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
MC2000
2R
2L
INPUT
049305
9
100
3R 3L
MAIN
049306
11
12
MC2000
3R
3L
MAIN
049306
4R
4L
POWER SUPPLY
049308
13
14
5
AC POWER 049309
15
16
MC2000
6
SWITCH REMOTE 049310
17
18
7R 7L
METER
049307
19
20
MC2000
8R 8L
10
LAMP
BIAS CONTROL
049311
049311
11R 11L
9R 9L
LOGO LAMP
METER LAMP
049311
049337
12R 12L
OUTPUT
049312
21
22
PARTS LIST
PART NO. DESCRIPTION REF. NO.
049305 Input
066316 CAP ELECT 10UF 20% 25V NP C1 C3
070047 SILICON DIODE 1N4148 T&R D1 D2
087056 REED RELAY FORM 1C 5V 125OHM K1 K2
117216 MALE CONN 5 PIN 0.1 POST ASSY J2117221 MALE CONN 3 POS RT ANGLE J3117722 9 POSITION RECEPTACLE J1132222 N. CHANNEL FET Q6
144015 MF RES 33.2K 1% 1/4W R1
144104 METAL FILM RES 20K 1% 1/4W R6
144141 MF RES 27.4K 1% 1/4W R4
144154 RES MF 12.1K 1% 1/4W R23
144269 METAL FILM RES 1M 1/4W R11 R12
144379 RES METAL FILM 4.75M 1/4W 1% R19
144412 MF RES 15K 1% 1/4W R24
144421 MF RES 221K 1% 1/4W R2
144423 MF RES 174 OHM 1% 1/2W R8 R20
144439 MF RES 24.9K 1% 1/4W R5 R7
049306 Main
061293 DISC 22PF 500V C1 C17
061295 DISC 3.3 PF 1000V C2
061306 DISC 220 PF 100V C18
064364 CAP POLYPROP .047MF 10% 250V C25
064431 POLYPRO 0.1MF 630V C9 C10
064432 POLYPRO 0.22MF 1000V 20% C12 C13
064433 POLYPRO 1.0MF 250V 20% C4
064435 POLYPRO 2.2 MF 250V 10% C5
066492 ELECT 10MF 100V C8 C11
066493 ELECT 10MF 250V C15 C16
066494 ELECT 10MF 450V C19
066495 ELECT 47MF 16V C22 C24
066497 ELECT 47MF 450V C20
066498 ELECT 100MF 6.3V C6 C7
066500 ELECT 1000MF 16V NONPOLAR C14
066502 ELECT 4700MF 25V C21 C23
070126 DIODE 200V 3A D1 D2
089088 FUSE 2A SLO-BLO 5 X 20 250VIEC F 1
117217 MALE CONN 7 PIN J3117218 MALE CONN 6-POS FRICTION LK J2117723 9 POSITION HEADER J1117724 9 CIRCUIT POST HEADER NATURAL J4117725 9 CIRCUIT POST HEADER RED J5122001 CHOKE 2.2 MH L1 L2 L3 L4
132136 TRANSISTOR NPN T092 Q1 Q2 Q3 Q4
Q5 Q6
133155 IC REGULATOR -12V IC2
133156 IC REGULATOR 12V IC1
134492 TRIM POT 2K 10% R7
139009 WIRE RES 220 OHMS 10% 5W R42 R43 R44
R45
139218 2.7 OHM 2W 5% WW RESISTOR FP R52 R53
144104 METAL FILM RES 20K 1% 1/4W R22
144106 33.2K 1% 1/4W R18 R51
144113 RES MF 100K 1% 1/4W R2
144119 METAL FILM RES: 332K 1% 1/4W R27
144141 METAL FILM RES 27.4K 1% 1/4W R50
144196 METAL FILM RES 100 OHM 1% 1/4W R14
144269 METAL FILM RES 1M 1/4W R9
144309 1K OHM 1% 1/2W METAL FILM R38 R39 R40
