EN-27
ISSUE
DRAWING NO.
DRAWING TITLE
DATE
Filename:
ECO No.
DESCRIPTION OF CHANGE
L281 CT2 L Channel.SchDoc
AMP019 Amp L
Contact Engineer:
L281CT
15/01/2021
INITIALS
Printed:
2
9
Sheet
of
Notes:
Contact Tel:
01223 203201
Jon Henderson
A & R Cambridge Ltd.
Cambridge CB25 9QE
Waterbeach
A3
ARCAM
AGND
Op Amp Decoupling
50V
C1043
100N
50V
C1044
100N
50V
C1046
100N
50V
C1047
100N
50V
C1042
10UF
50V
C1045
10UF
+14V
-14V
TOOL1000 TOOL1001
1
FIX1000
Dia 3.2mm
1
FIX1001
Dia 3.2mm
TOOL1002 TOOL1003
LIN
RV1000
1K
AGND
AGND
TR1005
BC856B
10
0V
C
10
14
82
P
AGND
TR1023
BC846B
10
0V
C
10
30
82
P
TR1002
2SC2690A
TR1021
KSA1220A
TR1001
MMBTA42L
TR
10
24
M
M
B
TA
92
L
0W
12
5
R
10
28
33
R
0W
12
5
R
10
96
33
R
0W
12
5
R
10
43
56
0R
0W
12
5
R
10
73
56
0R
0W125
R1030
10R
0W
12
5
R
11
10
22
R
0W
12
5
R
10
11
22
R
GND_B
GND_B
TR1003
2SC2690A
TR1018
KSA1220A
D
10
06
S
1D
D
10
10
S
1D
63V
C1008
22UF
63V
C1033
22UF
100V
C1005
1uF
GND_A
100V
C1032
1uF
GND_A
+VLIFT
-VLIFT
2W
R
10
55
0.18R
2W
R
10
65
0.18R
2W
R
10
64
0.18R
2W
R
10
54
0.18R
2W
R
10
53
0.18R
2W
R
10
63
0.18R
+Input L
-Input L
0W5
R1035
1R0
2
3
1
8
4
IC1000A
OPA1652AIDR
AGND
-14V
+14V
0W063
R1004
10K
AGND
D1000
BAV99
ERR +VE
ERR -VE
100V
C1001
470N
20C/W
HS1000A
5400-9130+0
20C/W
HS1001A
5400-9130+0
TR1014A
NJL1302DG
TR
10
14
B
N
JL
13
02
D
G
0W5
R1086
1R0
0W
12
5
R
10
68
10
0K
1206
FS1000
7.0A
1206
FS1001
7.0A
GND_L
1
2
8mm
J1000
LINK
1
2
8mm
J1002
LINK
1
2
8mm
J1003
LINK
1
2
8mm
J1004
LINK
1
2
8mm
J1005
LINK
1
2
8mm
J1007
LINK
1
2
8mm
J1001
LINK
1
2
8mm
J1006
LINK
-L Input
NF
AGND
P
10
65
P1059
P1074
P1066
P1055
P1056
P1035
P1041
P1017
P1064
P
10
92
P1044
P1029
P1060
P
10
32
P
10
42
P1026
P1048
P
10
24
P1099
P1061
P1100
P1080
P1079
P1073
P1105
P1096
P1109
P1115
P1114
P1107
P1108
P1098
P1116
P
11
18
P1002
P1011
P1005
P1006
P1001
P1004
P
10
10
P
10
16
P1063
P1078
P1111
P1015
P1023
P1037
P1020
P
10
18
P1013
P1014
P1019
P1028
P1049
P1030
P1025
P1057
P1027
P1022
P1031
P1040
P1043
P
10
50
P
10
72
P1076
P1090
P
10
89
P1085
P1088
P1036
P1039
P1054
P1095
P1091
P1103
P1102
P1086
P1094
P1101
P1077
P
11
10
P1113
P1097
P1068
P
11
04
P1058
P1093
10
0V
C
10
24
10
0N
100V
C1020
100N
FILM
-L Input
Out L
Out L
1
2
M20-973
CON1000
HARWIN
SHORT L
SHORT L
TR1000
MMBTA42L
25V
C1000
1uF
P1000
