ALTO SR400A Service Manual
Service Manual
Model: SR400A
ALTO
REV.2
CONTENTS
1. Specifications
2. Block Diagram
3. Schematic Diagram
4. Printed Circuit Board
5. Test Procedures
6. Structur al Drawing
7. Exploded View & Mechanical Parts List
8. Electrical Parts List
Test Result
100HZ:
SPECIFICATIONS
01-1
Model No: SR400A Test Date: 20040916 Tester: MO GUO ZHU
Test Item Test Conditions Spec Test Result Remark
1 Power Source AC: 230V；50 Hz
2 Idle Current AC 230 V No-Load 5 ±0.5 mV mV across R13 &R15
3 Power
Consumption
4 Rated Output Low Load : 4Ω 30---31 V THD:0.4↓ V
Rated Output.
Aux At 1KHz
A
W
A
W
Hi Load : 8Ω 18----19 V THD:0.8↓ _______V
FLAT
Aux At 1KHz FLAT.
Rated W
Load 16Ω V _______V
Load ____Ω （25V ） V V
Load____Ω （50V ） V V
Load____Ω （70V ） V V
Load____Ω （100V ） V V
5 Maximum at
Output 10% THD
Aux 1KHz dB
Load Ω
W W FLAT
7 Hum or Noise VR Line Max（Low ） 7↓ mV mV DSP OFF
VR Line Max (Hi ） 7↓ mV mV DSP OFF
8
Response
Input From Aux
Output At 1W
10KHZ: dB 10KHZ: dB
dB 100HZ: dBTone control
9 Puncture Voltage 5mA ， 5Sec 3750V V
10 MONITOR Aux 1KHz dB Load Ω FLAT
MONITOR NO: AUX,TAPE,TUNER,CD,MIC1,MIC2
CD PLAYER 1KHz 0dB
TUNER AM/FM
PRIORITY MIC1
TEL.PAGING 1KHz____dB
Load____Ω_______V
G-T___dB；
G-R___dB。
G-T___dB；G-R___dB。 FLAT
ZONE PAGING 100V ALL/ Z1，
Z2， Z3， Z4
AC : OUTPUT
REMOTE AC OUT or DC OUT
Test Result
Remark
SPECIFICATIONS
01-2
Model No：SR400A Test Date: Tester：MO GUO ZHU
Test Item 1. Input
2. Signal/Noise 3. Distortion at1W4. Distortion at
Sensitivity
Test Conditions
Test Result
FLAT Rated
Output 30V/18V
Load 4Ω/8Ω
FLAT Rated
Output 30V/18V
Load 4Ω/8Ω
FLAT Output
at 2V Load 4Ω
Low OUT -9 ±0.5 dBV 70↑ dB 0.5↓ % 0.4↓ % 22Hz~22KHz↑
LINE
Hi OUT -8±0.5 dBV 68↑ dB 0.5↓ % 0.8↓ % 25Hz~22KHz↑
TUNER dB dB % %
CD dB dB % %
AUX dB dB % %
AUX2
TAPE dB dB % %
TUNER dB dB % %
CD dB dB % %
AUX dB dB % %
TAPE dB dB % %
AUX3
TUNER dB dB % %
CD dB dB % %
LOW -50±0.5 dBV 60↑ dB 0.8↓ % 0.3↓ % 22Hz~22KHz↑
HI -50±0.5 dBV 60↑ dB 0.5↓ % 1↓ % 25Hz~22KHz↑
MIC
24V dB dB % %
UNBAL dB dB % %
MIC dB dB % %
MIC-2
LINE dB dB % %
24V dB dB % %
UNBAL dB dB % %
MIC dB dB % %
MIC-3
LINE dB dB % %
24V dB dB % %
UNBAL dB dB % %
MIC dB dB % %
MIC-4
LINE dB dB % %
24V dB dB % %
UNBAL dB dB % %
1. When the above items are tested, short circuit the 1st and the 2nd pin of 313115-1 (DSP) CN1. After the
test, remove the short circuit terminal.
2. Load connection: connect LOW output with 4Ohms, and connect HIGH output with 8Ohms.
3. Please check if the bass BOOST circuit is OK. If bass output is below 18V(ON LOAD), BOOST
circuit does not operates. If bass output is above 18V(ON LOAD), BOOST circuit starts operation.
4. FR test: use AP to scan DSP ON and DSP OFF respectively. Refer to the attached figure for frequency
response curves.
