McIntosh MC 275 MK V Service Manual

Page 1

MCZ 75

STEREO
POWER AMPLIFIER

STARTING WITH SERIAL NO. VN1 001

CONTENTS
Performance Specifications ....................................... 2 Amplifier Schematic and PCB ............................ 9 - 12
Notes ........................................................................ 2 Input Schematic and PCB 13 - 14
Rear Panel ................... 3 Parts List ................................... 15 - 16
Section Location .......... 4 Exploded View and Parts List ............................. 17 < 18
Block Diagram ............ 5 Repacking Instructions ............................................. 19

Interconnection Diagram ..................................... 7 - 8

SERVICE MANUAL

Page 2

PERFORMANCE SPECIFICATIONS

Power Output Stereo

Minimum sine wave continuous average power output
per channel, both channels operating is:

75 watts into 4, 8 or 16 ohm load

Power Output Mono (Parallel)

Minimum sine wave continuous average power output
is:

150 watts into 2 ohm, 4 ohm or 8 ohm load

Output Load Impedance
4, 8, or 16 ohm (Stereo Mode)
2, 4, or 8 ohm (Mono Mode)

Rated Power Band
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%

Inter-modulation Distortion

Maximum Intermodulation Distortion if instantaneous
peak output per channel does not exceed twice the rated
output, for any combination of frequencies from 20Hz to
20,000Hz, with both channels operating is 0.5%

A-Weighted Signal To Noise Ratio
100dB

Frequency Response
+0, -0.5dB from 20Hz to 20,000Hz
+0, >3dB from 10Hz to 70,000Hz

Sensitivity
1.2 Volt unbalanced inputs
2.5 Volt balanced inputs

Wide Band Damping Factor
Greater than 14

Inputlmpedanoe
100,000 ohms unbalanced
200,000 balanced

'Illbe Compliment

3 - 12AX7A Inputs and Phase Inverters
4 - 12AT7 Voltage Amplifier and Drivers
4 - KT88/6550 Power Output

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 right side panel of the MC275 for the correct
voltage.

Overall Dimensions
Width is 16-1/2 inches (41.91cm), Heightis 8-1/4 inches
(20.96cm) including feet, Depth is 12 inches (30.48cm)

Weight
67 pounds (30.5kg) net, 75 pounds (34.1kg) in shipping
carton

NOTES

. The heavy lines on the schematic denote the primary
signal path.

Unless otherwise noted, all voltages indicated on the
schematics are measured under the following conditions:
8.. AC input at 120 volts, 50/60Hz.

b. All voltages are +/-10% with respect to ground. A

high impedance (10 megaohm) voltmeter must be used.

. Unless otherwise specified:
a Resistor values are in ohms.
b. Capacitor values are microfarads (uF).
c. Inductor values are in microhenries (uH).

4. On PC board drawings, Square pad indicates:
a. Polarized Capacitors - Positive
b. Diodes - Cathode
c. Others - Pin 1

5. WARNING
Parts marked with the symbol A have critical
characteristics. Use only replacement pans recom-
mended by the manufacturer.

I)

Q

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