McIntosh C2500 Service Manual

63
64
9
TUBE 751461 SCH 1 of 3
1.2V
0V
LEFT
2B
2B
2B
J2:10
J2:11
J2:12
TO MAIN
2B J2:9
TO AUDIO PCB
475k
R6
475k
R5
.047µF
C6
.047µF
C5
GND
GND
1.2V
0V
PHONO AMP
0V
105V
PHONO AMP
R MM OUT
GND
J4:2
J4:1
2B
2B
J3:1
J3:2 2B
2B
953
R3
86V
47pF
C2
RIGHT
953
R1
86V
47pF
C1
.001uF
C9
75k
R8
1V
2.21M
R10
12AX7A
8
6
7
V2:2
.001uF
C8
75k
R7
1V
2.21M
R9
4.75k
R12
12AX7A
8
6
7
V1:2
10µF
C7
2.21k
R19
105V
33.2k
R22
2.21k
R18
33.2k
R20
DS6
4.75k
R75
4.75k
R76
MM-OUT-GND
GND
L MM OUT
6.49k .5%
R4
6.49k .5%
R2
4.75k
R13
267k
R16
47.5k
R11
267k
R14
2
1
3
Q2
2
1
3
Q1
#132352
DS5
3
1
2
Q8
DS3
R MM IN
L MM IN
10
R77
12AX7A
5
9
4
V1:3
12AX7A
5
9
4
V2:3
J2:2
J2:1
12AX7A
3
2
1
V2:1
J1:1
J1:2
12AX7A
3
2
1
V1:1
.0033µF
C11
1M
R17
100µF
C13
1µF
C15
.0033µF
C10
1M
R15
1µF
C14
J4:1
J4:5
J4:3
J4:7
TUBE_LED
157V
157V
157V
157V
18V 18V
145V
145V
145V157V
18V
10pF
C55
10pF
C56
100µF
C12
10k
R80
10k
R21
12AX7A
5
9
4
V3:3
-18V
Pulled high on Audio PCB
thru 10k pullup
156V
156V
0V
0V
18V
8
8
8
8
J5:7
8
J5:6
8
J5:5
J5:4
J5:1
-18V
18V
-18V
8
J5:8
8
J5:2
J5:3
J5:1
J5:7
J5:8
J5:2
J5:6
J5:4
J5:5
J5:3
157V
18V
-18V
TO POWER SUPPLY
47.5kR26
Rename high voltage nets to closely match measurements
1k
R87
1k
R88
47µF
C3
47µF
C4
18V
18V
DS4
DS2
DS1
(SHEILD ONLY)

McIntosh C2500 Specifications

General

Total Harmonic Distortion	0.08%
Signal to Noise Ratio	100dB
Rated Output Voltage	2.5V unbalanced, 5V balanced
Maximum Output Voltage	8V unbalanced, 16V balanced
High Level Voltage Gain	15dB
Type	Vacuum Tube Preamplifier
Inputs	6 unbalanced, 2 balanced, 1 phono MC, 1 phono MM
Outputs	3 unbalanced, 2 balanced
Weight	29 lbs (13.2 kg)
Input Impedance	47k ohms
Phono Voltage Gain	40dB (MM), 60dB (MC)
Frequency Response	+0, -0.5dB from 20Hz to 20, 000Hz +0, -3dB from 10Hz to 100, 000Hz