Pioneer SX-1250 User manual

AM
/FM STEREORECEIVER
sx-l?50
<ART,158-0>
77i <, "
- ^-C r
lif
f
' rl
(v)proNEER

Type Voltage Remarks
KCU 120Vonly CSA {Canada}
and UL {U.S.A) approved
with de'emphasisselector switch (25psl75ps)
HG 22OV and24OV (Switchable) SEMKO
{Sweden),
NEMKO
(Norwav),
DEMKO
(Denmark)
and
El (Finland)
approv€d
s1IOV, 12OV,22OV and240V {Switchable) Generalexport modelwith de-emphasisselector
switch{25pslsops/75psl
MODELSX.125O
COMES
IN
THREEVERSIONSDISTINGUISHED
ASFOLLOWS:
Whenrepairing
Sor HGtype,
please
see
the
manualonpage
101.
CONTENTS
SPECIFICATIONS
FRONTPANEL
FACILITIES
CONNECTION
DIAGRAM
CIFCUITDESCRIPTIONS
4,1 TunerSection
4.2 AudioSection
5.
6.
7.
8.
4.3 Protection
Circuit
. .......,. 17
4.4 Power
Supply
Circuit ....... 18
LEVEL
DIAGRAM
.,.. ......... 19
BLOCKDfAGRAM
....
. ....... 20
DlsAssEMBLY. ........22
PARTS
LOCATION
8.1 Front
Panel
View.. ........ 25
4.2 RearPanel
View .........,27
8.3 TopView ........29
8.4 Bottom
View ....., 31
8.5 Front
View .......33
ADJUSTMENTS
9.1 AMTuner ... . 3b
9.2 FM
Tuner ...........36
9.3 Power
Amplifier ...........38
9.4 Stabilizer ... .. ..... 38
DIALCORDSTRINGING ........ 39
EXPLODED
VIEWS
. ... . 40
SCHEMATICDIAGRAMS,
P.C.
BOARDPATTERNS
AND
PARTS
LISTS
1.
2.
3.
4.
4
6
I
11
14
9. Ii
I
10.
11.
12.
51
12.1 Miscellaneous-parts
I
I

'--
\o 12.2
12.3
12.4
12.5
12.6
12.7
12.8
12.9
12.10
12.11
12.12
12.13
12.14
12.15
12.16
12.17
12.18
sx-1 25C,
SchematicDiagram
Internal
Circuitryof Integrated
Circuits
The
Circuitof FMFrontEnd
(AWB-023)
Tuner
Assembly
(AWE-0681
De+mphasis
Switch
Assembty
(AWX-099)
Equalizer
Amplifier
Assembly
(AWF-021
)
Function
SwitchAssembly
(AWS-094)
FlatAmplifier Assembly
(AWG-042)
5PConnector
Assembly
(AWX-062)
ControlAmplifierAssembly
(AWG-0411
FilterAmplif
ierAssembly
(AWM-089)
Microphone
Jack
Assembly
(AWX-@71
Pourer
AmplifierAssembly
(AWH-048)
Speakers
SwitchAssembly
(AWS-G}S)
Protection
CircuitAssembly
(AWM-091)
Stabilizer
Assembly
(AWR-l
06)
Power
Supply
Assembly
(AWR-I07)
PACKING
PARTS
LIST
OF
EXPLODED
VIEWS
.
SUPPLEMENTS
FOR
SX-l250/HG
ANDSX-1250/5
15.1 Contrast
ofMiscellaneous-parts
.. ........101
15.2 Schematic
Diagramfor
SX-1250/S .....lO3
15.3 SchematicDiagram
forSX-l2sOlHG. ..... lOb
15.4 De-emphasis
SwitchAssembly
(AWX-101,
for
S
type) .. .....1O7
15.5 Speakers
SwitchAssembly
(AWS.098,
for
HGtype) ........ 108
15.6 Poriver
SupplyAssembly
(AWR-108,
for
HGtype) .........110
s3
55
56
57
63
64
68
70
75
76
80
83
84
88
90
93
96
98
99
13.
14.
15.
I
a
!

