McIntosh MA352 Service Manual
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McIntosh MA352 Service Manual

McIntosh MA352 Service Manual

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I N P U T
HEADPHONES
PUSH - TRIM
Performance Specifications ............................................... 2
Notes ................................................................................ 2
Rear Panel ........................................................................ 3
Section Location ............................................................... 4
Block Diagram .............................................................. 5-6
Interconnection Diagram ............................................... 7-8
Backup/Main Schematic and PCB ................................ 9-24
Power Supply Schematic and PCB ............................. 25-28
MA352
INTEGRATED AMPLIFIER
ALL SERIAL NUMBERS
BAL 1
30
125
CONTENTS
SERVICE MANUAL
15%
500
2k
10k
Control/EQ Schematic and PCB ................................29-34
L-Tube/R-Tube/Tube Light Schematic and PCB ..........35-40
Heatsink/Terminal Schematic and PCB .....................41-46
Display/Meter Light Schematic and PCB ...................47-50
Notes ........................................................................51-52
Parts list ....................................................................53-63
Notes ............................................................................. 64
Repacking Instruction .................................................... 65
MA352
VOLUME
STANDBY
PUSH - POWER

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  • Page 1: Table Of Contents

    MA352 MA352 INTEGRATED AMPLIFIER ALL SERIAL NUMBERS BAL 1 VOLUME I N P U T HEADPHONES STANDBY PUSH - TRIM PUSH - POWER CONTENTS Performance Specifications ..........2 Control/EQ Schematic and PCB ........29-34 Notes ................2 L-Tube/R-Tube/Tube Light Schematic and PCB ..35-40 Rear Panel ................

  • Page 2: Performance Specifications

    240 Volts, 50/60Hz at 3.3 amps Input Impedance Standby: Less than 0.5 watt High Level - 20K ohms Note: Refer to the rear panel of the MA352 for the correct voltage. Phono - 47K ohms; 50pF-800pF Overall Dimensions Preamplifier Output 2 (for rated input) Width is 17-1/2 inches (44.5cm)

  • Page 3: Rear Panel

    MA352 REAR PANEL R OUTPUT 1 L OUTPUT 1 MA352 INTEGRATED AMPLIFIER McINTOSH LABORATORY, INC. BINGHAMTON, NY HANDCRAFTED IN USA WITH US AND IMPORTED PARTS 4Ω/8Ω 4Ω/8Ω SERIAL NUMBER CLASS 2 WIRING CLASS 2 WIRING DATA POWER FUSE SERVICE T8AL 250V...

  • Page 4: Section Location

    SECTION LOCATIONS Top View TERMINAL DISPLAY HEATSINK METER LIGHT Bottom View L TUBE EQ PCB PWR SUPPLY MAIN TUBE LIGHT BACK UP R TUBE CONTROL...

