Pioneer SX-1280 User manual

XRABi3

Typo Volr.rp R.mark!
KU 120Vonly U.S.A.rnodel
KC 120Vonly Canads model
110v,120v.22OVand240V(Switchsble) Gen6ralexDortmodel
s/G 1'10V,120V,220V.nd 240V
{$i,itchsbl6l U.S.Milit8rymodel
six-1 eEto
MODEL
SX-1280
COMESINFOURVERSIONS
DTSTINGUISHED
AS FOLLOWS:
NOTICE:
r This
service
manual
is
applicableto the KUand
KC
types
. Asto theSandS/G
types,
please
refer
to page 81.
CONTENTS
1. SPECIFTCAT|ONS. 3
2, CONNECTIONDIAGRAM 5
3. FRONT PANEL
FACILITIES 7
4. LEVELDTAGRAM
.... ....... . 10
5. BLOCKDIAGRAM
.... ....... 11
6. CIRCUIT
DESCR]PTIONS
6.1 Tuner
Section ..........13
6.2 AF
Section ......14
6.3 Power
Supply
Circuit
. .....16
6.4 Proteqtion
Circuit.. .......11
7, DTSASSEMBLY ........ 18
8, PARTS
LOCATION
8.1 FrontPanel
View... ......20
8.2 Front
ViewwithPanel
Removed ...........21
8.3 Top
View .......22
8.4 Bottom
View ....29
8.5 RearPanel
View
.. . .. .... 24
9. DIAL
CORD
STRINGING ....
.. 25

IO. ADJUSTMENTS
10.1 FM
Tuner
1O.2 AMTuner
10.3 Power Amplifier
10.4 MeterAmplifier
11. EXPLODEDVIEWS
11.1 ExternalPart . , .
11,2 lnternalPart
12. PACKING
13. SCHEMATICDIAGRAMS,P.C.
BOARDPATTERNS
AND PARTS
LIST
13.1 SchematicDiagramand
MiscellaneousParts
. .
13.2 TunerAssembly
(AWE-092)
13.3 Microphone
JackAssembly
(GWM-I05)
13.4 Cartridge
LoadAssembly
(cWS-134)
13.5 Function
SwitchAssembly
(GWS-I33)
13.6 EOAmplifier
Assembly
(AWF-031)
. .. ..
13.7 Flat
AmplifierAssembly
(AWG-0601
13.8 Tone
AmplifierAssembly
(AWG-059)
. . ..
13.9 Filter
Amplif
ierAssembly
(AWM-119)
13.10 PowerAmplifier
Assembly
(AWH.074)
13.11 ResistorAssembly
(AWX-I27)
13.12 Meter
AmplifierAssembly
(AWM-I211
13,13 Power
SupplyAssembly
{AWR-I57) . . . .
13.14 'Fuse
Assembly
(AWX-I261
or (AWX-I391
13.15 Protection
CircuitAssembly
(AWM-I23)
ADDITIONAL
SERVICE
MANUAL
27
29
30
30
31
33
40
41
45
52
53
54
56
58
61
64
67
70
72
74
77
78
1. SPEC|F|CAT|ONS
... . ... ..... 82
2. CONTRAST
OF MISCELLANEOUS PARTS ,.... 82
3. EXPLODEDVIEW . ... . 84
4. SCHEMATIC
DIAGRAMS,
P.C.
BOARDPATTERNS
AND PARTS
LIST
SchernaticDiagram .. ...... gs
5PConnector
Assembly
(AWX-062)
... .......... g7
Fuse
Assembly
(AWX-134) .......88
NO?E: * .F'nseossembly
(AWX-I26) isapplicable
to theKII type,andAWX-tB9 isfor theKC type.
4.1
4.2
4.3
e

