McIntosh C32 Preamp Service Information.pdf

mtlntosh C 32 PREAMPLIFIER SERVICE INFORMATION STARTING WITH SERIAL NO. AY1001 MclNTOSH LABORATORY INC. BINGHAMTON, NEW YORK 13903 39-075 :32 PERFORMANCE LIMITS FREQUENCY RESPONSE +0 to -.5dB from 20Hz to 20,000Hz Equalizer Out: +0 to -IdB from 1OHz to 100,000Hz DISTORTION .05% maximum at rated output level, 20Hz to 20,0O0Hz INPUT SENSITIVITY AND IMPEDANCE Phono 1 5- 2: 2 millivolts at 47Kn 65pF Auxiliary: Tuner, tape I, tape 2 S- tape 3: 250 millivolts at 50Kn HUM AND NOISE Auxiliary, Tuner, tape 1, tape 2 and tape 3- IHF lOOdB; unweighted -90dB Phono 1 IHF 90dB; unweighted 80dB below 10 millivolt input or equivalent to less than 1 microvolt at the input terminals. VOLTAGE AMPLIFICATION In Decibels flat. with all equal ize rs and filters 1 npu t Ma i n Tape 1,2,3 Monitor Amp Headphone Jack Aux.,Tuner 20dB 0 dB 30dB 30dB Tape 1, 2 or 3 20dB 0 dB 30dB 30dB Phono 1 62dB 42dB 72dB 72dB Phono 2 62dB 42dB 72dB 72dB SEMICONDUCTOR COMPLEMENT 67 Transistors 35 Integrated Circuits 62 Diodes 2 Field Effect Transistors 1 Silicon Controlled Rectifier (SCR) POWER REQUIREMENT 120 volts, 50/60Hz, 25 to 85 watts OUTPUT LEVEL AND IMPEDANCE Main Output: 2.5 volts with rated input to operate into 5,000 ohm or greater load. Output Source Impedance 220 ohms. Tape Output: 250 millivolts with rated input to operate into 5,000 ohms or greater 1 oad. Monitor, Headphone, Line Output: 12 watts per channel continuous into 8n (3 less than .1% total harmonic distortion 20Hz to 20,000Hz or 5 volts RMS Into 600n line- level controls provided. PROGRAM EQUALIZER l2dB of boost or cut at 30, 150, 500, 1500 and 10,000Hz MECHANICAL INFORMATION Size: Front panel measures 16 inches wide (40.64 cm) by 5-7/16 inches deep (13.81 cm). Chassis measures 15 inches wide (38.1 cm) by 5 inches high (12,7 cm by 13 inches deep (33.02 cm), including PANLOC shelf and back panel connectors. Knob clearance required is 1-1/2 inches (3.81 cm) in front of the mounting panel Finish: Front panel is anodized gold and black with special gold/teal nomenclature ilium ination. Chassis is black. Mounting: Exclusive McIntosh developed profes sional PANLOC Weight: 26 pounds (11.8 kg) net, 36 pounds (17.2 kg) in shipping carton. Shipping Carton Size: 21 x 21 x 11 FEEDBACK GAIN lOdB FEEDBACK GAIN lOdB FEEDBACK GAIN lOdB FEEDBACK C32 INTERCONNECT e- IN C32 _|aV_RE0 EXPANDER 045-031 600 SERIES SYMBOL NOS RIGHT OUT GND GND LEFT OUT jT- OIOIOKS B+ OUT EXPAND LEVEL MATCH GND EXPAND SLOW GND EXPAND NORMAL RIGHT MAIN OUT Z GND s I g LEFT MAIN OUT BRN OV OV BRN/ CRN OV OV GRN/ RED 18V lev RED/ BLK OV OV BLK| BRN OV OV BRN| ORN OV OV ORN| jYEL OV OV YELi |6RN OV OV GRNi HEADPHONE AMP 045-116 900 SERIES SYMBOL NOS I LEFT HO. PH. OUT 1 RIGHT HD. PH.OUT 6 NO 2 LEFT HO. PH. OUT 2 RKHT HO. PH. OUT HEADPHONE! .24125126127) INDICATOR 045-119 1000 SERIES SYMBOL NOS TO SCR OV OLEFT OUTPUTf 2 OUTN GNDf ISWITCHED OUTPUT LEFT 045-122 I 2000 SERIES SYMBOL NOSl POWER ON/OFF GND LEFT OUTPUT I OUT PUSH BUTTON SWITCH 045-090 700 SERIES SYlteOL NO S RIGHT OUTPUT 2 OUTi GNDi 8 6ND a OTOIOXIOIOIOTOM TONE F 045- 600 SERIES ILTER 009 YMBOL NOS .OaO.OlOjOlO, o c.