F
1.SPECIFICATIONS
Semiconductors
FETS.... ...... 5
|Cs..... ......6
Transistors ......82
Diodes
.. ......60
PowerAmplifierSection
C.ontinuous
PowerOutputfrom 20 Hertz
to 20,000
Hertz
(Both
channels
driven).. 160
watts
per
channel
(8
ohms)
200watts
Per
channel
(4ohms)
Total
HarmonicDistortion
(20
Hertzto 20,000Hertz,
from
AUX)
ContinuousRated
PowerOutput.. . Nomorethan0.1%
80
watts
per
channel
power
output,
8ohms . . . Nomorethan0.05%
1watt
per
channel
power
output,8ohms . . . Nomorethan
O.O7%
Intermodulation
Distortion
(50
Hertz: 7,000Hertz
=
4: l,
fromAUX)
Continuous
RatedPower
Output.. . No morethan
0 1%
80
watt!
per
channel
power
output,8
ohms . . . Nomorethan
0.05%
1watt
per
channel
power
output,Sohms . . Nomore
than
0.O1%
FrequencyResponse
. .. ... . . .5H2to
100,000H2ildB
InputSensitivity/
|
mpedan
ce
POWER
Ar\4P
|N.........
Output
Speaker..
Headphone
DampingFactor
.......1V/50kohms
.
A, B,C,A+8, B+C,A+C
...... Lowlmpedance
(20H2
to
20,000H2,8
ohms). .......30
HumandNoise
(lHF,
short-;ircuited,
A Network)
. .100d8
Preamplif
ierSection
InputSensitivity/
lmpedance
PHONOI
PHONO
2
t\4tc....
AUX,..,
TAPEPLAYI.....,
TAPLPLAY2......
TAPEPLAY
2 (DlN conne(lor).
. .
PHONOOverload
Level
(T.H.D.
0.1%)
PHONO
I
PHONO
2
OutputLevel/l
mpedance
TAPL
RECI ...,.
,
TAPERLC2......
TAPE
REC2(DlN connector)
.. .
PRE
OUT
Totallllrmonic
Distortion
(20Hr
ot 20,000Hr,
IV ourpur) . . Nomore
thanO.02%
Frcquency
Rcsponse
PHONO
{R
IAAequ,rlizrrion).
.30}12
ro15,000H2r0.2dB
AUX,TAPE
PLAY
....... tOHzto50,000H.,lldB
ToneControl
BASS...
I'REBLE
.
Filter
LOW....
lV/1k
ohms
80dB
74dB
0.1%
HIGH
,..
Loudness
Contour
(Volume
control
set
at 40dB
position)
. . . . .+6dB
(100H2),+3dB
(t
okHz)
Hum and Noise (lHF, short,circuited,
A Network, rated
power)
PHONO........
AUX,
TAPE
PLAY
l\4uting
..
FM Section
Usable
Sensitivity.. . l\40No
..
STEREO..
Usable
Sensitivity
(lHF'58)
.....
50dB
Quieting
Sensitivity....
l\40No . . .
STEREO..
Signal-to-Noise
Ratio at65dBf . .
Distortion
at65dBfl00Hz.....
lkHz. . . . . .
6kHz
.
. . [4AlN 1l0dB (l00Hz)
SUB t sdB(s0Hz)
. . l\4AlN 1'l0dB (tokHz)
SUB t 5dB
(20kHz)
.. 30Hz
(12dB/oct.)
. . 8kHz
(12dB/oct.)
... 75dB
...90dB
. . 20dB
8.7dBf
(3.orv/300s})
la.sdBf
(s.8gV/300[l)
. . 1.5irV
11.sdBf
(a.1pV/3000)
36.0dBf
(69sV/300())
MONO.......
STEREO.....
i\40No......
STEREO....
MONO......
STEREO....
.
0.25%
.0.1%
. 0.2/o
. 2.5mV/50k
ohms
. 2.5mV/50kohms
. 6.5mV/50k
ohms
.150mV/50k
ohms
.150mV/50k
ohms
. I50mv/50k
ohms
.150mV/50k
ohms
. . 500mV
(1
kHz)
. . s00mV
(1kHz)
........150mV
........150mV
. 30mV/80k ohms
Frequency
Response
...l\40No....... 0.3%
STEREO.. . .. O.3Vo
. . 30Hztol5,000Hri?
3dB
Capture
Ratio ..........l.OdB
AlternatcChannelSelectivity ........ 83dB
Spurious
Response
Ratio... .......11OdB
lmage
Rcsponse
Ratio
... .........110d8
lF
Response
Ratio
... ...120d8
AMSuppression
Ratio... .........60d8
/VlutingThreshold .....13dBf(4.9pvl3004)
Stereo
Separation
. . 50dB (lkHz),
35dB
(30H2-t5kHz)
SubcarrierProductRatio .......... 14dB
SCARejection
Ratio... ..........74d8
AntennaInput 300ohms
balanced
75
ohmsunbalanced
I
.
I
I
s
I

