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

1 2 3
I
Pre Amp (PCB version 7.2)
R27
DUAL RCA
604r
R In
H
C18
GND
C19
L In
R24
RCA CONNECTOR
604r
G
B-POST HiLev I/O
R1
C1
200uF
F
4k7
R R
L L
R2
C2
OUT IN
E
200uF
4k7
D
LED 2
1
2
NOT USED
C
From PwrAmp
NOT USED
From PwrAmp
B
A
1 2 3
4 5 6
R11
R28
33k2
59k
330pF
7
6
U1
330pF
5
R25
33k2
1N4148 1N4148
D53
D54
C3
220pF
R6
10
R5
9
R4
D51 D52
R3 R9
2k7
C4
100k
1N4148 1N4148
R8
220pF
2k7
8
11
LED1
1
2
4 5 6
7 8 9
5k POT
C6
SW SPDT
REMOTE
1
LEVEL
3 2
220p
2
2
1
3
Phase Switch
NOT USED
1N4148 1N4148
R10
10k
D50 D55
2nd Order Hi-Pass
R33
+15V
8
U1
12k1
-15V 2
C17 C16
3
C5
150nF 100nF
C20
C21
R34
220pF
120k
100nF
100nF 100nF
2nd Order LO-PASS
7
0r
LoPass Defeat Sw.
R21
SW SPDT
1
C12 13
9
14
3
U2
100nF
R22
12
6k8
J1
10
NOT USED
R23
0r C13
12 100nF
42
7 8 9
10 11 12
R14
68k1
R12
1 6
7 C7 C8
45k3 U2
3 5
0r 0r
R13 R35 R15
33k2 137k NOT USED
2nd Order LO-PASS
LO PASS CONTROL 1
C10
R18 20k POT
1 3
6k8
2
100nF
-15V 13
1
R19
U2
20k POT
6k8
12
LM324 5
4 6
+15V
C23 C22 LO PASS CONTROL 2 C11
100nF
100nF
GAIN STAGE
R26
2
4k7 C30
NOT USED R30
10k
9
8
U2
10
Part No:
Revision 7.2 (PREAMP)
Date:
25-Oct-2001
Drawn:
MS/LL
Rev. Sheet:
1 2
1 of
10 11 12
13 14 15
3rd Order Hi-Pass
R16
NOT USED
2
1
C9
U1
3
TLO64
1k
R17
56k2
14
U1
R20
6k8
CONN 1
To Pin 11 U1/U2
+15V 6 +15V
mute
5
4 GND
3 GND
2 SIG
-15V 1 -15V
To Pin 4 U1/U2
NOT USED
13 14 15
I
H
G
F
E
D
C
B
A