- U.3 Z Z Ub 55 o 55 2 z 2 - ts 16 11 ANDER / BALANCE / LOUDNESS 045-169 500 SERIES SYMBOL NOS SWITCHED OUTPUT RIGHT 045-123 3000 SERIES SYMBOL NO 5 () 0 0 $) (;) SCHEMATIC NOTES C32 1. Unless otherwise specified: Resistance values are in ohms, 1/4 watt, and 5% tolerance; capacitance values smaller than I are in microfarads (pF); capacitance values greater than 1 are in picofarads (pF); inductors are in microhenries (pH). 2. Printed circuit board components are outlined on the schematics by dotted lines. The circled numbers around the dotted lines correspond to the numbers on the PC Board layouts. 3. The heavy lines on the schematics denote the primary signai path. The heavy dash lines on the schematics denote a secondary signal path. 4. The terminal numbering of rotary switches is for reference only. 5. All voltages indicated on the schematics are measured under the following conditions; a. Use of an II megohm input impedance VTVM. b. All voltages 10% with respect to chassis ground. c. No signal at input terminals. d. AC input at 120 volts, 50/60 Hz. e. Front panel controls at: Listen Record Mode Selector EquaIizer Freq. Volume Expander Ba1ance Loudness Push Switches Power Switch Aux Aux Stereo Center Detent CCW Off Center Detent Flat Out On All other controls at normal positions. 6. 1 n units with Serial No s below AY2076 7. 1 n units wi th Serial No s below AY1295 8. 1 n units with Serial No s below AY3000 9. 1 n units with Serial No s below AY3000 are .047pF and C637 and C638 are used. 10. 1 n units with Serial No s below AY3000 are 680K and R511 and R512 a re 1 S.8K. 1 1. 1 n units wi th Serial No s below AY2076 12. 1 n units w i th Serial No s Below AY3000 13. 1 n units V/i th Serial No s be 1 ow AY3000 C915 and C916 , are 220; 14. In units with Serial No s below AY2289 R239 PHONO I PHONO 2 AUX TUNER TAPE I TAPE 2 TAPE 3 16 19 LEFT INPUT SWITCHING 045-149 TUNER TAPE I K203 AA/V if /:. i 1 wyAp o o 0 0 o o 0 R90I-P 19 18 *18 8 14 15 AAAr ,Q2I7 Q2I9 Q23I K203 K205 D23S LEFT INPUT SWITCHING 045-149 TAPE 3 TAPE 2 TAPE I TUNER AUX PHONO 2 PHONO I AUX TUNER TAPE I TAPE 2 tape 3 33 34 35 36 IC20I LEFT INPUT SWITCHING PHONO Z PHONO I TUNER TAPE 2 TAPE 3 e(Q22 -wv 08 1ntegrated Circul t 133-045 Front Panel Glass 016-153 IC809.8IO 1 ntegrated C i rcui t 133-068 End Caps 018-160 IC8I1,812 1ntegrated Circui t ,133-068 Knob -Listen 090-156 1 C8I3 1ntegrated C i rcui t 133-068 Knob-Record 090-156 1 C90I,902 1ntegrated Circu1 t 133-068 Knob-Mode 090-159 Knob-Vo 1ume 090-170 CAPACITORS Knob-Eq. Frequency 090-171 C3,4 Elect 4700|jF 30v 066-276 Knob-Expander 090-171 RELAYS Knob-Ba1ance 090-187 Kl Relay SPST 087-020 Knob-Loudness 090-186 K201,202 Reed Relay 087-023 MISCELLANEOUS K203.204 Reed Relay 087-023 Shipping Carton 045-321 K205,206 Reed Relay 087-023 Mounting Temp #100 038-178 K801,802 Reed Relay - - . 087-024 e- Hardware Package 045-124 K901 Reed Relay 087-029 Front Panel Lamp Grommet 078-005 T: r C c vt . Fuseholder 178-099 R2 Volume Control 134-305 Line Cord 170-019 R501 ? .JBaldnce / LbuidSss s t,. . W 1-34-312 - ; Audio Cable 170-015 R502 Expand V . 