Pioneer sx 850 service manual

Page 2

SX-850 FEATURES

Latest Technology FrontEnd

Dual Gate MOS FET (field-effect transistor) is employed in
the FM front end, together with a 4-ganged variable tuning
capacitor. Together with carefully selected circuit compo-
nents, this provides outstanding performance in terms of
sensitivity, image rejection and spurious rejection. In all of
its specifications, the SX-850 FM tuner section compares
favorably with the most respected separate component type
tuners.

High Selectivity Stages

Excellent capture ratio, stable operation and sharp selec-
tivity are assured by three ceramic filters in the IF stages.
The filters never need realignment and contribute to high
reliability against aging and ambient temperature variations.

Quadrature Detector and PLL MPX
Demodulator

A balanced bridge differential amplifier performs quad-
rature detection of the FM signal. Linearity is assured
throughout the frequency band, while distortion becomes
minimized. Clear and stable separation is provided by the
PLL (phase locked loop) multiplex circuit design.

Reduced Distortion AM Circuit

Careful engineering is also evident in the AM tuner circuit.
Automatic gain control in the RF and IF stages, together
with a 3-gang variable capacitor and IC circuitry deliver
improved image ratio, selectivity and frequency response,
plus reduced distortion.

Heavy Duty Split Power Supply

The dual positive and negative power supply incorporates
extra large 15,000 uF electrolytic capacitors and posesses
plenty of reserve power. Protection and muting functions
are included to both safeguard equipment and eliminate
power on-off noise.

Precision RIAA Phono Equalizer

Deviation from the RIAA standard is performed within
:0.3d8, while the ability of the phono inputs to accept
relatively strong signal levels without distortion (200
mV rms) results in a wide dynamic range.

High Reliability Protection Circuit

In the event of malfunction, valuable semiconductors and
speaker are protected by a relay electronic protection
circuit that detects DC output voltage or impedance over-
load. This circuit also functions to reduce noise during
ONOFF operation of the power supply.

Versatile Tone Controls Plus Turn-over

Selectors

Active NFB type bass and treble control circuits provide
precise and stable control without affecting the mid-range.
Turnover frequency selector switches determine the points
at which the tone controls take effect, and a convenient
tone on-off switch is also employed to allow a flat
frequency response to be obtained at any time regardless
of tone control and turnover switch settings. This is useful
for checking the effects of the phono cartridge, speakers,
listening room acoustics, etc. on the spaciousness of the
sound.

Direct Coupled Power Amplifier

The power amplifier of the SX-850, is a direct-coupled,
pure complementary parallel push pull circuit, which uses
a differential amplifier at first stage. SX-850 delivers

Continuous power output of 65 watts per chan-
nel, min. RMS, at 8 ohms or 85 watts per chan-
nel at 4 ohms from 20 Hertz to 20,000 Hertz
with no more than 0.1% total harmonic distor-
tion.

Plenty of power is available for rich and stable stereo
reproduction.

Important Additional Features

Two tape monitor circuits allow two stereo tape decks to
be used for recording, playback and tape duplication.
Microphone input on the front panel adds to versatility
and enjoyment.

The audio muting switch can be used to temporarily reduce
the volume by 20dB when changing records or tapes or for
other reasons, without continually adjusting the volume
control.

Indicator lamps provide clear indication of operating mode.

Tasteful Styling Complements High

Performance

The exquisitely designed aluminum front panel is trimmed
with solid walnut. Control functions and layout also add
to both versatility and top grade components appearance.
In combination with high quality source components and
speaker systems, a magnificent stereophonic music system
is composed for providing rich audio enjoyment.

* Measured pursant to Federal Trade Commission's Trade
Regulation rule on Power Output Claims for Amplifiers.

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