  • Page 5: Block Diagram

    MA352 BLOCK DIAGRAM OUTPUT METER OUTPUT L HEADPHONE POSITIVE MUTING CURRENT LIMITER BAL 1 UNBAL METER OUTPUT BUFFER TUBE DRIVER BYPASS L OUTPUT 2 MUTING SWITCH CASCODE LEFT PG POWER DIFF BAL 2 VOLTAGE L OUTPUT 1 INDICATOR GUARD PREDRIVER...
  • Page 6 INTERCONNECT WARNING Parts marked with a triangle and exclamation point have critical characteristics. Use only CA16 replacement parts recommended by the manufacturer. CA19 GRN/YEL TERMINAL HEATSINK CA12 R TUBE JMP1 LOCATION POWER SUPPLY CA14 MET LT CA11 CA18 RD/GR PRIMARY A - I CA10 DISPLAY...
  • Page 7 MA352 BACKUP / MAIN 752613 SCH 1 of 7 +12VPC +12VPC +12VPC +24V +12VPC AD J R165 100k R166 R168 100k 475k R171 2.21k MAI N J36:1 DGND DGND TRIG OUT R182 R177 22.1k +3.3VBU +3.3VBU +3.3VBU PC LTS DGND...
  • Page 8 BACKUP / MAIN 752613 SCH 2 of 7 USB - USB + 12pF +3. 3VM +1. 2VM VOL CS 12.00MHz VOL DA 12pF 22.1 VOL CL EXT RXD EXT TXD NRST NRST +3.3V +3. 3VBU 22.1 E RA S E +3.
  • Page 9 MA352 BACKUP / MAIN 752613 SCH 3 of 7 +15V C100 R104 10µF MM L 47.5k 47pF 47pF R102 100k -15V NetTie1 .01µF .033µF 1000pF 7.5k 90.9k +15V -15V RM M GN D AGN D AGN D +7. 5V +7. 5V +7.
  • Page 10 BACKUP / MAIN 752613 SCH 4 of 7 1.2mm J1 :1 J1 :4 350mA J1 6:1 J1 :7 J1 6:2 J1 8:15 J1 8:16 +VBU +3. 3VBU VO U T J1 6:3 J1 8:17 J1 8:18 P R IM A R Y J1 6:4 J1 :10 J1 6:10...
  • Page 11 MA352 BACKUP / MAIN 752613 SCH 5 of 7 +3. 3VBU +3. 3VBU -15V 10µF 20.0k 10µF 2.21 +15V +15VI N I2C DA 10µF 20.0k I2C CL U20:1 +15V BAL 2 BAL 1 UNB 1 2.21 UNB 2 UNB 3...
  • Page 12 BACKUP / MAIN 752613 SCH 6 of 7 VOLU M E CON TROL C105 10µF L VOL J31:5 L VOL L INP C121 47µF AGN D Z/C REF L J31:2 L PR E +15V -15V L PR E L OUT AD R0 L REF C110...
  • Page 13 MA352 BACKUP / MAIN 752613 SCH 7 of 7 +10VM +10VM L M ETER DR IVER +10VM D 35 U 39:1 Q 26 -5VM L M ETER LOG AMP Q 24 Q 28 D 25 R 142 D 33 D 37...
  • Page 14 MA352 BACKUP / MAIN 752613 PCB...
  • Page 15 MA352 POWER SUPPLY 752577 SCH J4:1 +175V +175V +12. 6V J4:3 +12V L GR N J4:4 L GR N T° J1:1 J4:5 L RED L RED +12V ON/OFF GN D J4:2 12.1k 13.0k J5:12 J5:16 GRN/WHT J1:2 J5:13 J5:17 J5:14...
  • Page 16 MA352 POWER SUPPLY 752577 PCB...
  • Page 17 MA352 CONTROL / EQ 752286 1of 2 470pF 100µF +15VEQ +15VEQ +15VEQ +15VEQ R1:1 R5:1 100k R2:1 R3:1 R4:1 100k U1:1 U2:1 U3:1 U4:1 100k 100k 100k 10µF .033µF 2.2µF .01µF .47µF 2200pF .15µF 1000pF .033µF -15VEQ -15VEQ -15VEQ -15VEQ 150k 68.1k...
  • Page 18 CONTROL / EQ 752286 2 of 2 RIGHT HEADPHONE AMP +15H P +15H P INPUT +15V +15H P 49.9k L PRE 470µF 95.3 U6:2 -15V -15H P .22µF 95.3 PB DET J4:15 PB DET 470pF -15H P -15H P INP B J4:13 INP B INP A...
  • Page 19 MA352 CONTROL / EQ 752286 PCB...
  • Page 20 7 8 9 L-TUBE / R-TUBE / TUBE LIGHT MA352 (AHN SERIAL NUMBERS) 752287 SCH +173VL +173VL +173VL +173VR +173VR +173VR +12VL +12VR 475k 221k 221k 475k .01µF .01µF V1:3 V3:3 V3:2 V4:1 V4:3 V2:3 12AX7A 12AT7 12AT7 12AT7 12AT7...
  • Page 21 7 8 9 L-TUBE / R-TUBE / TUBE LIGHT MA352 (AHW SERIAL NUMBERS) 752519 SCH +173VL +173VL +173VL +173VR +173VR +173VR +12VL +12VR 332k 221k 221k 332k .01µF .01µF V1:3 V3:3 V3:2 V4:1 V4:3 V2:3 12AX7A 12AT7 12AT7 12AT7 12AT7...
  • Page 22 MA352 7 8 9 L-TUBE / R-TUBE / TUBE LIGHT 752287 and 752519 PCB...
  • Page 23 12 13 HEATSINK / TERMINAL 752294 SCH 1 of 2 +70V -14V +14V 10.5k 10.5k 22pF 2.21k VOLTAGE 22µF 10.5k AM P IN J1:17 +14V J1:18 2.21k U1:2 47µF U1:1 GN D J1:15 DIFFERENTIAL J1:16 -14V PT C1 J1:3 PT C1 PT C2 J1:6 PT C2...
  • Page 24 MA352 12 13 HEATSINK / TERMINAL 752294 SCH 2 of 2 J3 :3 + 7 0 V 1. 8V J3 :1 Q 41:2 Q 39:2 D R V + Q 27 D R IVER 1. 2V GN D J3 :2...
  • Page 25 12 13 HEATSINK / TERMINAL 752294 PCB...
  • Page 26 MA352 DISPLAY / METER LIGHT 752289 SCH 3.92k DS11:2 1.5k L METER J3:1 3.92k J3:2 DS12:2 1.5k 3.92k R M ET ER J4:1 DS13:2 1.5k GN D J4:2 DS10 3.92k DS14:2 1.5k J1:11 R M ET J1:10 L M ET...
  • Page 27 10 11 DISPLAY / METER LIGHT 752289 PCB...

  • Page 28: Notes

    NOTES...