six-1 Elscl
A\,?
AM Section
Scnsitivity
(lHF,
Ferritcantenna)
(lll
F,Ext.antenna)
Sclcctivity
Signal-to-Noise
Ratio
........
lmage
Rcsponse
Ratio.......
lFRcsponse
Ratio.. .
Antenna
..
l\4iscellaneous
PowerRcquircmcnts ... 120V
60HZ
.......6s0w(uL,csA)
'1200W
(max.)
Powcr
Consumption
Dimensions........
556(W)x186.5(H)
x464.5(D)
mm
21-7l8(w)
x7.3/8(H)
x 181/4(D)
in
Weight
Without
Packag€
. . 29.2kg(641b
4 oz)
WithPackage ..... 33.2kg
(73
lb1oz)
.
Built'inFcrrite
......300pV/m
.........l5irv
.........40d8
.........55d8
.........65dB
.........85dB
Loopstick
Antenna
Furn
ished
Parts
Fl\4
T-typc
Antcnnd
. .
Opcrating
Instructions
Hex.
Wrench
.1
,1
.t
NOTE:
Specifications
ond thedesigtr
subject
to possible
modifica.
tion uithout noticedue to improuements.
sHEX WRENCH
The accessoryHex. wrenchis provided
for removingthe
VOLUME and TUNING knobs, or for tightening its
setscrewin theeventit becomesloose.
If required,loosenthe setscrew
by insertingthe wrench
into the hole on the side of the knob and tuming the
wrench counterclockwise. Be particularly careful not to
scratch
the front panel whenemploying
the wrench.
5

F
2. FRONTPANEL FACILITIES
FUNCTION
SELECTOR
BUTTONS
To selectthe program
source,
push
eachbutton as
follows:
NOTE:
Only one FUNCTION button shouldbedepresaed
ot o
ttme.
AM
......... For
AMbroadcastreception.
PHONO
1
.....
AUX
........
oooA
\-' o
. . . . For FlVl
stereoreception.
Automatically
receives
monophonicallyduring
FlVlmono-
phonic
broadcasts.Th0 5TE
REOindic.rror
liihtsupwhen
lhebr"J,lL.r.tr\ n
\lcrcu.
PHONO
2/MtC.
TAPE
DUPLICATE
SWITCH
Set thi5switchin the ON (down) position
to duplicate
or edit a recorded
tapeusingtwo tape
decks.
To operate
aturntable connected
to the
PHONO1 input
jacks.
For listening
to audio component
(car-
tridgetape
player,
TV sound
tuner,etc.)
connected
to theAUX input
jacks.
As abovefor PHONO2 iacks,
or for
reproduction
through
microphonescon-
nected
to the Mlc iack
ison thefront
panel.
Note, when
the
microphone
is
connectedto the iack the turntable
connectedto the
PHONO2
iacks
cannot
Deuseo.
FM
VOLIJMECONTROL
AND AUDIO MUTING
SWITCH
The extremely high power output of the SX-1250
can be finely controlled by combining the cali-
brated VOLUME control and the AUDIO MUT-
ING switch.
The AUDIO MUTING switch can also be used to
briefly lower the volume when changingrecords or
taDes. r
VOL!ME
.-.
IrtI
I
I
tI
I
i
i
Iv
I
t
I
'I
I
I
t
I
I
I
I
I
i
i
Y
I
I
I
ADAPTOR
SWITCH
When
employing
adaptorcomponents,
suchasa graphic
equalizeradaptor,
RG processor, or Dolby NR adaptor,
depressthis
ADAPTOR
switchto ON.
s?F$
TAPE
MONTTOR
(1,
2) SWTTCHES
Set
theseswitchintheON (down)position
asfollow:
1 .. .. With a taDe deck connectedto the TAPE I
jacks (REC and PLAY), either playbackor
monitoringof a recording
in progre5s
arepos-
sible.
2 .. .. Sameasin 1 above,with a tapedeck
connected
to the
TAPE2jacks
(REC
andPLAY).
For
normaluse,leave
in theOFF (up)positions.