R41
144408 MF RES 562 OHM 1% 1/4W R13
144410 MF RES 1.2K 1% 1/4W R5 R10
144414 MF RES 18.2K R6 R8
144417 MF RES 93.1K 1% 1/4W R1
144418 MF RES 121K 1% 1/4W R4
144421 MF RES 221K 1% 1/4W R17 R21 R25
R26
144422 MF RES 1.5M 1% 1/4W R23 R24
144424 MF RES 3.92K 1% 1/2W R47
144427 MF RES 22.1K 1% 1/2W R46
144428 MF RES 47.5K 1% 1/2W R16 R20 R34
R35
144429 MF RES 100K 1% 1/2W R3 R11
144430 MF RES 121K 1% 1/2W R15
144431 MF RES 150K 1% 1/2W R19
144432 MF RES 1M 1/2W R32 R33
144435 MO RES 30.1K 1% 1W R36 R37
144436 MO RES 46.4K 1% 1W R28 R29 R30
R31 R48
144437 MO RES 10K 5% 2W R49
144438 MO RES 100K 5% 2W R54
178169 OCTAL TUBE SOCKET CERAMIC V4 V5 V6 V7
178170 9 PIN TUBE SOCKET CERAMIC V1 V2 V3
049308 Power Supply
064431 POLYPRO 0.1MF 630V C10
064434 POLY CAP .047UF 10% 1KV (MKP4) C9
066495 ELECT 47MF 16V C5
066496 ELECT 47MF 250V C6 C7 C8
066503 ELECT 810MF 300V C1 C2 C3 C4
070099 ZENER DIODE 12V 400MW D3
070131 DIODE RECTIFIER D5 D6
070165 BRIDGE RECT 1000V 6A D4
070166 MR253L TRANS. SUPPRESSOR D2
080017 TO-220 HEATSINK Q1
089088 FUSE 2A SLO-BLO 5 X 20 250VIEC F 1
117724 9 CIRCUIT POST HEADER NATURAL J2117725 9 CIRCUIT POST HEADER RED J1132284 MTP2955V FET POWER TRANSISTOR Q1
144415 MO RES 475 1% 1W R5
144425 MF RES 10K 1% 1/2W R1 R3 R4
144426 MF RES 15K 1% 1/2W R2
049309 AC Power
066501 ELECT 3300MF 35V C1
070031 SIL DIODE 400 PIV @ 1.5A (RED) D2
087071 RELAY TV8 5V COIL K1
089111 FUSE 50MA 5X20MM F1
117215 4-PIN CONNECTOR J8117216 MALE CONN 5-PIN 0.1 POST ASSY J9
117719 PCB MOUNT POWER CONNECTOR RED J10- J11- J12-
J13- J14- J15117726 .187 FASTON TAB J1 J2 J3 J4 J5 J6
J7
133108 IC +5V REGULATOR IC1
144090 METAL FILM RES 1K 1% 1/4W R1
144282 THERMISTOR RT1 RT2RT3
RT4
159314 TRANSFORMER 115/230-8/16V 6VA T1
178172 FUSE HOLDER 5X20MM F1
049310 SW Remote
061248 DISC CAP .1MF 25V Y5T C2
064329 CAP M POLY .22UF 5% 63VDC C1
117214 MALE CONN 3-POS MTS100 NORMAL J3
117218 MALE CONN 6-POS FRICTION LK J4117406 MIN. PHONO JACK R657 J1- J2-
132171 TRANSISTOR NPN Q1
133192 IC NAND SCHMIT 2-IN X 4 IC1
144082 METL FILM RES 68.1 OHM 1% 1/4W R5 R6
144090 METAL FILM RES 1K 1% 1/4W R1
144187 METAL FILM RES 22.1K 1% 1/4W R2 R3
144269 METAL FILM RES 1M 1/4W R4
148074 SLIDE SWITCH DPDT 3MM S1 S2
049307 Meter
061248 DISC CAP .1MF 25V Y5T C4 C9 C10 C11
061249 DISC CAP .47UF 50V MONOLITHIC C12 C13
