Service Manuals, User Guides, Schematic Diagrams or docs for : . Rare and Ancient Equipment Mc INTOSH Audio MA2275 hfe_mcintosh_ma2275_service
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TUBE
INTEGRATED AMPLIFIER
CONTENTS
Performance Specifications ........................................ 2 Data Schematic and PCB ................................... 27 - 28
Notes ......................................................................... 2 Pushbutton Schematic and PCB ........................ 29 - 30
Rear Panel .................................................................. 3 Amplifier Schematic and PCB ............................ 31 - 34
Section Location ........................................................ 4 Power Supply Schematic and PCB ..................... 35 - 38
Block Diagram ...................................................... 5 - 7 Meter Schematic and PCB ................................. 39 - 40
Interconnection Diagram .................................... 8 - 10 Backup PS Schematic and PCB ................................ 41
Main Schematic and PCB ................................. 11 - 16 Terminal Schematic and PCB ................................... 42
Control Schematic and PCB ............................. 17 - 20 Parts List ............................................................ 43 - 48
Balanced Schematic and PCB ........................... 21 - 22 Exploded View and Parts List ............................. 49 - 52
Volume/Tone Schematic and PCB ..................... 23 - 26 Repacking Instructions ............................................. 53
SERVICE MANUAL
PERFORMANCE SPECIFICATIONS
Power Output Preamplifier Maximum Voltage Output
Minimum sine wave continuous average power output per Phono: 8V
channel, both channels operating is: High Level: 8V
75 watts into a 2 ohm load Main Out: 8V at preamp output
75 watts into a 4 ohm load
75 watts into an 8 ohm load Voltage Gain
High Level to Tape output: 0dB
Rated Power Band High Level to Preamp output: 15dB
20Hz to 20,000Hz
Wide Band Damping Factor
Total Harmonic Distortion Greater than 18
Maximum Total Harmonic Distortion at any power level
from 250 milliwatts to rated power output is: Power Requirements
0.5% for a 2, 4 or 8 ohm load 100 Volts, 50/60Hz at 3.6 amps
110 Volts, 50/60Hz at 3.6 amps
Frequency Response 120 Volts, 50/60Hz at 3.6 amps
+0, -0.5dB from 20Hz to 20,000Hz 220 Volts, 50/60Hz at 1.8 amps
+0, -3dB from 10Hz to 50,000Hz 230 Volts, 50/60Hz at 1.8 amps
240 Volts, 50/60Hz at 1.8 amps
Sensitivity Note: Refer to the rear panel of the MA2275 for the correct
Phono: 4.4mV for 2.5V preamp output voltage.
High Level: 450mV for 2.5V preamp output
Power Amplifier Input: 2.5V for rated output Preamplifier Tube Compliment
2 - 12AX7A Phono Circuitry
A-Weighted Signal To Noise Ratio 2 - 12AX7A High Level Circuitry
Phono Input: 80dB below 10mV input
High Level: 97dB below rated output Power Amplifier Tube Compliment
Power Amplifier: 110dB below rated output 2 - 12AT7
4 - KT88/6550
Intermodulation Distortion
Maximum Intermodulation Distortion if instantaneous Overall Dimensions
peak output does not exceed twice the rated output, for Width is 17-3/4 inches (45.09cm), Height is 10-1/8 inches
any combination of frequencies from 20Hz to 20,000Hz is: (25.72cm) including feet, Depth is 18-3/4 inches (47.63cm)
0.5% for a 2, 4 or 8 ohm load including the Front Panel and Knobs
Input Impedance Weight
Phono: 47k ohms, 65pF 77 pounds (35 kg) net, 110 pounds (50 kg) in shipping
High Level: 22k ohms carton
Maximum Input Signal
Phono: 90mV
High Level: 8V
NOTES
1. The heavy lines on the schematic denote the primary 4. On PC board drawings, Square pad indicates:
signal path. a. Polarized Capacitors - Positive
b. Diodes - Cathode
2. Unless otherwise noted, all voltages indicated on the c. Others - Pin 1
schematics are measured under the following conditions:
a. AC input at 120 volts, 50/60Hz. 5. WARNING
b. All voltages are +/-10% with respect to ground. A Parts marked with the symbol have critical
high impedance (10 megaohm) voltmeter must be used. characteristics. Use only replacement parts recom-
mended by the manufacturer.
3. Unless otherwise specified:
a. Resistor values are in ohms.
b. Capacitor values are microfarads (uF).
c. Inductor values are in microhenries (uH).
2
MA2275
TOP AND REAR VIEWS
POWER OUTPUTS INPUTS
AMP IN PREAMP TAPE TAPE DVD TUNER CD CD 2 PHONO
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION AVIS R
FOR CONTINUED PROTECTION RISQUE DE CHOC ELECTRIQUE - NE PAS
GND MA2275
AGAINST FIRE HAZARD REPLACE ONLY WITH SAME OUVRIR. REMPLACER PAR UN FUSIBLE DE MEME
CD INPUT
TYPE AND RATING FUSE. TYPE, AMPERAGE ET VOLTAGE.
