McIntosh MA2275 User manual

SERVICE MANUAL
Performance Specifications ........................................ 2
Notes ......................................................................... 2
Rear Panel .................................................................. 3
Section Location ........................................................ 4
BlockDiagram ...................................................... 5 - 7
Interconnection Diagram .................................... 8 - 10
Main Schematic and PCB................................. 11 - 16
Control Schematic and PCB ............................. 17 - 20
Balanced Schematic and PCB ........................... 21 - 22
Volume/Tone Schematic and PCB ..................... 23 - 26
Data Schematic and PCB................................... 27 - 28
Pushbutton Schematic and PCB ........................ 29 - 30
Amplifier Schematic and PCB............................ 31 - 34
Power Supply Schematic and PCB..................... 35 - 38
Meter Schematic and PCB ................................. 39 - 40
Backup PS Schematic and PCB ................................ 41
Terminal Schematic and PCB ................................... 42
Parts List ............................................................ 43 - 48
ExplodedView and Parts List ............................. 49 - 52
Repacking Instructions ............................................. 53
CONTENTS
TUBE
INTEGRATED AMPLIFIER

PERFORMANCE SPECIFICATIONS
2
1. The heavy lines on the schematic denote the primary
signal path.
2. Unless otherwise noted, all voltages indicated on the
schematics are measured under the following conditions:
a. ACinputat120volts,50/60Hz.
b. All voltages are +/-10% with respect to ground. A
high impedance (10 megaohm) voltmeter must be used.
3. Unless otherwise specified:
a. Resistor values are in ohms.
b. Capacitorvaluesaremicrofarads(uF).
c. Inductor values are in microhenries (uH).
4. On PC board drawings, Square pad indicates:
a. PolarizedCapacitors-Positive
b. Diodes - Cathode
c. Others - Pin 1
5. WARNING
Parts marked with the symbol have critical
characteristics. Use only replacement parts recom-
mended by the manufacturer.
NOTES
Power Output
Minimum sine wave continuous average power output per
channel, both channels operating is:
75 watts into a 2 ohm load
75 watts into a 4 ohm load
75 watts into an 8 ohm load
RatedPowerBand
20Hz to 20,000Hz
Total Harmonic Distortion
Maximum Total Harmonic Distortion at any power level
from 250 milliwatts to rated power output is:
0.5% for a 2, 4 or 8 ohm load
Frequency Response
+0, -0.5dB from 20Hz to 20,000Hz
+0, -3dB from 10Hz to 50,000Hz
Sensitivity
Phono: 4.4mV for 2.5V preamp output
High Level: 450mV for 2.5V preamp output
Power Amplifier Input: 2.5V for rated output
A-Weighted Signal To Noise Ratio
Phono Input: 80dB below 10mV input
High Level: 97dB below rated output
Power Amplifier: 110dB below rated output
Intermodulation Distortion
Maximum Intermodulation Distortion if instantaneous
peak output does not exceed twice the rated output, for
any combination of frequencies from 20Hz to 20,000Hz is:
0.5% for a 2, 4 or 8 ohm load
InputImpedance
Phono: 47k ohms, 65pF
High Level: 22k ohms
Maximum Input Signal
Phono: 90mV
HighLevel: 8V
Preamplifier Maximum Voltage Output
Phono: 8V
HighLevel: 8V
Main Out: 8V at preamp output
Voltage Gain
High Level to Tape output: 0dB
High Level to Preamp output: 15dB
Wide Band Damping Factor
Greater than 18
Power Requirements
100 Volts, 50/60Hz at 3.6 amps
110 Volts, 50/60Hz at 3.6 amps
120 Volts, 50/60Hz at 3.6 amps
220 Volts, 50/60Hz at 1.8 amps
230 Volts, 50/60Hz at 1.8 amps
240 Volts, 50/60Hz at 1.8 amps
Note: Refer to the rear panel of the MA2275 for the correct
voltage.
Preamplifier Tube Compliment
2 - 12AX7A Phono Circuitry
2 - 12AX7A High Level Circuitry
Power Amplifier Tube Compliment
2 - 12AT7
4 - KT88/6550
Overall Dimensions
Width is 17-3/4 inches (45.09cm), Height is 10-1/8 inches
(25.72cm) including feet, Depth is 18-3/4 inches (47.63cm)
including the Front Panel and Knobs
Weight
77 pounds (35 kg) net, 110 pounds (50 kg) in shipping
carton

