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POWER AMPLIFIER

CONTENTS
Performance Specifications ........................................ 2 Notes ......................................................................... 2 Rear Panel .................................................................. 3 Section Location ........................................................ 4 Block Diagram ...................................................... 5 - 6 Interconnection Diagram ...................................... 7 - 8 Heatsink Schematic and PCB ............................. 9 - 14 Power Supply Schematic and PCB ..................... 15 - 16 Input Schematic and PCB .................................. 17 - 18 Meter/Lighting Schematic and PCB .................... 19 - 21 Meter Led Schematic and PCB .......................... 21 - 22 Parts List ............................................................ 23 - 26 Exploded View and Parts List ............................. 27 - 32 Repacking Instructions ............................................. 33

SERVICE MANUAL

PERFORMANCE SPECIFICATIONS
Power Output Stereo 250 watts into a 2, 4 or 8 ohm load is the minimum sine wave continuous average power per channel with both channels operating Power Output Mono Bridged 500 watts into a 4, 8 or 16 ohm load is the minimum sine wave continuous average power output Power Output Mono Bi-Amp 500 watts into a 1, 2 or 4 ohm load is the minimum sine wave continuous average power output Output Load Impedance Stereo: 2, 4 or 8 ohms Mono: 1, 2, 4, 8, or 16 ohms 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 0.005% Intermodulation 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 all channels operating is 0.005% Dynamic Headroom 2.0dB Frequency Response +0, -0.25dB from 20Hz to 20,000Hz +0, -3dB from 10Hz to 100,000Hz Sensitivity 1.6 Volts Unbalanced Input 3.2 Volts Balanced Input A-Weighted Signal To Noise Ratio 112dB below rated output Input Impedance 10,000 ohms Wide Band Damping Factor Greater than 40 Power Requirements 100 Volts, 50/60Hz at 8 amps 110 Volts, 50/60Hz at 7.2 amps 120 Volts, 50/60Hz at 6.6 amps 220 Volts, 50/60Hz at 3.3 amps 230 Volts, 50/60Hz at 3.3 amps 240 Volts, 50/60Hz at 3.3 amps Note: Refer to the rear panel of the MC252 for the correct voltage. Overall Dimensions 17-1/2 inches (44.45cm) W, 9-7/16 inches (23.97cm) H, 14-3/4 inches (37.5cm) D, including clearance for connectors Weight 94.5 pounds (207.9kg) net, 108.5 pounds (238.7kg) in shipping carton

NOTES
1. The heavy notes 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. 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. 3. 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 have critical characteristics. Use only replacement parts recommended by the manufacturer.

2

MC252

TOP AND REAR PANEL

3

SECTION LOCATIONS
TOP VIEW WITH COVER REMOVED

BOTTOM VIEW WITH COVER REMOVED

4

MC252

BLOCK DIAGRAM

5

6

1

INTERCONNECT

7

8

MC252

2A 2B

DRIVER SECTION

HEATSINK

049986

9

10

2A 2B

049986 HEATSINK SECTION

HEATSINK

11

12

MC252

2A 2B

HEATSINK

049986

13

14

3

POWER SUPPLY

049757

15

16

MC252

4

INPUT

049755

17

18

5

METER/LIGHTING

049756

19

20

MC252

5

METER/LIGHTING

049756

6

METER LED

049758

21

22

PARTS LIST
Ref. No.
1

Description

Part No.
117741 117741 117741 117741 117741 117741 117741 117741 070139 089105 117487 124084 124084 052008 052008 146243 146243 049763 049766 049766 074091 061249 061305 061305 066446 066462 066462 061305 061305 061301 061300 061300 066507 064308 064363 064364 066462 066462 061304 066446 066446 061304 061305 061300 061300 061305 064442 064442 070047 070047 070047 070047 070047 070126 070126 117244 117244 117404 117708 117215 117708