INTEGRATED AMPLIFIER
McINTOSH LABORATORY, INC.,
L BINGHAMTON, NY MADE IN USA
1 2
POWER CONTROL SUM
SERIAL
NUMBER
T 4AL 250V MAIN ACC DATA PORTS
120V 50/60Hz 3.6A SLO-BLO EXT SENSOR
R L
3
SECTION LOCATIONS
TOP VIEW WITH COVERS REMOVED
POWER
1 TRANSFORMER
OUTPUT
TRANSFORMER 1 1
OUTPUT
TRANSFORMER
METER VOLUME/TONE
PCB
10 5 PCB
PUSHBUTTON
7 PCB
CONTROL
PCB
3
DATA BALANCED
PCB PCB
6 4
TERMINAL
PCB
12
TERMINAL
13 PCB
AMP AMP
PCB
8R 8L PCB
MAIN
2 PCB
POWER SUPPLY
PCB
9
BACKUP POWER
SUPPLY PCB
11
CHOKE
1 FILTER
BOTTOM VIEW WITH COVER REMOVED
4
MA2275
BLOCK DIAGRAM
5 6 7
1 INTERCONNECT
8 9 10
MA2275
2A MAIN 049965 SH 1 OF 2
11 12 13
2B MAIN 049965 SH 2 OF 2 R47
C42
D4
U4 C44 K20
C73
R74
R48
J6
U2 J8
JM P1
129472
Rev. A K21
C85
C59
K1
C77
D1
C60
U9
R21
C14
R22
C13
U10 C47 C48
C86
C84
R53
R54
C9 C10
R15
R17
R18
R16
R43
C49
R55
C75
R57
R58
J10
R27
C55
V5 * C50 V6 *
C12
R61
J11
R20
R56
C11
R13
R19
Q1
C54
C53
C5 C51
R71
C52
R14
R12
C56
C6
R62
C8
R10
R59
R60
C7
R11
R9
C57
J5
C61
R65
R66
R63
R7
R8
C4
C76 C62
R64
V4 * V7 *
R70
C67 C63
R5
R4
C2
R1
R3
C3
R6
R2
C1
R77
R69
R67
R78
R68
U8
U6
C36 R 40
R37
R36
R39
C37
C35
C16 C64
C68
C32
C15
R26
R25
R75
R76
C38
C31
R79
R80
R33
R41
R44
R45
R42
K3 U3
J1 K2 Q4 C65 C66 J7
R73
R72
C39
R34
R35
R38
C34
C58
R92
R86
R95
R23
R96
C33
R24
C40 C29 Q2 C74
C30 R49
R52
R30 K19
C41 K18
R88
Q3
U7
D2
U1 K7 K6 K9 K8 K11 K10 K13 K12 K17 K16
U5
C80 C79
R85
R83
R84
R81
R87
R82
C82
R94
R93
R46 R31 R32 R28 R29
C45
C43
C83
C19 C46 U11
R90
R89
R51
R50
C72 C70 C71 C69 R91
C24
C23
C26
C25
C28
C27
C18
C17
C20
C78
C81
GP1
J2 GP2
J3 J4
PH CD2 CD TUNER DVD TAPE TAPE OUT 2 OUT 1 AMP IN
OUT
14 15 16
MA2275
3 CONTROL 049966
17 18
3 CONTROL 049966
129473 Rev.A
DS6
R15 R4 J3
Y1
JMP1
U2
R1
R8
R2
U1
C2
R3 C1
DS4 U5 DS5
DS7
DS12
DS11 DS13
R10 Q1 S1
DS10
C3 R22
DS14
R16 C5 DS9
C4
ASSY1
R18
R19
U3 U4
R17 R20
DS15
R11 R12 R21
R5 Q2 R23 R7
R9 R13 R6
J1 J2 R24
DS1 DS2
19 20
MA2275
4 BALANCED 049967
21 22
5A VOLUME/TONE 049968 5B VOLUME/TONE 049968
23 24
MA2275
5 VOLUME/TONE 049968
R53 R26 C12
129475 C42
C13
R14
R21
C18
Rev.A R10 C11 R11
C17
D1
J1
R19
R16
R9 R12
C16 U7
C19
K1 K3 K4 K2
R25
R15
R13
R22
R20
U2 C5
C20
R24
R23
C9
C3
R6
R7
R5
R2
C2
C14
U1
C4
C15
R8
R3
C1 C6 C7
C10
C8
R17 R18 R4 R1
25 26
6 DATA 049969
D3
D2
D1
Rev.A R14
C3
129476
R5
R11
R13
R16
R22
U3
C2
U4 J8
C4
U1
C1
R23 R6 U2
R19 C5
R15 R3 R21 R18
R9 R8 R7 R4 R2 R1 R10 R12 R20 R17
SP1 SP2
J6 J5 J4 J3 J2 J1 J7 J10 J11 J9
27 28
MA2275
7 PUSHBUTTON 049970
STANDBY/
5.6V J1:18 ON
3 J1:1
5.6V J1:17 MUTE
3 J1:2
5.6V J1:16 MONO
3 J1:3
TONE
STANDBY/ON MUTE MONO 5.6V J1:15 BYPASS
S1 S2 S3 3 J1:4
5.6V J1:14 REC MON
3 J1:5
J1:13 NC
NC 3 J1:6
TONE BYPASS REC MON 0V J1:12 MUTE
3 J1:7
S4 S5
MONO
TO DISPLAY
0V J1:11
3 J1:8
15V 0V J1:10 TONE
3 J1:9
DS1 MUTE 0V J1:9 REC MON
3 J1:10
R14
499
TUBE WARMUP J1:8 15V
15V 3 J1:11
DS2 MONO TUBE
J1:7 WARMUP
3 J1:12
0V J1:6 R HDPH
3 J1:13
8
7
6
5
J2
DS3 TONE BYPASS 3 5.6V J1:5 FP DATA
3 J1:14
DS8 2 HDPH
1 0V J1:4 GND
3 J1:15
DS4 REC MON J1:3 5.6V
5.6V 3 J1:16
2
3
4
1
J1:2 L HDPH
IR SENSOR 3 J1:17
R1 J1:1 GND
DS5 3 J1:18
324
STANDBY/ON 5V MT1
GND
Vout
Vcc
5.6V
1 2 3
5.6V
5.6V
100
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