Pioneer SX-1080 User manual

AM/FM STEREO RECEIVER
SX-IOSO
SERVICE MANUAL

sx-noso
MODEL SX-1080 COMES IN FIVE VERSIONS DISTINGUISHED AS FOLLOWS:
Type Voltage
Remarks
KU
120V only
U.S.A. model
KC 120V only Canada model
HG 220V and 240V (Switchablel Europe or Oceania model
S 110V. 120V, 220V and 240V (Switchable) General export model
S/G
110V. 120V, 220V and 240V (Switchable) U.S. Military model
NOTICE:
• This service manual is applicable to the SX-1080/KU.
• The SX'1080/HG, S/G, S, KC service manual is issued as an appendix.
CONTENTS
1. SPECIFICATIONS. 3
2. CONNECTION DIAGRAM. 5
3. FRONT PANEL FACILITIES. 7
4. DISASSEMBLY. 10
5. PARTS LOCATION
5.1 Front Panel View. 11
5.2 Front View with Front Panel Removed. 12
5.3 Top View with Bonnet Removed. 13
5.4 Bottom View with Bottom Plate Removed. 14
5.5 Rear Panel View. 15
6. LEVEL DIAGRAM. 16
7. BLOCK DIAGRAM . 17
8. CIRCUIT DESCRIPTIONS
8.1 Tuner .. 19
8.2 Phono, Mic Input Circuit. 20
8.3 Flat Amplifier. 20
8.4 Tone Control. 20
8.5 Power Amplifier. 20
' 8.6 Meter Amplifier... 21
8.7 Protection Circuit.-. 22
8.8 Power Supply. 22
1

9. ADJUSTMENT
9.1 AM Tuner. 23
9.2 FM Tuner. 24
9.3 FM MPX. 25
9.4 Power Amplifier. 26
9.5 Meter. 26
10. DIAL CORD STRINGING. 27
11. EXPLODED VIEWS. 28
11.1 Exterior. 29
11.2 Component of Panel Stay. 31
11.3 Component of Chassis. 33
11.4 Rear Panel. 35
12. SCHEMATIC DIAGRAMS, P.C. BOARD PATTERNS AND PARTS LIST
12.1 Miscellaneous Parts List. 36
12.2 Schematic Diagram. 39
12.3 Tuner Assembly (AWE-092). 41
12.4 Power Transistor Connector Assembly (AWX-125). 47
12.5 Tone Control Assembly (AWG-056). 48
12.6 Flat Amplifier Assembly (GWG-112). 51
12.7 Power Amplifier Assembly (AWH-071). 54
12.8 Speaker Selector Assembly (GWS-124). 57
12.9 Function Equalizer Assembly (GWS-125). 60
12.10 Filter Assembly (AWT-001). 64
12.11 Power Supply Assembly (AWR-152). 66
12.12 Terminal Assembly (GWS-126). 70
12.13 Terminal Assembly (GWS-127). 70
12.14 Speaker Terminal Assembly (GWS-128). 71
12.15 Protection Assembly (AWM-120). 72
13. PACKING. 75