  • Page 29: Parts List

    MA352 PARTS LIST INTERCONNECT BACKUP / MAIN PCB 752613 Cont’d Ref. No. Description Part No. Ref. No. Description Part No. OUTPUT CONNECTOR MINI 084228 CAP 12PF 50V 5% NPOSMD0805 061364 OUTPUT CONNECTOR MINI 084228 CAP ELECT 10UF 16V 066580 CAP MONO .1UF 50V +/-20% X7R SMD...
  • Page 30 PARTS LIST (Cont’d.) BACKUP / MAIN PCB 752613 Cont’d BACKUP / MAIN PCB 752613 Cont’d Ref. No. Description Part No. Ref. No. Description Part No. CAP 100PF 200V 5% SMD0805 061390 C143 CAP MONO .1UF 50V +/-20% X7R SMD 061365 CAP 100PF 200V 5% SMD0805 061390 C144...
  • Page 31 MA352 PARTS LIST (Cont’d.) BACKUP / MAIN PCB 752613 (Cont’d.) BACKUP / MAIN PCB 752613 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. BLADE FASTON W/FEET 117708 FERRITE 600 OHM 1 AMP SMD 076026 BLADE FASTON W/FEET...
  • Page 32 MA352 PARTS LIST (Cont’d.) BACKUP / MAIN PCB 752613 (Cont’d.) BACKUP / MAIN PCB 752613 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. RES SMD0805 1.5K 1/8W 1% 145022 RES TF 20.0K 0.1% 0.1W SMD0805 145072 RES TF 22.1 .5% .1W SMD0805 145133 RES TF 20.0K 0.1% 0.1W SMD0805...
  • Page 33 RES TF 100 1% 0.1W SMD0805 145060 IC SINGLE NAND SCHMITT SMD 133724 R185 RES TF 10 1% 0.1W SMD0805 145063 CRYSTAL 12.00MHZ SMD 180103 FIRMWARE V1.00 MA352 230287 R186 RES TF 10 1% 0.1W SMD0805 145063 R187 RES TF 10 1% 0.1W SMD0805 145063...
  • Page 34 MA352 PARTS LIST (Cont’d.) POWER 752577 POWER 752577 (Cont’d) Ref. No. Description Part No. Ref. No. Description Part No. CAP POLYPROP 0.22UF 400V 20% 064438 RES TF 1K 1% 0.1W SMD0805 145117 RES TF 221K .125W .5% SMD0805 145140 CAP MPF 0.033UF 5% 63VDC...
  • Page 35 MA352 PARTS LIST (Cont’d.) CONTROL / EQ PCB 752286 (Cont’d) CONTROL / EQ PCB 752286 (Cont’d) Ref. No. Description Part No. Ref. No. Description Part No. CAP .01UF PPS 50V 2% SMD1206 064473 RES SMD0805 681 1/8W 1% 145002 CAP .01UF PPS 50V 2% SMD1206...
  • Page 36 PARTS LIST (Cont’d.) L TUBE / R TUBE / TUBE LIGHT PCB 752287 (Cont’d) L TUBE / R TUBE / TUBE LIGHT PCB 752287 (Cont’d) Ref. No. Description Part No. Ref. No. Description Part No. CAP MPF 0.01UF 5% 250V 064472 RES TF 221K .125W .5% SMD0805 145140...
  • Page 37 MA352 PARTS LIST (Cont’d.) L TUBE / R TUBE / TUBE LIGHT PCB 752519 (Cont’d) DISPLAY / METER LIGHT 752289 (Cont’d) Ref. No. Description Part No. Ref. No. Description Part No. CONNECTOR LATCHING 2PIN RA SMD 118027 RES SMD0805 10M 1/8W 1%...
  • Page 38 PARTS LIST (Cont’d.) HEATSINK / TERMINAL 752294 (Cont’d.) HEATSINK / TERMINAL 752294 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. CAP NPO 1000pF 5% 100V SMD0805 061391 MP13 TRANSISTOR CLIP TO-247 414167 CAP NPO 1000pF 5% 100V SMD0805 061391 MP14 TRANSISTOR CLIP TO-247...
  • Page 39 HEATSINK / TERMINAL 752294 (Cont’d.) HEATSINK / TERMINAL 752294 (Cont’d.) Ref. No. Description Part No. Ref. No. Description Part No. RES TF 221K .125W .5% SMD0805 145140 RES SMD0805 1.5K 1/8W 1% 145022 RES SMD0805 221 1/8W 1% 145001 RES SMD0805 221 1/8W 1% 145001 RES TF 10.5K 1% 0.1W SMD0805 145064...

  • Page 40: Notes

    NOTES...

  • Page 41: Repacking Instruction

    To protect the tubes during shippment, the Foam 034616 Foam Middle Insert removed from the MA352 needs to be re- 034613 Foam Insert (for protecting inserted. Follow the unpacking instructions on pages the Tubes during shipping) 4-5 in the reverse order.
  • Page 42 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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