McIntosh C2500 Service Manual page 10

2 DISPLAY
751456 SCH 4 OF 4
Left Pushbutton PCB
PROC
S2
J6:4
J6:5 J6:2 J6:1 J6:6 J6:3 J6:11
PB SPARK GND-L
Also conn ects to switch tab g round.
4 5 2 1 6 3 11
To Left Pushbutton PCB
This Grou nd con nects to th e Ch assis.
9 8 11 12 7 10 2
J2:10 J2:2
J2:9 J2:8 J2:11 J2:12 J2:7
R55
10K
MH3
SPARK GND-L
Chassis h ole f o r Sp ark Grou nd
TONE BYPASS TRIM
S3 S4
J6:9 J6:10
J6:7 J6:8 J6:12
PB SPARK GND-R
Also con nects to switch tab g round.
7 9 10 8
12
6 4 3 5 1
J2:6 J2:4 J2:3 J2:5 J2:1
R46 R53
ADC-VREF-L
10K 10K
Button Common
Vout LT Levels
3.3V = Open
2.5V = Not used
2.2V = Proc
1.6V = Bypass
0V = Trim
15
Right Pushbutton PCB
MUTE OUT 1 OUT 2
S5 S6 S7
J10:9 J10:10 J10:8 J10:12
J10:4 J10:5 J10:2 J10:1 J10:6 J10:3 J10:11 J10:7
4 5 2 1 6 3 11 7 9 10
To Right Pushbutton PCB
This Ground connects to the Chassis.
9 8 11 12 7 10 2 6 4
J3:4
J3:9 J3:8 J3:11 J3:12 J3:7 J3:10 J3:2 J3:6 J3:3
R57
R13 R47
10K 10K 10K
MH10
Button Common
SPARK GND-R
Chassis hole for Spark Ground
R51 R58
1
22.1K 10K
D1
SPARK GND-R
STANDBY
S8
12
8
Left Pushbutton A/D Buffer
R64 22.1
3.3V
C4
.1µF
C3
ON Button +
10µF
3 5 1
J3:5 J3:1
100
3.3V BU
R12
R7
ADC-VREF-R
10K
Vout RT Levels
3.3V = Open
2.5V = Mute
2.2V = Out1
Vout RT
1.6V = Out2
0V = Standby/On
ON/RESET
To Push&Hold reset circuit on Control PCB.
Right Pushbutton A/D Buffer
This Transister buffers the Standby button for the A/D matrix
R65 22.1
Q5
3.3V
C57
.1µF
C58
10µF
16
2
-
R66
B+
1
LEFT PB AD
3 B-
22.1
+
Vout LT
C50
U1:1
.1µF
6
-
7
5
+
U1:2
2
-
R67
B+
1
RIGHT PB AD
3 B- 22.1
Vout RT +
C55
U3:1
.1µF
6
-
7
5
+
U3:2