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SERVICE MANUAL
AG-790
AM/FM Stereo Receiver
CONTENTS
1 SPECIFICATIONS 2
2 ADJUSTMENTS AND CHECKS 3
3 EXPLODED VIEWS AND PARTS LIST 6
4 PC BOARDS AND PARTS LIST 8
NOTES
PC boards shown are viewed from parts side.
The parts with no reference number or no parts number in the
exploded views are not supplied.
As regards the resistors and capacitors, refer to the circuit diagrams
contained in this manual.
£ Parts marked with this sign are safety critical components. They
must be replaced with identical components - refer to the appropriate
parts list and ensure exact replacement.
Effective : April, 2003 S-0092A
1 SPECIFICATIONS
Amplifier Section
Output Power....100 + 100 watts RMS (0.9 % THD, 1 kHz, 8 ohms) Voltage Conversion
Total Harmonic Distortion.................... 0.05 % (at 70 watts,1 kHz) (General export models only)
Input Sensitivity/Impedance .................. PHONO: 5 mV/22 kohms
LINE: 300 mV/22 kohms
Frequency Response ...................... PHONO: 20 Hz20 kHz, ±3 dB
LINE: 20 Hz50 kHz, +1/3 dB
Signal-to-Noise Ratio ................................ PHONO: 80 dB (IHF-A)
LINE: 80 dB (IHF-A)
Tone Control ............................................ BASS: ±10 dB at 100 Hz
TREBLE: ±10 dB at 10 kHz
Loudness Control (Volume at 40 dB Position) ..............................
+9 dB at 100 Hz, +8 dB at 10 kHz
FM Tuner Section
(Without notes 98.1 MHz, 65 dBf)
Be sure to remove the power cord from the AC outlet before
Tuning Range .................... 87.5 MHz108.0 MHz (100 kHz steps)
repositioning the voltage converter switch.
Usable Sensitivity (IHF) ............................................ Mono: 20 dBf
50 dB Quieting Sensitivity................ Mono: 39 dBf, Stereo: 46 dBf
1. Locate the voltage selector on the rear panel.
Capture Ratio ...................................................................... 2.8 dB
2. Using a flat-bladed screwdriver, set to the appropriate
Image Rejection Ratio .......................................................... 20 dB
230V or 120V position according to your area.
AM Suppresion Ratio............................................................ 48 dB
Harmonic Distortion (1 kHz) .............. Mono: 0.4 %, Stereo: 0.5 %
IN NORTH AMERICA USE ONLY ON 120 V SUPPLY.
Frequency Response................................ 30 Hz15 kHz, +2/3 dB
Stereo Separation (1 kHz) .................................................... 35 dB
Signal-to-Noise Ratio ........................ Mono: 57 dB, Stereo: 55 dB
AM Tuner Section
Tuning Range .......................... 530 kHz1,720 kHz (10 kHz steps)
Usable Sensitivity ............................................................ 55 dB/m
Total Harmonic Distortion .................................... 1 % at 85 dB/m
Signal-to-Noise Ratio ........................................ 48 dB at 85 dB/m
General
Power Requirements.................................. 120 V/230 V, 50-60 Hz
Power Consumption ............................................................ 180 W
AC Outlets ................ Unswitched x 2, Total 100 W max (1 A max)
Dimensions (W x H x D)................................ 435 x 139 x 335 mm
(17-1/8" x 5-1/2" x 13-3/16")
Weight (net) ................................................ 9.4 kg (20-11/16 lbs)
Standard Accessories .................................. AM Loop Antenna x 1
FM "T" Type Antenna x 1
Remote Control Unit x 1
· Design and specifications are subject to change without notice.
2
2 ADJUSTMENTS AND CHECKS
2-1 AMPLIFIER SECTION
Bias Current Adjustment
1. Turn the unit on, and set the input selector switch to "CD".
2. Set 7VR1 and 7VR2 to the center position.
3. Connect the DC voltmeter as shown below after preheating for
10 minutes, and adjust 7VR2 (Lch) so that the voltage
becomes 3.3 1.3mV.
4. Adjust 7VR1 (Rch) in the same way.
0.33/5W 0.33/5W 0.33/5W 0.33/5W
7R46 7R44 7R45 7R43
DC voltmeter DC voltmeter
7VR2 7VR1
MAIN PCB
3
2-2 TUNER SECTION
SETTING ADJUSTMENT
ITEM ADJUST
INPUT OUTPUT AG-790 POINTS
FM 87.5 MHz 2L3 (3.5T) DC 1.0 0.05V
FM 108.0 MHz Check DC 8.0 0.5V
å
1. VT Adjust 2R19 (VT)
2J2 (GND) AM 530 kHz 2T2 (RED) DC 1.1 0.05V
AM 1720 kHz Check 8.0V
AM 600 kHz 2T1 (BLK) Max.
2. AM Sensitivity
600 kHz/1500 kHz ç AM 1500 kHz 2TC2 Max.
50 dB/m REC OUT
400 Hz (30 % Mod)
After adjusting 2TC2, readjust 2T1 at 600 kHz.
3. AM IF
1000 kHz ç AM 1000 kHz 2T3 (WHT) Max.
