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TO XLR/PREAMP PCB
NLD
CON1
PLD
20
+L Input
P24
19
-L Input
18
BIAS L-
17
+R Input
P42
BIAS L+
16
-R Input
15
14
+SL Input
P48
13
-SL Input
12
NLD
11
+SR Input
P50
PLD
10
-SR Input
9
8
+BL Input
P53
BIAS R-
7
-BL Input
BIAS R+
6
5
+BR Input
P55
4
-BR Input
3
NLD
2
+C Input
P58
PLD
1
-C Input
MOLEX
BIAS SL-
52806
AGND
BIAS SL+
NLD
PLD
CON2
20
LIFT TEMP T1/AC FAIL*
BIAS SR-
19
LIFT TEMP T2
BIAS SR+
18
DC OFFSET
17
16
SPK MUTE
15
PA SHORT*
NLD
14
PLD
13
BIAS BL
12
11
BIAS SL
BIAS BL-
10
BIAS BL+
9
BIAS L
8
7
BIAS C
6
NLD
5
BIAS R
PLD
4
3
BIAS SR
2
BIAS BR-
1
BIAS BR
BIAS BR+
MOLEX
52806
DGND
NLD
PLD
BIAS C-
BIAS C+
TR4
HS1A
R30
TIP31C
+30V
+14V
R29
P32
PA SHORT*
R18
P33
P36
DC OFFSET
100R
100R
100R
C1
R8000
2W
2W
2W
100UF
6K8
63V
0W25
+3V3
P37
P8000
R21
10R
DZ8000
C8000
STARGND DEC
0W125
BZX384B
100N
3V3 2%
50V
R22
P38
3K3
C2
C3
DZ1
BIAS L-
0W25
10UF
100UF
BZX84C
AGND
BIAS L+
50V
25V
15V
BIAS R-
BIAS R+
BIAS SL-
BIAS SL+
AGND
BIAS SR-
BIAS SR+
C4
C5
DZ2
BIAS BL-
10UF
100UF
BZX84C
50V
25V
BIAS BL+
15V
BIAS BR-
R24
P41
BIAS BR+
3K3
BIAS C-
R25
0W25
BIAS C+
STARGND DEC
10R
BIAS L
0W125
BIAS R
P43
BIAS SL
C6
BIAS SR
100UF
63V
BIAS BL
BIAS BR
P44
R26
P45
BIAS C
P46
R31
-30V
-14V
100R
100R
TR6
HS2A
2W
2W
TIP32C
Left Channel
L281 CT2 L Channel.SchDoc
RLY2A
NLD
RLY2B
R2
P1
PLD
P2
+L Input
Out L
4R7
-L Input
SHORT L
L1
Omron
Omron
BIAS L-
ERR -VE
G2R-2A
G2R-2A
BIAS L+
ERR +VE
0.5uH
Right Channel
RLY3A
L281 CT3 R Channel.SchDoc
RLY3B
P7
R5
NLD
P8
PLD
Out R
4R7
+R Input
SHORT R
L2
-R Input
Omron
Omron
ERR -VE
BIAS R-
G2R-2A
G2R-2A
ERR +VE
BIAS R+
0.5uH
Surround Left
P10
R7
RLY1B
L281 CT4 SL Channel.SchDoc
P11
NLD
Out SL
4R7
PLD
SHORT SL
L3
Omron
+SL Input
ERR -VE
G2R-2A
-SL Input
ERR +VE
0.5uH
BIAS SL-
BIAS SL+
Surround Right
L281 CT5 SR Channel.SchDoc
NLD
P16
R9
RLY4A
PLD
P17
+SR Input
Out SR
4R7
L4
-SR Input
SHORT SR
Omron
BIAS SR-
ERR -VE
G2R-2A
BIAS SR+
ERR +VE
0.5uH
Back Left
L281 CT6 BL Channel.SchDoc
P19
R12
RLY1A
NLD
P20
PLD
Out BL
4R7
+BL Input
SHORT BL
L5
-BL Input
Omron
ERR -VE
BIAS BL-
G2R-2A
ERR +VE
BIAS BL+
0.5uH
Back Right
L281 CT7 BR Channel.SchDoc
P23
R13
RLY4B
NLD
P26
PLD
Out BR
4R7
+BR Input
SHORT BR
L6
-BR Input
Omron
ERR -VE
BIAS BR-
G2R-2A
ERR +VE
BIAS BR+
0.5uH
Centre Channel
RLY5A
L281 CT8 C Channel.SchDoc
P28
R17
RLY5B
NLD
P29
PLD
Out C
4R7
+C Input
L7
SHORT C
-C Input
ERR -VE
Omron
Omron
BIAS C-
G2R-2A
G2R-2A
ERR +VE
BIAS C+
0.5uH
Protection
L281 CT9 Protection Circuitry.SchDoc
ERR +VE
PA SHORT*
ERR -VE
DC OFFSET
SHORT L
SHORT R
SHORT SL
SHORT SR
SHORT BL
SHORT BR
SHORT C
Bias Circuit
L281 CT10 Bias Circuit.SchDoc
BIAS L-
BIAS L+
BIAS R-
BIAS R+
BIAS SL-
FD1
FD2
BIAS SL+
BIAS SR-
BIAS SR+
BIAS BL-
BIAS BL+
BIAS BR-
BIAS BR+
BIAS C-
BIAS C+
PCB1
BIAS L
BIAS R
DRAWING TITLE
BIAS SL
BIAS SR
BIAS BL
BIAS BR
ARCAM
BIAS C
A & R Cambridge Ltd.
