Pioneer SX-750 User manual

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sx-75ct
This
Service
Manual
is
applicable
only
to theKC,KUmodel.
CONTENTS
1. SPECIFICATIONS
BLOCK
DIAGRAM
FRONT
PANEL
FACILITIES 5
7
9
11
2.
3.
4.
5.
CONNECTION
DIAGRAM
CIRCUIT
DISCRIPTIONS
5.7 Protection
Circuit
5.6 Tone
Control
5.9 Power
Supply
5.8 Power
Amplifier
Circuit
5.3 FM
Muting
Circuit
5.5 Microphone
Circuit
5.4 Phono
Equalizer
Amplifier
5.1 AMTuner
5.2 FM
Tuner
DISASSEMBLY
13
13
15
15
15
15
16
17
17
18
19
20
21
6. ADJUSTMENTS
6.1 AM Section
6.2 FM
Section
6.3 MPX
Adjusrment
6.4 Power
Amplifier
Section
7.
8.
9.
10.
DIAL
CORD
STRINGTNG 22
23
24
25
27
29
31
33
35
37
38
39
40
41
42
43
LEVEL
DIAGRAM
PARTS
LOCATION
10.1 FrontPanel
View
1O.2 FrontPanel
View (with
removdfrontpanel)
10.3 TopView
10.5 Rear
View
10.4 BottomView
1I. EXPLODED
VIEW
11.1 Part
I
11.2 Part
ll
1
1.3 Part
Ill
11.4 Part
lV
11.5 Part
V
11.6 Part
Vl
11.7 Part
VlI

44
11.8 Packing.
12. SCHEMATIC
DIAGRAMS
P.C.
BOARD
PATTERNS
AND
PARTS
LIST
12.1 SchematicDiagrams
12.2 MiscellaneousParts
12.3 Internal
Circuitryof
Integrated
Circuits. .......... 48
12.4 Filter&
MutingAssembly
(AWM-094) .......... 50
12.5 ToneControl
Assembly
(AWG-046) '...- 52
12.6 PowerAmplifier
Assembly
(AWH-046) 54
12.7 PowerSupply
& ProtectionAssembly
(AWR-099) . . . 58
P.A PowerSupply
Assembly
(AWR-1001 62
12.9 HeadphoneJack
Assembly
(AWX-106) ......... 64
12.10Tuner,
AF
& Control
Assembly
(AWE-073) ....... 65
12.11 Amplifier
Assembly
(AWK-065) 73
12.12
De+mphasisSwitch
assembly
(AWXO95} .-..-'... 74
45
47