1.SPECIFICATIONS
Semiconductors
FETS... 5
lCs..... 6
Transistors ......61
Diodes.. ......50
Power
Amplifier Section
Continuous
power
output
of 185watts.
per
channel,
min.,at8 ohms
from20
Hertzto
20,000
Hertz
withn0morethan0.03%total
harmonicdistortion.
Total
HarmonicDistortion
(20Hertzto 20,000Hertz)
ContinuousRated
PowerOutput . .Nomorethan 0.03%
90watts
per
channel
power
output,Sohms . . Nomorethan 0.01%
I watt
per
channel
Power
output,
Sohms . . No morethan0.01%
IntermodulationDistortion
(50
Hertz:
7,000Hertz
=
4:1)
ContinuousRatedPowerOutput . .
Nomorethan
0.01%
90watts
per
channel
power
output,
8 ohms No morethan 0.006%
1wattper channel
power
output,8
ohms Nomore than0.005%
Frequency
Response
. . ... 5 Hertzto IO,OOOHertzl!aA
lnputSensitivity/lm
pedance
POWERAMPIN
..... .. lV/5Okilohms
Output
SPEAKERS . . . . . A,B,
C,A+8,B+C,C+A
Damping
Factor
(20
Hertzto
20,000
Hertz,8
ohms)
........... 30
Hum
and
Noise
(lHF,
short-circuited,
A Network). . 105d8
PreamplifierSection
Input
(sens
itivity/lm
pedance)
PHONO
I .
Cartridgeload
(capacitance)
. . .
PHONO2
t\4tc....
...2.5mV/50kilohms
'100,
200,
300,400pF
. . .2.5mV/50kilohms
. . .7.5mV/50kilohms
AUX... .. 'l50mV/50 kilohms
TAPE
PLAY'1
...... 150mV/50kilohms
TAPEPLAY2...... 150mVi50kilohms
PHONO
Overload
Level
(1kHz;T.H.D:
0.03%)
PHONOl,2...... 300mV
Output
Level/lmpedance
TAPERECl...... ..150mV
TAPEREC2...... 150mV
PREOUT ..... 1V/1kilohms
Total
HarmonicDistortion
(20H2
to20,000H2,1Voutput).. .Nomorethan0.01%
Frequency
Response
PHONO(RIAAequalization).20Hz
to20,000H2
l0.2dB
ToneControl
BASS...
TREBLE.
Filter
LOW
...
sx-,| 480
. ,LlOdB
(l00Hz)
main
control
a5dB
(50H2)
subcontrol
. r10dB (1okHz)
main
control
e5dB (20kHz)
subcontrol
HIGH...
LoudnessContour
(Volume
control
set
. 15Hz
(12dBloct.)
. 8kHz
(l2dB/oct.)
at
-40dB
position)
. . .. +6dB
(100H2),
+3Og
1'l6kli.1
Hum
and
Noise
(lH
F,
short-circuited,A Network)
PHONO .
AUX,
TAPEPLAY, . .
Muting..
FMTunerSection
UsableSensitivity
t\40No
..
50dB
Quieting
Sensitivity
MONO..
STEREO.
Signal-to-Noise
Ratio
(at
75dBf)
. . .STEREO.
(at
65dBf)
...MONO..
STEREO.
Distortion
(at
65dBf)
'f00Hz
MoNo/STEREO
.. ..o.1%1o.2%
lkHz MONO/STEREO ... O.1o/o10.'1570
6kHz I\4ONO/STEREO . ... 0.1YolO.2%
FrequencyResponse.. .... .. 3OHzto15,O0OHzl33dB
CaptureRatio ..........1.0dB
AlternateChannelSelectivity .........80d8
SpuriousResponseRatio. .. ........100d8
lmageResponse
Ratio
... ..........90d8
lFResponseRatio... ....110d8
AMSuppressionRatio... ....55d8
Muting
Threshold . . 19.2dBf(5gV)
StereoSeparation. . . 50dB(lkHz),35dB(30H2
- 15kHz)
SubcarrierProductRatio ...........65d8
SCARejectionRatio... ...........65d8
Antenna
Input 300
ohmsbalanced
75ohmsunbalanced
...80d8
. . .95dB
. .-20d8
AUX,TAPE
PLAY . . . 5HztoS0,OOOHZI?dB

AMTunerSection
Sensitivity
(lHF,Ferriteantenna)
... .......
(lHF,
Ext.
antenna).
Selectivity
Signal-to-Noise
Ratio... . . . . .
lmageResponseRatio.. . . . . .
lFResponseRatio.........
Antenna. .. Built-in
300!V/m
.. 15pV
. . .30dB
...50d8
. . .40dB
......40dB
FerriteLoopstick
Antenna
Misdellaneous
PowerRequirements...... .... 120V
60Hz
PowerConsumption..... 430W(UL),1000VA(CSA)
1100W
(max.)
Dimensions .. 556(W)x i86(H)x461(D)mm
21-11/l6(w)
x6-1sll6(H)x17-5l16(D)
in
WeightWithout
PackaSe.
. 28.7kg
(631b
3oz)
With
Package
FurnishedParts .32.1kg
(701b
10oz)
FMT-typeAntenna ..........1
OperatingInstruclions ........1
Hex.Wrench 1
*Meacurcd pursudnt to the Federal Trade Commission's
Trade Regulation rule on Pouer Output Claifis for
Amplifierc.
NO?E:
Specificotionsdnd thedesign
subjectto possible modifico-
tion uithout aoticedue to improuements.
HEX.WRENCH
The accessory
hexagonalwrench is provided for removing
the TUNING knob and VOLUME knob or tightening
their setscrewsshould they becomeloose.
If required, loosen the set screw by inserting the wrench
into the hole on the side.of the knob and tuming the
wrench counter-clockwise. Be particularly careful not to
scratchthe front panel when employing the wrench.