INTERCONNECT BP1 Binding Post BLK BP2 Binding Post RED BP3 Binding Post RED BP4 Binding Post RED BP5 Binding Post RED BP6 Binding Post RED BP7 Binding Post RED BP8 Binding Post BLK D1 Diode Bridge Rectifier F1 Fuse J1 Receptacle, AC Line MT1 Meter MT2 Meter RT1 Thermistor Assembly RT2 Thermistor Assembly S1 Switch S2 Switch T1 Power Transformer T2 Output Transformer T3 Output Transformer TB1 Terminal Block AC 049986 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 D1 D2 D3 D4 D5 D6 D7 J1 J2 J3 J4 J5 J7 HEATSINK CAP DISC MONO .47UF 50V CAP MONO .1uF 50V 20% Z5U CAP MONO .1uF 50V 20% Z5U CAP ELECT 47UF 35V CAP ELECT 10UF 100VDC CAP ELECT 10UF 100VDC CAP MONO .1uF 50V 20% Z5U CAP MONO .1uF 50V 20% Z5U CAP MONO 220PF 100V 10PO CAP MONO 100PF 100V 10% NPO CAP MONO 100PF 100V 10% NPO CAP ELECT 220UF 25V CAP MPF 0.0047UF 5VDC CAP POLYPROP 0.15UF 10VDC CAP POLYPROP .047UF 10VDC CAP ELECT 10UF 100VDC CAP ELECT 10UF 100VDC CAP MONO .01UF 50V 20% X7R CAP ELECT 47UF 35V CAP ELECT 47UF 35V CAP MONO .01UF 50V 20% X7R CAP MONO .1uF 50V 20% Z5U CAP MONO 100PF 100V 10PO CAP MONO 100PF 100V 10% NPO CAP MONO .1uF 50V 20% Z5U CAP MPF 0.47UF 5/100VDC CAP MPF 0.47UF 5/100VDC DIODE SILICON DIODE SILICON DIODE SILICON DIODE SILICON DIODE SILICON DIODE 200V 3A DIODE 200V 3A CONN MALE 9 POS FRICTION LK CONN MALE 9 POS FRICTION LK CONN HEADER 2 PIN 0.156 BLADE FASTON W/FEET CONN 4 PIN BLADE FASTON W/FEET

2A 2B

J8 J9 LD1 Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 Q19 Q20 Q21 Q22 Q23 Q24 Q25 Q26 Q27 Q28 Q29 Q30 Q31 Q32 Q33 Q34 Q35 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30

CONN 2 PIN MALE BLADE FASTON W/FEET LDR NETWORK VTL5C9 TRANSISTOR PNP TRANSISTOR NPN TRANSISTOR NPN TRANSISTOR N JFET TRANSISTOR N JFET TRANSISTOR N JFET TRANSISTOR NPN POWER TRANSISTOR SI NPN 25V TRANSISTOR NPN POWER TRANSISTOR PNP TRANSISTOR NPN POWER TRANSISTOR SI NPN 25V TRANSISTOR NPN TRANSISTOR SI NPN 25V TRANSISTOR NPN TRANSISTOR PNP TRANSISTOR NPN 25C3334C TRANSISTOR PNP 2SA32IC TRANSISTOR NPN SILICON TRANSISTOR PNP SILICON TRANSISTOR NPN TRANSISTOR NPN 25C3334C TRANSISTOR PNP 2SA32IC TRANSISTOR NPN TRANSISTOR PNP TRANSISTOR NPN POW 2SC5200 TRANSISTOR PNP POW 2SA1943 TRANSISTOR NPN POW 2SC5200 TRANSISTOR PNP POW 2SA1943 TRANSISTOR NPN POW 2SC5200 TRANSISTOR PNP POW 2SA1943 TRANSISTOR NPN POW 2SC5200 TRANSISTOR PNP POW 2SA1943 TRANSISTOR NPN POW 2SC5200 TRANSISTOR PNP POW 2SA1943 RES MF 10 OHM 1% 1/4W RES MF 10 OHM 1/4W RES MF 4.75K 1% 1/4W RES MF 100 OHM 1% 1/4W RES MF 475 OHM 1% 1/4W RES MF 22.1K 1% 1/4W RES MF 10M 1% 1/4W RES MF 267K 1% 1/4W RES MF 2.21K 1% 1/4W RES MF 221 OHM 1% 1/4W RES MF 267K 1% 1/4W RES MF 47.5K 1% 1/4W RES MF 47.5K 1/4W RES MF 3.32K 1% 1/4W RES MF 221 OHM 1% 1/4W RES MF 1K 1% 1/4W RES MF 221 OHM 1% 1/4W RES MF 3.32K 1/4W RES MF 221 OHM 1% 1/4W RES MF 1K 1% 1/4W RES MF 221 OHM 1% 1/4W RES MF 499 OHM 1% 1/4W RES MF 267K 1% 1/4W RES MF 187K 1% 1/4W RES MF 324 OHM 1% 1/4W RES MF 324 OHM 1% 1/4W RES MF 6.49K .5% 1/4W RES MF 13.7K 1% 1/4W RES MF 221 OHM 1/4W RES WW 2 OHM 10% 5W

