McIntosh MC301 Service Manual
McIntosh MC301 Service Manual

McIntosh MC301 Service Manual

Quad balanced power amplifier
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Performance Specifications .....................................2 - 3
Notes ...........................................................................2
Rear Panel ...................................................................3
Section Location ..........................................................4
Block Diagram .......................................................5 - 6
Interconnection Diagram ........................................7 - 8
Power Supply Schematic and PCB ..........................9 - 14
MC301
QUAD BALANCED
POWER AMPLIFIER
SERIAL NO. ADU1001 And Above
CONTENTS
SERVICE MANUAL
Main Schematic and PCB ...................................15 - 24
Heatsink Schematic and PCB ..............................25 - 28
Terminal Schematic and PCB ..............................29 - 32
Display/Meter Light Schematic and PCB .............33 - 36
Parts List .............................................................37 - 42
Repacking Instruction ................................................43
MC301

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Summary of Contents for McIntosh MC301

  • Page 1: Table Of Contents

    MC301 MC301 QUAD BALANCED POWER AMPLIFIER SERIAL NO. ADU1001 And Above CONTENTS Performance Specifications ........2 - 3 Main Schematic and PCB ........15 - 24 Notes ................2 Heatsink Schematic and PCB ......25 - 28 Rear Panel ..............3 Terminal Schematic and PCB ......29 - 32 Section Location ............4...
  • Page 2: Performance Specifications

    3.4 Volts Balanced 240V ~ 50/60Hz at 1.9 Amps 1.7 Volts Unbalanced Standby: less than 0.3 watt Note: Refer to the rear panel of the MC301 for the correct Signal To Noise Ratio (A-Weighted) voltage. 95dB Balanced (120dB below rated output)
  • Page 3: Rear Panel

    MC301 REAR PANEL...
  • Page 4: Section Location

    SECTION LOCATIONS TOP VIEW FROM REAR METER LIGHT DISPLAY MAIN HEATSINK TOP VIEW FROM FRONT TERMINAL POWER SUPPLY...
  • Page 5: Block Diagram

    MC301 QUAD BALANCED POWER AMPLIFIER BLOCK DIAGRAM POSITIVE CURRENT LIMITER VOLTAGE RECTIFIER METER POWER DIFF VOLTAGE PREDRIVER GUARD DRIVER OUTPUT CURRENT ThermalTrak SOURCE DC BIAS UNBALANCED OUTPUT DIFF VOLTAGE PREDRIVER DRIVER OUTPUT UNBALANCED INPUT NEGATIVE CURRENT LIMITER INPUT MODE POWER GUARD...
  • Page 6 INTERCONNECT HEATSINK TERMINAL PWR SUPPLY METER LT MAIN MAIN FUSE VOLTAGE 100V T6.3AL 250V 110V / 120V T5AL 250V 220V T4AL 250V 230V / 240V T3.15AL 250V DISPLAY CONVERSION JUMPER VOLTAGE JMP1 100V 17198500 110V / 120V 17198600 JMP1 220V 17198700 HEATSINK 230V / 240V...
  • Page 7 MC301 QUAD BALANCED POWER AMPLIFIER 2 POWER SUPPLY 751644 SCH 1 of 2 AC F J1:1 +12V VOUT .1µF 350mA .1µF 220µF 1000µF 1000µF PRIMARY .15µ F AC D ETE C TOR BAC KU P PWR SU PPLY 150k AC DET GN D .1µ...
  • Page 8 2 POWER SUPPLY 751644 SCH 2 of 2 L M ET L M E T J12:2 J13:2 L M ET R M ET R M E T J12:18 J13:18 R M E T L PG LT L P G ON J12:4 J13:4 L P G LT...
  • Page 9 MC301 QUAD BALANCED POWER AMPLIFIER 2 POWER SUPPLY 751644 PCB...
  • Page 10 3 MAIN 751627 SCH 1 of 4 R109 +57V R R111 10µF 3.32k R123 +57V J6:9 +57V R DIFFERENTIAL VOLTAGE -57V J6:6 -57V R R104 R106 47µF R INP DRV + J6:8 R DRV + R102 2.21k 1000pF R117 R112 R100 2.21M J6:7...
  • Page 11 MC301 QUAD BALANCED POWER AMPLIFIER 3 MAIN 751627 SCH 2 of 4 +15V M R +15V M R +15V M R R METE R DRIVER R157 U10:1 +15V +15V M R -15V -5V M R R METE R LOG AMP 5.1V...
  • Page 12 3 MAIN 751627 SCH 3 of 4 +57V L LB + 10µF 3.32k +57V J5:9 +57V L D IFFE R EN TI AL VOL TA GE -57V J5:6 AM P AM P -57V L 47µF L INP D R V + J5:8 L DRV + 2.21k...
  • Page 13 MC301 QUAD BALANCED POWER AMPLIFIER 3 MAIN 751627 SCH 4 of 4 1.65k 22.1 2.21k 2.21k 2.21k +14V -14V .1µF .1µF +14V +14V U1:1 100pF 10µF +15V R PG MU 47pF 2.21M -14V Vocm +14V 22.1k 100pF -14V U7:2 U7:1 1.65k...
  • Page 14 3 MAIN 751627 PCB...
  • Page 15 MC301 QUAD BALANCED POWER AMPLIFIER 4 HEATSINK 751631 SCH +57V J4:1 +57V +57V 100pF J4:2 -57V -57V 1.8V DRIVER Q 36:2 1µF 1µF 1.2V Q 32:1 .1µF OUTPUTS - BI AS AD JU ST M EN T - AD JU ST R 47...
  • Page 16 4 HEATSINK 751631 PCB...
  • Page 17 MC301 QUAD BALANCED POWER AMPLIFIER 5 TERMINAL 751734 SCH J1:1 .65µH OUT 8 + J1:3 J3:2 OUT 8 + 8Ω .15µF .047µF .65µH OUT 8 + J1:4 J3:3 4 5W .15µF .047µF OUT 2 + J2:4 J3:1 OUT 4 +...
  • Page 18 5 TERMINAL 751734 PCB 130265...
  • Page 19 MC301 QUAD BALANCED POWER AMPLIFIER DISPLAY/METER LIGHT 751735 SCH J5:1 J6:12 METER J1:1 J5:12 J6:1 J1:2 8.25k STANDBY DISPLAY J5:9 J6:4 PWR GUARD LOGO POWER J5:10 J6:2 J5:11 J6:3 J2:2 J5:7 J6:5 J5:8 J6:6 J2:1 J5:5 J6:7 J5:6 J6:8 METER LIGHT...
  • Page 20 DISPLAY/METER LIGHT 751735 PCB...
  • Page 21: Parts List

