NAD-T751-avr-sm 电路图 维修手册.pdf

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1、NAD SERVICE MANUAL T 751 SURROUND SOUND RECEIVER T 751 SURROUND SOUND RECEIVER RadioFans.CN 收音机爱 好者资料库 PRODUCT SAFETY SERVICING GUIDELINES CAUTION : DO NOT ATTEMPT TO MODIFY THIS PRODUCT IN ANY WAY. NEVER PERFORM CUSTOMIZED INSTALLATIONS WITHOUT MANUFACTURERS APPROVAL. UNAUTHORIZED MODIFICATIONS WIL

2、L NOT ONLY VOID THE WARRANTY, BUT MAY LEAD TO YOUR BEING LIABLE FOR ANY RESULTING PROPERTY DAMAGE OR USER INJURY. SERVICE WORK SHOULD BE PERFORMED ONLY AFTER YOU ARE THOROUGHLY FAMILIAR WITH ALL OF THE FOLLOWING SAFETY CHECKS AND SERVICING GUIDELINES. TO DO OTHERWISE, INCREASES THE RISK OF POTENTIAL

3、 HAZARDS AND INJURY TO THE USER. WHILE SERVICING, USE AN ISOLATION TRANSFORMER FOR PROTECTION FROM AC LINE SHOCK. SAFETY CHECKS AFTER THE ORIGINAL SERVICE PROBLEM HAS BEEN CORRECTED. A CHECK SHOULD BE MADE OF THE FOLLOWING. SUBJECT : FIRE CONNECT A 1500 OHM 10 WATT RESISTOR, PARALLELED BY A .15 MFD,

4、 150V AC TYPE CAPACITOR BETWEEN A KNOWN GOOD EARTH GROUND (WATER PIPE, CONDUIT, ETC.) AND THE EXPOSED METALLIC PARTS, ONE AT A TIME. MEASURE THE AC VOLTAGE ACROSS THE COMBINATION OF 1500 OHM RESISTOR AND .15 MFD CAPACITOR. REVERSE THE AC PLUG AND REPEAT AC VOLTAGE MEASUREMENTS FOR EACH EXPOSED METAL

5、LIC PART. VOLTAGE MEASURE MUST NOT EXCEED 75 VOLTS R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP AC ANY VALUE EXCEEDING THIS LIMIT CONSTITUTES A POTENTIAL SHOCK HAZARD AND MUST BE CORRECTED IMMEDIATELY. SUBJECT : GRAPHIC SYMBOLS SUBJECT : TIPS ON PROPER INSTALLATION 1. NEVER INSTALL ANY PRODUCT IN A CLOSE

6、D-IN RECESS, CUBBYHOLE OR CLOSELY FITTING SHELF SPACE. OVER OR CLOSE TO HEAT DUCT, OR IN THE PATH OF HEATED AIR FLOW. 2. AVOID CONDITIONS OF HIGH HUMIDITY SUCH AS: OUTDOOR PATIO INSTALLATIONS WHERE DEW IS A FACTOR, NEAR STEAM RADIATORS WHERE STEAM LEAKAGE IS A FACTOR, ETC. 3. AVOID PLACEMENT WHERE D

7、RAPERIES MAY OBSTRUCT REAR VENTING. THE CUSTOMER SHOULD ALSO AVOID THE USE OF DECORATIVE SCARVES OR OTHER COVERINGS WHICH MIGHT OBSTRUCT VENTILATION. 4. WALL AND SHELF MOUNTED INSTALLATIONS USING A COMMERCAL MOUNTING KIT MUST FOLLOW THE FACTORY APPROVED MOUNTING INSTRUCTIONS A PRODUCT MOUNTED TO A S

8、HELF OR PLATFORM MUST RETAIN ITS ORIGINAL FEET (OR THE EQUIVALENT THICKNESS IN SPACERS) TO PROVIDE ADEQUATE AIR FLOW ACROSS THE BOTTOM, BOLTS OR SCREWS USED FOR FASTENERS MUST NOT TOUCH ANY PARTS OR WIRING. PERFORM LEAKAGE TEST ON CUSTOMIZED INSTALLATIONS. 5. CAUTION CUSTOMERS AGAINST THE MOUNTING O

