Alto MC250.8 Service Manual
MODEL: MC250.8
CONTENT
2
3
1. INTRODUCTION……………………………………………………………………………..1
2. TECHNICAL SPECIFICATION……………………………………………………………..
3. BLOCK DIAGRAM……………………………………………………………....................3
4. SCHEMATIC DIAGRAM…………………………………………………………………….4
5. WIRING DIAGRAM…………………………………………………………………………12
6. PCB LAYOUT……………………………………………………………………………….
7. TEST PROCEDURE…………………………………………………………....................18
8. EXPLODED VIEW & MECHANICAL PARTS LIST…………………………………….
9. BOM………………………………………………………………………………………….25
1
22
1. INTRODUCTION
Innovative design and high stability power amplifier
Fan-cooled AB class high power amplifier in 19", 2U size
8
independent channels with separate protection system
DC, infrasonic, overheat & short circuit protection
Smart-designed protection system for auto re-operation after fault
Parallel-input: channel 1 to channel 2, channel 3 to channel 4, channel 5 to channel 6, channel 7 to channel 8
Allowing selection of Stereo, Bridge or parallel operation
Ultra low-noise and hum
High-pass filter , allow selection of flat, 35 Hz or 75Hz, protect speakers and prevent speaker transformer saturation
with minimal effect on program material.
DIP switch control for clip limit, high-pass filter, bridge-mono stereo selections
AUTO variable- speed-low-noise fans ensure high reliability even under demanding conditions.
Detachable Euroblock: " Barrier strip" input connectors.
Rugged amplifier in a strong, compact chassis
- 1 -
BRIDGE MODE:
2. TECHNICAL SPECIFICATION
- 2 -
8ohms,1kHz,0.1%THD (EIAJ) 4×500W
Distortion(SMPTE-IM) <0.05%
MONO MODE:
8 ohms per channel(EIAJ) 8x180W Output Power
(20Hz 20kHz THD @ 0.1%)
Frequency Response 20Hz-20kHz 1dB, -3dBpoint: 10Hz-60kHz
Damping Factor,1kHz,0.1%THD(EIAJ) >300@8ohms
Signal to Noise,20Hz-20kHz 90dB
Voltage Gain 40×( 32dB)
Input sensitivity@ 4 ohms 1Vrms
Input clipping 10Vrms(+22dB)
Input impedance 10K ohms unbalanced, 20Kohms balanced
Controls
Indicators
4 ohms per channel(EIAJ) 8x250W
Front: AC Switch, Ch1-Ch8 Gain Knobs
Rear: MODE SWITCHES