SX-1 080
1. SPECIFICATIONS
Semiconductors
FETs. 5
ICs. 8
Transistors . 36
Diodes. 42
Power Amplifier Section
Continuous power output of 120 watts* per
channel, min. at 8 ohms or 150 watts* per
channel at 4 ohms from 20 Hertz to 20,000
Hertz with no more than 0.05% total harmonic
distortion.
Total Harmonic Distortion (20 Hertz to 20,000 Hertz)
Continuous Rated Power Output . , No more than 0.05%
60 watts per channel power
output, 8 ohms . No more than 0.02%
1 watt per channel power
output, 8 ohms . No more than 0.02%
Intermodulation Distortion (50 Hertz: 7,000 Hertz = 4:1)
Continuous Rated Power Output . . No more than 0.05%
60 watts per channel power
output, 8 ohms , . . . No more than 0.02%
1 watt per channel power
output, 8 ohms . No more than 0.02%
Frequency Response .... 5 Hertz to 100,000 Hertz^^^^dB
Input Sensitivity/ Impedance
POWER AMP IN.lV/50kilohms
Output
Speaker . A, B, A+B
Damping Factor
(20 Hertz to 20,000 Hertz, 8 ohms). 30
Hum and Noise (iHF, short-circuited, A Network). . lOOdB
Preamplifier Section
Input (Sensitivity/Impedance)
PHONO 1,2 .2.5mV/50 kilohms
MIC.7.5mV/50 kilohms
AUX .150mV/50 kilohms
TAPE PLAY 1.150mV/50 kilohms
TAPE PLAY 2.150mV/50 kilohms
PHONO Overload Level (IkHzjT.H.D; 0.05%)
PHONO 1,2 . 200mV
Output Level/Impedance
TAPE REC 1. 150mV
TAPE REC 2.150mV
PRE OUT.lV/1 kilohms
Total Harmonic Distortion
(20Hz to 20,000Hz IV output) . . .No more than 0.05%
Frequency Response
PHONO(RIAA equalization) .20Hz to 20,000Hz ±0.2dB
AUX.TAPEPLAY. 5Hz to 80,000Hz l?dB
Tone Control
BASS.±7dB/+10d8 (lOOHz)
Turnover Frequency 200Hz/400Hz
TREBLE.±7dB/+10dB (lOkHz)
Turnover Frequency 5kH2/2.5kHz
Filter
LOW .15Hz(6dB/oct.)
HIGH.6kHz {6dB/oct.)
Loudness Contour (Volume control set
at-40dB position).+6dB (100Hz)+3dB (10kHz)
Hum and Noise
(IHF, short-circuited, A Network)
PHONO .76dB
AUX, TAPE PLAY.90dB
Muting.-20dB
FM Section
Usable Sensitivity
MONO.9.8dBf {1.7/iV)
50dB Quieting Sensitivity
MONO.14.2dBf {2.8/iV)
STEREO.37dBf (39AiV)
Signal to Noise Ratio
(at75dBf) . . .STEREO .74dB
(at65dBf) . . .MONO.80dB
STEREO .71dB
Distortion (at 65dBf)
100Hz MONO/STEREO.0.1%/0.2%
IkHz MONO/STEREO.0.1%/0.15%
6kH2 MONO/STEREO.0.1%/0.2%
Frequency Response.30Hz to 15,000Hz ±0.5dB
Capture Ratio .I.OdB
Alternate Channel Selectivity.80dB
Spurious Response Ratio.lOOdB
Image Response Ratio.90dB
tF Response Ratio .lOOdB
AM Suppression Ratio.55dB
Muting Threshold. 19.2dBf (S/zV)
Stereo Separation .. 50dB (1 kHz), 35dB (30Hz - ISkHz)
Subcarrier Product Ratio.65dB
SCA Rejection Ratio.65dB
Antenna Input. 300 ohms balanced
75 ohms unbalanced
3

AM Section
Sensitivity (iHF, Ferrite antenna). 300/uV/m
(iHF, Ext. antenna) . 15 /jV
Selectivity.30dB
Signal-to-Noise Ratio.50dB
Image Response Ratio.40dB
IF Response Ratio .40dB
Antenna.Built-in Ferrite Loopstick Antenna
Miscellaneous ^
Power Requirements.120V 60Hz
Power Consumption. 350W (UL), 800W (CSA)
1100W (max.)
Dimensions. 526(W) x 176(H) x 440(D) mm
21-11 /16(W) X 6-15/16(H) x 17-5/16(D) in
Weight Without Package.21.3kg (471b)
With Package. 24.2kg (531b 6oz)
Furnished Parts
FM T-type Antenna . 1
Operating Instructions. 1
Hex. Wrench. 1
*Measured pursuant to Federal Trade Commission's Trade
Regulation rule on Power Output Claims for Amplifiers.
NOTE:
Specifications and the design subject to possible modifica¬
tion without notice due to improvements.

