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NAD T 975 C/AH Service Manual

Seven channel amplifier
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Summary of Contents for NAD T 975 C/AH

  • Page 2: Table Of Contents

    CONTENTS FRONT PANEL/REAR PANEL VIEW SPECIFICATIONS ALIGNMENT PROCEDURE/ALIGNMENT POINTS WIRING DIAGRAM SCHEMATIC DIAGRAM 8-15 PCB LAYOUT 16-23 ELECTRICAL PARTS LIST 24-37 EXPLODED VIEW EXPLODED VIEW PARTS LIST PACKING DIAGRAM SERVICE SAFETY PRECAUTIONS 1. Replacing the Fuses CAUTION: FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE OF FUSE.
  • Page 3 - 3 -...

  • Page 4: Specifications

    SPECIFICATIONS CONTINUOUS AVERAGE POWER 140 W (21.5 dBW) OUTPUT INTO 8 OHMS OR 4 OHMS (Min. power per channel, 20 Hz – 20 kHz, both channels driven, with no more than rated distortion) Rated Distortion 0.03% (THD 20 Hz – 20 kHz) Clipping power 170 W(22.3 dBW) (maximum continuous power per channel).
  • Page 5 ALIGNMENT PROCEDURE (T975) A. THERMAL SENSE ADJUSTMENT This adjustment should be always done when the T975 is in a cool condition. (That means the temperature inside the unit should be almost same as the ambient temperature.) Connector P208B that connects the transformer and power board should be removed to avoid the Idling current heating up the unit excessively) At ambient temperature of 25 C degrees and when the unit is just turned on (still in cool condition), adjust the pot RV103 (as marked as “Thermal Sense ADJ”...
  • Page 6 For example; all 7 channels at 50W/4 ohms for 10 minutes or 5 minutes or even less (as long as the fan can starts turning). Turn off the signal but still keep the unit operating for 1 minute. Then run all 7 channels at 1kHz, 0.25W at 4 ohms load, monitor the voltage at TP1 J201.

  • Page 7: Wiring Diagram

    WIRING DIAGRAM TRIGGER BOARD CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4 CHANNEL 5 CHANNEL 6 CHANNEL 7 P102A P102A P102A P102A P102A P102A P102A P102A P102A P102A P102A P102A P102A P102A MOLEX 41662 MOLEX 41662 MOLEX 41662 MOLEX 41662 MOLEX 41662 MOLEX 41662 MOLEX 41662...

