Optonica sa 2121 h service manual

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K.

= OPTONICA

09899:?!32

SERVICE MANUAL

Stereo Receiver

MODEL SA-2121H

' identical to those specified be used.

.I In the interests of usersafety the set should be lestored to its original condition and only paIts J

INDEX TO CONTENTS

SPECIFICATIONS .......................... 2
FEATURES ............................... 2
PREPARATION FOR USE ................... 3
DISASSEMBLY ............................ 3
DIAL CORD STRINGING .................... 4
FRONT PARTS LAYOUT .................... 5
REAR PARTS LAYOUT ..................... 5
BLOCK DIAGRAM ...................... 6 ~ 7
CIRCUIT DESCRIPTION
AM SECTION ................. , .......... 8
FM RF SECTION ...................... 8
FM IF SECTION ......................... 9
FM DETECTION SECTIONS (Quadrature Detector) .9
FM STEREO DEMODULATOR SECTION ...... 10
FM MUTING CIRCUIT ................... 11
LOW-PASS FILTER ...................... 11
TONE AMP. CIRCUIT .................... 12
EQUALIZER ........................... 12
MAIN AMPLIFIER SECTION. . . . . . . . . . . . 13~ 14

PROTECTION CIRCUIT (RELAY CIRCUIT), 14 ~ 15
POWER SUPPLY CIRCUIT ................. 16

10.

11.

12.

13

14.

15

16.
17.
18.
19.

ALIGNMENT INSTRUCTIONS
REQUIRED EQUIPMENT .................. 17
AF ALIGNMENT ........................ 18
AM IF ALIGNMENT ..................... 18
MW RF ALIGNMENT .................... 20
LW RF ALIGNMENT ..................... 21
FM ALIGNMENT ........................ 22

FM TUNING METER ADJUSTMENT AND
DISTORTION FACTOR ADJUSTMENT. . .23

FM MUTING ADJUSTMENT AND FM STEREO
V.C.0.,SEPARATION ADJUSTMENT . , .23

ADJUSTMENT OF AIR CHECK CAL ......... 24
EQUIVALENT CIRCUIT 0F _
INTEGRATED CIRCUIT ...... 25 ~ 28
SCHEMATIC DIAGRAM ................. 29 ~ 30
.WIRING SIDE OF P.W BOARD ........... 31 ~ 36
POWER TRANSISTOR REPLACEMENT ......... 37
.TRANSISTOR TYPES .......... : ............ 3 8
TROUBLE SHOOTING GUIDE. . . .......... 39~ 43
DIODE TYPES ........................... 44
WIRE CLIP .............................. 44
PARTS LIST ......................... 45 ~ 52

SHARP CORPORATION OSAKA, JAPAN

SA-2121H

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SPECIFICATIONS

.GENERAL DESCRIPTION Intermediate

Power source:
Power consumption:
Circuit

Tuner:

Main amplifier:

Tone amplifier:
Equalizer:

Semiconductors:

Dimensions:

Weight:

0 FM SECTION
Tuning range:
Intermediate

frequency:
Sensitivity:

AC 110/220/240V, 50/60Hz
460W

Superheterodyne system,
LW/MW/FM 3-bands tuner, with
P.L.L. stereo demOdulation circuit,
FM muting circuit

Differential amplifier and all stage
direct coupled pure complimentary
O.C.L. (Output Capacitor-Less) cir-
cuitry.

NF type tone control circuit.
Dual power supply IC amplifier
circuit

7-IC (Integrated circuit)
28-transistor (1-FET)

31-diode (4-Zener diode)

2-LED
Width ..... 550 mm
Height. . . 3.142 mm
Depth ..... 390 mm
14.5 kg

87.6 ~ 108 MHz

10.7 MHz
1.8].lV (at S/N 26 dB, 40 kHz
deviation, antenna terminal voltage)

Distortion (40 kHz deviation)

Mono:
Stereo:

Im age rejection ratio:

I.F. rejection ratio:
Spurious frequency
rejection ratio:

AM suppression ratio:

Selectivity:
Capture ratio:
Stereo separation:
Antenna input:

0AM SECTION
Tuning range:

0.5%
0.8%
50 dB
70 dB

60 dB

40 dB (modulated by 30% AM
and 75 kHz deviation FM)

50 dB (IHF at 40 dB)

2 dB

34 dB (1 kHz)

75 ohms unbalanced

240 ohms balanced

MW 520 ~ 1620 kHz
LW 150 ~ 370 kHz

MW/LW 455 kHz

MW 400uV/m (at 1000 kHz)

LW 400iN/m (at 220 kHz)

Image rejection ratio: MW 34 dB (at 1400 kHz)

LW 30 dB (at 340 kHz)

MW 49 dB (at 600 kHz)

LW 40 dB (at 340 kHz)

LW/MW 1.6%

Built-in ferrite bar antenna and
external antenna terminal

frequency:
Quieting Sensitivity:

I.F. rejection ratio:

Distortion:
Antenna:

.MAIN (POWER) AMPLIFIER
Continuous power output:
2 x 45W/4 driven at 1 kHz, 0.1% distortion
2 x 30W/8-ohms, both channels
driven at 1 kHz, 0.1% distortion
Total harmonic distortion:
0.05% at 20W(AUX IN)
Intermodulation distortion:
0.1% at 20W(AUX IN)
More than 20 (at 1 kHz, 4-ohms)
20 Hz ~ 20 kHz

Damping factor:
Power bandwidth:

0 PRE-AMPLIFIER
Input sensitivity and input impedance

PHONO 1: 2.5 mV/SOK ohms

PHONO 2: 2.5 mV/SOK ohms

AUX: 150 mV/SOK ohms

TAPE playback

1 and 2: 150 mV/50K ohms

Output level and loaded impedance

REC 1 and 2: 150 mV/SOK ohms

REC l and 2 (DIN socket):

30 mV/SOK ohms
Phono overload: 140 mV (RMS 1 kHz,
0.1% T.H.D.)

RIAA curve deviation (Phono):
21.5 dB (30 HZ ~15 kHz)
Frequency response: 10 Hz ~ 50 kHz I 1.5 dB (AUX.,
TAPE playback)
Tone control
Bass; I 10 dB at 100 Hz
Treble: I 10 dB at 10 kHz
Low cut filter: 3 dB at 30 Hz, 6 dB/oct

Audio muting: 7 20 dB

FEATURES

1) The equalizer amplifier that operates on dual power SLIpply 3) Power source/circuit protection indicator making use of
(plus and minus) to allow the maximum 140 mV phono 2~color LED element, which will light up in red if there
input. is something abnormal in the internal circuitry. In a normal
2) With a built-in protection circuit, the loudspeaker remains condition, it is lit green.
always safe even if the amplifier circuit gets in trouble 4) Because of the circuit being ITL (Input Transformerless),
and reversely the amplifier is protected against a possible OTL (Output Transformerless), OCL (Output Capacitor-
short-circuit of the loudspeaker cord. less) and pure-complementary system, low-distortion
characteristic is more assured. \
5) FET and 3gang variable capacitor adopted at the FM U
front-end circuit more improve overall characteristics.
6) The PLL (Phase Locked Loop) demodulator circuit assures
a stabilized characteristic.