McIntosh MC452 Service Manual
McIntosh MC452 Service Manual

McIntosh MC452 Service Manual

Quad balanced power amplifier
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Performance Specifications ..........................................2
Notes ...........................................................................2
Rear Panel ...................................................................3
Section Location .....................................................5 - 6
Block Diagram .......................................................7 - 8
Interconnection Diagram ......................................9 - 10
Main Schematic and PCB ...................................11 - 18
Capacitor Schematic and PCB ............................19 - 22
SERVICE MANUAL
MC452
QUAD BALANCED
POWER AMPLIFIER
SERIAL NO. AAT1001 - AAT1196
CONTENTS
Left Input Schematic and PCB .............................23 - 26
Right Input Schematic and PCB ..........................27 - 30
Heatsink Schematic and PCB ..............................31 - 36
Left Terminal Schematic and PCB .......................37 - 40
Right Terminal Schematic and PCB .....................41 - 44
Display Schematic and PCB................................45 - 48
Parts List .............................................................49 - 55
Repacking Instruction ................................................57
MC452

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Summary of Contents for McIntosh MC452

  • Page 1: Table Of Contents

    MC452 MC452 QUAD BALANCED POWER AMPLIFIER SERIAL NO. AAT1001 – AAT1196 CONTENTS Performance Specifications ..........2 Left Input Schematic and PCB ......23 - 26 Notes ................2 Right Input Schematic and PCB ......27 - 30 Rear Panel ..............3 Heatsink Schematic and PCB ......31 - 36 Section Location .............5 - 6...
  • Page 2: Performance Specifications

    4.2 Volts Balanced 240V ~ 50/60Hz at 6 Amps 2.1 Volts Unbalanced Standby: less than 0.5 watt Note: Refer to the rear panel of the MC452 for the correct Signal To Noise Ratio (A-Weighted) voltage. 95dB Balanced (122dB below rated output)
  • Page 3: Rear Panel

    MC452 REAR PANEL...
  • Page 4 NOTES...
  • Page 5: Section Location

    MC452 SECTION LOCATIONS Top View Bottom View...
  • Page 6: Block Diagram

    BLOCK DIAGRAM POSITIVE CURRENT LIMITER POWER DIFF VOLTAGE CURRENT INDICATOR PREDRIVER DRIVER TRANSDUCER GUARD OUTPUT CURRENT ThermalTrak CURRENT SOURCE DC BIAS UNBALANCED VOLTAGE DIFF INPUT PREDRIVER DRIVER OUTPUT RECTIFIER METER UNBALANCED OUTPUT THERMAL LEFT NEGATIVE VOLTAGE SENSORS METER OUTPUT CURRENT HOLD SWITCH LIMITER...
  • Page 7 MC452 INTERCONNECT MC452 TRANSFORMER WIRING AND FUSE REPLACEMENT (CONTACT MCINTOSH FOR CURRECT TRANSFORMER P/N) Voltage BLK BLK/GRY GRY VIO WHT/VIO BRN 1 BRN 2 Jumper Location (JMP1) Main Fuse (F1) T15AH250V T15AH250V T15AH250V WHT 24 AWG WHT 18 AWG TERMINAL...
  • Page 8 MAIN 751134 SCH 1 of 3 +15V PC OUTPUT +15V +15V DRIVER 13.2V MODE MODE J26:1 MUTE J21:5 MUTE -18V +15V J26:5 +15V L PG LT J21:1 -15V J26:7 -15V +15V J21:3 +15V PC OUT J26:3 PC OUTPUT PC OUT DELAY -15V J21:4...
  • Page 9 MC452 MAIN 751134 SCH 2 of 3 +14VML U8:1 -5VML 150k L METER DRIVER -5VML +14VML +14VML U8:2 1000µF HS OUT J29:1 18.2k U10:2 AUTOF J29:2 L METER LOG AMP +15V +14VML 47 .5 W HOLD L 200k J32:1 MET [+]...
  • Page 10 MAIN 751134 SCH 3 of 3 J1:1 J1:4 PRIMARY J1:7 J1:10 J2:10 J2:1 J2:4 J3:2 TEST ONLY ON/OFF NO CONNECTION APPLY 12VDC TO ENERGIZE RELAYS W ITH NO AC POWER J3:1 47.5K T° AC F AC DET PWR RLY AC DETECTOR REFER TO +15V CONNECTION...
  • Page 11 MC452 MAIN 751134 PCB...
  • Page 12 CAP/RECTIFIER 751135 SCH +V BRG BRIDGE RECTIFIER -V BRG +V AMP J13:1 +V AMP +V CAP -V AMP J13:2 -V AMP -V CAP +V AMP J14:1 -V AMP J14:2 +V AMP J15:1 -V AMP J15:2 +V AMP J16:1 -V AMP J16:2...
  • Page 13 MC452 CAP/RECTIFIER 751135 PCB...
  • Page 14 LEFT INPUT 751136 SCH J5:8 FB COM 1.82k 22.1 2.21k J5:7 L (-) L - INP J5:9 +14VL +14VL .1µF J5:12 U1:1 Vocm J3:1 J5:11 PG ATT L PG HT SNK 2.21M J5:2 10µF 22.1k -14VL L PG PG ATT J5:3 -14VL 1.82k...
  • Page 15 MC452 LEFT INPUT 751136 PCB...
  • Page 16 RIGHT INPUT 751221 SCH J5:8 FB COM 1.82k 22.1 2.21k J5:7 R (-) R - INP J5:9 +14VR +14VR .1µF J5:12 U1:1 Vocm PG ATT J3:2 R PG HT SNK 2.21M J5:2 10µF 22.1k -14VR R PG J5:1 PG ATT J5:3 -14VR 1.82k...
  • Page 17 MC452 RIGHT INPUT 751221 PCB...
  • Page 18 HEATSINK 751152 SCH 1 of 2 +V AMP 47 .5 W DIFFERENTIAL VOLTAGE J1:4 100µF PG ATT J1:5 PG ATT FB COM J1:1 FB COM DRV + 1.8V J1:3 2.21M -18V 2.21M AMP MUTING CURRENT SOURCE FB 8 J2:3 J2:5 FEEDBACK NETW ORK FB 2 J2:1...
  • Page 19 MC452 HEATSINK 751152 SCH 2 of 2 +V AMP 1.8V DRV + DRIVER 1.2V Q28:1 CURRENT Q30:1 OUTPUTS LIM ITER Q32:1 Q34:1 BIAS ADJUSTMENT ADJUST R52 FOR 21-25 mV DC ACROSS J5 WITH NO INPUT SIGNAL AND HEATSINKS COOL Q36:1...
  • Page 20 HEATSINK 751152 ASSY...
  • Page 21 MC452 LEFT TERMINAL 751138 SCH LEFT OUTPUTS J8:6 L (+) L + FB8 FB 8 J8:7 J8:5 L (+) L + FB2 FB 2 J8:2 L (-) L - FB8 FB 8 J8:3 J8:1 L (-) L - FB2 FB 2...
  • Page 22 LEFT TERMINAL 751138 PCB...
  • Page 23 MC452 RIGHT TERMINAL 751222 SCH BREAKAWAY J8:6 R (+) R + FB8 FB 8 J8:7 J8:5 R (+) R + FB2 FB 2 R (-) J8:2 R - FB8 FB 8 J8:3 J8:1 R (-) R - FB2 FB 2...
  • Page 24 RIGHT TERMINAL 751222 PCB...
  • Page 25 MC452 DISPLAY/METER LIGHT 751139 SCH J5:1 J7:8 POWER J5:3 J7:10 J5:5 J7:12 FP OFF J1:7 FP OFF DISPLAY FP ON J1:4 FP ON J1:1 R INTENSITY R COLOR J5:2 J7:7 J5:4 J7:9 R BLU R BLU J5:6 J7:11 R GRN...
  • Page 26 DISPLAY/METER LIGHT 751139 PCB...
  • Page 27: Parts List