2. CONNECTION
DIAGRAM
Turntable
I (PHONO
1)
AM outdoor antenna
Cartridge
type
player
(AUX)
-'--'t
& Grc ou €^L E!
-
-
-
j-,
-
--
-
-
-
-
Turntable
2 (PHONO
2)
300ohm
feeder
T.tvpc FM anicnna FM outdoor antenna
5

six-1 eElo
Connectthe power plug to the wall outlet because
this
receiver
requires
alotof
Tape deck 1
(TAPE 1) Tape
deck 2
(TAPE
2}
Speakersystems
A
(SPEAKERS
A}
Dolby*NR adaptor
Right
ru
onm
ax
ial
0re
L-_,
,fi.
/i\
TI
Ac12ov
m
60Hz
only
Switched Unswitched
SWITCHED:
(50W
max.)
Speakersystems B
(SPEAKERS
B}
Speakersystems
C
(SPEAKERS
C}
A frequently used component
(turntable,
tape deck,etc.)can be
plugged into this outlet. By leav-
ing the power switch of that
component in the ON position,
power supply to the component
will be coupled with the receiver
switchoperation.
UNSWITCHED: Less
frequently usedcomponents,
(Total lOOW which do not require couplec
max'' power, can be plugged
into either
of these outlets.
Lef
t Right
* Tlre
word "Dolby" is a trademarkof Dolby LaboratoriesInc.