Waterbeach
Cambridge CB25 9QE
SK1
SPK MUTE
SPK R
RETURN R
SPK L
P3
2W
SPK C
RETURN C
+30V
SPK R
P9
2W
SPK L
RETURN L
Donghe Metal & Plastic
DH
SPK SL
SK2
R14
SPK MUTE
P12
SPK BR
2W
2K2
0W125
RETURN BR
RETURN SR
+30V
SPK SR
SPK SR
P18
2W
Donghe Metal & Plastic
DH
SK3
SPK SL
SPK BL
R19
P21
SPK MUTE
2W
RETURN SL
2K2
0W125
RETURN BL
SPK BL
SPK BR
Donghe Metal & Plastic
P27
2W
DH
SP2
STARLINK
P63
P65
SPK C
AGND
P30
2W
P67
P68
RETURN BR
RETURN BL
P69
P70
RETURN SR
RETURN SL
P71
DGND
RETURN L
P72
P73
P74
RETURN R
RETURN C
GND_B
GND_BR
SP1
P77
GND_C
GND_SR
STARGND DEC
GND_R
P79
STARLINK
STARGND
P80
TO PREAMP PCB
GND_BL
GND_ZC
CON5
+14V
STARLINK
GND_L
1
P81
2
AGND
GND_A
GND_SL
3
JST
-14V
VH
1
L281PB
Blank PCB L281PB AMP019 AMP PCB
21_E001
AMP019 Top Level
20_E002
Filename:
L281 CT1 Top Level.SchDoc
19_E027
Notes:
19_E007
18_E048
ECO No.
Contact Engineer:
Jon Henderson
Contact Tel:
01223 203201
EN-26
+30V
R1
+3V3
CON7
1
180R
2
0W25
P14
HARWIN
D1
RLY1C
M20-973
Omron
BAS21LT1
G2R-2A
P4
TR1
P5
R3
P6
MMBTA42L
SPK MUTE
R11
2K2
R4
180R
0W125
100K
0W25
0W063
P51
D3
RLY3C
Omron
BAS21LT1
DGND
G2R-2A
+30V
R6
P22
TR3
180R
P25
MMBTA42L
0W25
P57
R15
D2
RLY2C
100K
BAS21LT1
Omron
0W063
G2R-2A
P13
DGND
TR2
R8
P15
SPK MUTE
MMBTA42L
R16
2K2
R10
180R
0W125
100K
0W25
P60
0W063
D4
RLY4C
BAS21LT1
Omron
DGND
G2R-2A
P31
+30V
R23
TR5
P35
MMBTA42L
180R
0W25
R20
P34
100K
RLY5C
D5
0W063
Omron
BAS21LT1
G2R-2A
DGND
P47
TR7
R27
P49
MMBTA42L
SPK MUTE
2K2
R28
0W125
100K
0W063
DGND
FROM LIFTER PCB
CON3
1
P61
+55V
2
P62
-55V
3
NLD
P64
4
PLD
P66
5
STARGND DEC
6
STARGND DEC
7
STARGND DEC
8
STARGND DEC
JST
CON4
XH (VERTICAL)
CON6
P39
5
1
1
LIFT TEMP T1/AC FAIL*
+VLIFT
+VLIFT
2
LIFT TEMP T2
P76
6
2
3
STARGND
STARGND
+30V
4
-30V
7
3
5
STARGND
STARGND
STARGND DEC
6
STARGND DEC
8
4
-VLIFT
-VLIFT
JST
P40
MOLEX
XH (VERTICAL)
44472
PK
12/01/21
Change speaker relays
3.0
PK
06/01/20
PCB change only
2.0
PK
20/05/19
No changes to this sheet
1.0
JH
11/02/2019
No changes to this sheet
G.0
PK
28/11/18
No changes to this sheet
F.0
INITIALS
DATE
DESCRIPTION OF CHANGE
ISSUE
L281CT
Sheet
1
of
10
A3
DRAWING NO.
Printed:
15/01/2021
P75
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