McIntosh C2500 Service Manual

TUBE PREAMPLIFIER
C2500
25
26
3
CONTROL
751457 SCH 4 of 5
Power_Relay
133717, 1.25A
OPEN
C35
VFD 5V8V_UNREG
VFD PS ON
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U13
47.5K
R46
INFO VFD PS
133717, 1.25A
3.3V BU
+VBU
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U14
100K
R51
3.3V BACKUP PS
Atmel micro
Front/Rear IR Sensors
Standby LED
Power Control In
440mA Max
12
L9
12
L10
133717, 1.25A
8V_UNREG
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U10
47.5K
R39
133717, 1.25A
8V_UNREG
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U11
100K
R44
133717, 1.25A
C16
.1UF
C15
50k internal pulldown
Low = Enable
High = Disable
18V
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U6
221K
R21
1K
R13
3.3V MISC
15V
? mA Max
60mA Max?
100mA Max ?
12
L7
12
L8
12
L5
5V MISC
15V
3.3V
5V
Fiber optic LEDs
Mute Relays
Audio Switching
Audio Outputs
22.1R22
22.1
R41
GP3:1
GP3:2
GP3:3
GP3:4
470uF
C34
470uF
C39
470uF
C26
470uF
C30
133724
1
2
4
53
VCC
GND
U15
3
1
2
Q26
DGND DGND
2.21K
R48
.1UF C38
DGND
3.3V BU
LVC NAND
3.3V B U
DGND
.1UFC43
3.3V BU
Pwr_Supply
DGND
High=Off, Low=On
10K
R47
3.3V BU
10uF
C37
0.1 sec delay
AC PwrUp noise filter
40mA Max
LVC AND
470uF
C41
Power_On
133502
4
2
1
3
B+
GND
5
U16
(During Standby)
OPEN
R34
.1UFC22
-18V
1.82K
R31
10K
R30
1K
R32
-15V
? mA Max
12
L6
-15V
Audio Switching
Audio Outputs
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4
5
U9
USB Audio
USB Audio
HS4
Power_On
Power_On
Data In
4
2
1
3
B+
GND
5
U12
3
1
2
NP1
DGND
.1UF
NP2
150K
R40
AC DETECTOR
.1UF
C29
100K
R37
3
1
2
Q25
AC DET
DGND DGND
DGND
DGND
3.3V
3.3V 3.3V
133717, 1.25A
18V
IN
ON/OFF
OUT
GND ADJ
___
TAB
1
6
2
3
4 5
U29
56.2K
R176
12V P.C.
125mA Max
12
L29
12V_PC
470uF
C71
Power Control
Power_On
Logic Gates- ON Mode
22.1
R20
Power_On
22.1R36
Power_On
18.2K
R23
J24:1
J24:3
7
POWER
RLY
7
TO BACKUP PS
7
+VBU
GND
J24:2
+VBU
Vout = 1.24x
(1+R1/R2)
USB PCB
USB PCB
AC WINDING
220uF
C12
220uF
C13
J6:2
J6:6
J6:3
J6:4
J6:1
J6:7
18V
8V_UNREG
8V_UNREG
18V
J7:3
J7:7
J7:1
J7:6
J7:4
J7:2
-18V
-18V
AC WINDING
POWER TEST LEDs
DGND
DS6
10K
R238
VFD 5V
12V_PC
3.3V BU
15V
3.3V
5V
DS2
22.1K
R220
DS3
47.5K
R218
DS4
10K
R236
DS5
22.1K
R237
DS7
47.5K
R239
4 5
6
2 1 3
S1
15V
1KR274
LED Hold-off Bias
DGND
J7:5
J6:5
8
8
8
8
8
8
8
8
8
8
8
8
8
8
No Pop
No Pop
ON OFF
15V
OPEN
R275
50k internal pulldown
Low = Enable
High = Disable
50k internal pulldown
Low = Enable
High = Disable
50k internal pulldown
Low = Enable
High = Disable
50k internal pulldown
Low = Enable
High = Disable
50k internal pulldown
Low = Enable
High = Disable
50k internal pulldown
Low = Enable
High = Disable
.1UF
C23
.1UFC28
.1UF
C32
.1UF
C36
.1UF
R52
OPEN
.1UF
C73
.1UF
C42
R38
150K
C27
100pF
R42
R42
C78
332K
332K
100pF
R45
150K
R49
332K
C40
100pF
R50
332K
R174
1M
R175
1M
C72
100pF

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