9、F A PRODUCT ON SLOPING SHELF OR A TILTED POSITION, UNLESS THE PRODUCT IS PROPERLY SECURED. 6. A PRODUCT ON A ROLL-ABOUT CART SHOULD BE STABLE ON ITS MOUNTING TO THE CART. CAUTION THE CUSTOMER ON THE HAZARDS OF TRYING TO ROLL A CART WITH SMALL CASTERS ACROSS THRESHOLDS OR DEEP PILE CARPETS. 7. CAUTIO

10、N CUSTOMERS AGAINST THE USE OF A CART OR STAND WHICH HAS NOT BEEN LISTED BY UNDERWRITERS LABORATORIES, INC. FOR USE WITH THEIR SPECIFIC MODEL OF TELEVISION RECEIVER OR GENERICALLY APPROVED FOR USE WITH T.V.S OF THE SAME OR LARGER SCREEN SIZE. 8. CAUTION CUSTOMERS AGAINST THE USE OF EXTENSION CORDS,

11、EXPLAIN THAT A FOREST OF EXTENSIONS SPROUTING FROM A SINGLE OUTLET CAN LEAD TO DISASTROUS CONSEQUENCES TO HOME AND FAMILY. THE LIGHTNING FLASH WITH ARROWHEAD SYMBOL, WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE USER TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE” WITHIN THE PRODUCTS E

12、NCLOSURE THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK. THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE USER TO THE PRESENCE OF IMPORTANT OPERATING AND MAINTENANCE (SERVICING) INSTRUCTIONS IN THE LITERATURE ACCOMPANYING THE APPLIANCE. RadioF

13、ans.CN 收音机爱 好者资料库 SERVICING PRECAUTIONS CAUTION : Before servicing the A/V Receiver covered by this service data and its supplements and addends, read and follow the SAFETY PRECAUTIONS. NOTE : if unforeseen circumstances create conflict between the following servicing precautions and any of the safe

14、ty precautions in this publication, always follow the safety precautions. Remember Safety First: General Servicing Precautions 1. Always unplug the A/V Receiver AC power cord from the AC power source before: (1) Removing or reinstalling any component, circuit board, module, or any other assembly. (2

15、) Disconnecting or reconnecting any internal electrical plug or other electrical connection. (3) Connecting a test substitute in parallel with an electrolytic capacitor. Caution : A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazar

16、d. 2. Do not spray chemicals on or near this A/V Receiver or any of its assemblies. 3. Unless specified otherwise in this service data, clean electrical contacts by applying an appropriate contact cleaning solution to the contacts with a pipe cleaner, cottontipped swab, or comparable soft applicator

17、. Unless specified otherwise in this service data, lubrication of contacts is not required. 4. Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service manual might be equipped. 5. Do not apply AC power to this A/V Receiver and/or any of its electrical assem

18、blies unless all solid-state device heat sinks are correctly installed. 6. Always connect test instrument ground lead to the appropriate ground before connecting the test instrument positive lead. Always remove the test instrument ground lead last. Insulation Checking Procedure Disconnect the attach

19、ment plug from the AC outlet and turn the power on. Connect an insulation resistance meter(500V) to the blades of the attachment plug. The insulation resistance between each blade of the attachment plug and accessible conductive parts (Note 1) should be more than 1M-ohm. Note 1 : Accessible Conducti

20、ve Parts including Metal panels, Input terminals, Earphone jacks, etc. Electrostatically Sensitive (ES) Devices Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical Es d

21、evices are integrated circuits and some field effect transistors and semiconductor chip components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity. 1. Immediately before handling any semiconductor component or semiconductor-equip

22、ped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed for potential shock reasons prior to applying power to the unit under test. 2. After removin

23、g an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly. 3. Use only a grounded-tip soldering iron to solder or unsolder ES devices. 4. Use only an antistatic solder remov

24、al device. Some solder removal devices not classified a “anti-static” can generate electrical charges sufficient to damage ES devices. 5. Do not use freonpropelled chemicals. These can generate electrical charge sufficient to damage ES devices. 6. Do not remove a replacement ES device from its prote

25、ctive package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil, or comparable conductive material). 7. lmmediately before removing the protective material from the leads of a rep

26、lacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. Caution : Be sure no power is applied to the chassis or circuit, and observe all other safety precautions. 8. Minimize bodily motions when handing unpackaged replacement ES d

