Introduction; Service Notes; Am Tuner - Marantz QUADRADIAL 4 Service Manual

INTRODUCTION
This service manual was prepared for use by Authorized Warranty Stations and contains
service information for Marantz Model 4430 Quadradial 4 RE!ceiver.
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 parts list 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 4430 consists of 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P100
2. AM Tuner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P150
3. FM IF Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P200
4. MPX Stereo Decoding Amplifier . . . . . . . . . . . . . . . . . mounted on P. W. Board, P300
5. Pre, Tone Amplifier.. . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P400
6. Noise and DC Amplifier . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P470
7. Vari-Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P500
8. Loudness, Hi-Filter and Speaker Switch Unit . . . . . . . mounted on P. W. Board, P550
9. Temparature Compensation . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P580
10. Power Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P600
11. Phono Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P700
12. Tone Control Unit ........................... mounted on P. W. Board, P750
13. Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P800
14. AC Rectifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P850
15. Balance Control Unit . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P900
16. Indicator Lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mounted on P. W. Board, P950
2. AM TUNER
All components except tuning capacitor and ferrite bar antenna are mounted on a printed
circuit board P150.
The AM signals induced in a ferrite bar antenna are applied to the base of RF amplifier
transistor H151 through a capacitor of C151 and amplified to the level required for overcoming
the conversion noises, thus giving good
SIN
performance. The tuned circuits inserted in both
out and input circuit of the RF amplifier assure very high image and spurious rejection per-
formance. Thus amplified and selected AM signals are then applied to the base of converter
transistor H152 through a coupling capacitor C156. While the local oscillator voltage is injected
to the emitter of H 152 through a capacitor C157, 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 L 153 consisting of one ceramic filter and
two tuned circuits.
The output of L153 is led to the transistor H 153 which in turn apply its output to the
transistor of next stage H154. The fully amplified IF output is then applied to the diode H157
to detect audible signal through the detector transformer L154. The detected audio signal is
filtered and amplified and the final audio output is obtained from the collector of H 155 and
applied to the TAPE OUT jacks and the function switch.
The DC component of the detected IF signal is used as a AGC voltage to control emitter