064329 CAP M POLY .22UF 5% 63VDC C8
064337 POLY CAP 1MF 5% 50V C7
066491 ELECT 4.7MF 100V C1
066499 ELECT 220MF 25V C2 C3
066510 CAP ELEC 1 UF 50V C14
070047 SILICON DIODE 1N4148 T&R D1 D3 D4 D6
D7 D8 D9 D10
D13
070085 ZENER DIODE 6.2V 5% 500MW D12
070131 DIODE RECTIFIER D2 D11
089088 FUSE 2A SLO-BLO 5 X 20 250VIEC F 1
117221 MALE CONN 3 POS RT ANGLE J2117223 MALE CONN 6 PIN RT ANGLE J1117240 4 PIN RT. ANGLE J3131021 TRIAC 8A 200V Q8
132223 TRANSISTOR NPN MPS4124 2K/REEL Q1 Q5
132224 TRANSISTOR PNP Q2 Q6
132226 TRANSISTOR P.CHANNEL JUNC.FET Q7
132254 TRANSISTOR NPN Q3 Q4
133155 IC REGULATOR -12V IC2
133156 IC REGULATOR 12V IC1
133260 DUAL OPERATIONAL AMPLIFIER IC3 IC4
134383 TRIM POT 100K OHM 20% R10
141060 RES CF 3.3K 5% 1/4W R23
141125 RES CF 2.7M 5% 1/4W R1
141136 RES CF10 5% 1/4W R26
141179 CARB FILM RES 680 OHMS 5% 1/2W R24
144053 RES MF 10K 1% 1/4W R7 R20 R22
144053 RES MF10K 1% 1/4W R7 R22
144087 MF 499 OHMS R17
144090 METAL FILM RES 1K 1% 1/4W R19 R25
144103 16.5K 1% 1/4W R18
144117 METAL FILM RES 200K 1% 1/4W R6 R12
144125 METAL FILM RES 150K 2% 1/4W R9
144187 METAL FILM RES 22.1K 1% 1/4W R21
144196 METAL FILM RES 100 OHM 1% 1/4W R11 R16
144264 METAL FILM RES 10M 1% 1/4W R8
144269 METAL FILM RES 1M 1/4W R2
144271 METAL FILM RES 2.74M OHM 1/4W R13
144411 MF RES 3.92K 1% 1/4W R15
144412 MF RES 15K 1% 1/4W R5 R14
144342 MF RES 13.7K 1% 1/4W R20
049311 Bias Control
117217 MALE CONN 7 PIN J1134497 TRIM POT 100K 10% R1 R2
144106 33.2K 1% 1/4W R3
150059 TACT SWITCH S1 S2
049337 Lamp
146252 3 POSITION 2POLE ROTARY SWITCH S1
049312 Output
064431 POLYPRO 0.1MF 630V C1
117726 .187 FASTON TAB J1 J2 J3 J4 J5
139119 WIRE RES 4 OHMS 5% 5W R1
23
240
MC2000
EXPLODED VIEW
1 OF 2
25
26
EXPLODED VIEW
2 OF 2
PARTS LIST
Ref.
No.
1 016403 FRONT GLASS
2 049334 GOLD KNOB
3 104164 FELT WASHER
4 018628 HANDLE FRONT
5 018625 PANEL SIDE LEFT
6 018624 PANEL SIDE RIGHT
7 100200 MS 10-32 X 1/2 PHIL TRUSS BLK
8 017790 PLEXIGLAS PANEL
9 092424 METER COLOR FILTER
10 005007 PANEL PLATE
11 101142 CAP SCREW 1/4 -20 X 1-1/4
12 101215 SEMS MS 8-32 X 1/4 PHIL PAN
13 004961 DUST COVER
14 005006 GUSSET RIGHT
15 005005 GUSSET LEFT
16 005039 TOP SUBPANEL BRACKET
17 102003 MACH NUT: 6-32 W/LOCK
18 101078 TS 8-32 X 5/16 PHIL PAN BLK
19 126588 SIGNATURE NAMEPLATE
20 049379 WINDOW TRIM
21 101054 TS 6-32 X 1/4 PH PAN TAPTITE BLK
Part
No.