27、evices. (Normally harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES device.) RadioFans.CN 收音机爱 好者资料库 2 SERVICE SAFETY PRECAUTIONS 1.Replacing the fuses CAUTION: FOR CONTINU

28、ED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE OF FUSE. Reference NoPart NumberDescription M751*AH5120-0200-0Fuse 5A 125V Time Lag 5x20 MM MITI/UL/CSA M754*AH5120-0052-0Fuse 1.6A 250V Time Lag 5x20 MM UL/CSA M752*C5120-0024-0Fuse 3.15A 250V Time Lag 5x20 MM SEMKO/VDE NOTE: : USA,

29、 CANADIAN MODEL ONLY. : EUROPEAN MODEL ONLY. 2.Safety check out (Only U.S.A. model) Before returning the product to the customer, make leakage current or resistance measurements to determine that exposed parts are acceptably insulated from the supply circuit. Parts marked with the symbol are critica

30、l with regard to the risk of fire and electric shock. Replace only with parts recommended by the manufacturer. CONTENTS DESCRIPTIONPAGE SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4 REAR PANEL / FRONT PANEL . . . .

31、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 DISASSEMBLY INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32、 . . . . . . . . . . . . . . . . . . . . .7-8 BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 ADJUSTMENT POINTS DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 INS

33、TRUMENT SETUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 ALIGNMENT PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12 IMPORTANT NOTES . . . . . . . . . . . . . . . . . . .

34、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 PCB LAYOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-19 SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35、. . . . . . . . . . . . . . .20-38 IC BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39-46 ELECTRICAL PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47-69 EXPLODED VIE

36、W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 EXPLODED VIEW PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71-72 PACKING DIAGRAM . . . . . . . . . . . . . . . . . . . . . .

37、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 3 SPECIFICATIONS POWER AMPLIFIER AND PREAMPLIFIER SECTIONS Rated distortion(THD 20Hz-20 kHz FC/C/FR) 0.08% (THD 20Hz-20 kHz SL/SR) 0.3% Input Sensitivity(ref. 8 ohms, 1 kHz)180+/-30 mV S/N Ratio(A-wtd, 1KHz, 1W, 8 ohm) -76 dB (A-w

38、td, 1KHz, 70W, 8 ohm) -90 dB Frequency Response(20 Hz - 20 kHz)0 0.8 dB Channel Balance(1 dB to -40 dB, 1 kHz) 2 dB (-41 dB to -50 dB, 1 kHz) 3 dB Audio muting at 1kHz 53 dB Headphone O/P in 0.1%, 600 ohm load, CD in 500mV, 1 kHz 10V Subwoofer out, 500mV in(THD at 2V O/P, 100 Hz) 0.5% (S/N at 2V O/P

39、, 100 Hz) 80 dB Crosstalk(2V input, 10W, 1 kHz) -68 dB Continuous average power output 70 W Controls Bass(at 500mV in, 1W out, 100 Hz) 9 dB Treble(at 500mV in, 1W out, 10 kHz) 9 dB SURROUND SECTION Channel separation I/p mode : L, R: 1V in, 1 kHz, Ch R, L 45 dB : o/p at unexpected, 1 kHz, Ch C 35 dB

40、 I/p mode : L= -R: 1V in, 1 kHz, Ch R, L 28 dB : o/p at unexpected, 1 kHz, Ch C 30 dB I/p mode : L= R: 1V in, 1 kHz, Ch R, L 45 dB : o/p at unexpected, 1 kHz, Ch SL, SR 30 dB Frequency Response I/p mode : L, R: 1V in, 1W, Ch R, L40Hz0 1.5 dB 20kHz0 0.8 dB I/p mode : L= R: 1V in, 1W, Ch C300Hz0 0.8 d

41、B 20kHz0 0.8 dB I/p mode : L= -R: 1V in, 1W, Ch SL, SR30Hz0 1.0 dB 6.5kHz-3 1.0 dB S/N Ratio ( 200mV in, 1, A-WTD w/ 1k termination) I/p mode : L, R: 1 kHz, Ch L, R 65 dB I/p mode : L=R: 1 kHz, Ch C 65 dB I/p mode : L=-R: 1 kHz, Ch SL, SR 65 dB THD (2.2V in, 1W, w/ 80 kHz LPF, 1 kHz) 0.2% AC-3/DTS S

