Alto A500.2 Service Manual
MODEL: A500.2
www.altoproaudio.com
Version 1.0
CONTENT
1. Introduction.............................................................................................1
2. Specification............................................................................................2
3. Schematic Diagram...............................................................................3
4. Wiring Diagram......................................................................................9
5. Printed Circuit Board.........................................................................10
6. Exploded View & Mechanical Parts List.......................................11
7. Electrical Parts List............................................................................13
1. Introduction
˙ 1.5U 1/2 rack, stereo high power amplifier.
˙ Fantastic audio quality even with extremely high volume levels.
˙ Solid and durable, can be mounted into a cabinet.
˙ User-controllable clip limiter.
˙ 2×480 Watts on 4 ohms (EIAJ)
˙ Balanced XLR inputs and 1/4”TRS jack to ensure noiseless long wiring.
˙ Neutrik Speak-on connectors for output.
˙ Front panel LED indicators for signal, limit and clip.
˙ Accurate gain control.
˙ Independent thermal overload protection on each channel automatically
protects amplifier and speakers.
˙ Single channel over-heat protection.
- 1 -
2. Specification
MODEL
20Hz 20KHz@0.1%THD, Stereo Mode
8 ohms per channel(EIAJ)
4 ohms per channel(EIAJ)
4 ohms per channel(RMS)
Input Sensitivity @4 ohms
Controls
Indicators (per channel)
Connectors of each channel
A500.2 DRAGONFLY
260W
480W
245W (at THD 1%)
+3dBu
FRONT: Power switch, CH1 & CH2 LEVEL knobs
REAR: CH1 & CH2 LIMITER
Power-On: Green LED
Clip: Red LED
Limit: Yellow LED
Signal: Green LED
Input: COMBO connector
Output: NEUTRIK Speak-on connector
Power Supply
Dimension
Net Weight
190-240 Vac~50Hz / 95-120Vac~60Hz
314W x 208.5D x 66.6H mm / 12.4" x 8.2" x 2.6"
3.85 kg (8.49lb)
- 2 -
3. Schematic Diagram
D
8
C
CLIP
SIG
R22
30R
SIG
CLIP
R23
30R
B
A
7654321
CN4
C11
LED5
C13
R26
56pF/50 cer
1
2
CON2
GND1
R6
10K
56pF/50 cer
R5
CH1-OUT
U2
GR
R15
82K
VTL5C2
10K
270R
LIMITER
1
3
2
R25
10K
41
7
5
6
LED2
RED
R21
82R
R19
180R
123
CN8
LED1
YEL
GND1-1GND1
12345
CN7
U5:1
NJM4580L
R27
10K
GND1
CN3
2 3
U1:2
NJM4580L
C12
56pF/50 cer
R9
10K
GND1
LED6
GND1-1
4
CON4
CON5
C14
R29
82K
56pF/50 cer
12345
CON5
U4
VTL5C2
R14
10K
10K
R12
GR
R17
270R
LIMITER
7
5
6
R28
10K
41
7
5
6
LED4
RED
R24
82R
GND1-1
R20
180R
LED3
YEL
U5:2
NJM4580L
R30
10K
GND1
1
2
CN5
CON2
GND1
123
CN6
2 3
CH2-OUT
U3:2
NJM4580L
R13
10K
GND1
15V1
84
CON3
-15V1
GND1
C21
10u/25V
C22
10u/25V
U5:3
NJM4580L
C19
104P
C20
104P
GND1
VR1
A100K
C9
47uF/25V
1
C6
R4
100pF/50 cer
R1
C1
22uF/50V
D
10K
2
15K
CN1
U1:1
3
R2
15K
123
NJM4580L
R3
C2
CON3
22uF/50V
10K
C5
CH1-IN
CH1 GAIN
C7
GND1
GND1
100pF/50 cer
GND1
C10
47uF/25V
1
R8
10K
100pF/50 cer
2
R7
15K
C3
22uF/50V
CN2
C
VR2
U3:1
NJM4580L
R11
10K
3
C8
R10
15K
C4
22uF/50V
123
CON3
CH2-IN
A100K
100pF/50 cer
GND1
GND1
GND1
GND1
CH2 GAIN
B
84
U3:3
NJM4580L
C17
104P
C18
84
U1:3
NJM4580L
C15
104P
C16
104P
104P
1 2 3 4 5 6 78
A
- 3 -
D
4
321
C
B
A
X1X2X3
CN1
CN5
12345
CN9
1
2
123
CON3
SW1: 1
SW1: 2
6
CN-BAL-COMBI
3
SW PS-22E85L
4
5
6
P
SW PS-22E85L
CH1
CON4
4
5
6
SW3: 2
1
SW3: 1
P
SW PS-22E85L
2
3
X1X2X3
SW PS-22E85L
CN2
CN6
12345
123
CON3
6
CN-BAL-COMBI
CH2
123
4
1 2 34
D
C
B
A
- 4 -
D
4
321
C
B
A
4
CN1
1
1
2
CN5
CON2
CN6
CH1_SP+
CN-SP
2-
1+
2+
1-
2
2
3
1
CON2
CH1_SP-
1
2
CN7
CH2_SP+
1
CON2
4
CN2
CN8
CN-SP
2-
1+
2+
1-
2
2
3
1
CON2
CH2_SP-
1 2 34
D
C
B
A
- 5 -
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