Power-On: Blue LED
Protection: Red LED
Signal: LED Green
Clip: Red LED
Parallel-input: Yellow LED
Bridge: Yellow LED
Connectors, each channel
cooling Continuously variable-speed fan, front-to- rear airflow
Load protection On/Off muting, overheat & short circuit protection
Power supply 220-240(110-120)Vac50-60Hz
Dimensions 17.7"(44.95cm)(D)*3.5"(8.9cm)(H)*19.02"(48.3cm)(L)
Net weight 21.6Kg
Input: Terminal Block
Output: Screw-terminal Barrier Block
D
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
35/75Hz
FILTER
PT-MC250.8
3. BLOCK DIAGRAM
- 3 -
BRIDGE2
SPEAKER
C
BRIDGE4
SPEAKER
B
A
8
SPEAKER
CH3
CH4
SPEAKER
SPEAKER
CH7
CH8
SPEAKER
123
4
CH3,4
OUTPUT
+24V
7654321
CH1,2,3, 4
Heat Prot ection
&+$03
&/,3
/,0,7(5
CH3
LEVER
123
CH3
INPUT
RELAY
&+$03
&/,3
/,0,7(5
CH4
LEVER
123
CH4
INPUT
CH5,6,7, 8
Heat Prot ection
&+$03
&/,3
123
CH7
INPUT
123
4
CH7,8
OUTPUT
+24V
RELAY
&+$03
/,0,7(5
CH7
&/,3
/,0,7(5
123
CH8
LEVER
PS8
BRIDGE
PS7
BRIDGE
PS6
BRIDGE
LEVER
CH8
INPUT
BRIDGE
PS5
CH5,6,7,8 RELAY PS
BRIDGE
PS4
BRIDGE
BRIDGE1
SPEAKER
CH1
SPEAKER
SPEAKER
CH2
123
4
CH1,2
OUTPUT
+24V
CH1,2,3, 4
Heat Prot ection
&+$03
&/,3
/,0,7(5
CH1
LEVER
RELAY
&+$03
&/,3
/,0,7(5
CH2
LEVER
+24V
CH5,6,7, 8
Heat Prot ection
&+$03
&/,3
/,0,7(5
BRIDGE3
SPEAKER
CH5
SPEAKER
SPEAKER
CH6
123
4
CH5,6
OUTPUT
&+ &+ &+ &+ &+ &+
&+
&+
PS3
BRIDGE
PS2
BRIDGE
OUTPUT1 OUTPUT2 OUTPUT3 OUTPUT4 OUTPUT5 OUTPUT6 OUTPUT7 OUTPUT8
PS1
BRIDGE
G3 G4
CH5,6,7,8 FAN PS
BRIDGE
CH1,2,3,4 RELAY PS
BRIDGE
G1 G2
9 99 9
CH1,2,3,4 FAN PS
BRIDGE
RELAY
&+$03
&/,3
/,0,7(5
CH5
LEVER
CH6
LEVER
POWER SWITCH
BREAKER
123
CH1
INPUT
123
CH2
INPUT
D
123
CH5
INPUT
C
123
CH6
INPUT
B
A
1 2 3 4 5 6 78
4. SCHEMATIC DIAGRAM
D
8
J1_1
0&$03
7654321
+60V_A
OUTPUT_1
+60V_A
123
CN1_1
V1+
-60V_A
CON3
V1-
GND1
C
CN1_3
2.54 2P
1
2
D1_16
1N4004
DB107G
GND1
GND1
TR1_4
Q1_5
C1815
GND1
MPSA42
R1_60
1K
R1_48
47K
R1_47
47K
-60V_A
72&+
RELAY PS
0.1uF/50V
C1_19
220UF/25V
C1_18
SP-2+
TP-2
10R 3W
R1_41
500R 3W
K1_1
SIG2- LED+
R1_55
1K-1W
MI-SH-224L
100nF/250V poly
C1_17
D1_12
GND1