3
MA2275
TOP AND REAR VIEWS
PHONO
GND
EXT SENSOR
POWER
AMP IN
T 4AL 250V
SLO-BLO
120V 50/60Hz 3.6A
PREAMP TAPE
OUTPUTS
POWER CONTROL
SUM
DATA PORTS
MAIN ACC
SERIAL
NUMBER
MA2275
McINTOSH LABORATORY, INC.,
BINGHAMTON, NY MADE IN USA
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION FOR CONTINUED PROTECTION
AGAINST FIRE HAZARD REPLACE ONLY WITH SAME
TYPE AND RATING FUSE.
CD INPUT
INTEGRATED AMPLIFIER
L
R
L
R
DVD TUNER CD 2CD
INPUTS
TAPE
12
AVIS RISQUE DE CHOC ELECTRIQUE - NE PAS
OUVRIR. REMPLACER PAR UN FUSIBLE DE MEME
TYPE, AMPERAGE ET VOLTAGE.

4
SECTION LOCATIONS
BOTTOM VIEW WITH COVER REMOVED
510
POWER
TRANSFORMER
METER
PCB
OUTPUT
TRANSFORMER
3
CONTROL
PCB
OUTPUT
TRANSFORMER
VOLUME/TONE
PCB
7
PUSHBUTTON
PCB
8R 8L
AMP
PCB
AMP
PCB
11
BACKUP POWER
SUPPLY PCB
9
POWER SUPPLY
PCB
13
TERMINAL
PCB
2
MAIN
PCB
12
TERMINAL
PCB
6
DATA
PCB
CHOKE
FILTER
4
BALANCED
PCB
1
1
1
1
TOP VIEW WITH COVERS REMOVED

5 76
MA2275
BLOCK DIAGRAM

8109
1
INTERCONNECT

11 1312
MA2275
2A
MAIN 049965 SH 1 OF 2

C20
C58
C43
R96
R95 R23
C15
R6 R15
R5 R4
R11
C2
R17
C16
R35 C31 R1 R10 C42
R44 R3
R12
R43
R45 R27
C32
R42
R64
C53
R73 R72 JMP1
R76
R79 R70 R60
R81 R84 R71 R61 R82 R87 R80
R94 R93
R21
R19
R22
R8
R20
R37
R39
R
40
R77
R66
C19
R56 C59
C46
R68
C45
R69 R63
C71 C69
C82
R46
C41
C24
C84
C85
C26 C25 C28 C27 C17
R30
R24
D4
R91
GP1
U1
U5
R92 R86
J11
R25
K2 K3
R26R34
C3
R2
C11
C5
R9
C7
R18
R74
C73
R32 R28
C35
C36
C33
C40
C37
R41
C30
U3
C34
C1
C6
R14
C8
C12
C86
R16
C10
K21
K1
U4
R29
C68
C39
C38
C29
R33
R38
C67
R62
C56
R59
C50
R83
Q4
Q2
C65
R75
C54
C52
C55
R53 R54
R85
C74
Q1
C81
C79
D2
K7
R13
C76
U9
K9 K8 K11
C4
R7
R36
U2
R90 R89
K13 K12
C61
R65R67
U8
R78
R57 R58
C77 C60
Q3
R51 R50
C72 C70
K16
R55
C48C47
K19
R88
C83
R52
J1
C18 C23
R48
C9
129472
R31
C64
R49
C66
C63
C51
C57
V5 V6
C44
R47
K20
GP2
C80
J7
J6
C13
K6 K10
J3
K17
K18
J10
C75
V4
J5
U6
C62
V7
C49
D1
C14
J8
U11
U7
C78
U10
J4
J2
**
**
Rev. A
CD DVDPH CD2 TUNER TAPE
OUT
TAPE OUT 2 AMP INOUT 1
14 1615
2B
MAIN 049965 SH 2 OF 2

