Preamp (Pcb Version 7.2) - JBL PowerBass PB12 Service Manual

PB12 Revision 1 Schematic Diagrams
1 2
I
DUAL RCA
R In
H
GND
L In
RCA CONNECTOR
G
B-POST HiLev I/O
C1
200uF
F
R R
L L
C2
OUT IN
E
200uF
D
C
From PwrAmp
From PwrAmp
B
A
1 2
3 4 5 6
R27
604r
R11
R28
33k2
59k
C18 330pF
7
6
U1
C19
330pF
5
R25
33k2
R24
604r
1N4148 1N4148
D53
D54
R1
C3
220pF
+15V
R6
4k7
10
U1
R5
9
R4
D51 D52
-15V
R3 R9
R2
2k7
C4
100k
1N4148 1N4148
4k7
R8
220pF
2k7 220pF
LED 2
8
1
2
NOT USED
11
LED1
1
2
NOT USED
3 4 5 6
7 8 9 10
5k POT
C6
REMOTE SW SPDT
1
R12
LEVEL
1
3 2
220p 2
2 45k3
3
1
3
Phase Switch
NOT USED
R13
33k2
1N4148 1N4148
R10
10k
D50 D55
2nd Order Hi-Pass
R33
8
12k1
-15V
2
1
C17 C16
U2
3
LM324
C5
+15V
150nF 100nF
C20 C23
C21
R34
120k
100nF
100nF 100nF
2nd Order LO-PASS
7
0r
LoPass Defeat Sw.
R21
SW SPDT
1
C12 13
R26
9 2
14 3
U2
4k7
100nF
R22
12
6k8
J1
10
NOT USED
R23
0r C13
12 100nF
Part No:
Date:
Drawn:
Rev.
7 8 9 10
54

PREAMP (PCB version 7.2)

11 12 13
3rd Order Hi-Pass
R16
R14
68k1
NOT USED
6 2
7 C7 C8 1
C9
U2 U1
5
3
TLO64
1k
0r
0r
R17
R35 R15
137k NOT USED 56k2
2nd Order LO-PASS
LO PASS CONTROL 1
C10
R18 20k POT
1 3
6k8
2
100nF
13
R19
14
U1
20k POT
6k8 12
5
4 6
C22 LO PASS CONTROL 2 C11
100nF
100nF
R20
6k8
GAIN STAGE
CONN 1
To Pin 11 U1/U2
C30
+15V 6
NOT USED R30
5
10k
4
9
3
8
U2
2
-15V 1
10
To Pin 4 U1/U2
NOT USED
Revision 7.2 (PREAMP)
25-Oct-2001
MS/LL
Sheet:
1 2
1
of
11 12 13
14 15
I
H
G
F
E
D
+15V
mute
GND C
GND
SIG
-15V
B
A
14 15