Service Manual

Product
Date:
Filename:
PCB# of
Sheet
Rev:
42
V09
M1231V09SCH.sch2006
NX750P
Wed June 09, 2021
M1231NX750P
TP2
-15V
-15V
+15V
-15V
+15V
-15V_C
+15V_C
1/4W
1K4
R70
.
1/4W
1K4
R63
.
1/2W
150K
R48
.
1/4W
2K2
R24
MINI
-56V
+56V
FROM POWER SUPPLY
1/4W
1K4
R74
.
1/4W
1K0
R66
MINI
HORNGND
+24V
LVGND
+5V_MOD
+15V
SILENT
2
W2:B 0
-56V
+56V
+22V
6
W2:F 0
-145V
+145V
-15V_C
+/-15V_C
7
9 W10:G
6
9 W10:F
3
9 W10:C
2
9W10:B
1
9 W10:A
+56V
-15V
+15V
+15V_MOD
+4V7_LS
PSGND
SILENT
R20
1/4W
RAD
1M
-145V
-15V_MOD
R13
1/4W
MINI
2K2
+5V_MOD
WOOFGND
HORNGND
+5V_MOD
-145V
+5V_MOD
+4V7_LS
D19
0A2 BAT85
+15V_LS
R14
1/4W
RAD
18K
+
-15V_MOD
R23
1/4W
FUSIBLE
11R
1N5246B 16V0
D90W5
TP1
1N5246B
16V0
D2 0W5
HORNGND
100V
C91
100N
5.0W
12K
R105
.
+15V
PSGND WOOFGND
-22V
1
W2:A 0
3
W2:C 0
4
W2:D 0
PSGND
8
W2:H 0
7
W2:G 0
R44
1/8W
FLMP
10R0
9
9 W10:I
4
9 W10:D
5
9 W10:E
8
9 W10:H
1N5254B
D4
0W5
27V0
LVGND
1/4W
4K7
R10
RAD
100V
100N
C58
PSGND
-15V_MOD
R56
1/4W
MINI
6K8
R51
1/4W
MINI
6K8
WOOFGND
R38
1/8W
FLMP
10R0
+15V_C
R34
1/4W
MINI
47K
+24V
100V
C56
100N
100V
C55
100N
-15V_MOD
100V
C48
100N
100V
C47
100N
R73
1/8W
FLMP
10R0
100V
C41
100N
R64
1/8W
FLMP
10R0
-15V_MOD
1/4W
6K8
R59
MINI
R45
1/4W
MINI
6K8
C28
100V470P
+15V_MOD
C18
100V220P
100V
C57
100N
PSGND
PSGND
100V
C49
100N
+15V_LS
R54
1/4W
MINI
1K0
R36
1/8W
FLMP
100R0
4148
D14
+5V_MOD
1N750ARL
D23
0W5
4V7
-145V
100V
C42
100N
100V
C17
100N
-145V
63V
C143
470N
+4V7_LS
WOOFGND
1N750ARL
D18
0W5
4V7
-15V_MOD
C29
100V10N
+15V_MOD
1N750ARL
D12
0W5
4V7
LVGND
4148
D5
WOOFGND
7 14
-145V
+5V_MOD
3
IN
4
OUT
U9:B
74HC14N
6603
1/4W
2K2
R212
MINI
WOOFGND
1/4W
22K
R40
MINI
+5V_MOD
WOOFGND
U6:D
MC33079P
100V
C8
680P
100V
C46
470P
1/4W
220R
R221
MINI
-145V
+5V_MOD
WOOFGND
TO92
BC560C
Q5
5102
TO92
2N5401
Q7
5108
100V
C38
3N3
1/4W
47K
R166
MINI
WOOFGND
1/4W
100K
R25
RAD
TO92
2N5401
Q8
5108
1/4W
3K9
R5
.
R219
1/4W
RAD
470R
HORNGND
R72
1/4W
RAD
82K
C142
100V100N
TO92
2N5551
Q17
5107
100V
C34
100N
63V
C35
1U
1/2W
1R
R46
SMALL
R37
1/4W
MINI
150R
D15
0A2 BAT85
1/4W
2K2
R16
MINI
25V
C4
68U
R1
1/4W
MINI
22K
1/4W
180K
R71
MINI
1N5248B
D20
0W5
18V0
1/4W
1M
R57
RAD
1/4W
1M
R41
RAD
TO92
MPSA92
Q13
5114
1/4W
680R
R7
RAD
1/4W
10K
R8
RAD
1/4W
2K2
R9
MINI
1/8W
1K5
R60
FLMP
-145V
5.0W
0R047
R58
.
NET00055
1/8W
1K5
R33
FLMP
5.0W
0R047
R31
.
100V
C15
220P
+145V
D11
0W5
12V0
1N5242B
R6
1/4W
FUSIBLE
11R
D1
0W5
12V0
1N5242B
+4V7_LS
WOOFGND
1.0W
0R47
R17
FLMP
-22V
MR854
D10
1.0W
0R47
R18
FLMP
+22V
MR854
D3
PSGND
HORN-POS
4
YEL
400V
C118
2N2
HORN-NEG
3
BLK
100V
C71
680P
100V
C53
100N
100V
C52
100N
5
W2:E 0
100V
C50
100N
TO92
2N5551
Q4
5107
100V
C44
100N
U2:B
MC33078P
8
V+
4
V-
U2:C
5.0W
12K
R75
.
63V
C32
220N
OUTIN
GND
6728 TO92
MC78L05ABPRM
U11
5.0W
12K
R67
.
5.0W
12K
R68
.