  • Page 8: Schematic Diagram

    SCHEMATICS DIAGRAM R112 R112 +12V 3.3K 3.3K F101 F101 D187 D187 +62V +62V T6.3AL/250V T6.3AL/250V R121 R121 1N5404 1N5404 ISCTRIG R194 R194 -12V D182 D182 D183 D183 R170 R170 OFFSET 0.05 0.05 OFFSET 470K 470K BAV21 BAV21 Q191 Q191 4.7V 4.7V /1/2W R195...
  • Page 9 SCHEMATICS DIAGRAM +12V -12V C143 C143 C141 C141 R10F R10F R10M R10M R105 R105 C125 C125 100nF 100nF /250V +68V CNI5 CNI5 +68V 4.7uF 4.7uF 4.7K 4.7K D121 D121 IC101 IC101 47pF 47pF /1KV 100nF 100nF /250V BAV21 BAV21 NJM79M12FA NJM79M12FA R109 R109...
  • Page 10 SCHEMATICS DIAGRAM F201 F201 G2G1 G2G1 T1.6AL/250V T1.6AL/250V IC201 IC201 LM7812CT LM7812CT BR201 BR201 Ground Solder Tap Ground Solder Tap +12VD DB104G DB104G +18V +18V +18V C204 C204 Q205 Q205 R213 R213 C206 C206 C208 C208 2SC4793 2SC4793 10nF 10nF /100V +70V 10uF...
  • Page 11 +5VD R343 R343 R344 R344 STANDBY LED Q329 Q329 Q330 Q330 2SA1015 2SA1015 2SC1815 2SC1815 STBYLED is +0.7V at normal working condition and is +5V at STNADBY mode. R345 R345 P302A P302A P701A P701A PROT1-PROT7 each is +10.5V at normal working condition.When any GREEN R347 R347...
  • Page 12 SCHEMATICS DIAGRAM SCLED SCLED R405 R405 SCP_4 SCP_4 D401 D401 R401 R401 +62V_4 +62V_4 R409 R409 /1/2W C401 C401 /50V C402 C402 /50V D402 D402 R402 R402 R410 R410 -62V_4 -62V_4 /1/2W S401 S401 R406 R406 SCN_4 SCN_4 SCP_3 SCP_3 R407 R407 D403...
  • Page 13 SCHEMATICS DIAGRAM P801A P801A S801 S801 LIVE P503B P503B P501B P501B W501 W501 TR501 TR501 JUMPER JUMPER SDDLB1027U-RN SDDLB1027U-RN PCFS250L PCFS250L ONLY USED FOR C VERSION 2PIN2.54-C 2PIN2.54-C 2PIN2.54-A100B 2PIN2.54-A100B POWER SWITCH BOARD W502 W502 C501 C501 100nF/275V 100nF/275V JUMPER JUMPER P506B P506B...
  • Page 14 SCHEMATICS DIAGRAM P601B P601B P602B P602B AGND SCLED MOLEX 52207 RIGHT ANGLE/SMT/ZIF/TOP CONTACT STYLE/16PIN MOLEX 52207 RIGHT ANGLE/SMT/ZIF/TOP CONTACT STYLE/16PIN DGND SCLED DGND DGND ISCTRIG_7 -18V DGND PROT7 ISCTRIG_6 ISCTRIG_5 +18V PROT1 PROT6 ISCTRIG_4 ISCTRIG_3 ACOFF PROT2 PROT5 ISCTRIG_2 ISCTRIG_1 +68V PROT3 PROT4...

  • Page 15: Schematic Diagram

    SCHEMATICS DIAGRAM J901 J901 2PIN2.54-C 2PIN2.54-C - 15 -...

  • Page 16: Pcb Layout

    PCB LAYOUT AMP BOARD - COMPONENT SIDE Q12 3 Q124 Q117 IC102 IC101 CB101 Q122 Q191 L101 R121 C10 9 R159 R147 R1G1 Q128 Q121 Q126 C144 Q125 Q127 C105 CNI6 CNI5 R143 R151 R152 R150 R149 C143 C106 C102 BUS101 R136 C180...
  • Page 17 PCB LAYOUT Fan Cut Off Adjustment PSU BOARD - COMPONENT SIDE T975POW VM1.0 P208B The two links should be shorted P209B P204B P205B during the test for 8ohms load P203B RV201 and should be resumed after F201&F202 IS T1AL/250V C241 C242 the test.
  • Page 18 PCB LAYOUT SOFTCLIPPING PROTECT LED BOARD - COMPONENT SIDE R348 331R346 R345 R301 301R315 R322 R302 R309 R303 303 R304 R311 R325 318 319 R319 R312 320 R320 R306 R321 307 R314 C301 R347 R310 R318 R326 R327 R313 R328 R307 R305 D303...
  • Page 19 PCB LAYOUT TRIG BOARD - COMPONENT SIDE S402 S401 R411 D403 D401 R409 R402 D402 R406 R407 R405 R404 S401 R403 R401 R410 R413 C404 C403 R408 D404 R412 P401B C401 C402 VM1.0 2006/05/18 T975 SOFTCLIPPING TRIG BOARD TRIG BOARD - SOLDER SIDE - 19 -...
  • Page 20 PCB LAYOUT CONNECTION BOARD - COMPONENT SIDE VM1.0 2006/05/18 T975 CONNECTION BOARD CONNECTION BOARD - SOLDER SIDE - 20 -...
  • Page 21 PCB LAYOUT POWER LED BOARD T975 POWER LED BOARD P701A - 21 -...
  • Page 22 PCB LAYOUT SWITCH BOARD T975 SWITCH BOARD VM1.0 2006/05/18 S801 P801A - 22 -...