50 dB/m REC OUT
400 Hz (30 % Mod)
4. FM Sensitivity
90 MHz FM 90 MHz 2L2 (4.5T) Max.
10~20 dBf REC OUT
1 kHz (100 % Mod)
5. FM Distortion
98 MHz © FM 98 MHz 2T4 (PINK) Min. distortion
60 dBf REC OUT
1 kHz (100 % Mod)
é
6. FM Stereo
98 MHz © FM 98 MHz 2T5, 2T6 Min. distortion
60 dBf REC OUT
Stereo signal L-R
4
DC Voltmeter
A
2R19 TUNER PCB
2J2
2T1 2TC2
2L2
2T2
2L3
2T5
2T3 2T4
2T6
AM Signal Generator
B
AM Loop
Antenna AC Voltmeter
C
60cm
FM Signal Generator AC Voltmeter
D F
Distortion Analyzer
G
E
Stereo Signal Generator
5
3 EXPLODED VIEWS AND PARTS LIST
6
EXPLODED VIEW LIST
£
£
£
£
£
£
INCLUDED ACCESSORIES
7
4 PC BOARDS AND PARTS LIST
MAIN PCB
8
FRONT PCB HEADPHONE PCB
SP SEL PCB
TUNER PCB SP JACK PCB POWER PCB
9
MAIN PCB ASSY FRONT PCB ASSY
£
£
£
£
£
£
£
£
£ TUNER PCB ASSY
£
£
£
£
£
£
£
£
£
£
£
£
£
10
HEADPHONE PCB ASSY
£
SP SEL PCB ASSY
SP JACK PCB ASSY
POWER PCB ASSY
£
£
£
£
£
11
SCHEMATIC DIAGRAM AG-790 MAIN PCB (1/2)
1 2 3 4 5
5C5
4C19 4R17 -12V 47U/16V 5R9 -12V
47U/16V 100 100
4R1 4R3 4R5 4 5R1
470 390 22K 3 4N1-1 4R13 4R15 1K 4 5N1-1
3 4558D
PHONO/L 4558D 1k 33K
4C9 L-1
102 1 4C17 1
2 2U2/50V 5R3 2
47k
4R11
A 4C1
471
4C3
181
4C5
181 4R9 12K 180K
4C15
5C3
101
22 5C1
47U/16V 5R5 5R7
15k 47K
4C7 4R7 4C11 4C13
47U/16V 270 562 223
4C20 +12
47U/16V 4R18 100
5C6 5R10 +12
4R2 4R4 4R6 47U/16V 100
470 390 22K 8 4N1-2
5 4558D 4R14 4R16
2U2/50V
PHONO/R 1k 33K
4C10
5R2
4C18
102 7 5N1-2
1K 8
6 5 4558D
4R12 R-1
4C2 4C4 4C6 4C16 7
471 181 181 4R10 12K 180K 22 5R4 6
47k
3C22
2U2/50V 5C4
101
4C8 4R8 4C12 4C14 5C2
47U/16V 562 223 47U/16V 5R6
270 15k 5R8
3C28 47K
3C20 103
3C11 2U2/50V
3R1 1K
2U2/50V 3C32 3C34 3C36
CD/L
0.47U/50V
3C1 152 104 47U/16V
471 3C24 3C26 +9V
3R9 47K 3R20
3C30
2U2/50V 473
1K
B 3V2 3R22 3R23
2SC2878 3C38 100 470 3D1
33
32
31
30
29
28
27
26
25
24
23
3R10 47K 4U7/50V
3C2 3C12 +9V 3C45 6V8
471 2U2/50V 104 3C44
CD/R 100U/16V
R-TO-O
SW-OUT
VR-OUT
R-VRIN
A-GND
R-TO-I
T1
T2
T3
LD1
LD2
3R2 1K
3R3 1K 3R21 3R32 100K
AUX/L 3R18 100
3C3 2K2 3C18
3C13 2U2/50V 3R34 100K
471 3R11 47K 2U2/50V 34 22 3C40
R-IN4 PVR-IN 3R36 100K
4U7/50V
35 21
R-IN3 R-FOUT
3C4 3R12 47K
36 20
471 R-IN2 R-ROUT
3C46
100U/16V
AUX/R 104
3C14 3C42 37 19
10
11
12
13
14
3R4 1K R-IN1 VDD
3C47
8
9
2U2/50V 100U/16V
38 18 1XS5
VCC STB
3C41 3N1
3O/I
4O/I
4C
1C
3I/O
4I/O
3R5 1K 1
VDD
47U 39 TC9421 17
TAPE/L VREF DATA 2
3C5 3C43 3
471 3C15 104 40 16
3R13 47K VSS CK 4 3N2
2U2/50V
41 15 CD4066
L-IN1 GND
2O/I
1O/I
VSS
2I/O
1I/O
42 14 3C39
3C
2C
3R14 47K L-IN2 L-ROUT
3C6 4U7/50V
471 43 13
TAPE/R 3C16 L-IN3 L-FOUT
2U2/50V
7
6
5
4
3
2
1
3R6 1K
C 44
L-IN4 FVR-IN
12
3C17
3R7 1K 3R27 100K
SW-OUT
2U2/50V
VR-OUT
L-VRIN
L-TO-O
A-GND
L-TO-I
REC/L 3R16
3C7 3R24 3R15 3R25
LD1
LD2
471 3R39 22k 1k 1k 22K
T1
T2
T3
3R28 100K
47K
3C23 3R31 100K
3C37
1
2
3
4
5
6
7
8
9
10
11
R L 2U2/50V 4U7/50V
3C8
3
2
1
471 1XS1
REC/R TUNER IN
3R8 1K 3R38 3R19 3C25
47K 1K 473 3C29
0.47U/50V 3C31 3C33 3C35
3
2