SIG1- LED+
SP-1-
TP-2
GND1
SP-1+
J1_2
TP-2
R1_40
5R6 2W
OUTPUT_1
J1_3
R1_51
1K-1W
OUT2
L1_1
2uH 10A
R1_37
B
CH2-AMP
MC8AMP -CH2. SCH
D1_17
ZD5.6V 1W
TP SW
72&+
SW101
95C
R1_49
120K
CH3-AMP
MC8AMP -CH3. SCH
R1_52
56K
C1_26
100uF/16V
TR1_3
MPSA42
R1_61
3.3K
Q1_8
MPSA42
C1_24
47uF/25V
CH4-AMP
MC8AMP -CH4. SCH
GND1
Q1_9
MPSA42
R1_62
22K
R1_46
3.3K
R1_56
22K
C1_31
47uF/25V
A
GND1
D1_11
1N4004
GND1
GND1
PRO 1
Q1_1
D1_9
ZD3V9 1/2W
C4382
D1_5
1N4148
C1_14
TP1_1
TP-2
R1_36
R1_34
300R
R1_32
47K
NTC 500R
R1_31
R1_27
1.8k
D1_15
1N4937
C1_13
2.2nF/50 cer
7
C1_11
56pF/50 cer
6
C1_16
22nF/100V p oly
GND1
3.3nF/50 cer
4R7
TR1_2
MPSA92
TR1_1
R1_30
680R
D1_14
1N4937
U1_1B
NJM4580L
5
D1_4
1N4148
C1_15
3.3nF/50 cer
Q1_6
4R7
R1_35
R1_33
300R
MPSA42
R1_28
330R
R1_26
15R
C1_12
22nF/50 c er
A1668
D1_10
ZD3V9 1/2W
Q1_3
A684
R1_14
0.1R 3W
Q1_2
2SA1943
R1_12
22R 2W
0.2A
331
C1_29
R1_7
2K 3W
D1_3
+15V
1N4148
C1_2
220uF/25V
Vic1+
R1_9
820R
D1_7
ZD15V1W
GND1
331
C1_30
R1_10
C1_3
220uF/25V
GND1
D1_8
820R
D1_13
1N4004
R1_39
330K
R1_15
0.1R 3W
Q1_7
2SC5200
PRO 2
0.2A
R1_13
22R 2W
R1_8
3K 2W
10K5
R1_44
C1_23
-15V
27pF/50 cer
D1_6
1N4148
Vic1-
ZD15V1W
12K
R1_43
330R
R1_29
GND1
R1_38
330K
PRO 1
CN1_4
CON2
1
2
G1
R1_45
68K
PWR ON LED
U1_4
CN1_6
2P-2.5
1
2
G1
D1_18
1N4004
C1_25
10uF/50V
C1_28
R1_54
NTC500R
3
2
1
LM317T
C1_27
470u/35V
100nF/50V
0R
1 2
R1_53
1K8
R1_6
G1
CH1-2BRIDGE
2 1
LIMITER
GND1
(FTR VT90N1 VACTEC+)
CH1 PHOTO COUPLER
D1_1
DB107G
GND1
U1_3
VTL5C2
AK
CH1-LIM-2
CH1-LIM-1
R1_5
47R
1
U1_1A
NJM4580L
3
2
R1_2
4K7
GND1
R1_1
4K7
10K
R1_21
U1_1C
NJM4580L
GND1
123
2.54 3P
CN1_20
C1_9
47uF/25V
D1_2
DB107G
7
R1_19
15K
5
R1_18
100R
GND1
CLIP1- LED+
CLIP1- LED-
CLIP
6
C1_8
C1_5
C1_4
0.22uF/50 cer
CH1-35Hz
CH1 GAIN
U1_2B
NJM4580L
0.047uF/50 cer
CH1-75Hz
CH1-FILT ER
R1_17
47K5
C1_10
47uF/25V
1
U1_2A
0.1uF/50 cer
R1_16
4K75
C1_6
R1_25
100pF/50 cer
R1_22
10K
C1_20
10uF/25V
CH1-IN-
NJM4580L
10K
3
2
R1_24
10K
C1_7
R1_23
10K
C1_21
10uF/25V
CH1-IN+
84
Vic1+
84
Vic1+
GND1
GND1
100pF/50
Vic1-
U1_2C
NJM4580L
Vic1-
16K
R1_3
CH1 PROT
