McIntosh C2300, Service Manual

Page: 11 / 40

C2300
17 18
MAIN
750761 SCH 5 OF 6
2E
0V
0V
0V
0V
0V
.3V
-.5V
-3.7V
0V
0V
1
1
1
0V
0V
0V
.3V
-.5V
1
0V
0V
LEFT
DGND
-3.7V
LEFT
-3.7V
-3.7V
4.75k
R115
LEFT
METER DRIVER
LEFT METER
RIGHT -
RIGHT +
LEFT -
J22:2
RIGHT
LEFT
47uF
C66
RIGHT
.1
uF
C
64
806
R94
47uF
C65
D
1
22
0u
F
C
69
D6
D7
D11
RIGHT
D10
D9
D
13
D
12
3
1
2
Q39
METER DRIVER
4.75k
R114
LEFT
J23:1
J23:2
LEFT +
J22:1
47.5
R95
D8
3
1
2
Q40
1M
R
11
0
1M
R
11
1
3
2
1
Q44
3
2
1
Q43
3
1
2
Q45
3
1
2
Q46
RIGHT METER
METER BUFFER
LEFT METER
LOG CONVERTER
METER BUFFER
METER RECTIFIER
.2
2u
F
C
71
RIGHT METER
METER
ON/OFF CONTROL
D5
100k
R99
LOG CONVERTER
806
R97
2
3
1
-
+
8
4
B+
B-
U10:1
.1
uF
C
67
.1
uF
C
68
8
10
9
+
-
U11:3
D3
100k
R98
806
R96
100k
CCW
1
2
3
R107
1u
F
C
72
.2
2u
F
C
73
10
0k
R
10
5
22.1k
R101
100k
CCW
1
2
3
R106
1u
F
C
70
10
0
R
10
8
DGND
METER RECTIFIER
10
0k
R
10
3
22.1k
R100
METER
ON/OFF CONTROL
D4
7
5
6
+
-
U11:2
D2
6
5
7
-
+
U10:2
10
0
R
10
9
3
2
1
Q42
1
3
2
+
-
4
11
B+
B-
U11:1
3
2
1
Q41
14
12
13
+
-
U11:4
10k
R116
10k
R117
-5V
10V
10V
-5V
15V
-15V
-5V
10V
METER_MUTE
L_MAIN
R_MAIN
10V
-5V
-15V
15V
2.
21
R
11
3
15K
R38
D30
2.
21
R
11
2
15K
R37
806
R249
806
R250
.01uF
C170
.01uF
C169
22
1k
R
25
1
22
1k
R
25
2
LEFT METER
ADJUST
RIGHT METER
ADJUST
METER CALIBRATION PROCEDURE
APPLY A 1kHz SIGNAL TO BOTH CHANNELS. ADJUST THE LEVEL FOR 2.5VAC
AT L AND R MAIN UNBALANCED OUTPUT. ADJUST R106 FOR 0dB ON THE
LEFT METER. ADJUST R107 FOR 0dB ON THE RIGHT METER.