Description
22 124071 METER
23 005008 SWITCH BRACKET
24 049357 METER ROTARY SWITCH PCB
25 049338 PANEL/LED LIGHT PCB
26 104163 M7 INTERNAL TOOTH LOCKWASHER
27 110004 M7 X .75 HEX CONTROL NUT
28 004970 SUBPANEL
29 092401 BLUE FILTER PALE
30 092400 BLUE FILTER AZURE
31 017749 METER LIGHT BOX
32 049336 METER LIGHT BOX PCB
33 114072 PLASTIC RIVET
34 049307 METER PCB
35 100296 SEMS 4-40 X 5/16 PHIL PAN
36 094360 FOAM TAPE 1/2” X 1/2”
37 094017 FOAM TAPE 1/4” X 1/4”
38 049339 PANEL LIGHT PCB
39 005018 CHASSIS GOLD
40 165065 12AX7A TUBE
41 165067 12AT7 TUBE
42 165069 KT88 TUBE
43 017761 AIR PIPE
44 049305 INPUT SWITCH PCB
45 114139 PCB SUPPORT
46 017801 PLASTIC RIVET
47 100292 MS 6-32 X 3/8 PH FH BLK ZINC
48 102006 MACH NUT: 10-32 W/LOCK
49 049304 POWER TRANSFORMER
50 126582 POWER TRANSFORMER DECAL
51 049301 OUTPUT TRANSFORMER
52 126581 OUTPUT TRANSFORMER DECAL
53 052093 TUBE COVER
54 101214 SCREW, TUBE COVER
55 049306 MAIN AMP PCB
56 004967 FOOT CHANNEL RIGHT
57 004968 FOOT CHANNEL LEFT
58 018626 FOOT
59 004971 CHASSIS SUPPORT
60 024010 FOOT PAD
61 005071 INPUT SHIELD BRACKET
62 005032 CHASSIS BASE
63 049310 SWITCH REMOTE PCB
64 049308 POWER SUPPLY PCB
65 049309 AC POWER PCB
66 018622 HANDLE REAR
67 117742 RCA JACK RED
68 117743 RCA JACK WHITE
69 117487 AC LINE RECEPTACLE
70 178122 FUSE HOLDER W/HARDWARE
71 117741 BINDING POST BLACK
72 117740 BINDING POST RED
73 117744 XLR RECEPTACLE
74 100195 MS 4-40 X 3/8 PHIL OVAL GOLD
75 104165 LW INTERNAL TOOTH
76 102052 NUT GOLD
77 100110 1/4-20 X 5/8 PAN PH BLK ZINC
78 104162 LOCKWASHER INTERNAL TOOTH
79 102051 HEX NUT M9 X .75 GOLD PLATED
80 049312 OUTPUT TERMINAL PCB
81 005035 BIAS PLATE LEFT
82 005036 BIAS PLATE RIGHT
83 049311 BIAS PCB
84 101193 SEMS 4-40 X 1/4 PHIL PAN BLK ZINC
85 004974 BIAS COVER
86 100193 MS 4-40 X 1/4 FLAT PH BLK ZINC
87 004969 BOTTOM COVER
88 100159 MS 10-32 X 3/4 PH PAN BLK ZINC
27
280
REPACKING INSTRUCTIONS
29
POWER AMPLIFIER
SERVICE MANUAL
The continuous improvement of it’s products is the policy of McIntosh Laboratory Incorporated, who reserve the right to improve design without notice.
Because of the constant upgrading of McIntosh products’ circuitry and components, the Company cannot insure, and does not warrant, the accuracy of the
within schematic material, which is intended for information only.
McINTOSH LABORATORY, INC., 2 CHAMBERS STREET, BINGHAMTON, NEW YORK 13903 Printed in U.S.A. Part Number 040702
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