CLIP1- LED+CLIP1- LED-
1 2
J1_5
R1_4 16K
CH2 PROT
SIG1- LED+
SIG2- LED+
PAR1-LED+PAR1-LED-
PRO T1-LED+
PRO T2-LED+
3 4
5 6
7 8
9 10
11 12
13 14
BRD1-LED- BRD1-LED+
PRO T1-LED-
PRO T2-LED-
J1_6
15 16
HEADER 8X2
CLIP2- LED- CLIP2- LED+
GND1
BD1
CH1-75Hz
1 2
CH1-35Hz
CH2-IN+
CH2-75Hz
CH2-LIM-1
CH2-LIM-2
CH2-FILT ER
3 4
5 6
7 8
9 10
11 12
13 14
CH1-IN-
CH1-IN+
CH2-35Hz
PAR1-SW
CH1-FILT ER
250v2A
G1
1
2
CN1_5
2P-3.9
CH2-IN-
BRD1-S W
15 16
17 18
19 20
HEADER 10 X2
GND1 GND1
CH1-LIM-1
CH1-LIM-2
1 2 3 4 5 6 78
D
C
B
A
- 4 -
- 5 -
- 6 -
- 7 -
D
4
C
B
A
/('6FKHPDWLF
LD2_1
GR
LD2_2
LD2_3
LD2_4
RED
YEL
YEL
3
PROT
J1HEADER 8X2
16
14
12
10
8
6
4
2
15
13
11
9
7
5
3
1
LD4_1
LD4_2
LD4_3
LD4_4
GR
RED
YEL
YEL
16
14
12
10
8
6
4
2
34
J2HEADER 8X2
15
13
11
9
7
5
3
1
LD3_4
LD3_3
LD3_2
LD3_1
YEL
YEL
RED
GR
2
CLIP LIMIT PAR BRD G LIMIT CLIP
PROT PROT
LD1_4
YEL
2
LD1_3
YEL
LD1_2
LD1_1
RED
GR
CLIPPROT LIMIT PAR BR D G LIMIT CLIP
1
D
C
- 8 -
B
A
1
D
8
C
B
A
,1387287387
7654321
BRIDGE PIN6(+)~PIN7(-)
BRIDGE PIN2(+)~PIN3(-)
CH1 OUTPUT
CH2 OUTPUT
CH3 OUTPUT
CH4 OUTPUT
--+
+--++
1234567
CN10
8
CON8
BRIDGE PIN2(+)~PIN3(-)
BRIDGE PIN6(+)~PIN7(-)
CH5 OUTPUT
CH6 OUTPUT
CH7 OUTPUT
CH8 OUTPUT
--+
+--++
1234567
CN11
8
CON8
CN1
CH2-FILTER
1 2
1
CH1-
3 4
2
CH1+
CH2-FILTER75HzCH2-FILTER35Hz
5 6
CON2
CH2_LIM_S W1
7 8
9 10
CH2_LIM_S W2
CN2
CH2_IN+
11 12
1
2
CH2-
CH2+
CH2_IN-
CH2 BRIDGE
13 14
15 16
17 18
CON2
19 20
CN22
CN3
HEADER 10X2
GND1 GND1
1
2
CH3-
CH3+
CN4
CON2
1
2
CH4-
CH4+
CON2
CN5
1
2
CON2
CH5-
CH5+
CH4-FILTER75HzCH4-FILTER35Hz
CH4-FILTER
1 2
3 4
5 6
1
2
CN6
CH6-
CH6+
CH4_IN+
CH4_IN-
CH4_LIM_S W1
CH4_LIM_S W2
7 8
9 10
11 12
13 14
15 16
CON2
CH4 BRIDGE
17 18
19 20
CN7
CN21
HEADER 10X2
1
CH7-
2
CH7+
GND2 GND2
CN8
CON2
1
2
CON2
1.CLIP LIMIT-CH1
3.FILTER_FEQ -C H1
2.FILTER-ON/OFF-CH1
4.PARALLEL+
5.PARALLEL-
6.PARALLEL-LED
CH8-
CH8+
CH6_IN+
CH6_IN-
CH6_LIM_S W1
CH6_LIM_S W2
CH6-FILTER75HzCH6-FILTER35Hz
CH6-FILTER
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
MOD E SWITCH SETTIN G S
CH6 BRIDGE
CN20
17 18
19 20
HEADER 10X2