3. FRONT PANEL FACILITIES
POWER
SWITCH
Flipthis
switchtothe
ONposition tosupply
power
tothe
stereoreceiver.
Therewill bea shortdelaywhenit i; set
to ON, becausethe mutingcircuit hasbeen
actuatedto
suppressthe unpleasantnoise
thatissometimes
generated
when
the
power
isswitched
onandoff.
PHONES
JACK
Plugthe headphonesinto this jack when you want to
listen
through
yourstereoheadphones.
Release
the allSPEAKERSbuttonsif you want to listen
to thesoundthrough
your headphones
only (This means
that
allthreebuttons
will bereleased).
SPEAKERS
BUTT
Press
the button corresponding
to thespeakers
connerrted
to theSPEAKERSterminals
(A, B,C) on therear
panel.
You can presrtwo of thesebuttonsto listen
to sound
from two pairs
of speaker systemsat thesametime.
NOTE:
No ound utill beheardthrough the speahers if all lhree
buttou are
p?esed
ot lhe same
time.
BALANCE
CONTROL
Usethir control to balancethe volume
of the left and
right chennels.First, however,
setthe MODE switchto
MONO, and adiust
so that the soundappears
to c,)me
from somewhere
exactly
betweenthetwo speakers.ll the
sound
appears
to be louder
on the right,
it means
that
the
volumeof therightchannel
is
higher.TurntheBALAIICE
control to the left and adiust.
Conversely,if the sound
appears
to be louder on the left, it meansthat the
volume
of the left channelishigher.
Therefore,
turn the
BALANCE control to the right
andadiust.After adjust-
ing,returntheMODE
switchto STEREO.
POWER
METERS
Thesepower meters allow you to read out the rated
powerlevelwhen speakers
with a nominalimpedanceof
8 ohmsareconnectedto the receiver'sspeakerterminals.
NOTE:
These ualuesare related to the impedanceof the
speahersand they wry accprding to the frequency.
In order to find out the exactoutput leuel,connectan
8-ohmdummy loadinsteadof thespeahers.
FUNCTION
INDICATOR
MEMORYMARKERS
These
arevery
convenientfor frequenttuning in to the
same
broadcastingstation.
MUTINGSWITCH
Set this switch to the -20d8 position
to attenuatethe
audiooutputindicated
by the VOLUME
controlby 20d8.
There is no needto adiust
the VOLUMEcontrolif you
usethis switch when turningdown the audiooutput
temporarily and when changing
over records or tapes.
VOLUME
CONTROL
Usethiscontrolto adlusttheoutputlevelto thespeakers
andheadphones.Turn it clockwiseto increasetheoutput
level.No sound
will beheardif you set it to-. The scale
is graduated in dB which indicate
the attenuation
when
themaximum
outputlevel
is0dB.
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_TONE
SWITCH
Set this switchto ON when adjusting
the BASS
and
TREBLE controls.
In the OFF position,
it causes
the
amplifierto operate
withaflat frequency
response.
FUNCTION
BUTTONS
Press
the functionbutton whichcorresponds
to the pro-
gram source.
Turn the VOLUME control down first
before selectinga different function button while the
soundfrom one
program
sourceis
beingreproduced.
FM. . . . . Press
this
buttonfor FMbroadcasts.
The FM STEREO
indicator
tights
up
when
the
receiveris
tunedin
toanFM
stereo
broadcast.
The soundis auto-
matically received monophonically
during
FM
monophonic
broadcasts.
TWIN
BASS
AND
Use these
controlsTREBLE
CONTR
to adjust the bass
and the treble.
TAPE
DUPLICATE
SWITCH
Setthisswitch
to ON when
youwant
to duplicate
oredit
a pre-recorded
tape using two tape decks.
TAPE
MONTTOR
SWTTCHES
(1,2)
SetswitchI to ON with a tape
deck
which isconnected
to theTAPE 1 jacks
(REC
andPLAY)when youwanr
to
monitor
theplayback
or recording
of atape.
Thetape
on
a deck
whichisconnected
to theTApE 2 jacks
(REC
and
PLAY) can
besimilarly
monitored
by setting
switch
2to
oN.
NOTE:
Set theseswitches to the upper (offl position when
Iistening
to records
or a broadcast.
AM..
.
AUX..
PHONO
2IMIC
. .
Press
this button for AM broadcasts.
Press
this
buttonwhenlistening
to an
audio component cornected to the
AUXinput
jacks.
Press
this button when playing a
record
on the turntable
connected
to
the PHONO
2 iacks, or when
using
a
microphone
which you have plugged
intothe
MIC
iack.
Press
this button when playinga
record
on the turntable
connected
to
thePHONO
i jacks.
PHONO
1
... ..
NOTES:
1. Unplug the microphone from the MIC jach when you
do not intend to use the microphone otherwise you
will not beable to use
thePHONO 2 jachs.
2. Only one function button should be pressed at a
time.
Plug
your
microphone
into
this
lack.
The microphone
signals
arereproduced
in monothrough
the
leftand
right
speakers.
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TUNING
METER
Whentuning
in to an FM station,
theoptimumreception
position
is indicated
whenthe metei'
pointer
deflects
to
deadcenter.
Checkthat theSIGNAL meter
pointer
has
deflected
asfarto theright as
possible.
SIGNALMETER
When
tuningin to an AM or FM station,
theoptimum
reception
position
is indicated
by the maximum
deflec.
tionof the
meter
pointer
to theright.
FM
MULTIPATH
BUTTON
Usethis
switchto detectmultipath
soundwhen
installing
the FM antenna
ina position
which
yields
theminimum
multipath interference.
STEREOINDICATOR
FILTER
15Hz BUTTONS
. When thisbuttonispressed,
a 12dB/oct
atten-
uation can be provided
for frequencies
below
l5Hz. Thismeans
that
youcancancel
out noise
in the ultra-lowfrequencies
whichis
generated
by low-pitched
rumblefrom a turntable
and
other forms of distortion.
Although
thisnoise
cannot
be heard,
it can
generate
intermodula-
tiondistortion.
8kHz . . Press
this button to provide
a l2dBloct atten-
uation
at frequencies
above
8kHz.
Setit to this
positionwhen you find high-frequency
noise,
such
asthat from scratched
records,unpleasant.
FM
25ps
BUTTON
Press
this
buttonwhen
listeningto a *Dolby FM broad-
cast;
otherwisekeep
thisbuttonat thereleased
position.
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PHONO1 CARTRIDGE
LOADSWITCH
Usethis knob to selectthe input capacitance
(pF) in
accordance
with the sp.ecifiedload capacitance
of the
moving
magnet
(MM)cartridgeconnected
to the
PHONO
1jacks.
TUNING
KNOB
Usethis
to tune
into broadcasting
stations.
Selectthe stationand tune for optimum reception
by
observing
the SIGNAL meter
for AM stations
andboth
the
SIGNAL
andTUNING
metersfor FM
stations.
MODE
SWITCH
Usethis
switchfor selectingmonoor stereo
performances.
STEREO: Setto thisposition for normal
stereoopera-
tion.
MONO: Whenset
to thisposition,
the left andright
channel
signals
will bemixed
andreproduced
monophonically
from both speakersystems.
FM
MUTING
BUTTON
ON (released
position)
. . . Release
this button to sup-
press
unpleasant
inter-station
noise
whentuningin to FM
stations.
OFF
(depressed
position)
. Depress
this.
button to pick
upweal(
stattons.
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