2. CONNECTION DIAGRAM
FM outdoor antenna
T-type FM antenna
O’O'
SX-i 080
Tape deck 2
ITAPE 21
tSBOO*;
AC 120 V
60Hz
Left Right
Speaker system
(SPEAKERS B>
B

3. FRONT PANEL FACILITIES
POWER METERS-
These power meters allow you to read out the rated
power level when speakers with a nominal impedance of
8 ohms are connected to the receiver’s speaker terminals.
NOTE:
These values are related to the impedance of the
speakers and they vary according to the frequency.
In order to find out the exact output level, connect an
S-ohm dummy load instead of the speakers.
PHONES JACK-
Plug the headphones into this jack when you want to
listen through your stereo headphones.
Release the all SPEAKERS buttons if you want to listen
to the sound through your headphones only. (This means
that all two buttons will be released).
-FILTER BUTTONS
15Hz When this button Is pressed, a 6dB/oct atteiiua-
tion can be provided for frequencies b ow
15Hz. This means that you can cancel out r >ise
in the ultra-low frequencies which is gener ted
by low-pitched rumble from a turntable md
other forms of distortion. Although this r jise
cannot be heard, it can generate intermo<ula-
tion distortion and damage the speakers.
6kHz , . Press this button to provide a 6dB/oct atlc ua-
tion at frequencies above 6kHz. Set it to this
position when you find high-frequency n lise,
such as that from scratched records, unpIca; jnl.
I— FUNCTION BUTTONS
Press the function button which corresponds to the pro¬
gram source. Turn the VOLUME control down first
before selecting a different function button while the
sound from one program source is being reproduced.
FM.Press this button for FM broadcasts.
The FM STEREO indicators light
up when the receiver is tuned into an
FM stereo broadcast. The sound is
automatically received monophonical-
ly during FM monophonic broadcasts.
AM.Press this button for AM broadcasts.
AUX.Press this button when listening to an
audio component connected to the
AUX input jacks.
POWER SWITCH^-
Flip this switch to the ON position to supply power to the
stereo receiver. There will be a short delay when it is set
to ON, because the muting circuit has been actuated to
suppress the unpleasant noise that is sometimes generated
when the power is switched on and off.
SPEAKERS BUTTONS
Press the button corresponding to the speakers connected
to the SPEAKERS terminals (A, B) on the rear panel. You
can press two of these buttons to listen to sound from
two pairs of speaker systems at the same time,
BASS TURNOVER SWITCH
Use this switch to change over the frequency in which the
sound adjustment with the BASS control is starting to
take effect. Select 200Hz or 400Hz in accordance with
the characteristics of your listening room and of your
speakers, and with your general preference.
TONE SWITCH-
Set this switch to ON when adjusting the BASS and
TREBLE controls. In the OFF position, it causes the
amplifier to operate with a flat frequency response.
BASS AND TREBLE CONTROLS
Use these controls to adjust the bass and the trlble.
If you set the TONE switch to ON and turn the B
control to the right from its center position, you wi
able to emphasize the sound in a frequency range whilti is
lower than that selected by the BASS TURNOt
switch. Conversely, turning this control from the ctfiter
position to the left will attenuate the sound.
You can use the TREBLE control to adjust the sound
frequency higher than that selected by the TREBLE
TURNOVER switch.
hSS
be
n a
LOUDNESS SWITCH
Set this switch to ON when listening at a low volume.
The frequency response of the human ear varies according
to the listening volume, and setting this switch to the ON
position compensates for hearing response by emphasizing
the bass and treble.
TREBLE TURNOVER SWITCH
Use this switch to change over the frequency in which the
sound adjustment with the TREBLE control is starting to
take effect. Select 2.5kHz or 5kHz in accordance with
the characteristics of your listening room and of your
speakers, and with your general preference.
PHONO 2/MIC.. Press this button when playing a
record on the turntable connected to
the PHONO 2 jacks, or when using a
microphone which you have plugged
into the MIC jack.
PHONO 1.Press this button when playing a
record on the turntable connected to
the PHONO 1 jacks.
NOTES:
1. Unplug the microphone from the MIC jack when you
do not intend to use the microphone otherwise you
will not be able to use the PHONO 2 jacks.
2. Only one function button should be pressed at a
time.
MIC JACK
Plug your microphone into this jack.
The microphone signals are reproduced in mono through
the left and right speakers.
NOTE:
A high impedance (approx. 50 kilohms) dynamic type
microphone with a standard plug can be connected to
this jack.
VOLUME CONTROL
Use this control to adjust the output level to the speakers
and headphones. Turn it clockwise to increase the output
level. No sound will be heard if you set it to The scale
is graduated in dB which indicate the attenuation when
the maximum output level is OdB.
MUTING SWITCH
Set this switch to the -20dB position to attenuate the
audio output indicated by the VOLUME control by 20dB.
There is no need to adjust'the VOLUME control if you
use this switch when turning down the audio output
temporarily and when changing over records or tapes.
BALANCE CONTROL
Use this control to balance the volume of the left and
right channels. First, however, set the MODE switch to
MONO, and adjust so that the sound appears to come
from somewhere exactly between the two speakers. If the
sound appears to be louder on the right, it means that the
volume of the right channel is higher. Turn the BALANCE
control to the left and adjust. Conversely, if the sound
appears to be louder on the left, it means that the
volume of the left channel is higher. Therefore, turn the
BALANCE control to the right and adjust. After adjust¬
ing, return the MODE switch to STEREO.
y

