NAD-C720BEE-rec-sm1 维修电路原理图.pdf
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1、NADSERVICE MANUALC 720BEESTEREORECEIVERC 720BEESTEREORECEIVERRadioFans.CN 收音机爱 好者资料库TABLE OF CONTENTS DESCRIPTION P A G E SERVICE CAUTION.3 REAR PANEL/FRONT PANEL VIEW.4 SPECIFICATIONS.5-7 ALIGNMENT PROCEDURE.6-7 WIRING DIAGRAM8 BLOCK DIAGRAM. .9-15 ALIGNMENT PROCEDURE.16 SCHEMATICS.17-20PCB LAYOUT
2、21-24 SPECIAL FUNCTION/TROUBLE SHOOTING GUIDE.25 ELECTRICAL PARTS LIST.26-34 EXPLODED VIEW.35 EXPLODED VIEW PARTS LIST.36 - 2 -PROTECT IC CHANGE .37 RadioFans.CN 收音机爱 好者资料库SERVICING PRECAUTIONS CAUTION:Before servicing the Stereo Receiver covered by this service data and its supplements and addends,
3、 read and follow the SAFETY PRECAUTIONS. NOTE: if unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions in this publication, always follow the safety precautions. Remember Safety First: General Servicing Precautions 1. Always unplug th
4、e Stereo Receiver AC power cord from the AC power source before: (1) Removing or reinstalling any component, circuit board, module, or any other assembly. (2) Disconnecting or reconnecting any internal electrical plug or other electrical connection. (3) Connecting a test substitute in parallel with
5、an electrolytic capacitor. Caution: A wrong part substitute or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard. 2. Do not spray chemicals on or near this Stereo Receiver or any of its assemblies. 3. Unless specified otherwise in this service data, clean e
6、lectrical contacts by applying an appropriate contact cleaning solution to the contacts with a pipe cleaner, cottontipped swab, or comparable soft applicator. Unless specified otherwise in this service data, lubrication of contacts is not required. 4. Do not defeat any plug/socket B+ voltage interlo
7、cks with which instruments covered by this service manual might be equipped.5. Do not apply AC power to this Stereo Receiver and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed. 6. Always connect test instrument ground lead to the appropriate grou
8、nd before connecting the test instrument positive lead. Always remove the test instrument ground lead last.Insulation Checking Procedure Disconnect the attachment plug from the AC outlet and turn the power on. Connect an insulation resistance meter (500V) to the blades of the attachment plug. The in
9、sulation resistance between each blade of the attachment plug and accessible conductive parts (Note 1) should be more than 1 M-ohm. Note 1: Accessible Conductive Parts including Metal panels, Input terminals, Earphone jacks, etc. Electrostatically Sensitive (ES) Devices Some semiconductor (solid sta
10、te) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical Es devices are integrated circuits and some field effect transistors and semiconductor chip components. The following techniques should be used t
11、o help reduce the incidence of component damage caused by static electricity. 1. Immediately before handing any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially
12、available discharging wrist strap device, which should be removed for potential shock reason prior to applying power to the unit under test. 2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic c
13、harge 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 removal device. Some solder removal devices not classified a “anti-static” can generate electrical charges sufficient to damage ES devices. 5. Do no
14、t use freonpropelled chemicals. These can generate electrical charge sufficient to damage ES devices. 6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted t
15、ogether by conductive foam, aluminum foil, or comparable conductive material). 7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. Caution: Be sure
16、no power is applied to the chassis or circuit, and observe all other safety precautions. 8.Minimize bodily motions when handing unpackaged replacement ES devices. (Normally harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can gene
17、rate static electricity sufficient to damage an ES device.)- 3 -1&2 FM&AM ANTENNA3. SPEAKER A&B4. SWITCHED AC OUTLET5. AC LINE CORD6. VACATION SWITCH ON/OFF7. SOFT CLIPPING8. SUBW OUT9. MAIN IN10. PRE-OUT11. RECORD OUT/ZONE 212. TAPE IN13. AUX INPUT14. VIDEO INPUT15. CD INPUT16. DISC INPUT17. IR INP
18、UT/OUTPUT18. +12V TRIGGER OUTFRONT PANEL/REAR PANEL- 4 -Power Amplifier SectionCONTINUOUS AVERAGE POWEROUTPUT AT 8 OHMS50W (17dBw) (Minimum RMS power per channel, both channels driven, With no more than the rated distortion)Rated distortion (THD)(20Hz 20kHz)?0.03%Channel Separation?70dB(MAIN IN, 20W
19、 Out at 8?,1k? shorted, 1kHz)Clipping power, 1kHz68W(Maximum continuous power per channel)Dynamic Headroom at 8 ohms3.4dBDynamic power8ohms110W(Maximum short-term power per channel )4ohms160W2ohms210WDamping factor?100Slew factor?50Slew rate?20V/?secT.H.D and SMPTE I.M.?0.03% (Distortion from 250mW
20、to rated output)IHF I.M. (CCIF IM) and T.I.M distortion?0.03% (From 250mW to rated output)Input impedance22k?/470pFInput sensitivity( For 50 Watts out) ?700mVPower amp gain29dBPreamplifier SectionInput Impedance22k?/100pFSPECIFICATIONSNAD C720BEE Stereo ReceiverNote: Specifications are measured in a
21、ccordance with EIAStandard RS-490 (IHF A-202) for amplifiers and ANSI-IEEEStandard 185(1975), i.e. input and converted to equivalent300-ohm values.- 5 -Signal-to-Noise ratio110dB ref 500mV(A-weighted, 1kHz CD In, Pre-Out)Rated distortion (THD)(20Hz 21kHz)?0.03%Channel Separation?70dB2V CD IN, 2V Pre
22、-Out,1k? shorted,1kHzInput Sensitivity320mV for 1V outInput Overload?10VFrequency responsetone defeat+/-0.1dBtone on+/-0.5dBTHD (SUB OUT)?0.03%(2V CD in, 2V SUB out; 50Hz, 80kHz LPF)THD (ZONE 2 OUT)(2V CD IN, 1kHz, 80kHz LPF)?0.03%Frequency Response(SUB OUT)50Hz)?3dB at 100HzOutputsPreamp output imp
23、edance80?Zone2 output impedanceSource Z+ 600?ControlsTreble5dB at 10kHzBass8dB at 100HzPre-in ,Power AMP out,input 2VSignal-to-Noise ratio, A-weighted98dB ref 1 W out(500mV CD in, SPK out, 8?, A weighted)Rated distortion (THD)(20Hz 20kHz)?0.03%Input sensitivity225mV(CD in, SPK out, at rated power, v
24、olume max.)Channel Separation?70dB(CD in, 20W out at 8?, 1k? shorted, 1kHz)Frequency responsetone defeat+/-0.1dBtone on+/-0.5dBUsual sensitivityMono, -30dB THD+N?12dBuVMono, 50 dB S/N?25dBuVTuner FM Section(At 75kHz deviation for AH ; 40kHz for C)- 6 -Capture ratio (at 45 and 65 dBf)?3 dBAM rejectio
25、n (at 65 and 85dBf)?40 dBAlternative channels Selectivity?40 dB(RF400KHz, at 30dB)Image rejection(at usable sensitivity)?70 dBI.F. rejection (at usable sensitivity)?70 dBPilot suppression (1kHz, 60dBu)?55 dBTHDMono, 1kHz, 60dBu?0.8%Stereo, 1kHz, 60dBu?1%Signal-to-noise ratio (Mono, 60dBu) ?60 dBFreq
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