  • Page 23: Pcb Layout

    PCB LAYOUT TP BOARD - 23 -...

  • Page 24: Electrical Parts List

    ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT AH P/N 01-97501-10 C P/N 01-97501-20 PCB1 BOARD (AMP) DIODE D101 Switch Diode 1N4148 33-44148-00 DAX/.300X.080/.031 D102 Switch Diode 1N4148 33-44148-00 DAX/.300X.080/.031 D108 Switch Diode 1N4148 33-44148-00 DAX/.300X.080/.031 D109 Switch Diode 1N4148 33-44148-00 DAX/.300X.080/.031...
  • Page 25 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT Q157 Transistor 2SC2240-GR 31-02240-00 TO92/100/ECB Q158 Transistor 2SA970-GR 31-00970-00 TO92/100/ECB Q159 Transistor 2SC2362 31-02362-00 TO92/100/ECB Q159 Transistor 2SC2240-GR 31-02240-00 TO92/100/ECB Q160 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q161 Transistor MPSA92 31-00092-00 TO92/100/EBC Q162 Transistor MPSA92...
  • Page 26 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT R160 Metal Oxide Film Resistor 2.7Ω, 2W, 5% 07-30279-02 AX/.800X.200/.037 R167 Metal Film Resistor 220KΩ, 1/6W, 5% 07-20224-50 AX/.200X.080/.031 R168 Metal Film Resistor 100KΩ, 1/6W, 5% 07-20104-50 AX/.200X.080/.031 R170 Metal Film Resistor 470kΩ, 1/6W, 5% 07-20474-50 AX/.200X.080/.031...
  • Page 27 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT R10V Metal Film Resistor 100KΩ, 1/6W, 5% 07-20104-50 AX/.200X.080/.031 CAPACTIOR C102 Polyester capacitor 100nF, 10%, 63V 25-10461-00 RAD/.300X.150/LS.200/.035 C103 ALU Electrolytic Capacitor 06-10121-02 CPCYL1/D.300/LS.200/.031 100uF/25V, 20%, 105 C104 ALU Electrolytic Capacitor 10uF/50V, 20%, 105 06-10051-01 CPCYL1/D.200/LS.200/.031...
  • Page 28 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT L101 Inductor 0.7uH, horizontal type 08-01079-01 RAD/.850X.450/LS.700/.059 RELAY RL101 RELAYS JQX-115F/024/1HS1 12-03101-03 RELAY_1 RV101 5K, RK09K1110482-5KA 09-01502-00 VPOT1 RV102 SEMI POT 300Ω, vertical type 09-02301-01 VRES17 RV103 SEMI POT 500Ω, vertical type 09-02501-02 VRES17 RV104...
  • Page 29 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT BR206 BRIDGE KBJ2506 33-32562-00 BRIDGE/1.180X.180/.087 BR207 BRIDGE KBJ2506 33-32562-00 BRIDGE/1.180X.180/.087 BR208 BRIDGE DB104G 33-30142-00 BRIDGE/.400X.500/.051 TRANSISTOR Q201 Transistor KSA1220AYSTU 31-01220-00 TO126/90/ECB Q202 Transistor KSC2690AYSTU 31-02690-00 TO126/90/ECB Q203 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q204 Transistor...
  • Page 30 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT R214 Metal Film Resistor 1K8Ω, 1/6W, 5% 07-20182-50 AX/.200X.080/.031 R215 Metal Film Resistor 1K8Ω, 1/6W, 5% 07-20182-50 AX/.200X.080/.031 R216 Metal Film Resistor 1K8Ω, 1/6W, 5% 07-20182-50 AX/.200X.080/.031 R217 Metal Film Resistor 220Ω, 1/6W, 5% 07-20221-50 AX/.200X.080/.031...
  • Page 31 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT R284 Metal Film Resistor 10KΩ, 1/6W, 5% 07-20103-50 AX/.200X.080/.031 R285 Metal Film Resistor 10KΩ, 1/6W, 5% 07-20103-50 AX/.200X.080/.031 R286 Metal Film Resistor 10KΩ, 1/6W, 5% 07-20103-50 AX/.200X.080/.031 R287 Metal Film Resistor 10KΩ, 1/6W, 5% 07-20103-50 AX/.200X.080/.031...