117213 117708 144179 132224 132223 132223 132222 132222 132222 132255 132254 132255 132224 132255 132254 132223 132254 132223 132224 132285 132286 132171 132172 132223 132285 132286 132268 132267 132291 132292 132291 132292 132291 132292 132291 132292 132291 132292 144157 144157 144097 144196 144086 144187 144264 144118 144298 144172 144118 144108 144108 144095 144172 144090 144172 144095 144172 144090 144172 144087 144118 144406 144338 144338 144401 144342 144172 139005

R31 R32 R33 R34 R35 R36 R37 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 R56 RT1 U1
3

RES WW 4 OHM 5W RES FP 22 OHM 1/4W 5 RES FP 22 OHM 1/4W 5 RES MF 324 OHM 1/4W RES MF 324 OHM 1/4W RES MF 2.21K 1/4W RES MF 22.1K 1/4W RES MF 22.1K 1/4W RES MET OX 680 OHM 5% .5W RES MET OX 680 OHM 5% .5W RES MF 1.82K 1% 1/4W RES MET OX 430 OHM 5% .5W POT TRIM 200 OHM 20% HORIZ AD RES MF 1.82K 1% 1/4W RES MET OX 47 OHM 5% .5W RES WW DUAL .47 OHM 5% 5W RES WW DUAL .47 OHM 5% 5W RES WW DUAL .47 OHM 5% 5W RES WW DUAL .47 OHM 5% 5W RES WW DUAL .47 OHM 5W RES MF 1K 1% 1/4W RES MF 1K 1% 1/4W RES WW DUAL .47 OHM 5W RES WW DUAL .47 OHM 5% 5W RES WW DUAL .47 OHM 5% 5W SENSOR THERMAL IC OPAMP NE4558N POWER SUPPLY CAP POLY .047UF 10% 250VDC CAP ELECT 10UF 50V 27000uF 100V ELECTROLYTIC 27000uF 100V ELECTROLYTIC CAP ELECT 22UF 100V CAP ELECT 3300UF 35V CAP ELECT 3300UF 35V CAP ELECT 4.7UF 50V CAP ELECT 10UF 100VDC DIODE RECTIFIER DIODE RECTIFIER DIODE RECTIFIER DIODE RECTIFIER DIODE RECTIFIER DIODE RECTIFIER DIODE SILICON HEATSINK T0220 HEATSINK T0220 BLADE FASTON W/FEET BLADE FASTON W/FEET BLADE FASTON W/FEET BLADE FASTON W/FEET BLADE FASTON W/FEET BLADE FASTON W/FEET CONN MALE 7 PIN CONN 4 PIN BLADE FASTON W/FEET CONN HEADER 2 PIN 0.156 CONN HEADER 2 PIN 0.156 BLADE FASTON W/FEET CONN MALE 9 POS FRICTION LK CONN MALE 9 POS FRICTION LK CONN MALE 9 POS FRICTION LK BLADE FASTON W/FEET BLADE FASTON W/FEET RELAY 48V 18.8mA TRIAC DRIV OPTOCPLR 600V TRANSISTOR NPN TRANSISTOR PNP

139119 137033 137033 144338 144338 144298 144187 144187 137093 137093 144296 137095 134390 144296 137096 139199 139199 139199 139199 139199 144090 144090 139199 139199 139199 144249 133028 064364 066445 066489 066489 066506 066509 066509 066512 066462 070131 070131 070131 070131 070131 070131 070047 080014 080014 117708 117708 117708 117708 117708 117708 117217 117215 117708 117404 117404 117708 117244 117244 117244 117708 117708 87052 131022 132223 132224

049757 C1 C2 C3 C4 C5 C6 C7 C8 C9 D1 D2 D3 D4 D5 D6 D7 HS1 HS2 J1 J2 J3 J4 J5 J6 J7 J8 J9 J11 J12 J13 J14 J15 J16 J17 J18 K1 Q1 Q2 Q3

23

24

MC252

PARTS LIST con't
Q4 Q5 Q6 Q7 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 SP1 SP2 SP3 SP4 U1 U2
4