GND3 GND3
7.BRIDGE ON/OFF
10.CLIP LIMIT-CH2
8.FILTER_FEQ -C H2
9.FILTER-ON/OFF-CH2
CH8_IN+
CH8_IN-
CH8 BRIDGE
CH8_LIM_S W1
CH8_LIM_S W2
CH8-FILTER75HzCH8-FILTER35Hz
CH8-FILTER
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
CN6
19 20
HEADER 10X2
GND4 GND4
CH3_LIM_S W1
CH3_IN+
15
CH3/4-PAR_LED
CH3_LIM_S W2
CH3_IN-
3
2
CN4
1
GND2
CH6_IN+
12
13
14
DIP10
10 11
CH4-FILTER75Hz CH4-FILTER35Hz
CH4-FILTER
CH4 BRIDGE
CH4_LIM_S W1 CH4_LIM_SW2
CN3
CH6_IN-
3
2
1
CH5_IN+
CH5_IN-
CH5-FILTER
CH5-FILTER35Hz CH5-FILTER75Hz
CH5-FILTER35HzCH5-FILTER75Hz
18
19
20
ON
12345678 910
SW2
123456789
GND3 GND3
CH5-FILTER
CH5_LIM_S W1 CH5_LIM_SW2
CH5/6-PAR_LED
17
CH5_IN+ CH6_IN+
CH5_LIM_S W1
CH5_LIM_S W2
CH5_IN+
CH5_IN-
3
2
1
CN2
GND3
CH8_IN+
12
13
14
15
16
DIP10
10 11
CH6-FILTER75Hz CH6-FILTER35Hz
CH6-FILTER
CH5_IN- CH6_IN-
CH6 BRIDGE
CH5/6-PAR_LED
CH6_LIM_S W1 CH6_LIM_SW2
B
CN1
CH8_IN-
3
2
1
CH7_IN+
CH7_IN-
CH7-FILTER
CH7-FILTER35Hz CH7-FILTER75Hz
CH7-FILTER35HzCH7-FILTER75Hz
17
18
19
20
ON
12345678910
SW1
123456789
GND4 GND4
CH7_IN+ CH8_IN+
CH7_LIM_S W1 CH7_LIM_SW2
CH7-FILTER
CH7_LIM_S W1
CH7_LIM_S W2
CH7_IN+
CH7_IN-
CH7/8-PAR_LED
GND4
12
13
14
15
16
DIP10
10 11
CH8-FILTER75Hz CH8-FILTER35Hz
CH8-FILTER
CH7/8-PAR_LED
CH7_IN- CH8_IN-
CH8 BRIDGE
CH8_LIM_S W1 CH8_LIM_SW2
1 2 3 4 5 6 78
A
CH3-FILTER
CH3-FILTER35Hz CH3-FILTER75Hz
CH1_LIM_S W1
CH1_LIM_S W2
CH1_IN+
CH1_IN-
CH1-FILTER
CH1-FILTER35Hz CH1-FILTER75Hz
CH1/2-PAR_LED
3
2
1
CN8
CH2_IN+
CH2_IN-
3
2
1
CN7
CH1_IN+
CH1_IN-
CH1-FILTER35HzCH1-FILTER75Hz
16
17
18
19
20
ON
12345678910
SW4
123456789
GND1 GND1
CH1-FILTER
CH1_IN+ CH2_IN+
CH1_IN- CH2_IN-
CH1_LIM_S W1 CH1_LIM_SW2
D
GND1
12
131415
DIP10
10 11
CH2-FILTER75Hz CH2-FILTER35Hz
CH2-FILTER
CH2 BRIDGE
CH1/2-PAR_LED
CH2_LIM_S W1 CH2_LIM_SW2
3
2
1
CN6
CH4_IN+
CH4_IN-
3
2
1
CN5
CH3_IN+
CH3_IN-
ON
SW3
GND2 GND2
CH3/4-PAR_LED
CH3-FILTER35HzCH3-FILTER75Hz
16
17
18
19
20
12345678910
123456789
CH3_IN+ CH4_IN+
CH3_IN- CH4_IN-
CH3_LIM_S W1 CH3_LIM_SW2
CH3-FILTER
C
- 9 -
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