-
1.
SPECIFICATIONS
Semiconductors
FET
lCs
Transistors.....
Diodes........
AmplifierSection
Continuous
Power
Output
from20 Hertzto 20,000Hertz
(Both
channelsdriven). . 50watts
per
channel
(8
ohms)
60watts
per
channel
(4
ohms)
Total
HarmonicDistortion
(20
Hertzto 20,000Hertz,fromAUX)
ContinuousRatedPowerOutput . ..
Nomorethan
O.1o/o
25watts
per
channel
power
output,8
ohms .. Nomorethan0.05%
1wattper channel
Power
output,8ohms .. .
Nomore
than
0.05%
lntermodulation
Distortion
(50
Hertz:7,000
Hertz=4:1,from
AUX)
ContinuousRatedPowerOutput . . Nomore than
0.1%
25
watts
per
channel
power
output,8ohms .. .
Nomorethan0.05%
1watt
per
channelpower
output,8ohms........
DampingFactor
(20
Hertzto 20,000Hertz). .
Input
(Sensitivity/
lm
pedance
)
PHONO
. .. 2.5mV/50kohms
l\41C.... ... 5mV/50kohms
AUX... .. 150mV/50kohms
TAPEPLAY1...... 150mV/50kohms
TAPEPLAY2...... 150mV/50kohms
TAPEPLAY2
(DlN
connector)... l50mV/50kohms
PHoNooverloadt"""' tt n o .o. t."':l
.. 200mV
(1kHz)
Output
(Level/l
mpedance)
TAPERECI
.............
TAPEREC2...... .........150mV
TAPEREC2
(DlN
connector)
..... 30mV/80kohms
SPEAKER ....... A,
B,A+B
HEADPHONES. . . ..... Lowlmpedance
FrequencyResponse
PHONO
(RIAA
equalization)
.. .... 30Hertzto 15,000Hertz !O.2dB
AUX,TAPEPLAY l0 Hertz
to 50,000Herrz .-?
dB
I
7
42
.....40
ToneControl
BASS
.....
TREBLE... ..
+8dB, 7dB (100
Hz)
..
+9d8, 7dB
(10
kHz)
Filter
H|GH... ... 6kHz(6dB/oct.)
LoudnessContour
(Volume
controlset
at 40dB
position)
.... +6dB(100
Hz),
+3dB(10
kHz)
Humand
Noise
(lH
F,short-circuited,A Network,rated
power)
PHONO. ...70dB
AUX,TAPEPLAY... ..........9OdB
FM Section
usable
sensiriviry l\4oNo . . .. . . .. .10.7d8f(1.99v)
STEREO....
... .19.0dBf
(9.8sV)
50dB
Quieting
Sen5itivity
i\4ONo......... 17.2dBf
(4.0pV)
STEREO....
.... 39.2dBf
(50gV)
Signalto NoiseRatioat
65dBf
MONO.. .....72d8
STEREO. ....67d8
Distortionat
65dBfl00Hz...MONO........ O.15y.
STEREO.......
O.3yo
lkHz....MONO........ O.15Yo
STEREO.......
O.3v.
6kHz....lvlONO....... . OA%
STEREO_......0A%
Frequency
Response
.. -... . 30Hzto 15,OO0Hz
+-8:E
dB
Capture
Ratio .........1.0d8
AlternateChannelselectivity ........ 80dB
SpuriousResponseRatio.
.. .......90d8
lmageResponseRatio... .........80dB
lFResponseRatio... ...100d8
AlVlSuppressionRatio... ......... 55d8
l\4utingThreshold ladBf (2.8t/V)
Stereo
Separation . . 40dB
(l kHz),30dB (30H2
- l5kHz)
SubcarrierProductRatio .......... 62dB
SCARejectionRatio... .......... 62dB
Antennalnput .300ohmsbalanced
75ohmsunbalanced
150mV
5

six-75c'
AMSection
Sensilivity
(lH
F,Ferriteantenna)..
(lH
F,
Ext.
antenna)
Selectivity
Signalto
NoiseRatio . .. .. .
lmage
Reiection
lFRejection
Antenna.......... Built-in ......65dB
FerriteLoopstickAntenna
. .13.7kg(30lb2oz)
'l
s.3kg
(33
lb1
'1
oz)
.300s
V/m
....15ttV
. . . .
35dB
.. . .50dB
. . . .40dB
Miscellaneous
PowerRequirements... ...120V,60H2
PowerConsumption 160W
(UL),
350W
(max.)
Dimensions .. 480(W)x149(H)
x371(D)mm
18-718
(w)
x
s-7l8(H)
x 14-sl8(D)in.
Weight
withoutpackage........
with package
FurnishedParts
FN4T-typeAntenna.
OperatingInstructions
NOTE:
Specifications
and designsubjectto possible
modificotion
without notice,dueto improoements.