P1003
P1008
Bias measurement
ERR +VE
ERR -VE
BIAS L+
BIAS L-
BIAS L+
BIAS L-
D
10
03
N
S
R
10
20
D
10
12
N
S
R
10
20
-14V
+14V
D1004
NSR1020
+14V
50V
C1007
100N
AGND
50V
C1012
100N
5V6
DZ1000
BZX84C
0W125
R1041
220K
AGND
+14V
-14V
50V
C1037
100N
5V6
DZ1003
BZX84C
25
V
C
10
35
1U
F
25
V
C
10
13
1U
F
-14V
+14V
AGND
AGND
P1083
+L Input
+L Input
5
3
4
TR
10
10
B
B
C
84
6B
D
2
6
1
TR
10
10
A
B
C
84
6B
D
2
6
1
TR
10
12
A
B
C
84
6B
D
5
3
4
TR
10
12
B
B
C
84
6B
D
2
6
1
TR
10
22
A
B
C
84
6B
D
2
6
1
TR
10
20
A
B
C
84
6B
D
4
3
5
TR
10
04
A
B
C
85
6B
D
4
3
5
TR
10
07
A
B
C
85
6B
D
1
6
2
TR
10
16
B
B
C
85
6B
D
4
3
5
TR
10
16
A
B
C
85
6B
D
4
3
5
TR
10
19
A
B
C
85
6B
D
1
6
2
TR
10
19
B
B
C
85
6B
D
1
6
2
TR
10
04
B
B
C
85
6B
D
5
3
4
TR1020B
BC846BD
5
3
4
TR
10
22
B
B
C
84
6B
D
1
6
2
TR1007B
BC856BD
100V
C1009
1N0
AGND
-14V
AGND
0W
12
5
R
10
99
22
0K
AGND
TR1017
KSC3503
TR1011
KSA1381
GND_C
P
10
09
P1007
P1012
0W25
R1005
68R
GND_C
P
11
19
P
11
20
P
11
17
0W25
R1117
68R
TR1009
BC846B
TR1008
BC856B
TR1015
BC846B
TR1013
BC856B
50V
C1021
10UF
50V
C1018
10UF
0W25
R1036
12K
0W25
R1088
12K
0W
25
R
10
34
12
K
0W
25
R
10
90
12
K
D1005
BAS21LT1
D1009
BAS21LT1
P1082
P1081
P
10
87
P
10
33
P1034
P1051
P1069
P1045
P1075
P1070
P1053
P1052
P1071
P1038
P1084
27V
DZ1001
GLZ
27V
DZ1002
GLZ
D
10
07
B
A
V
19
9
D
10
08
B
A
V
19
9
100V
C1002
220UF
100V
C1039
220UF
0W1
0.10%
R1059
1K0
0W1
0.10%
R1089
1K0
50V
C1016
470P
50V
C1026
470P
D1001
NSR1020
D1014
NSR1020
0W
25
R
10
46
68
R
0W
25
R
10
69
68
R
N
F
N
F
N
F
50V
C1010
22N
50V
C1029
22N
100V
C1019
150P
100V
C1028
150P
100V
C1017
33P
100V
C1027
33P
D
10
13
N
S
R
10
20
-55V
+55V
R
E
D
LE
D
10
01
06
03
R
E
D
LE
D
10
00
06
03
0W
06
3
R
10
71
68
R
0W
06
3
R
10
72
68
R
0W
06
3
R
10
98
1K
5
0W
06
3
R
10
17
1K
5
0W
06
3
R
10
08
5K
1
0W063
R1003
3M3
0W063
R1012
20K
0W
06
3
R
10
66
15
K
50V
C1015
100N
0W063
R1108
360R
50V
C1038
100N
0W
06
3
R
11
00
4K
7
50V
C1040
1N0
0W
06
3
R
11
14
1K
5
50V
C1031
100N
0W
06
3
R
10
74
1K
5
0W
06
3
R
10
83
68
R
0W
06
3
R
10
84
68
R
0W
06
3
R
10
39
4K
7
0W
12
5
R
10
94
6K
8
0W
12
5
R
10
60
6K
8
0W
06
3
R
11
09
1K
5
0W063
R1107
68R
0W
06
3
R
11
12
1K
0
0W
06
3
R
11
16
47
R
0W063
R1111
100R
100V
C1041
1uF
50
V
C
10
34
1N
0
AGND
0W
06
3
R
10
70
0R
0
0W063
R1057
0R0
0W063
R1058