SPEAKERBUTTONS
Three
setsof speaker
terminals,A, B,andC,are
provided
on therear
panel,
andtherequiredspeaker
systems
canbe
selectedbydepressing
theSPEAKERS
buttons
asfollows:
A ........... Speaker
systemsAoperate
B ........... Speakersystems
Boperate
C ,.......... Speakersystems
Coperate
NO?ESr
1. Whetr any two buttons (A+8, B+C, C+A) ore de'
preaeed
simultaneously, the eorresponding
pairs of
speakersystems
will comeinto operation.
Howeuer,
it
is not possible
to operote all three speaher
systems
ot
the same time, euen though all the buttons ore
depressed.
2. For priuote listening through heodphones,
return all
the SPEAKERSbuttons to the OFF (undepressed)
Dosition.
PHONES
'ACK
Acceptsstereo
headphones.
WARNING:
Do notpluga microphoneinto thePHONES
jachosmay
domagethe microphone.
POWERSWITCH
After turning
thisswitchON thereisa
delayof some 6to
8 seconds,during which time the protection circuit
operates
to eliminateunpleasantnorse.
TWINBASSCONTROLS
Adiustlow frequencytone.
100H2: Adiustsfrequencybandbelow
400H2.Control
effectiveness
at 100H2 is
r10dB.
50Hz: Provides
additionalcontrolfor the frequency
band below 200H2.Control effectiveness
at
50Hz
is
r5dB.
TONESWITCH
IntheOFF (up)position,
this
switch
causestheamplifier
section
to operatewith a flat frequencyresponseregard'
lessof the
tonecontrol
setting.
FMTUNING
METER
With the SIGNAL meter needledeflected
to
make fine adiustment
by centering
the FM
meter
needle
(indicating
optimum
reception).
SIGNAL
METER
the right,
TUN
ING
TUN
Sele,
obse
stGl
Ft\4|
Lear
ForAN4
and
Al\4
tuning:
FMtuning:
Flvlstation
tunings.
Tune for maximum deflection of the
SIGNAL meterneedle
to theright.
Both
the
SIGNALand
FMTUNING
meters
work together.Theoptimum point of the
SIGNAL
meter
needle
is
thesameas
in
AM
tuning.Then
usetheFl\4TUNING rn€ters.
supF
tw€{
supF
oepr
SPEAKER
SYSTEMINDICATOR
FMSTEREO
INDICATOR
LOWCUT (30H2)
FILTERBUTTON
whenlow-oitched
rumble{fromturntable
motoror other
source) is obstrusive
depressthis button to provide
l2dBloctave,attenuation
at frequencies below 30H2.
lf
nointerferenceisexperienced,release
thisbutton.
HIGHCUT
(8kHz)
FILTER
BUTTON
When
highfrequency
scratchnoise
(from
wornrecords
or
othersource)isunpleasant,depress
thisbuttonto provide
12dB/octaveattenuationat frequencies
above8kHz. lf
thereisno interference,releasethisbutton.
FM
Whr
oepl
the
tnts
Adi
10k
TWI
20k