2.FRONT
PANEL
FACILITIES
POWER
INDICATOR
LAM
Lightswhen
SPEAKERSswitch
ismovedto any
position
from POWEROFF, and AC power is suppliedto the
receiver.
SPEAK.ERSSWITCH
Functionsboth as powerswitchand speakerselection
switch.
POWER
OFF:ACpower isoff.
A:
OFF:
B:
AiB:
PHONES
OUTPUT
Insertheadphone
plug into this jack when headphone
listening
isdesired.
Inthiscase,
SPEAKERSswitchshould
bein
OFF
position.
BASS,
TREBLE
CONTROLS
For toneadjustment
when
TONE switch
is in ON posi-
tion.
Whenknobsareturned
clockwisefrom "0" position,
responsein bass
or treblerange,respectively,isboosted.
Turningcounterclockwise
attenuates
response.
TONESWITCH
ControlsON-OFFooeration
of tonecontrolcircuit.
lnthe
ON position, tone control by meansof BASS and
TREBLEknobs
maybeaccomplished.
In the
OFF posi-
tion, the tone controlcircuit is bypassedandfrequency
responseinhigh
andlowrangesis
flat.
HIGH
FILTER
SWITCH
For highfrequencynoisedueto scratcheson the record,
place
switchin 6kHz position.
This will provide 6dB/
octaveattenuation
atfrequencies
above
6kHz.
Fornormal
operationswitch
shouldbeinOFF (upper)
position.
Sound will be heardfrom speakerscon-
nectedto A speakerterminals.
No soundwill be heardfrom speaker
sys-
tems.
This position shouldbe usedwhen
listening
withheadphones.
Sound will be heardfrom soeakerscon-
nectedto Bspeakerterminals.
Sound will be heardfrom speakerscon-
nectedto A terminals
andfrom speakers
connected
to Bterminals.
STEREOINDICATORLAMP
Lights
whenFM
stereobroadcast
is
being
received.
(\D
r'IONCGT. BT
EPEAKEFg .* ;'l?."
BALANCE
CONTROL
For adjustment
of relative
output levels
of L and R
channels
of speakersystems
or headphones.
Clockwise
rotation
from center
position
increases
volume
of R over
L channel.
Counterclockwise
rotation
increasesvolume
of
L channel
over
R.
VOLUME
CONTROL,
For adjustment
of speakeror headphone
output level.
Levelincreases
withclockwise
rotationof knob-
LOUDNESS
SWITCH
SIGNAL
METER
For FM and AM reception,
needle
of the SIGNALmeter
theright.
turn
TUNINGknobuntil
isdeflecteda maximumto
level,
placing
this
switchin
response
in low and high
FALANCI
FMTUI
With thr
right, fi
TUNIN(
MODE
For sel
playbac
STERE(
channel
speaker:
NOTE:
Recordi
MONO,
rate.
DUPLIC
Withsu
two tap
onto th
operatic
For listening
at low volume
the ON position
will boost
frequency
ranges.
The response
of the human
earto low and highsound
volumes
is different. At low volumelevels,
the ear is
relatively
insensitive
to sounds
at either
extreme
of the
frequency
scale.
By means
of the LOUDNESS
switch,
these
sounds
are
given
additional
amplification.
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ii.
FM
TUNINGMETER
Withthe needle
of the SIGNALmeter
deflectedto the
right, fine-tuneFM broadcastby centeringneedleof
TUNINGmeter.
PROGRAM
SOURCEINDICATORS
Indicate
program
sourceselected
by meansof FUNCTION
switch.
TUNING
KNOB
For
selectionof FM
orAMstations.
FM MUTINGBUTTON
Foi selectionof FM broadcasts,buttonshouldbein ON
(released)position.
When button is in ON position, unpleasantinterstation
noiseis suppressed.When
signal
strengthispoor, it may
notbe
possible
to bringinthedesiredstationif MUTING
isON. In thiscase,
press
buttonto place it intheOFF
position.
FUNCTION
SELECTOR
Forselectionof program
source.
AM:
FM: AM broadcasts
FMbroadcasts
PHONO: Playing
records
AUX/MIC: For useof component
connectedat AUX
terminalsof receiver,
or microphoneswhich
maybe
plugged
intoMlc jack.
NOTE:
AUX and MIC programsourcescannot be usedsimul-
taneously. When using AUX hi-fi component,micro-
phone
should
bedbconnected.
rc
JAcK
Acceptsstandard6mm{ plug.Microphoneinput signal
entersbothRandL channels.
TAPEMONITOR
SWITCH
1: For program sourcesother than tapedeck
(playback).
(REC
or
PLAY).
SOURCE: For programsources
otherthantape deck
(playback).
2: For monitoring
of playback
or record mode
of tape
deckconnectedto TAPE2 terminals
(REC
orPLAY).
NOTE:
When
not monitoringrecord
orplayback mode
of a tape
dech,
switchshouldbein SOURCE
position.
Inposition
1 or 2, the
programsourceindicatedby theFUNCTION
selectorwill not be heardthroughspeahersysfemsor
headphones.
i',,1
,,,t
* ;s-
andR
ockwise
'Rover
lume
of
rt level.
vitchin
nd
high
l sound
3ear is
r
of the
switch,
to*s ueoiwer: !
MODE
SWITCH
For selection
of stereophonic
or monophonic
modeof
playback.
In normaloperation,
switch shouldbe in
STEREO
position.
In the MONO position,
R and L
channel
signalswill be mixed,and
soundscomingfrom
speakersof bothchannels
will bethesame.
NOTE:
Recording
stereophonicallywith theMODE switchin the
MONOposition may causechannelseparation
to deterio-
rate.
DUPLICATE
SWITCH
With switchin ON position, signalsrecordedon oneof
two tapedecksconnectedto thereceivermayberecorded
onto the other, with or without editing. For normal
operation,thisswitchmustbein
OFF
(upper)position.
a
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3.CONNECTIONDIAGRAM
REAR
VIEW
Outdoor FM antenna
Centerwire
-tl
mesh
75 ohm coaxial cable
{indoor
oroutdoorl
k
A*ry
ANTENNA
PLACEMENT
Makenote
ot rhelollowing
po'nts when choosing e location
for the FM antenna.
300 ohm leeder cable
Direction ot signals
1.5meter (5 ft.) above
More than 4 meters
(15ft.) above
ground
Please
seetollowing section,
"Antenna and Ground
Connections,"
for instructions
regarding
Fl/1
antenna
FM do-rmph6i5 3witch: For normal FM recebtion rhis switch
shorrld
be seton "75!S" (unir is set to rhis when leavingfactory).
The "25pS" setting is used only when listening to FM Dolby*
transmissaons.
When listening
ro FM Dotby transmissions,
it wi
be
necessarylo use an NR adaptor wiich can be purchased separately.
More detailedinstructions
witt be found in the section,
,,FM Dotbv
Reception."
Antennashouldnot
tte placed where it
will be subiect to elec-
tracalinterlerence
from motor vehicles.
Fig.I
s
r L_t
6E E
B E^A tr
Feeder wire and cSle a Length should b€ a
should be insulated at short aspossible.
mounting points, a Feeder
wire should not
b€ coiled.