100V
C43
100N
R42
1/4W
MINI
2K
1N5251BRL
22V0
D8 0W5
R47
1/4W
RAD
1M
1/4W
10K
R22
RAD
TO92
2N5401
Q18
5108
9
IN
8
OUT
U9:D
74HC14N
6603
7 14
1/4W
2K74
R213
0.1%
R80
1/4W
0.1%
4K12
1/4W
4K7
R49
MINI
100V
C45
470P
R77
1/4W
.
37K4
R81
1/4W
.
37K4
100V
C33
100N
U3:B
6964
100V
C16
100N
R128
0.6W
SMALL
18k7
7
GND
14
V+
U3:C
6964
63V
C3
4U7
1/4W
4K7
R62
RAD
R50
1/8W
FLMP
75R
100V
C24
100N
C6
500V10P
63V
C9
4U7
4148
D6
2.0W
2K2
R3
.
1/4W
270R
R15
RAD
NET00206
100V
C5
100N
100V
C14
680P
340V
C51
3U3
1.0W
0R47
R11
FLMP
140V
C22
3U3
140V
C20
3U3
140V
C31
3U3
1.0W
0R47
R12
FLMP
1/4W
6R2
R220
.
14
V+
7
V-
U5:E
+/-15V_MOD
+15V_MOD
WOOFGND
HORNGND
+5V_MOD
+15V_MOD
WOOFGND
-15V_MOD
+5V_MOD
+15V_MOD
R19
1/4W
MINI
2K2
+4V7_LS
-145V
+4V7_LS
C92
100V3N3
WOOFGND
WOOF_SILENT
U6:B
MC33079P
100V
C37
470P
100V
C26
100N
100V
C21
100N
-15V_MOD
FROM INPUT PCB
100V
C54
100N
R79
1/4W
MINI
1K0
+4V7_LS
1
IN
2
OUT
U10:A
74HC14N
6603
1N5240BRL
D22
0W5
10V0
1
IN
2
OUT
U9:A
74HC14N
6603
R52
1/4W
.
1K4
U6:C
MC33079P
+15V_MOD
100V
C36
68N
R55
1/4W
MINI
1K0
100V
C27
100N
R43
1/4W
MINI
47R
-15V_MOD
1/4W
22K
R32
MINI
2
+
3
-
4
V-
8
V+
5
BAL
1
GND
7
OUT
6
STROBE
LM311
U1
6640
WOOFGND
R28
1/4W
MINI
4K7
+15V_MOD
SILENT ON/OFF
TO92
Q9
5119
2N5638
WOOFGND
1/4W
4K12
R76
0.1%
4148
D24
WOOFGND
WOOFGND
5
IN
6
OUT
U10:C
74HC14N
6603
R65
1/4W
MINI
1K0
R53
1/4W
.
6R2
10
9
8
U5:C
74HC86N
6605
4
5
6
U5:B
74HC86N
6605
UF4004
D17
+4V7_LS
R39
1/4W
.
2R2
4148
D21
TO92
BC560C
Q6
5102
1/4W
18K
R21
MINI
1N5242B
D7
0W5
12V0
C144
100V10N
R4
2.0W
.
2K2
6887
U8:B
TO92
Q20
5119
2N5638
13
IN
12
OUT
U10:F
74HC14N
6603
SILENT ON/OFF
3
IN
4
OUT
U10:B
74HC14N
6603
11
IN
10
OUT
U9:E
74HC14N
6603
13
IN
12
OUT
U9:F
74HC14N
6603
L1
3792
288UH
1N5248B
D16
0W5
18V0
1/4W
1K0
R29
MINI
R26
1/4W
FLMP
2K21
1/4W
100R
R27
RAD
63V
C13
10U
.
6873_S
Q11
MJE340
TO126
D S
G
P
IRFP9140N
Q1:A
6932
TO247
.
BDX53C
6912
Q2
TO220
.
R2
1/4W
FLMP
2K21
RED
6
POS-WOOFER
5
BLK
NEG-WOOFER
LVGND
4
V+
11
V-
U6:E
63V
C7
10U
PHANTOM SUPPLY
1/8W
100R0
R83
FLMP
WOOFGND
5.0W
12K
R69
.
2
+
3
-
4
V-
8
V+
5
BAL
1
GND
7
OUT
6
STROBE
LM311
U4
6640
U6:A
MC33079P
U2:A
MC33078P
R35
1/8W
FLMP
100R0
-15V_MOD
2
+
3
-
4
V-
8
V+
5
BAL
1
GND
7
OUT
6
STROBE
LM311
U7
6640
63V
C12
1U
63V
C11
2U2
1/4W
2K
R30
MINI
+5V_MOD
TO92
MPSA92
Q19
5114
R82
1/4W
.
37K4
R78
0.6W
SMALL
18k7
WOOFER AMP
250V
C141
4N7
63V
C25
1U
13
12
11
U5:D
74HC86N
6605
1
2
3
U5:A
74HC86N
6605
U8:A
6887
IR2110
HORNGND
100V
C10
15P
100V
C39
5N6
11
IN
10
OUT
U10:E
74HC14N
6603
9
IN
8
OUT
U10:D
74HC14N
6603
5
IN
6
OUT
U9:C
74HC14N
6603
G
D
S
IRFP23N50L
N
Q14:A
6967
TO247
G
D
S
IRFP23N50L
N
Q15:A
6967
TO247
TO92
BC550C
Q3
5101
BDX54C
6911
Q10
TO220
.
100V
C1
680P
63V
C2
10U
G
D
S
IRFP140N
N
Q12:A
6931
TO247
.
WOOFER
S2
15" 8R 600W
YS#7525
S1
HORN
1" 8R 30W
YS#7393
Bias accross TP1 & TP2
= 0.1mV - 5mV
6964
U3:A
HORN AMP