0R0
0W
06
3
R
10
26
1K
0
0W063
R1032
68R
0W
06
3
R
10
27
47
R
0W125
R1097
10K
0W125
R1040
10K
0W063
R1031
100R
100V
C1006
1uF
AGND
50
V
C
10
11
1N
0
N
F
N
F
0W063
R1015
10R
0W063
R1105
10R
0W
06
3
R
10
48
22
0R
N
F
0W063
R1016
10R
0W063
R1106
10R
100V
C1036
220N
100V
C1004
220N
0W
06
3
R
10
29
22
0R
0W
06
3
R
10
93
22
0R
0W063
R1101
3K3
0W063
R1019
3K3
0W063
R1047
0R0
0W063
R1050
0R0
0W063
R1033
1K0
0W063
R1085
1K0
0W
06
3
R
10
44
43
0R
0W
06
3
R
10
76
43
0R
0W
06
3
R
10
45
2K
7
0W
06
3
R
10
77
2K
7
0W
06
3
R
10
01
10
K
0W063
R1000
4K7
0W063
R1038
330R
0W063
R1079
330R
0W
25
R
10
67
2K
7
0W
25
R
10
80
2K
7
0W
06
3
R
10
25
1K
5
0W
06
3
R
10
95
20
R
TH
10
01
10
0R
@
25
C
TH
10
00
47
k@
25
C
TH
10
02
47
k@
25
C
N
F
NF
N
F
NF
N
F
N
F
NF
0W5
R1024
0R47
0W5
R1023
0R47
1W
R1102
47R
1W
R1006
47R
1W
R
10
37
1K
5
1W
R
10
91
1K
5
2W
R
10
75
3R
3
100V
C1003
22P
1
FIX1002
Dia 3.2mm
1
FIX1003
Dia 3.2mm
FIX1005
Dia 4.0mm
FIX1006
Dia 4.0mm
FIX1007
Dia 4.0mm
TR1006A
NJL3281DG
TR
10
06
B
N
JL
32
81
D
G
AGND
0W063
R1002
1K0
0W063
R1007
1K0
P1127
P1047
P1062
P1123
P1125
P1126
P1128
P1134
P1130
P1135
P1136
P1131
P1129
P1121
P1122
P1133
P1132
P1124
P
11
37
P1112
P
10
46
P
10
67
TR1025
MMBTA42L
+55V
TR
10
26
M
M
B
TA
92
L
-55V
PLD
PLD
P
10
21
0W125
R1103
47K
-55V
0W063
R1020
47R
D1002
BAS21HT1G
P
11
06
NLD
NLD
0W125
R1118
47K
+55V
0W063
R1104
47R
D1011
BAS21HT1G
50V
C1023
22UF
2
3
1
8
4
IC1001A
LM4562MA
6
5
7
IC1001B
LM4562MA
0W125
Thin Film
R1013
15K
0W125
Thin Film
R1014
15K
0W
06
3
R
10
21
27
0R
0W
06
3
R
10
22
3K
3
100V
C1022
22P
100V
C1025
22P
0W
06
3
R
10
81
18
0R
0W
06
3
R
10
49
10
R
18_E048
PK
28/11/2018
F.0
Amplifier improvements
19_E007
JH
11/02/2019
G.0
Rx113 changed to 360R
0W063
R1113
360R
FIX1008
1
FIX1004
1
0W
06
3
R
10
18
6K
8
0W
06
3
R
11
15
6K
8
0W
12
5
R
10
82
22
0K
0W125
Thin Film
R1010
10K
0W
06
3
R
10
51
4R
7
0W
06
3
R
10
61
4R
7
0W
06
3
R
10
52
33
0R
0W
06
3
R
10
62
33
0R
NF
NF
NF
NF
0W125
R1092
4R7
19_E027
PK
20/05/19
1.0
Value changes protection and compensation
0W
1
0.
10
%
R
10
09
30
K
0W1
0.10%
R1056
3K0
0W1
0.10%
R1087
3K0
0W1 0.10%
R1042
2K0
0W1 0.10%
R1078
2K0
20_E002
PK
06/01/20
2.0
PCB change only
21_E001
PK
12/01/21
3.0
No change to this sheet
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 ...