TRANSISTOR NPN TRANSISTOR PNP TRANSISTOR P CHAN JUNC FET TRANSISTOR PNP RES MF 33.2K 1% 1/4W RES MF 33.2K 1% 1/4W RES MF 2.74M 1/4W RES WW 1.5K 10% 5W RES MF 1.1K 1% 1/4W RES MF 22.1K 1% 1/4W RES MF 1M 1/4W RES MF 12.1K 1% 1/4W RES MF 2.1K 1% 1/4W RES MF 12.1K 1% 1/4W RES MF 3.32K 1% 1/4W RES MF 20K 1% 1/4W RES MF 2.1K 1% 1/4W RES MF 150K 1% 1/4W RES WW 2.7 OHM 10W RES WW 2.7 OHM 10W BRACKET PCB CARD MOUNTING BRACKET PCB CARD MOUNTING BRACKET PCB CARD MOUNTING BRACKET PCB CARD MOUNTING IC REGULATOR 15V IC REGULATOR -15V INPUT CAP ELECT 10UF 50V CAP ELECT 10UF 50V CAP ELECT 10UF 50V CAP ELECT 10UF 50V CAP MONO 47PF 200V 10% NPO CAP MONO 22PF 200V 10% NPO CAP MONO 47PF 200V 10% NPO CAP MONO 22PF 200V 10% NPO CAP MONO 22PF 200V 10% NPO CAP MONO 22PF 200V 10% NPO CAP MONO .1uF 50V 20% Z5U CAP ELECT 10UF 50V CAP MPF 0.22UF 5% 63VDC CAP MONO .1uF 50V 20% Z5U CAP MONO .1uF 50V 20% Z5U XLR FEM HORIZ PCB WITH LATCH XLR FEM HORIZ PCB WITH LATCH JACK PHONO GOLD PJ261G JACK HEADPHONE DUAL BLK 1/8 CONN MALE 9 POS FRICTION LK CONN MALE 9 POS FRICTION LK RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 40.2K 1% 1/4W RES MF 40.2K 1% 1/4W RES MF 20K 1% 1/4W RES MF 40.2K 1% 1/4W RES MF 1K 1% 1/4W RES MF 20K 1% 1/4W RES MF 1K 1% 1/4W RES MF 40.2K 1% 1/4W

132223 132224 132226 132224 144015 144015 144271 139079 144091 144187 144269 144154 144299 144154 144095 144104 144299 144419 139173 139173 003611 003611 003611 003611 133154 133153 066445 066445 066445 066445 061299 061298 061299 061298 061298 061298 061305 066445 064329 061305 061305 117814 117814 117436 117825 117244 117244 144104 144104 144104 144104 144104 144104 144104 144104 144107 144107 144104 144107 144090 144104 144090 144107

R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 S1 SP1 U1 U2 U3
5

RES MF 20K 1% 1/4W RES MF 20K 1% 1/4W RES MF 3.32K 1% 1/4W RES MF 3.32K 1% 1/4W RES MF 20K 1% 1/4W RES MF 100 OHM 1% 1/4W RES MF 68.1 OHM 1% 1/4W RES MF 1M 1/4W RES MF 20K 1% 1/4W RES MF 10 OHM 1% 1/4W RES MF 10 OHM 1% 1/4W JSA4320-0201 BRACKET PCB CARD MOUNTING IC OPAMP NE4558N IC NAND SCHMIT 2-IN X 4 IC REGULATOR +5 VOLT

144104 144104 144095 144095 144104 144196 144082 144269 144104 144157 144157 148069 003611 133028 133192 133093 061305 061305 064329 064337 066445 061305 061305 064329 064337 066445 070130 058133 058133 070047 070047 070047 070047 070047 070047 070047 070047 070047 070047 070047 070047 058165 058165 058165 058109 117244 117215 117214 117766 117215 117766 132223 132223 132223 132223 132223 132223 132223 132223 132223 132223 132223 132223 144406 144154 144364

049755 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 J1 J2 J3 J4 J5 J6 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16