TOP
VIEW
six-750
Accessory AC outlets:
Switched ...... Power to this outlet is controtted by the SX-750
pow€r switch.Wh€n power to the receiver
is "On," this oudet will
provide
AC currenr{10Owattsmaxamuml.
Unslvitchod.....
Power
to thisoutlet isnot controtted
by theSX,75O
power swilch. As long as the power cord is plugged
into a tive
outlet, thisoutlet will supply AC current{maximum 300 warts).
AC outl€ts
L channel R chr
A SPEAKER SYSTEMS
L channel
m
R channel
m
0000
0
0
000000
00[|
00000000rt000000000000000000000000000000||0000000
BSPEAKERSYSTEMS
Carrridg€ tape deck Tape deck
Fig.2

4. BLOCKDIAGRAM
ANTENNA
FI1
TSQ
FM
300si
GND
Af1
IF
amp
CF . HA12O1CF HAl13
?T410614P
Ratio
detecfon
SIGNAL
meter^
vlu
CONTROL
SECTION
TAl136P1
TAl 136Pi
A11
TUNER
*,;t-l
AMP
TA1136Pl
!
IlICAH
P
c! c!
35
Tone
control
ON
I
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t-- rF
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p
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ON
OFF
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lc
0N6.l
OFF
t,
16ng
gQnTfol
ON
DCPOWER
SUPPLY
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AC POWER
C\J C!
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outlet AC
ouilet
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illunrination