17 18
MA2275
CONTROL 049966
3

19 20
CONTROL 049966
3
R2
R5 Q2 R12
R13
C4
C5
Q1
R6
R15
R17
C2
C1
R1 R8
C3 R22
S1
DS2
DS14
DS13
DS12
JMP1
129473
U4
R11
R9
R21
R23
R19
R16 DS9
R10
DS1
DS4
Y1
J2J1
R20
R24
R18
DS10
DS11
U1
J3
R7
U5
DS7
U3
DS15
DS6
R3
R4
ASSY1
DS5
U2
Rev.A

BALANCED 049967
4
MA2275
21 22

23 24
VOLUME/TONE 049968
5A
VOLUME/TONE 049968
5B

25 26
MA2275
VOLUME/TONE 049968
5
R13
C19 R21
R22 R20
D1
R19R24
C17C20
R25
R6
R5 R2
C4
K1
C16
C13 R14
R15
U2
C14
K4 K2
R16R23
129475 C11
C1
C8
C6
C3
C42
C5
C9
C12
R7
C15
R18 R4
C10
U1
R8 R3
R10
R9
R11
R12
K3
C18
J1
R53 R26
C2
C7
R17 R1
U7
Rev.A

DATA 049969
6
27 28
C5
C1
C4
D3
C2
R13 R16
R14
R19
R22
R8 R7
R5
R2 R10 R20
129476
R23 R6
R3
U4
D2
U3
C3
R11
R21
D1
J8
SP1
J5 J4 J2 J7 J10 J9
R9 R4 R1 R12 R17
R15
U1 U2
R18
J6
SP2
J3 J1 J11
Rev.A

29 30
PUSHBUTTON 049970
7
MA2275
0V
5.6V
NC
3
3
3
3
3
3
3
3
3
3
3
3
J1:18
J1:17
J1:16
J1:13
J1:12
J1:11
J1:8
J1:7
J1:6
J1:3
J1:2
J1:1
15V
5.6V
0V
3
3
3
3
3
3
J1:15
J1:14
J1:10
J1:5
J1:9
J1:4
TO DISPL
TONE BYPASS
STANDBY/ON
324
R1
REC MON
MUTE
REC MON
MUTE
.1uF
C1
MONO
47uF
C2 5.6V
IR SENSOR
5.6V
15V
5.6V
5.6V
5.6V
5.6V
HDPH
GND
FP DATA
15V
REC MON
TONE
MUTE
REC MON
TONE
BYPASS
MUTE
STANDBY/
ON
S4
TONE BYPASS
MONO
S5
100
R2
5.6V
L HDPH
GND
R HDPH
TUBE
WARMUP
MONO
MONO
1
2 3 45
6 7 8
DS8
R14
S1 S2 S3
213
Vcc
Vout
GND
MT1
STANDBY/ON
TUBE WARMUP
5V
J1:2
J1:7
J1:12
J1:17
DS5
DS4
DS2
J1:1
J1:3
J1:6
J1:5
J1:8
J1:11
J1:10
J1:13
J1:16
J1:15
J1:18
DS3
1
3
2
J2
DS1
J1:4
J1:9
J1:14
AY
NC
5.6V
5.6V
0V
0V
0V
0V
499

31 32
AMPLIFIER 049971
8R
L

33 34
AMPLIFIER 049971 8
MA2275
R30
R21
L1
R10
Q7
R32
C1
R17
R14
Q2
R5
R11
R36
R7
R6
R9
R13
J3
J4
J9
Q9
R16
R37
R35
Q8
J1
R33
C10
C8
C2
C7
R8
R34
Q4
Q6
J5
J6
J2
C3
U1
C4
C11 L2
R31
R27
F1
R23
R22
Q5
Q3
R15
R12 R19
R25
129478
C6
R20
R24
C5
V1
J7
V2
R28
V3
Rev.A
YEL GRY
BLU GRN
YEL/WHT BLU/WHT