049756 METER/LIGHTING C4 CAP MONO .1uF 50V 20% Z5U C5 CAP MONO .1uF 50V 20% Z5U C8 CAP MPF 0.22UF 5% 63VDC C9 CAP MPF 0.1UF 100V C10 CAP ELECT 10UF 50V C11 CAP MONO .1uF 50V 20% Z5U C12 CAP MONO .1uF 50V 20% Z5U C13 CAP MPF 0.22UF 5% 63VDC C14 CAP MPF 0.1UF 100V C15 CAP ELECT 10UF 50V D1 DIODE ZENER 8.2V 1/2W D9 LED AMBER D13 LED AMBER D14 DIODE SILICON D15 DIODE SILICON D16 DIODE SILICON D17 DIODE SILICON D18 DIODE SILICON D19 DIODE SILICON D20 DIODE SILICON D21 DIODE SILICON D22 DIODE SILICON D23 DIODE SILICON D24 DIODE SILICON D25 DIODE SILICON DS5 LED GREEN 5MM HI-INTENSITY DS6 LED GREEN 5MM HI-INTENSITY DS7 LED GREEN 5MM HI-INTENSITY DS8 LED SQUARE RED J1 CONN MALE 9 POS FRICTION LK J2 CONN 4 PIN J3 CONN 3 POS MLE MTS100 NORM J4 HEADER 2 PIN LATCHING J5 CONN 4 PIN J6 HEADER 2 PIN LATCHING Q1 TRANSISTOR NPN Q2 TRANSISTOR NPN Q3 TRANSISTOR NPN Q4 TRANSISTOR NPN Q8 TRANSISTOR NPN Q9 TRANSISTOR NPN Q10 TRANSISTOR NPN Q11 TRANSISTOR NPN Q12 TRANSISTOR NPN Q13 TRANSISTOR NPN Q14 TRANSISTOR NPN Q15 TRANSISTOR NPN R6 RES MF 187K 1% 1/4W R8 RES MF 12.1K 1% 1/4W R9 RES MF 475K 1% 1/4W

R11 R13 R18 R19 R28 R29 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R53 R54 R55 R56 R57 R58 R59 R60 R61 U1 U2
6

RES MF 4.75K 1% 1/4W RES MF 681 OHM 1% 1/4W RES MF 12.1K 1% 1/4W RES MF 4.75K 1% 1/4W RES MF 562 OHM 1/4W RES MF 806 OHM 1/4W RES MF 187K 1% 1/4W RES MF 681 OHM 1% 1/4W RES MF 475K 1% 1/4W RES MF 200K 1/4W RES MF 10.2K 1% 1/4W RES MF 10M 1% 1/4W RES MF 2.21M 1/4W RES MF 100 OHM 1% 1/4W RES MF 187K 1% 1/4W RES MF 1.21K 1% 1/4W RES 82.5K 1/4W POT TRIM 100K OHM 20% RES MF 221K 1% 1/4W RES MF 6.81K 1/4W RES MF 100 OHM 1% 1/4W RES MF 200K 1/4W RES MF 10.2K 1% 1/4W RES MF 10M 1% 1/4W RES 82.5K 1/4W RES MF 2.21M 1/4W RES MF 187K 1% 1/4W RES MF 6.81K 1/4W POT TRIM 100K OHM 20% RES MF 1.21K 1% 1/4W IC DUAL OPERATIONAL AMP IC DUAL OPERATIONAL AMP METER LED LED BLUE 5MM HI-INTENSITY LED BLUE 5MM HI-INTENSITY LED GREEN 5MM HI-INTENSITY LED GREEN 5MM HI-INTENSITY LED BLUE 5MM HI-INTENSITY LED BLUE 5MM HI-INTENSITY LED GREEN 5MM HI-INTENSITY LED GREEN 5MM HI-INTENSITY CONN 4 PIN RIGHT ANGLE RES MF 221 OHM 1% 1/4W POT TRIM 500 OHM 20% HOR ADJ RES MF 221 OHM 1% 1/4W POT TRIM 500 OHM 20% HOR ADJ RES MF 221 OHM 1% 1/4W POT TRIM 500 OHM 20% HOR ADJ RES MF 221 OHM 1% 1/4W POT TRIM 500 OHM 20% HOR ADJ

144097 144195 144154 144097 144408 144089 144406 144195 144364 144117 144130 144264 144265 144196 144406 144191 144112 134383 144421 144297 144196 144117 144130 144264 144112 144265 144406 144297 134383 144191 133260 133260 058166 058166 058165 058165 058166 058166 058165 058165 117240 144172 134410 144172 134410 144172 134410 144172 134410

049758 DS1 DS2 DS3 DS4 DS5 DS6 DS7 DS8 J1 R1 R2 R3 R4 R5 R6 R7 R8

25

26

EXPLODED VIEW

27

28

MC252

EXPLODED VIEW con't

29

30

EXPLODED VIEW PARTS LIST

Ref No.