42、ECTION Frequency Response FL, FR, C, SL, SR:200Hz0 0.8 dB 20kHz0 0.8 dB Distortion 1W all channels0.08% S/N 1 W ( CCIR/ARM, 200 Hz NOTCH & 400 Hz HPF) 85 dB 4 AM TUNER SECTION Input level is expressed as the reading in open-circuit of 75-ohm source impedance signal generator Usable sensitivity (999/

43、1000kHz) 30 dB S/N Ratio (5mV in) 38 dB THD (5mV in) 3% IF Rejection (450 kHz) 36 dB Image Rejection (F+2xIF) 28 dB Selectivity 17 dB Output130+/- 20mV Loop sensitivity (20dB S/N) 999/1000 kHz 66 dB 603/600 kHz 66 dB 1404/1400 kHz 66 dB Frequency response (100 - 2.3 kHz, 5mV) 6 dB FM TUNER SECTION*C

44、*AH Input level is expressed as the reading in open-circuit of 75-ohm source impedance signal generator Usable Sensitivity ( 98 MHz) 15 dB 15 dB Signal / Noise RatioMono 72 dB 72 dB (60 dB, IHF wtd)Stereo 66 dB 66 dB Frequency Response (20 Hz - 15 kHz, 60 dB)0 1.5 dB0 1.5 dB Channel Separation (60 d

45、B)100 Hz 30 dB 30dB 1 kHz 38 dB 38 dB 10 kHz 30 dB 30 dB Alternate Channel Selectivity (40 dB, 400 kHz) 60 dB 45 dB Capture Ratio (40 dB) 3 dB 3 dB AM Suppression (60 dB, 100% Mod.FM, 30% Mod.AM) 48 dB 48 dB Image Rejection (119.4 MHz) 85 db 40 dB I.F. Rejection ( 10.7 MHz) 78 dB 65 dB Pilot Suppres

46、sion (60 dB) 60 dB 60 dB THD (60 dB, L=R 75 kHz for AH, 40 kHz Dev for C) Mono 0.25% 0.25% Stereo 0.35% 0.35% Auto-Search SensitivityOn 24 dB 24 dB Off 15 dB 15 dB RDS decode Sensitivity 26 dB 26 dB PHYSICAL SPECIFICATIONS Dimensions (Width x Height x Depth)435 x 131 x 348mm Net weight12.27kg (27 lb

47、s) Shipping weight13.63kg (30 lbs) 5 2 1 78 34116125 1091413 REAR PANEL / FRONT PANEL REAR PANEL FRONT PANEL 1. FM & AM ANTENNA 2. AM STEPPING FREQUENCY 3. TAPE 1 & CD INPUTS 4. 5.1 CHANNEL INPUTS 5. VIDEO 1 - VIDEO 4 (AUDIO & VIDEO) INPUTS 6. DIGITAL AUDIO INPUTS 7. AUDIO PRE-OUTS / SUBWOOFER OUT 8

48、. MONITOR OUT 9. FRONT, CENTER & SURROUND SPEAKERS 10. SOFT CLIPPING 11. NAD-LINK INPUT/OUTPUT 12. SWITCHED POWER OUTLETS (*AH ONLY) 13. AC POWER CORD 14. COOLING FAN 1. POWER 2. STAND-BY 3. DISPLAY 4. FM MUTE / MODE 5. MEMORY 6. PRESET / TUNE 7. DOWN / UPAND 8. VFL DISPLAY 9. VOLUME 10. HEADPHONE S

49、OCKET & VIDEO 5 INPUT 11. AUDIO & VIDEO INPUT SELECTORS & SURROUND MODE 12. BASS & TREBLE CONTROLS 751 6 DISASSEMBLY INSTRUCTIONS 1. Remove machine screws M 4.0 x 6.0 ( 1 to 6 ) from the side panels. Remove tapping screw 3.0 x 8.5 ( 7 ) from the back panel. Refer to Figure No.1. Figure No.1 2. Pull both sides of the TOP COVER slightly outwards 8 and tilt approx. 35 and then remove in the direction as indicated by the arrow 9 . Refer to Figure No.2. Figure No.2. 7 6 5 4 1 3 2 9 8 8 SURROUND AMPLIFIER PCB AC OUTLET PCB (*AH ONLY) J708B M001 C834 TRIGGER PCB FRONT AMPLIF