to eliminate

points

at

AC voltmeter

on AC

maximum indica-

indication

dial

indication

A and

on AC

variations in

C.

to

to

r

:

tr@

1k ohm resistor

FM SECTION

9.2

1. Through
FM signal
antenna terminals and
and IOOVo modulation.

Connect

2.

REC

3. Set FUNCTION
switch
Set FM

(90MHz).

A
Adjust T3

(t.

Adjust T5
tion on Tuning meter.

,7

Set FM SG
T2 for maximum
Set FM

8.

(106MHz).

C

300 ohm dummy

generator

AC VM and distortion

jack

(L

R).

or

to

OFF.

SG and SX-550

for maximum
lower core for

for 9dB output and

SG and SX-550 dia.l

antenna,

to the 300 ohm

set for

switch

dial

indication on AC VM.

400H2 at 100d8

meter to

to FM and MUTING

indication to

indication on AC VM.

center of scale

adjust T1 and

indication to

connect

FM

TAPE

point

indica-

point

9. Adjust TC3, then TC1 and TC2
indication on AC VM.

10. Again set FM SG and SX-550 dial indication to
point

A.

11. Adjust T3,
cation

12. Repeat
sensitivity at

13. Adjust T4 for maximum sensitivity.

14. Detune to noise only and adjust Tb

for center of scale indication on Tuning meter.

15. Set SX-550 dial
and adjust FM
on

Tuning meter.

16. Set FM SG output to 60dB and adjust Tb
upper core for

1?.

Repeat

minimum distortion

then T1 and T2 for maxirnum indi-

on AC VM.

steps 8-11 to eliminate variations in

points

steps 14-16 to eliminate variations in

A and C.

indication

for center of scale indication

SG

minimum distortion.

position.

for

maximum

lower

point B (98MHz)

to

core

AC voltmeter

!

*

Distortion meter

Flvl

signal

generator

u@

sx-55Cl

9.3 MPX

1. Through
signal
terminals.

2.

Connect
modulation terminals

3. Connect
SG
TP

SECTTON

300

generator

multiplex signal
oscilloscope

pilot

output

(No.

31)

of circuit

ohm dummy

antenna,

to

300 ohm

generator

of FM SG.

horizontal input

and vertical input

board

connect

FM antenna

to externa.l

via

FM

to MPX

probe

to

4.

Set SX-550
FM

SQ

meter.

5. With

6.

FM SG unmodulated,
lissajous
tionary.
With

MPX SG
deviation
for

minimum

dial indication

for

center

pattern

modulation 1kHz,

and Pilot

distortion.

Oscilloscope

to 98MHz

scale

of

on oscilloscope

7.5kHz

indication

adjust

deviation. adiust

MPX

signal

and adjust
on Tuning

VR1 so that

becomes sta-

L+R

67.5kHz

generator

T4

n

AC voltmeter

E

300 ohm

dummy antenna

o

Distortion

ll-

meter

POWER

9.4
Set BASS

1.
positions.

2. Connect DC voltmeter
terminals
adjust VR3

3.

Readjust
fication range is 15mV to 40mV).

AMPLIFIER

and TREBLE

=

(L

34 o, 33

(L)

and VR4

after approximately

(IDLE

to circuit board TP

g;

(R)

CURRENT)

controls to

fi, = 35 @,36

for 25mV.

15

minutes

FLAT

o) and

(speci

voltmeter

DC

E

io

1

10.

10.1

PARTS

FRONT

PANEL

LOCATION

VIEW

panel

Front

ANB.417

assembly

(SPEAKER)

Knob
AAB.lOO

- -

Knob

{BASS,

AAB.O99

TREBLE)

Knob

AAD.l

i

(FM

MUTING,

1O

MONO)

(TUNING)

Knob

AAA-036

Knob IBALANCE)
AAB.O99

(VOLUME)

Knob

AAB.11O

(FUNCTION)

Knob

AAB.lOO

'IO.2

REAR PANEL VIEW

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23

(ANTENNA)

ina |

Term
AKE.O28

Term inal 4P
AKB-027

DIN connector

(REC/PLAY)

AKP 011

socket