NAD-M12-pre-sm 维修电路原理图.pdf
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1、NADSERVICE MANUAL ?DIGITALPREAMPDAC?DIGITAL PREAMPDACRadioFans.CN 收音机爱 好者资料库TABLE OF CONTENTS DESCRIPTION P A G E SERVICE CAUTION.3-4SPECIFICATIONS. 5WIRING DIAGRAM.6 BLOCK DIAGRAM. .7-9 .12-28 8 PCB LAYOUT.29-40ELECTRICAL PARTS LIST.41-67 EXPLODED VIEW.68EXPLODED VIEW PARTS LIST.69 CIRCUIT DIAGRAMS
2、TROUBLE SHOOTING A GUIDE.10TROUBLE SHOOTING B GUIDE.11PACKING ACCESSORY SECTION.70RadioFans.CN 收音机爱 好者资料库3SUBJECT: GRAPHIC SYMBOLSPRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO PRODUCTSA.C. VOLTMETERGOOD EARTH GROUNDSUCH AS THE WATERPIPE. CONDUIT. ETCPLACE THIS PROBEON EACH EXPOSEDMETAL PARTCAUTION :
3、 DO NOT ATTEMPT TO MODIFY THIS PRODUCT IN ANY WAY, NEVER PERFORM CUSTOM-IZED INSTALLATIONS WITHOUT MANUFACTURERSAPPROVAL. UNAUTHORIZED MODIFICATIONS WILL NOT ONLY VOID THE WARRANTY, BUT MAY LEAD TO YOUR BEING LIABLE FOR ANY RESULTING PROP-ERTY DAMAGE OR USER INJURY.SERVICE WORK SHOULD BE PERFORMED O
4、NLY AFTER YOU ARE THOROUGHLY FAMILIAR WITH ALL OF THE FOLLOWING SAFETY CHECKS AND SERVIC-ING GUIDELINES. TO DO OTHERWISE,INCREASES THE RISK OF POTENTIAL HAZARDS AND INJURY TO THE USER.WHILE SERVICING, USE AN ISOLATION TRANS-FORMER FOR PROTECTION FROM A.C. LINESHOCK.SAFETY CHECKSAFTER THE ORIGINAL SE
5、RVICE PROBLEM HAS BEEN CORRCTED. A CHECK SHOULD BE MADE OF THE FOLLOWING.SUBJECT : FIRE & SHOCK HAZARD1.BE SURE THAT ALL COMPONENTS ARE POSI- TIONED IN SUCH A WAY AS TO AVOID POSSIBILITY OF ADJACENT COMPONENT SHORTS.THIS IS ESPE-CIALLY IMPORTANT ON THOSE MODULES WHICH ARE TRANSPORTED TO AND FROM THE
6、 REPAIR SHOP.2. NEVER RELEASE A REPAIR UNLESS ALL PROTEC-TIVE DEVICES SUCH AS INSULATORS, BARRIERS, COVERS, SHIELDS, STRAIN RELIEFS, POWER SUPPLY CORDS, AND OTHER HARDWARE HAVE-BEEN REINSTALLED PER ORIGINAL DESIGN. BE SURE THAT THE SAFETY PURPOSE OF THE POLAR-IZED LINE PLUG HAS NOT BEEN DEFEATED.3.
7、SOLDERING MUST BE INSPECTED TO DISCOVER POSSIBLE COLD SOLDER JOINTS, SOLDER SPLASHES OR SHARP SOLDER POINTS. BE CER-TAIN TO REMOVE ALL LOOSE FOREIGN PARTICLES.4. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE OR DETERIORATION TO PARTS AND COMPONENTS. FOR FRAYED LEADS, DAMAGED INSULATION (INCLUDING A.C. CORD)
8、. AND REPLACE IF NECES-5. NO LEAD OR COMPONENT SHOULD TOUCH A RECIVING TUBE OR A RESISTOR RATED AT 1 WATT OR MORE. LEAD TENSION AROUND PROTRUNING METAL SURFACES MUST BE AVOIDED.6. ALL CRITICAL COMPONENTS SUCH AS FUSES, FLAMEPROOF RESISTORS, CAPACITORS, ETC. MUST BE REPLACED WITH EXACT FACTORY TYPES,
9、 DO NOT USE REPLACEMENT COMPONENTS OTHER THAN THOSE SPECIFIED OR MAKE UNRECOM-MENDED CIRCUIT MODIFICATIONS.7. AFTER RE-ASSEMBLY OF THE SET ALWAYS PER-FORM AN A.C. LEAKAGE TEST ON ALL EXPOSED METALLIC PARTS OF THE CABINET, (THE CHANNEL SELECTOR KNOB, ANTENNA TERMINALS. HANDLEAND SCREWS) TO BE SURE TH
10、E SET IS SAFE TO OPERATE WITHOUT DANGER OF ELECTRICAL SHOCK. DO NOT USE A LINE ISOLATION TRANS-FORMER DURING THIS TEST USE AN A.C. VOLTME-TER, HAVING 5000 OHMS PER VOLT OR MORE SEN-SITIVITY, IN THE FOLLOWING MANNER; CONNECT A 1500 OHM 10 WATT RESISTOR, PARALLELED BY A .15 MFD. 150.V A.C TYPE CAPACIT
11、OR BETWEEN A KNOWN GOOD EARTH GROUND (WATER PIPE, CONDUIT,ETC.) AND THE EXPOSED METALLIC PARTS, ONE AT A TIME. MEASURE THE A.C. VOLT-AGE ACROSS THE COMBINATION OF 1500OHM RESISTOR AND .15 MFD CAPACITOR. REVERSE THE A.C. PLUG AND REPEAT A.C. VOLTAGE MEASURE-MENTS FOR EACH EXPOSED METALLIC PART. VOLT-
12、AGE MEASURED MUST NOT EXCEED 75 VOLTS R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP A.C ANY VALUE EXCEEDING THIS LIMIT CONSTITUTES A POTENTIAL SHOCK HAZARD AND MUST BE COR-RECTED IMMEDIATELY.THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDEDTO ALERT THE SERVICE PERSONNE
13、L TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE” 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 SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE. SERVI
14、CING PRECAUTIONS CAUTION:Before servicing the Stereo amplifier 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 safety precautions in this
15、 publication, always follow the safety precautions. Remember Safety First: General Servicing Precautions 1. Always unplug the Stereo amplifier 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
16、 reconnecting any internal electrical plug or other electrical connection. (3) Connecting a test substitute in parallel with 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 ch
17、emicals on or near this Stereo amplifier 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. Unless specifie
18、d 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 Stereo amplifier and/or any of its electrical assemblies unless a
19、ll 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 attachment plug from
20、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 1 M-ohm. Note 1: Accessible Conductive Parts inclu
21、ding 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 devices are int
22、egrated 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 handing any semiconductor component or semiconductor-equipped assembly, d
23、rain 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 reason prior to applying power to the unit under test. 2. After removing an electrical
24、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 removal device. Some
25、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 protective package un
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