SX-i OBO
FM MUTING BUTTON-
ON (released position) . . . .Release this button to sup¬
press unpleasant inter-station
noise when tuning in to FM
stations.
OFF (depressed position) . Depress this button to pick
up weak stations.
FM 25t^S BUTTON -
Press this button when listening to a Dolby* FM broad¬
cast; otherwise keep this button at the released position.
|—TUNING KNOB
Use this to tune in to broadcasting stations.
Select the station and tune for optimum reception by
observing the SIGNAL meter for AM stations and both
the SIGNAL and TUNING meters for FM stations.
pSlGNAL METER
When tuning in to an AM or FM station, the optimum
reception position is indicated by the maximum deflec¬
tion of the meter pointer to the right.
FM MULTIPATH BUTTON-
Use this switch to detect multipath sound when installing
the FM antenna in a position which yields the minimum
multipath interference.
rTUNING METER
When tuning in an FM station, the optimum reception
position is indicated when the meter pointer deflects to
dead center. Check that the SIGNAL meter pointer has
deflected as far to the right as possible.
MEMORY MARKERS
These are very convenient for frequent tuning in to the
same broadcasting station.
STEREO INDICATOR
This indicator lights up when the receiver is tuned to
receive a stereo broadcast.
TAPE MONITOR SWITCHES (1,2)
Set switch 1 to ON with a tape deck which is connected
to the TAPE 1 jacks (REC and PLAY) when you want to
monitor the playback or recording of a tape. The tape on
a deck which is connected to the TAPE 2 jacks (REC and
PLAY) can be similarly monitored by setting switch 2 to
ON.
NOTE:
Set these switches to the upper (off) position when
listening to records or the broadcast.
MODE SWITCH
Use this switch for selecting mono or stereo performances.
Set to this position for normal stereo opera¬
tion.
When set to this position, the left and right
channel signals will be mixed and reproduced
monophonically from both speaker systems.
TAPE DUPLICATE SWITCH
Set this switch to ON when you want to duplicate or edit
a pre-recorded tape using two tape decks.
♦ The word "Dolby" is a trademark of Dolby Laboratories Inc.
9

4. DISASSEMBLY
1. Remove screws O ~ O remove the bon¬
net.
2. Remove screws 0-0 , all the knobs, and
remove the two nuts and two washers at the
front panel. (However, loosen the set screws
with the accessory alien wrench before at¬
tempting to remove the TUNING and VOL¬
UME knobs.)
3. Remove screws © ~ 0 and remove the bot-
1 o

SX-1 080
5. PARTS LOCATION
5.1 FRONT PANEL VIEW
Front panel assembly
ANB-543
Push knob (SPEAKERS. FILTER. FM)
AAD-140
Lever knob assembly (POWER}
AAD-139
Push knob {FM, AM, AUX, PHONO 2
MIC, PHONO 1)
rKnob (TUNING}
AAA047
Lever knob (MUTING)
Knob (BASS)
AAB-175
Knob (VOLUME)
AAB-174
Lever knob (TONE
AAD-138
Knob (TREBLE)
AAB-175
Knob (BALANCE)
AAB-176
Lever knob (DUPLICATE, MONITOR 1,2,
MODE, LOUDNESS)
AAD-138