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INTRODUCTION
This service manual
was prepared
for use by Authorized Warranty Stations and contains
service information for Marantz Model 2220 Stereophonic Receiver.
,
Servicing information and voltage data included in this manual are intended for use by the
knowledgeable
and experienced
technician only. All instruction
should
be read carefully. No
attempt
should
be made
to proceed
without
a good
understanding
of the operation
in the
receiver.
The
part lists furnish
information
by which
replacement
part may
be ordered
from the
Marantz Company.
A simple description is included for parts which can be usually be obtained
through local suppliers.
1. Service Notes
As can be seen from the circuit diagram,the chassis of Model 2220 consists of the following
units. Each unit mounted on a printed circuit board is described within the square enclosed by a
bold dotted line on the circuit diagram.
1. FM Front End & AM Tuner
...............
+.
.mounted on P.C. Board, P100
2. FM IF Amplifier, Detector, Muting Control
and Meter Amplifier Unit
= 8 .............048.
mounted on P.C. Board, P200
3. MPX Stereo Decoding Amplifier
................
mounted on P.C. Board, P300
4. Phono Amplifier...
2... ...
0.2
eee
ee
ee
ee
mounted on P.C. Board, P900
5. Tone Amplifier...
.-.
ee
ee
ee
ee
es mounted on P.C. Board, P500
6. Tone Control Volume Unit
...
1... 2.22202 eee mounted on P.C. Board, P650
7. Power Amplifier...
2... 2.0...
ee
ee
ee
ee
mounted on P.C. Board, P700
8. Power Supply
.......0.
0.0.0
eee ee
ee
ee mounted on P.C. Board, P800
9. Loudness, Muting, High and
Low Filter Switch Unit
.....
mounted on P.C. Board, P600
2. AM Tuner
All components except Tuning capacitor and ferrite bar antenna are mounted on a printed
circuit board P100.
The AM signals induced in a ferrite bar antenna are applided to the base of Mixer transistor
H102 through a capacitor of C109, while the local oscillator voltage is injected to the emitter of
H102
through
the capacitor C110. Both AM signals and oscillating voltage are mixed at the
base-emitter junction and converted into 455KHz intermediate frequency. The resulting IF signal
is applied to the first IF transformer L102 consisting of one ceramic fifter and two tuned circuits.
The
output
of L102
is led to the transistor
H103
which
in turn apply its output to the
transistor of next stage H104. The fully amplified IF output is then applied to the diode H108 to
detect audible signal through the detector transformer L103. The detected audio signal is filtered
and amplified and the final audio output is obtained from the collector of H105 and applied
one
to the tape out jacks through monitor switch on the front panel and the other to the function
rotary switch.
The DC component of the detected
IF signal is used as a AGC voltage to control emitter
current of H103 and H102 through the resistors R113 and R106 respectively. A part of IF signal
output is also applied to the diode H109 through a capacitor C125 and rectified to obtain DC
current for energizing the AM signal strength. meter M001.
3. FM Tuner
The FM Tuner section of Model 2220 is divided into three functional blocks: FM front end,
IF amplifier & Detector, Muting control and MPX stereo decoding circuit.
FM signals induced on a FM antenna are led to FM antenna coi! L106. These signals are then
applied to the FET
RF amplifier which in turn applies its output to the next Transistor Mixer
H112
through
a high-O tuned
circuit.
The
Mixer
convert
its input signal
into
10.7MHz
intermediate frequency and amplifies it. The H111
is a local oscillator and its output is injected
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