134-313 R601,602 Equal izer Freq-. - T34-,3ie. . - R603,604 Equa11zer Freq. 134-316 R605 jEtiualizer Freq;. r * t-* V- 134-316., R909,910 Right/Left Gain 134-306 R947 Level Match 134-306 CAPACITORS C3,4 Elect 4700(jF 30V 066-276 039-075 15C01I257-M8075-2 SERVICE BULLETIN CORRECT POSSIBLE SHORTING CONDITION MODEL: C 32 Preamplifier Serial No.: Below AY1295 PURPOSE OF MODIFICATION: To correct the condition where by the pre amplifiers headphone amplifier channels are shorted together when plugging headphones into the top headphone jack. WHEN MODIFICATION SHOULD BE MADE: When any other service is performed on the unit. MCINTOSH MODIFICATION KIT NO.: No kit available. PARTS REQUIRED: QUANTITY PART NUMBER DESCRIPTION 2 136453 Res. loon, 10%, IW R943,944 PROCEDURE: 1. Remove top cover. 2. Make a sketch of the connectors connections to the head phone monitor PC boards. 3. Remove the connectors from headphone monitor PC board and remove headphone monitor PC board from the chassis. 4. Replace jump wire that jumps K901 to connector pin 28 with a 136453 lOOn 10% IW resistor. 5. Replace jump wire that jumps K901 to connector pin 24 with a 136453 lOOn 10% IW resistor. 6. Reinstall the headphone monitor PC board and replace top cover. t/i 00 o z vj O N3 (OVER) McIntosh Laboratory Incorporated 2 Chambers Street Binghamton, New York 13903 Phone; Area Code 607-723-3512 REMOVE JUMPERS AND REPLACE WITH lOOfl 10% IW RESISTORS - .HEADPHONE MONJTOR PC BOARD 045-ire 039-061A SERVICE BULLETIN c -32 S.B: No. 2 ELIMINATION OF FEEDBACK.fROM TAPE OUTPUTS -i : . MODEL: C 32 Preamplifier Serial No;:; -.-Below AY2076 T-ni PURPOSE OF MODIFICATION: To eliminatevOSOi11 ation when switching the record switch from “any tape po.siiTon to anothereh Jiape out puts are in use. . - vjx ; U WHEN MODIFICATION SHOULD BE MAQE :_;V/hnj/he ciuatogrlcbmpfa rris of the osci 1 1 at ion. -f; -.I-.- PARTS REQUIRED: ; * r!,. * 1. QUANTITY PART-NOMBER j .J2SQRIPTiaN 3 066216 ICF, i6v E|itrolytic i- - “ Capacitor 3 r e 070085 62 V 2#3e r D i od-e- PROCEDURE: 3 e ; 1. Remove front panel and bottom cover. - 2. Remove record sw i tch w i th PCS . _ _ _ 3. Lift the base leg*of Sat1ltrahsiVtdir (Q301 , Q302, and Q303) off the PCB. 4. Insert banded end of zener diode into holes on component side of PCB and solder other end to the transistors base leg. 5. Solder the capacitors from zener to embitter of each transistor on the.foil side of PCB. Connect ( + ) terminal of capacitor to zener. 6. Install record switch. Insert and tape ribbon cable. 7. Replace front panel, and bottom cover. 039-066A cn CD O 2 Vj O NJ N McIntosh Laboratory Incorporated 2 Chambers Street Binghamton, New York 13903 Phone: Area Code 607-723-3512 S.B. No. 3 SERVICE BULLETIN PREVENT FALSE TURN ON OF PREAMP MODEL: C 32 Preamplifier PURPOSE OF MODIFICATION: To prevent false turn on of preamp by auto ON circuit. WHAT UNITS ARE AFFECTED: All units with Serial Nos, below AY2289 WHEN MODIFICATION SHOULD BE MADE: When any other service is performed on the unit. PARTS REQUIRED: QUANTITY 1 PART NUMBER 061113 DESCRIPTION Disc. Cap. O.lpF lOOV +80 -20% (Dua1) PROCEDURE: 1. Remove bottom cover. 2. Locate the 045121 - Auto-On PC board. 3. As indicated, solder disc, capacitor on to the foil-side of the PC board, between the cathode and gate of SCR 4001. 4. Replace bottom cover. 5. Check unit for normal operation AUTO-ON PC BOARD 045H21 o Z VO O M Vo 039-092 McIntosh Laboratory Incorporated 2 Chambers Street Binghamton, New York 13903 Phone; Area Code 607-723-3512