Part No.

Description

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

016469 016487 018717 018711 018710 049321 104164 094016 100342 092426 005351 005312 101074 100276 005237 017913 094430 101054 017901 005239 146243 021159 021030 049756 102001 124084 017881 005229 102045 049758 104014 005236 100200 126948 005234 078025 117741 117740 178161 117487 100250 101197 049755 018690 084206

GLASS CENTER PANEL GLASS PANEL W/HOLE END CAP CENTER EXTRUSION TOP/BOTTOM END CAP ASSY KNOB WASHER BLK FELT 1 X 1 /4 X 1/16 TAPE FOAM 1/4 X 1/8 SCREW 6-32 X 3/8 FILLISTER HD FILTER COLOR METER GLASS PANEL, PLATE PLATE GAP SCREW TAPPING 4-40 X 1/4 PH PN SCREW MACH SEMS 6-32 X 5/16 PH PN TITLE MOUNT LOGO BACKLIGHT TAPE FOAM WHITE 1/2W X 1/8 THK SCREW TAPTITE 6-32 X 1/4 PH PN LOGO PUSHBUTTON BACKLIGHT SUBPANEL SWITCH POWER BUSHING SWITCH SPACER 6 X 1/4 ASSY METER/LIGHTING PCB NUT KEP 4-40 CADMIUM PLATE METER BACKLIGHT METER METER PLATE NUT KEP 6-32 SPECIAL ASSY METER LED PCB WASHER INT STAR 3/8 X .507 X .002 DUST COVER SCREW MACH 10-32 X 1/2 PH TRS HD DECAL TOP COVER CHASSIS GROMMET RUBBER 3/4ID POST BINDING BLK POST BINDING RED HOLDER FUSE 5 X 20mm IEC RECEPTACLE AC LINE SCREW MACH SEMS 6-32 X 1/4 PH PN SCREW HI-LO 4-24 X 3/8 PH HD BLK ASSY INPUT PCB HEATSINK ISOSTRATE

46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85

112087 114141 101059 049986 005235 049766 049763 126946 126947 101078 102006 101176 102005 102003 104005 070139 084135 017452 104016 102052 104162 102051 005240 049757 005238 005308 094391 074091 104001 104004 102022 005242 106007 017218 104080 100159 100188 066489 101172 094429

SPACER PCB 1/4 CLIP RIGHT ANGLE SCREW SM 6 X 5/8 PH PN TYPE A ASSY HEATSINK PCB HEATSINK COVER POTTED TRANSFORMER OUTPUT POWER TRANSFORMER POWER DECAL OUTPUT TRANSFORMER DECAL POWER TRANSFORMER SCREW TAP 8-32 X 5/16 PH PN BLK NUT MACH 10-32 W/LOCK SCREW TC 6-32 X 1/2 PH PN TYPE F NUT MACH 8-32 W/LOCK NUT MACH 6-32 W/LOCK WASHER FLAT STEEL 6 X 3/8 X .032 DIODE BRIDGE RECTIFIER THERMAL PAD KLIP WIRE WASHER INT STAR .5 X .630 X .022 NUT GOLD SUPPLIED W/117758 WASHER LOCK INTERNAL TOOTH NUT HEX M9 X .75 GOLD PLATED HEATSINK VENT ASSY POWER SUPPLY PCB CHASSIS SUPPORT BRACKET CAPACITOR STRAP TAPE FOAM 1/8 X 3/4 3M #4508 TERMINAL BLOCK AC WASHER FLAT STEEL 4 X 9/32 X .025 WASHER LOCK 5 X .255 INT STAR NUT MACH 4-40 X 3/16 X 1/16 BOTTOM COVER SPRING CLIP LATCH TYPE FOOT PLASTIC BLK WASHER FELT #10 CLEAR ZINC SCREW MACH 10-32 X 3/4 PH PN BLK SCREW MACH SEMS 10-32 X 3/8 CAP ELECT 2700uF 100V SCREW TC 6-32 X 1/4 PH FL U/C TAPE FOAM 1/32 THK

31

32

MC252

REPACKING INSTRUCTIONS

33

POWER AMPLIFIER
SERVICE MANUAL

The continuous improvement of its 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 040880