Authorization by： Check by：
Rated
FLAT Rated
Output 30V/18V
Load 4Ω/8Ω
5. Frequency
Response
FLAT Output at
1W REF-3dB
Load 4Ω
D
02-1
C
B
A
1
第 版
VER1.0
1/1
Revision
MO GUO ZHU
4321
Sheet of:
Drawn By:
DSP MODULE
HI SPEAKER
AMP
HI POWER
HI PRE
AMP
HPF
LOW SPEAKER
AMP
LOW PRE LOW POWER
AMP
LPF
POWER SUPPLY
SWITCH
HI
LOW
V+ & V- V+ & V-
T6.3A
HI V+
LOW V+
T6.3A
HI V-
T6.3A
LOW V-
T6.3A
SR400A
Title
SR400A BLOCK DIAGRAM
Number
SR400A
A3
Size:
Date:
File:
SR400A BLOCK DIAGRAM
MIX AMP PRE AMP
SIGNAL INPUT
D
VOLUME
C
238094
130 deg SW
POWER SWITCH
B
1 2 3 4
AC INPUT
A
D
03-1
C
B
A
1 第 版
VER1.0
87654321
Revision
1/1
MO GUO ZHU
Sheet of:
Drawn By:
P-110018-SR400A
Number
2004/08/27
SR300A
SR400A
Title
Size:
A3
Date:
File:
+5VD
330E
R13
CN2
FROM INPUT TO 313115-1 DSP BOARD
SW1
0E
DL1
CLIP
1
+15V
-15V
HIGH
14
CN-7PX2-F
TO 313120-1 AMP PCB
LOW
IC3C
8
C26
22P
+
_
33079
9
10
C19
1
2
VR1
D50K
3
C28
10u/63V
7
R21
IC2
L4962
V+
820E
IC3B
+
_
33079
6
5
R17
4.7K
C29
10u/63V
1
IC3A
+
_
33079
3
L1
22P
2
C18
10u/63V
7
NC
8
NC
9
NC
16
NC
6
NC
1
NC
3
OUT
2
1
3
5
TP-SEV1924-03
+5VD
D1
OSC
GND
GND
GND
GND
FC
SS
FB
BYV27
12345678910111213
+5VA
1 2
3 4
5 6
7 8
9 10
1112
1314
1516
1718
1920
+15V
SIGNAL
3
R
G
2
R9
1K2
-15V
SIGN/LIMIT
CN-10PX2-180
47u/63V
22P
0.0033u
6K8
C17
C7
10K
C6
R3
CN1
14
IC3D
+
_
33079
13
12
1
R5
IC1A
+
_
33079
2
3
R4
10K
C4
220u/63V
C9
330P
C12
0.0022u
R6
15K
R8
3K9
C8
C13
2u2 100V
C24
1000u/6V3
C25
470u/25V SLL*
0.033u
14
4
5
12
13
11
15
10
2
4
+15V
IC1E
IC3E
C15
0.1u
33079
33079
C14
470u/25V SLL
11 4
11 4
0.1u
-15V
C10
470u/25V SLL
C11
0.0033u
6K8
R14
C1
47u/63V
C5
IC1B
_
R2
R1
6
10K
10K
47u/63V
7
R7
33079
5
C21
C16
0.0033u
+
R11
10K
6K8
R10
47u/63V
IC1C
_
9
10K
47u/63V
8
R12
33079
10
C22
C2
+
390E
22P
R16
FL5R
MIC2
CN-BAL-MALE
C20
15K
L2
213
4
R15
15K
R19
FL5R
HIGH INPUT
+4dB
14
IC3D
+
_
33079
13
12
15K
12V1W
12V1W
L3
X1X2
XLR
MIC1
ZD3
ZD2
X3
22P
12345
C23
12V1W
12V1W
15K
ZD4
ZD5
R18
GND
456
P
SW2B
R22
10E
123
C27
SW2A
6
0.01uF/400V
SW PS-22E85L
SW PS-22E85L
1 2 3 4 5 6 7 8
D
C
B
A
D
03-2
C
B
A
1
第 版
VER1.0
1/1
Revision
MO GUO ZHU
4321
Sheet of:
Drawn By:
P-313121-1
Number
2004/08/27
黃
Vac
橙
+VCC2
藍
-VCC2
紫
+VCC1
D4
KBU806
GBU8D
-VCC1
棕
SR400A
Title
Size:
SR300A
A4
Date:
File:
D2
1N4002
C2
KBPC25
BP25-06PWS
C1400V/10N
T6.3A
F1
S1
F2
S2
D1
T6.3A
0.01uF400V
F3
T6.3A
F4
T6.3A
S4
S5
S3
1 2 3 4
D
C
B
A
4321
03-3
1 第 版
H
G
TIP36C
TR14
TIP35C
R13
0E2 5W
R15
TR16
BC857
LOW OUT+
+VCC2
D4
1N4002
D14
+VCC1