    MC301 PARTS LIST INTERCONNECT Ref No. Description Part No. Ref No. Description Part No. CAP X7R .1uF 50V ±20% SMD 061365 OUTPUT CONNECTOR MINI 084228 OUTPUT CONNECTOR MINI 084228 CAP ELECT 10UF 50V 066445 OUTPUT CONNECTOR MINI 084228 CAP X7R .1uF 50V ±20% SMD...
  • Page 22 PARTS LIST cont’d. POWER SUPPLY PCB 751644 (Cont’d.) Ref No. Description Part No. Ref No. Description Part No. RES SMD0805 221K 1/8W 1% 145038 CAP 100pF 200V 5% SMD0805 061390 RES SMD0805 47.5K 1/8W 1% 145013 CAP 47pF 200V 10% NPO SMD 061368 RES SMD0805 22.1K 1/8W 1% 145012...
  • Page 23 MC301 PARTS LIST cont’d. MAIN PCB 751627 (Cont’d.) Ref No. Description Part No. Ref No. Description Part No. DIODE ZENER 5.1V 5% SMD 070215 TRANSISTOR NPN 2SC3324 SMD 132345 DIODE ZENER 5.1V 5% SMD 070215 TRANSISTOR NPN 2SC3324 SMD 132345...
  • Page 24 PARTS LIST cont’d. MAIN PCB 751627 (Cont’d.) Ref No. Description Part No. Ref No. Description Part No. RES SMD0805 332 1/8W 1% 145006 R165 RES SMD0805 47.5K 1/8W 1% 145013 RES MO 430 OHM .5W 5% 137101 SWITCH SLIDE DPDT 148082 RES SMD0805 33.2K 1/8W 1% 145033...
  • Page 25 MC301 PARTS LIST cont’d. HEATSINK PCB 751631 (Cont’d.) TERMINAL PCB 751735 Ref No. Description Part No. Ref No. Description Part No. CAP .47UF 50V 20% X7R SMD0805 061373 TRANS PNP THERM TRAK 132331 CAP .47UF 50V 20% X7R SMD0805 061373...
  • Page 26 NOTES...
  • Page 27: Repacking Instruction

    Cus- 40120400 #10 x2-1/2 cap screw tomer Service Department of McIntosh Laboratory. Refer to 40403300 #10 x 1-3/4 washer page 3. Please see the Part List for the correct part numbers.
  • Page 28 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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Adu1001

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