35 36
POWER SUPPLY 049972
9
11
11
11
11
11
1
1
1
1
1
1
1
1L1
1L1
1
1
RED
14V
-15V
15V
-15V
15V
2
2
2
2
2
2
8L
8L
8L
8L
11
1
1
RED
-24V
24V
2
2
2
8L
8L
J11:6
J11:5
J11:3
J11:2
J11:1
T1
T1
T1
T1
T1
T1
T2L
T2R
GND
GND
5V
D5
24V
300V
100k
R5
TURN/ON
-15V
15V
-24V
300V
FIL_B
AMP_MUTE
-400V
FIL_B
FIL_A
-400V
J5:9
J5:7
14V
J5:6
J5:5
FIL B
J5:4
FILGND
FIL A
J5:1
GND
8R
FIL B J7:6
8R J7:5
FILGND
FIL B
8R J7:2
TURN ON
8R
-400V J7:1
J7:6
J7:5
FILGND
J7:4
FIL A
TURN ON
J7:1
J11:4
T1
T1
5V
.047uF
C13
47uF
C6
2.2k 2w
R10
2
34
1
AC
AC
D1
-24V
4700uF
C14 47uF
C7
-400V
680uF
C4
680uF
C3
10uF
C15
47uF
C5
D3 D2
100k 2w
R2
18k
R1
1uF
C8
100k
R6
3
1
2
G
D
S
Q6
AMP_MUTE
100k
R9
14V
24V
FIL_A
TURN/ON
J5:8
J5:3
TO MAIN
-15V
15V
J5:2
300V
8R
8R
TO R AMP
J7:4
J7:3
FIL B
J7:2
J7:3
-400V
TO BACKUP PS
4700uF
C11 680uF
C9
680uF
C10
10uF
C12
D10 3
1
2Q2
221k
R8
TO L AMP
TO POWER TRANSFORMER
J11:1
POWER ON
POWERON
J11:5
J11:6
BLK J14
BLU D9
BLU/BLK
BLU J8
GRN
GRN/BLK J6
FIL_A
BLU J1
RED J12
RED J13
-24V
POWER ON
POWERON
J18:6
J18:5
J17:6
J17:1
J16:5
J11:3
J11:2
POWER ON
F2
2A
J10
D8
3
1
2IN OUT
U3
F1
2A
J7
D6
2
31 IN OUT
U2
FIL_B
GRN J5
D4
RED
J4
J3
.047uF
C2
J2
1M
R7
-15V
23
1
Q1
J18:8
J18:9
J18:4
J18:3
J18:2
J18:1
AMP MUTE
J17:5
J17:2
J17:3
J17:4
J16:6
AMP MUTE
J16:1
J16:2
J16:3
TURN/ON
AMP_MUTE
1
GP1
J9
J11:4
D7
1
3
2Q3
2.74M
R4
J18:7
J16:4
15V REGULATOR
-15V REGULATOR
300V REGULATOR
100k 2w
R75
100k 2w
R76
POWER AMPLIFIER
TURN ON CONTROL
485V
485V
485V
490V
.47uF
C1

J13
C13
R9
R6 R7
C8
R4
J12
D10
J5 J6 J7
D5
D3
D2
129526
D4
R8
Q6 Q3
R5
Q2
J3
J4 J2 J1
C5
Q1
C15
D6 D8 D9
F1 F2
C12
GP1
J18
J17
C7
R10
C6
C2
R1
J9
C14 C11
J11
J10
J14
D7
U3 U2
J8 D1
C9
J16
C3
R2
C4
C10
BLU BLUBLU/BLK
GRN
RED
RED
Rev.A
GRN
RED BLK RED BLU
RED
GRN/BLK
R76 R75
37 38
MA2275
POWER SUPPLY 049972
9

METER 049973
10
39 40