6A2
D24
1N4002
0E2 5W
D17
1N4002
D3
-VCC1
6A2
D5
1N4002
-VCC2
S4
LOW SPEAKER
S3
GND
R28
R25
820E
68E
-0.5V
TR10
2N5551
R29
R46
12K
4K7
D7
-15V
1
100K
R74
R40
12K
Vout
GND
0.2V
+15V
R39
4K7
+5VA
3
C33
1000U 6.3V
1N4148
R44
68K
-0.34V
R9
560E
470E
R59
R31
68K
TR12
2N5401
0.6V
+VCC2
+VCC1
+15V
D21
27.0K
DL2
-15V
-VCC1
-VCC2
1N4148
2
1
D5
C16
C14
100P
R71
15K
TO POWER LED
0.1U
DL2
47P
F
E
D
1
2
3
4
5
6
6P/P=3.96
CN1
C
B
R78
15K
FROM 110018 INPUT PCB
R77
22K
6
_ IC6B
5
+
MC33078
+5VA
CN2
1
3
5
7
9
11
13
CN-7PX2-F
R79
47E/5W
7
2
4
6
8
10
12
14
10000/63V
C9
10000/63V
C8
10000/50V
10U NP
C11
10000/50V
C12
C36
C32
2200U/63V
1
1
R80
-15V
+15V
IC4 7815
IC3 7915
R76
1K
1K
D27
4148
Vin
Vin
R69
100E PTC
GND
2
GND
C31
R75
47K
4N7
-15V
48
2
_
+
3
IC6A
MC33078
+15V
33P
C35
D26
4148
3
Vout
IC2 7805
1
Vin
C36
2
10/25V
C37
10/25V
Vout
C15
100P
0.001U
C1
1K5
R10
TR1
MJE802
VR1 470E
R23
820E R24
DL1 47P
R70
-15V
48
2
_
+
3
+15V
6
_ IC5B
5
+
R73
10E
NJE350
7V5 1W
+1.4V
-1.4V
MJE340
68E
47K
IC5A
MC33078
MC33078
TR9
D14
D10
7V5 1W
TR7
1
7
R60
47K
R34
8K2 2W
7.6V
C25
10/50V
-7.6V
R41
8K2 2W
R11
10K
R8
47K
1U/50V
R64
4K7
OFFSET PROTECTION
1U 50V NP
+15V
R46
150K
-7.7V
C22
C18
220U/25V
C20220U 25V
C2
R3
22K
C28
1000U/6V3
20.2V
R66
8K2
R21
8K2
R22
12K
R57
12K
R58
D13
1N4002
47E
R56
D25
8K2
R59
47K
C10
220P
TR5
R20
12K
R32
12K
220P
R21
10K
R63
10K
TR25
BC857
MJE340
R19
4E7
R26
4E7
TR13
C17
MJE350
R52
8K2
R51
47E
R53
47K
IC1
TDA7294
+VCC1
78
12
13
2
3
10
MUTE
11
ST-BY
D1
TDA7294
4148
1
15
-VCC1
TR18
BC857
C23
220U/50V
R48
330E
8.6V
R49
33K
D12
1N4002
D11
1N4002
C6
10UF/50V
14.9V
TR23
BC847
1N4002
C27
0.0047U
C13
0.0047U
R2
R4
1K
R32
33K
R62
10K
R61
10K
TR24
BC847
680E
TR22
BC847
R33
C21
1K
470P
24V
R43
2K2
C39
330P
TR4
MJE15030
R18
470E
R16
470E
C40
330P
R17
2K2
-24V-20.2V
C24
470P
C3
22UF/50V
6
14
5
4
9
C4
10UF/50V
R12
22K
R35
10K
R47
10K
8.84V
14.2V
R36
10K
9.4V
TR17
BC857
D17
C7
1N4148
0.1U
-15V
0.0047U
MJE340
TR6
MJE15031
MJE350
C25
0.0047
R55
1K
R1
22K
R12
10E 0.5W
C5
0.1U
SOFT START
TR11
BC32725
D8
1N4148
R30
10K
R37
470E
TR15
NJE15031
C23
TR21
R14
TR19
R42
390E
HIGH OUT +
RL1
OZ-SS-124LM1
DC 24V 16A
TR2
2SC5200
or NJL21184
R17
10E
10E
2SA1943
or MJL21193
S1
S2
GND
R27
390E
TR8
or SIMILAR
TR3
TR20
MJE15030
Hi SPEAKER
H
G
F
E
D
C
B
A
Title
SR400A
Size:A2Number
P-313120-1-SR400A
Date:
2004/08/27
File:
1 2 3 4
SR300A
Sheet of:
Drawn By:
Revision
VER1.0
1/1
MO GUO ZHU
A
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