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SERVICE MANUAL



AG-370
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-0091A
1 SPECIFICATIONS
Amplifier Section
Output Power .... 50 + 50 watts RMS (0.9 % THD, 1 kHz, 8 ohms) Voltage Conversion
Total Harmonic Distortion.................... 0.05 % (at 45 watts,1 kHz) (General export models only)
Input Sensitivity/Impedance .................. PHONO: 4 mV/22 kohms
LINE: 270 mV/20 kohms
Frequency Response.................... PHONO: 20 Hz20 kHz, +/3 dB
LINE: 20 Hz30 kHz, +1/3 dB
Signal-to-Noise Ratio.............................................. PHONO: 60 dB
LINE: 68 dB
Tone Control .......................................... BASS: +/9 dB at 100 Hz
TREBLE: +/7 dB at 10 kHz
Loudness Control (Volume at 40 dB Position) ..............................
+7 dB at 100 Hz, +5 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 .......................... 520 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



General
Power Requirements.................................. 120 V/230 V, 50-60 Hz
Power Consumption ............................................................ 120 W
AC Outlet .......................... Unswitched x 1, 100 W max (1 A max)
Dimensions (W x H x D) ........................ 17-1/8" x 5-1/8" x 12-5/8"
(435 x 130 x 320 mm)
Weight (net) .................................................. 15-7/16 lbs (7.0 kg)
Standard Accessories .................................. AM Loop Antenna x 1
FM "T" Type Antenna 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 7VR1 (Lch) so that the voltage
becomes 3.3 1.3mV.
4. Adjust 7VR2 (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-370 POINTS

FM 87.5 MHz 2L3 (3.5T) DC 1.0 0.05V


FM 108.0 MHz Check DC 8.0 0.5V

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 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 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)


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
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6
EXPLODED VIEW LIST

































INCLUDED ACCESSORIES




7
4 PC BOARDS AND PARTS LIST
MAIN PCB




8
FRONT PCB TUNER PCB




SP SEL PCB SP SEL PCB HEADPHONE PCB POW SEL PCB POWER PCB




9
MAIN PCB ASSY CONTROL PCB ASSY












TUNER PCB ASSY































10
SELECT PCB ASSY




SELECT PCB ASSY




HEADPHONE PCB ASSY









POWER SELECT SW PCB ASSY









POWER SOCKET PCB ASSY











11
SCHEMATIC DIAGRAM AG-370 MAIN PCB (1/2)
1 2 3 4 5

1XS2 AND 1XP2
6C9 100U/16V TREBLE
4R17
4C19 -12V -12V 6VR2
100 6
100U/16V
6R13 5
6C7
6R23 1K 4 6N1-1 6R17
4
47 3 4558D 5K6
4R1 4R3 4R5 100 3
4 4C15 6C11
470 390 22K 3 4N1-1 4R13 2
4U7 6R7 1 4U7/50V 5
L 4558D 1K 6C15 1
4C9 1K 2
104
102 1
A 4C3
2
6R5 6C5 TREBLE
7 2




4C5
4R11 4R15




181
4C1 181 4C17 6C1 10K 820 6VR2-1 3




6R15
4R9 12K 180K 100K




6R16




6R21
471 220 4U7/50V 100KB 6C13




1K
6R1 10K




1K




1K
102
1 5
6R3 33K 6 6R9 15K




6R19
PHONO




5K6
4C7 4C11 4C13 1 5
4R7 BASS 6 6R11 1XP4
47U/16V 562 223




6VR3
50KB
270 6VR1-1 33K
L
100KB 1
4C20 +12 6C3 G




6VR4
100K
6S1
4R18 100 2




4U7/50V
100U/16V 153 R
3




6C12
+12
R G L
6C10 100U/16V
4R2 4R4 4R6
8 4N1-2 4C16




3
2
1




6R20
470 390 22K 4R14 6R24




5K6
5 4558D 4U7
R 1K 100 6R14
6C8
1K 8 1XS3
4C4 4C10 7 47 5 6C14




6R22
181 102 6 102




1K
6C6 7 6C16
4C6




4R12 4R16
181




4C2 820 6 104
4R10 12K 180K 100K 6N1-2 1XP3
471 4C18
4558D
220 1 4




3
2
1
6R6 6R8
TREBLE 6
10K 1K R G L
4C8 4C12 4C14 6VR2-2 6VR1
4R8 6
47U/16V 562 223 6C2 100KB 6R18
270 5
4U7/50V 5K6
6R2 10K 6R10 15K 4
3R1 3
2 4
3K9 6R4 33K 3 2
B 3R9 BASS
2
3
4
6R12
1
CD/L BASS
3C1 33K 6VR1-2 33K
1XS1 AND 1XP1
471 100KB
6C4
3C2 153
471
3R10
CD/R
3R2 3K9 33K
-12V
3R3 3K9
5C1 5C7
5R1 5R11
4U7/50V 100U/16V
3R11 1K 4 100
AUX/L 5
3C3 33K
-12V
471 3R15
7
100 5R13
3C4 6
5N1-1 1K
8

7

6

5

4

3

2

1




471 1XS6 5R3 5R5
3R12 4558D
AUX/R 47K 100K
3C11




3R4 3K9 33K




1
2
3
104
Y
VSS

VEE

S

Y1

Y3



Y2

Y0




3D1
5R9
6V8




TAPE
3R5 3K9 33K




SW1
SW2




100K
3R20
3N1




1

2

3

4

5

6

7
5C3
3R13 CD4052 5R7
TAPE/L 22U/16V
3C5 33K 15K
3D2
VDD




2C

3C
1I/O