  • Page 32 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT C223 Polyester capacitor 10nF, 10%, 250V 25-10322-01 RAD/.300X.150/LS.200/.036 C224 ALU Electrolytic Capacitor 1000uF/80V, 20%, 105 06-10281-01 CPCYL1/D.900/LS.400/.062 C225 ALU Electrolytic Capacitor 1000uF/80V, 20%, 105 06-10281-01 CPCYL1/D.900/LS.400/.062 C226 ALU Electrolytic Capacitor 10uF/50V, 20%, 105 06-10051-01 CPCYL1/D.200/LS.200/.031...
  • Page 33 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT MOLEX 52807 RIGHT ANGLE/NON-ZIF/TOP BLKCON.100/VH/TM2SQB/W.300/1 P205B CONNECTOR 13-21016-02 CONTACT STYLE/16PIN FPC1.0-16P) P206B HOUSING 12PIN2.0-C 13-22012-00 BLKCON.100/VH/TM1SQ/W.200/12 P207A Connector Ribbon 6P2.0-A100B 1569-26AWG 14-97506-00 PHB-2.0A-6Y P208B HOUSING 5PIN7.5-C 13-27505-00 BLKCON.295/VH/TM1SQ/W.600/5 P209B HOUSING 5PIN3.96-C 13-23905-00 BLKCON.156/VH/TM1SQB/W.355/5...
  • Page 34 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT Q316 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q317 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q318 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q319 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q320 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q321 Transistor 2SC1815-GR 31-01815-00 TO92/100/ECB Q322 Transistor 2SA1015-GR...
  • Page 35 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT D401 Zener Diode 24V, 1/2W 33-12400-00 DAX/.300X.080/.031 D402 Zener Diode 24V, 1/2W 33-12400-00 DAX/.300X.080/.031 D403 Zener Diode 24V, 1/2W 33-12400-00 DAX/.300X.080/.031 D404 Zener Diode 24V, 1/2W 33-12400-00 DAX/.300X.080/.031 RESISTOR R401 Metal Film Resistor 24KΩ, 1/6W, 1% 07-22402-50...
  • Page 36 ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT MOLEX 52207 RIGHT P602B Connector ANGLE/SMT/ZIF/TOP 13-21016-01 CONTACT STYLE/16PIN P603B Connector S10B-PH-SM3-TB 13-22010-01 MOLEX 2145/3215 TOP P604B Connector 13-25009-00 ENTRY/9PIN MOLEX 2145/3215 TOP P605B Connector 13-25009-00 ENTRY/9PIN MOLEX 2145/3215 TOP P606B Connector 13-25009-00...

  • Page 37: Electrical Parts List

    ELECTRICAL PARTS LIST DESIGNATOR DESCRIPTION PART TYPE PART NUMBER FOOTPRINT TRANSFORMER 18-97132-01 CONNECTOR One terminal:KST FDFD2- 187(8), another terminal KST FDFD2-250, Connector Ribbon 14-97301-00 wire:16AWG,double- insulated,white,300V,105C 1672 , L=600mm One terminal:KST FDFD2- 187(5), another terminal KST MDFN2-250, Connector Ribbon 14-97301-01 wire:16AWG,double- insulated,blue,300V,105C 1672 , L=600mm...

  • Page 39: Exploded View

    EXPLODED VIEW PARTS LIST R E F .NO P AR T NO. DE S C R IP T ION Qty. R E F .NO P AR T NO. DE S C R IP T ION Qty. C 001 66-075002-0 C has s is R 002 11-05202-10 S witch...

  • Page 40: Packing Diagram

    PACKING DIAGRAM - 40 -...

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