    DIODE SMALL SIGNAL 4148 SMD 070199 ASSY AUTOFORMER POTTED 751170 DIODE SMALL SIGNAL 4148 SMD 070199 CONTACT McINTOSH SERVICE DEPT DIODE SMALL SIGNAL 4148 SMD 070199 DIODE SMALL SIGNAL 4148 SMD 070199 MAIN PCB 751134 DIODE SMALL SIGNAL 4148 SMD...
  • Page 28 PARTS LIST (Cont’d.) MAIN PCB 751134 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. RES SMD0805 100K 1/8W 1% 145014 DIODE SMALL SIGNAL 4148 SMD 070199 RES POLYSWITCH RXE110 144671 DIODE SMALL SIGNAL 4148 SMD 070199 RES POLYSWITCH RXE110 144671 HEADER SHROUDED 10 PIN 2MM 117973...
  • Page 29 MC452 PARTS LIST (Cont’d.) MAIN PCB 751134 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. CAP 100PF 50V SMD0805 061316 RES MF 12.1K 1% 1/4W 144550 CAP 47PF 200V 10% SMD0805 061368 RES MF 200K 1% 1/4W 144531 CAP MONO .1UF 50V 20% SMD0805...
  • Page 30 PARTS LIST (Cont’d.) RIGHT IMPUT PCB 751221 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. TRANSISTOR N JFET 132319 STANDOFF 6-32 X 1/4 PCB MOUNT 112130 IC DUAL OP AMP 5532 SMD 133718 (GP1) SCR SM6-18X5/8 PH PAN 401059 IC OP AMP DIFFERENTIAL SMD 133772...
  • Page 31 MC452 PARTS LIST (Cont’d.) HEATSINK ASSY 751152 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. (Q31) CLIP TRANSISTOR 214 414119 RES MO 47 OHM .5W 5% 137102 TRANS NPN 260V THERM TRAK NJL3281D 132330 RES MO 47 OHM .5W 5%...
  • Page 32 PARTS LIST (Cont’d.) LEFT TERMINAL PCB 751138 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. RES WW 4 OHM 5% 5W 139248 CONN 12 PIN FFC SMD 118001 RES WW 4 OHM 5% 5W 139248 CONN 12 PIN FFC SMD 118001 PCB1 PC BD DISPLAY...
  • Page 33 MC452 PARTS LIST (Cont’d.) DISPLAY/METER LIGHT PCB 751139 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. RES SMD0805 1.5K 1/8W 1% 145022 RES SMD0805 221 1/8W 1% 145001 RES SMD0805 1.5K 1/8W 1% 145022 IC SINGLE NAND SCHMITT SMD...
  • Page 34 NOTES...
  • Page 35: Repacking Instruction

    If a shipping carton or any of the interior 401212 1/4 - 20x2-1/4 cap screw part(s) are needed, please call or write Customer 104058 Flat washer Service Department of McIntosh Laboratory. Refer to page 3. Please see the Part List for the correct part numbers.
  • Page 36 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.

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Aat1001Aat1196

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