EN-26
ISSUE
DRAWING NO.
DRAWING TITLE
DATE
Filename:
ECO No.
DESCRIPTION OF CHANGE
L281 CT1 Top Level.SchDoc
AMP019 Top Level
Contact Engineer:
L281CT
15/01/2021
INITIALS
Printed:
1
10
Sheet
of
Notes:
Contact Tel:
01223 203201
Jon Henderson
A & R Cambridge Ltd.
Cambridge CB25 9QE
Waterbeach
A3
ARCAM
ERR -VE
ERR +VE
SHORT R
BIAS R-
BIAS R+
+R Input
-R Input
Out R
PLD
NLD
Right Channel
L281 CT3 R Channel.SchDoc
ERR -VE
ERR +VE
+SL Input
-SL Input
Out SL
SHORT SL
BIAS SL-
BIAS SL+
NLD
PLD
Surround Left
L281 CT4 SL Channel.SchDoc
ERR +VE
ERR -VE
+SR Input
-SR Input
Out SR
BIAS SR+
BIAS SR-
SHORT SR
NLD
PLD
Surround Right
L281 CT5 SR Channel.SchDoc
ERR -VE
ERR +VE
+BL Input
-BL Input
Out BL
BIAS BL+
BIAS BL-
SHORT BL
NLD
PLD
Back Left
L281 CT6 BL Channel.SchDoc
ERR -VE
ERR +VE
+BR Input
-BR Input
Out BR
BIAS BR+
BIAS BR-
SHORT BR
NLD
PLD
Back Right
L281 CT7 BR Channel.SchDoc
ERR -VE
ERR +VE
SHORT L
BIAS L+
BIAS L-
-L Input
+L Input
Out L
NLD
PLD
Left Channel
L281 CT2 L Channel.SchDoc
ERR -VE
ERR +VE
+C Input
-C Input
Out C
BIAS C+
BIAS C-
SHORT C
PLD
NLD
Centre Channel
L281 CT8 C Channel.SchDoc
2W
R2
4R7
L1
0.5uH
SPK L
2W
R5
4R7
L2
0.5uH
SPK R
P2
P1
P3
P7
P9
2W
R7
4R7
L3
0.5uH
2W
R9
4R7
L4
0.5uH
2W
R12
4R7
L5
0.5uH
2W
R13
4R7
L6
0.5uH
2W
R17
4R7
L7
0.5uH
P8
P11
P17
P20
P26
P29
SPK SL
SPK SR
SPK BL
SPK BR
SPK C
SPK MUTE
D4
BAS21LT1
0W063
R20
100K
DGND
0W125
R19
2K2
P35
P31
P12
P18
P21
P27
P30
TO XLR/PREAMP PCB
+30V
+55V
-30V
-55V
NLD
PLD
FROM LIFTER PCB
STARGND DEC
+VLIFT
-VLIFT
1
2
3
4
5
6
7
8
44472
CON4
MOLEX
-VLIFT
+VLIFT
STARGND
STARGND
STARGND
STARGND
P40
P39
STARGND DEC
DGND
GND_B
+L Input
-L Input
+R Input
-R Input
+SL Input
-SL Input
+SR Input
-SR Input
+BL Input
-BL Input
+BR Input
-BR Input
+C Input
-C Input
AGND
+30V
+14V
-14V
-30V
TR4
TIP31C
TR6
TIP32C
0W125
R21
10R
0W125
R25
10R
2W
R18
100R
STARGND DEC
STARGND DEC
P46
P43
P45
P41
P38
P32
P36
P37
P33
P44
P10
P16
P19
P23
P28
+30V
SPK MUTE
D3
BAS21LT1
0W063
R15
100K
DGND
0W125
R14
2K2
P25
P22
+30V
AGND
RETURN R
RETURN C
RETURN BR
RETURN BL
RETURN SR
RETURN SL
RETURN L
STARGND
15V
DZ1
BZX84C
15V
DZ2
BZX84C
SPK MUTE
D1
BAS21LT1
0W063
R4
100K
DGND
0W125
R3
2K2
P5
P6
P4
+30V
SPK MUTE
D2
BAS21LT1
0W063
R10
100K
DGND
0W125
R8
2K2
P15
P13
+30V
PA SHORT*
DC OFFSET
ERR +VE
ERR -VE
SHORT R
SHORT L
SHORT BR
SHORT C
SHORT BL
SHORT SR
SHORT SL
Protection
L281 CT9 Protection Circuitry.SchDoc
PA SHORT*
DC OFFSET
+14V
AGND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
52806
CON1
MOLEX
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
52806
CON2
MOLEX
LIFT TEMP T2
LIFT TEMP T1/AC FAIL*
-14V
BIAS L+
BIAS L-
BIAS R+
BIAS R-
BIAS L
BIAS R
BIAS BR-
BIAS SL
BIAS SL-
BIAS BL-
BIAS SR-
BIAS SR+
BIAS BL+
BIAS BR+
