McIntosh MC-2000 Service manual
POWER AMPLIFIER
CONTENTS
Performance Specifications ........................................ 2
Notes ......................................................................... 2
Rear Panel .................................................................. 3
Section Location ........................................................ 4
Block Diagram ...................................................... 5 - 6
Interconnection Diagram ...................................... 7 - 8
Input PCB and Schematic.................................... 9 - 10
Main PCB and Schematic.................................. 11 - 13
Power Supply PCB and Schematic ........................... 14
AC Power PCB and Schematic .......................... 15 - 16
SERVICE MANUAL
Switch Remote PCB and Schematic .................. 17 - 18
Meter PCB and Schematic................................. 19 - 20
Bias Control PCB and Schematic ...................... 21 - 22
Meter Lamp PCB and Schematic ....................... 21 - 22
Lamp PCB and Schematic ................................. 21 - 22
Logo Lamp PCB and Schematic ........................ 21 - 22
Output PCB and Schematic............................... 21 - 22
Parts List ............................................................ 23 - 24
Exploded View and Parts List ............................. 25 - 28
Repacking Instructions ............................................. 29
PERFORMANCE SPECIFICATIONS
Power Output
130 watts into 8, 4 or 2 ohm loads is the minimum sine
wave continuous average power output per channel from
20Hz to 20,000Hz with both channels operating.
Total Harmonic Distortion
0.5% maximum harmonic distortion at any power level
from 250 milliwatts to rated power per channel from
20Hz to 20,000Hz with both channels operating.
Intermodulation Distortion
0.5% maximum intermodulation distortion if instantaneous peak power output does not exceed twice the
output rating per channel with both channels operating,
for any combination of frequencies from 20Hz to
20,000Hz.
Rated Power Band
20Hz to 20,000Hz
Frequency Response (at 1 watt)
+0, -0.25dB from 20Hz to 20,000Hz
+0, -3dB from 10Hz to 100,000Hz
Hum and Noise (A-Weighted)
100dB below rated output
Damping Factor
Greater than 18
Output Load Impedance
2, 4 or 8 ohms
Input Sensitivity (Switch Selectable)
2.5 volts for rated output
1.2 volts for rated output (1 volt for 100 watts output)
T ube Compliment
8 – KT88 or 6550 Output Tubes
4 – 12AX7A Input Tubes
2 – 12AT7 Driver Tubes
Power Requirement
100 Volts, 50/60Hz at 5.8 Amps
120 Volts, 50/60Hz at 4.8 Amps
230 Volts, 50/60Hz at 2.5 Amps
Note: Refer to the rear panel of the MC2000 for the correct voltage.
Dimensions
17-3/4 inches (45.1cm) wide by 11 inches (27.9cm)
high. Depth behind front panel is 18-3/4 inches (47.6
cm). Handle clearance required in front of the mounting
panel is 1-5/8 inches (4.1 cm).
Finish
Stainless Steel Chassis with Titanium Gold Super Mirror
Finish, Black Transformer Enclosures, Black Base,
Glass Front Panel with gold plated Handles and Knobs
Weight
Amplifier - 135 pounds (61.2 kg) net, 144 pounds
(65.3 kg) in shipping carton
Accessories - 18 pounds (8.2 kg) in shipping carton
Input Impedance
20k ohms Unbalanced (RCA Phono Jacks)
40k ohms Balanced (XLR Connectors)
1. The heavy lines on the schematics denote the
primary signal path.
2. Unless otherwise noted, all voltages indicated on
the schematics are measured under the following
conditions:
a. AC input at 120 volts, 50/60Hz
b. All voltages are +/-10% with respect to ground.
A high impedance (10megaohm) voltmeter must
be used.
3. Unless otherwise specified:
a. Resistors values are in ohms.
b. Capacitor values are in microfarads (uF).
c. Inductor values are in microhenries (uH).
NOTES
4. On PC Board Drawings, Square Pad Indicates:
a. Polarized Capacitors - Positive
b. Diode - Cathode
c. Others - Pin 1
5. WARNING:
Parts marked with the symbol have critical
characteristics. Use only replacement parts recom
mended by the manufacturer .
2
REAR PANEL
MC2000
3
SECTION LOCATION
TOP VIEW WITH COVER REMOVED
BOTTOM VIEW WITH COVER REMOVED
4
BLOCK DIAGRAM
VOLTAGE
N.F.B.
MC2000
LEFT
INPUTS
UNBALANCED
BALANCED
+
-
UNITY
GAIN
AMP
UNITY
INVERTING
AMP
BALANCED/
UNBALANCED
RELAY
BALANCED/
UNBALANCED
MODE SWITCH
1.2V/2.5V
LEVEL
RELAY
INPUT
LEVEL
SWITCH
MUTE
INPUT
AMP
PHASE
INVERTER
METER
HOLD
SWITCH
BUFFER
BUFFER
DRIVER
AMP
DRIVER
AMP
LOG
AMP
LOG
AMP
BUFFER
BIAS
CONTROL
BUFFER
RECTIFIER
HOLD
CIRCUIT
HOLD
CIRCUIT
RECTIFIER
OUTPUT
AMP
OUTPUT
AMP
DC
AMP
DC
AMP
DC
AMP
OUTPUT
TRANS-
FORMER
L. METER
8
4
2
COM
9
9
LEFT
OUTPUT
9
RIGHT
INPUTS
BALANCED
UNBALANCED
-
+
UNITY
INVERTING
AMP
UNITY
GAIN
AMP
BALANCED/
UNBALANCED
RELAY
1.2V/2.5V
LEVEL
RELAY
PHASE
INVERTER
MUTE BUFFER
INPUT
AMP
BUFFER
VOLTAGE
N.F.B.
DRIVER
AMP
DRIVER
AMP
BUFFER
BIAS
CONTROL
BUFFER
R. METER
DC
AMP
OUTPUT
AMP
OUTPUT
TRANS-
FORMER
OUTPUT
AMP
POWER SUPPLY SECTION
100/120/230VAC
50/60Hz
8
4
2
COM
POWER
RELAY
FUSE
9
9
RIGHT
OUTPUT
9
12VAC
LEFT
POWER
SUPPLY
RIGHT
POWER
SUPPLY
FUSE
FUSE
STANDBY
TRANSFORMER
INRUSH
CURRENT
LIMITER
INRUSH
CURRENT
LIMITER
CONTROL
5V SUPPLY
INPUT
VOLTAGE
SELECTOR
INPUT
VOLTAGE
SELECTOR
POWER
SWITCH
POWER
TRANSFORMER
POWER
TRANSFORMER
POWER
CONTROL
-+
12V
DC
12VAC
-+
12V
DC
IN
OUT
REMOTE
JACKS
12V
DC
12V
DC
MAIN 500V
DC SUPPLY
MAIN 500V
DC SUPPLY
-
150 AND
-
300V DC
-
150 AND
-
300V DC
REMOTE
LAMP
5
6
INTERCONNECT
7
8
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