I of the
t.
G meters
nt of the
as
in
AM
m€Iers.
TOR
orother
provide
lOHz.
lf
rcords
or
,provide
3kHz.lf
TUNINGKNOB
Selectthe station
and tune for optimum reception
by
observing
the SIGNAL meter
for AlVl
stations,
andboth
SICNALand
TUNINGmeters
for FMstations.
FMMUTING
BUTTON
Leavethis button undepressed (in the ON position)
to
suppressunpleasantinterstation
noise
while tuning be-
tweenFl\4stations.
Low-strengthsignals
may also be
suppressed
by thisfunction,
so
to pickup aweakstation
depressthis
buttonto the
OFF position.
PROGRAM
SOURCE
INDICATOR
FM MULTIPATHBUTTON
When selecting the bestpositionfor the Fl\4antenna,
depressthis button sothat multipathnoiseis heard
from
the speaker
systems.To listen
to FN,lbroadcasts,
release
thisbutton.
TWIN
TREELECONTROLS
Adjustshighfrequencytone.
1okHz: Adjustsfrequency
bandabove2.5kHz.
Control
effectiveness
at lokHz isr10dB.
20kHz: Providesadditionalcontrol for the frequency
band above 5kHz. Control effectiveness
at
20kHzis
r5d
B.
six-1 e50
MIC
JACKS
(L andR)
Forconnecteachchannel
jack5
the left
andrightchannel
microphone5.
NOTE:
Usethe hEh impedance
(oboue
20ks7)with 6mm diatn.
phoneplugs.
VOLUMECONTROL
Adjusts
output levelto speakers
andheadphones.
Scale
isgraduated in dB, and when usedin conjunction
with theMUTINGswitch,finer
andwiderrange attenua-
tion canbe performed. Seeadditionaldescription
on
page
6.
AUDIOMUTING
SWITCH
_2OdB
Depressthis switch to attenuatethe audio output by
20dB.
Thisconvenient featuresaveshavingto disturbthe
VOLUME control,for example
whenansweringthetele-
ph
one.
LOUDNESSSWITCH
Depress
this switch when listening
at low volume.The
frequency
responseof the humanearvariesaccording
to
the listening
volume,and the depressed
position
com-
pensates
for hearingresponseby emphasizingthebass
and
treble.
IIIODESWITCH
For stereo
playback,
leavethis switch undepressed
(or
depress
to release,if alreadydepressed).
Whendepressed
for MONOplayback,
leftandrightchannel
stereosignals
will be mixed to produce
monophonicsound
from both
speakersystems.
BALANCE
CONTROL
Adjusts
the balance between
thesound
volumefrom the
leftandrightspeaker
systemsorheadphones.
right,
o6ru'"-6*6

3.CONNECTIONDIAGRAM
TURNTAELE
OUTDOOR
FMANTENNA
T.TYPE
FMANTENNA
TAPEI
3O0A teeder
FM OE.EMPHASIS
SWITCH
Normally, set this swatch to "75!s". Be sure to set ir to
"25ps" only when listening to an F[, broadcast (pre-
ernphasis; 25rrsec.l with a Oolby' system NR adaptor con-
nected berween the ADAPTOR OUT and ADAPTOR lN
* The word "Dolby" i! a trademarkof Dolby Laboratories
Inlj.
ffi-[] 4.V
GND
TURNTABLE
RIGHT LEFT RIGH'
SPEAK
ER
SYSTEMSA

IAPE OECK
(open{eel,
casselre}
LINE LINE
INPUT OUIPUT LINE LINE
INPU-T OUTPUT
irulr(il -00r0r ftrovt ScRtyis
yr 30rrtr 0Tct
DOLBY
NR ADAPTOR 4 CHANNEL DISCRETE
FM ADAPTOR
ose
. I e0
LINE LINE
INPUT OUTPUT
PR€/POWE
R AMP
The bridg€ connecting plugs beiween pRE OUT and
POWER lN iacks
shouldalwaysbe teft in position in
normal us€. ll rhey are disconnected
or removed,
no
soundwill come from the speakers.Atwaysbesureto
swatch off the power supply before artempring to
CONVENIENCE
OUTLETS
Unswitchod: Less frequenttyused
components,
which do
l2O0W
max.) not require
coupled
power,
can be
ptugged
into eitherot theseoutlets.
A frequ€ntlyused
component (turntabte,
tape
deck. elc.) can be plugged into this outlet.
By leaving the power switch of rhat compo,
nent in the ON position, povver
suppty
ro the
componenr wi
be coupled
with thesx_1250
switch
operation.
lr tP
t-t t-t t-l
t=Jt=Ju Switchsd:
(sow
max.l
Itl:i.i+l rl '
EE
RIGHT LEFT RIGHT
SPEAKER
SYSTEMS
8SPEAKER
SYSTEMSC