BIAS C
BIAS BL
BIAS BR
BIAS C+
BIAS C-
BIAS SL+
BIAS SR
Bias Circuit
L281 CT10 Bias Circuit.SchDoc
BIAS L+
BIAS L-
BIAS R+
BIAS R-
BIAS SL+
BIAS SL-
BIAS SR+
BIAS SR-
BIAS BL+
BIAS BL-
BIAS BR+
BIAS BR-
BIAS C+
BIAS C-
BIAS SL
BIAS SR
BIAS BL
BIAS BR
BIAS C
BIAS L
BIAS R
BIAS L+
BIAS L-
BIAS R+
BIAS R-
BIAS SL+
BIAS SL-
BIAS SR+
BIAS SR-
BIAS BL+
BIAS BL-
BIAS BR+
BIAS BR-
BIAS C+
BIAS C-
RETURN L
RETURN R
RETURN SL
RETURN SR
RETURN BL
RETURN BR
RETURN C
Blank PCB L281PB AMP019 AMP PCB
L281PB
PCB1
1
1
2
3
VH
CON5
JST
HS1A
NLD
PLD
NLD
PLD
NLD
PLD
NLD
PLD
NLD
PLD
NLD
PLD
NLD
PLD
HS2A
SPK L
SPK R
SPK SL
SPK BR
SPK BL
SPK SR
SPK C
0W25
R1
180R
0W25
R6
180R
0W25
R11
180R
0W25
R16
180R
TR1
MMBTA42L
TR2
MMBTA42L
TR3
MMBTA42L
TR5
MMBTA42L
DH
SK2
Donghe Metal & Plastic
DH
SK3
Donghe Metal & Plastic
DH
SK1
Donghe Metal & Plastic
63V
C1
100UF
63V
C6
100UF
50V
C2
10UF
50V
C4
10UF
25V
C3
100UF
25V
C5
100UF
2W
R26
100R
TO PREAMP PCB
GND_A
GND_C
AGND
SP2
STARLINK
STARLINK
GND_R
GND_ZC
GND_BR
GND_BL
GND_SR
GND_SL
GND_L
SP1
STARLINK
STARGND DEC
STARGND DEC
STARGND DEC
STARGND DEC
STARGND DEC
1
2
3
4
5
6
7
8
XH (VERTICAL)
CON3
JST
1
2
3
4
5
6
XH (VERTICAL)
CON6
JST
SPK MUTE
PA SHORT*
DC OFFSET
LIFT TEMP T2
LIFT TEMP T1/AC FAIL*
BIAS SL
BIAS SR
BIAS BL
BIAS BR
BIAS C
BIAS L
BIAS R
DGND
P63
P68
P70
P71
P73
P74
P69
P67
P77
P14
P57
P60
P75
P76
P50
P48
P42
P24
P53
P55
P58
P79
P80
P51
P64
P66
P65
P72
P62
P61
P81
SPK MUTE
D5
BAS21LT1
0W063
R28
100K
DGND
0W125
R27
2K2
P49
P47
+30V
0W25
R23
180R
TR7
MMBTA42L
P34
FD1
FD2
+3V3
AGND
3V3 2%
DZ8000
BZX384B
50V
C8000
100N
0W25
R8000
6K8
P8000
18_E048
PK
28/11/18
F.0
No changes to this sheet
1
2
M20-973
CON7
HARWIN
2W
R30
100R
2W
R29
100R
0W25
R22
3K3
0W25
R24
3K3
2W
R31
100R
+3V3
SPK MUTE
19_E007
JH
11/02/2019
G.0
No changes to this sheet
19_E027
PK
20/05/19
1.0
No changes to this sheet
20_E002
PK
06/01/20
2.0
PCB change only
G2R-2A
RLY2A
Omron
G2R-2A
RLY2B
Omron
G2R-2A
RLY2C
Omron
G2R-2A
RLY3A
Omron
G2R-2A
RLY3B
Omron
G2R-2A
RLY3C
Omron
G2R-2A
RLY4A
Omron
G2R-2A
RLY4B
Omron
G2R-2A
RLY4C
Omron
G2R-2A
RLY5A
Omron
G2R-2A
RLY5B
Omron
G2R-2A
RLY5C
Omron
G2R-2A
RLY1A
Omron
G2R-2A
RLY1B
Omron
G2R-2A
RLY1C
Omron
21_E001
PK
12/01/21
3.0
Change speaker relays
Summary of Contents for HDA PA720
Page 1: ...SERVICE MANUAL POWER AMPLIFIER PA720 ISSUE A ...
Page 2: ...EN 2 Revision History Issue A Initial release ...
Page 14: ...EN 14 EN 14 L281 Power Amplifier PCB Issue 3 ...
Page 36: ...EN 36 EN 36 L282 Pre amp PCB Issue 2 ...
Page 50: ...EN 50 EN 50 L283 PSU PCB Issue 1 ...
Page 54: ...EN 54 L284 Lifter PCB Issue 1 ...
Page 59: ...EN 59 L285 Front Panel PCB Issue 1 ...
Page 62: ...EN 62 Overall Dimensions ...
Page 64: ...EN 64 Exploded Drawings ...