NAD-C445-tun-sm 维修电路原理图.pdf
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1、NADC 445FM / AMDAB TUNERC 445CFM / AMDAB TUNERSERVICE MANUALRadioFans.CN 收音机爱 好者资料库PRODUCT SAFETY SERVICING GUIDELINES CAUTION : DO NOT ATTEMPT TO MODIFY THIS PRODUCT INANY WAY. NEVER PERFORM CUSTOMIZED INSTALLATIONSWITHOUT MANUFACTURERS APPROVAL. UNAUTHORIZEDMODIFICATIONS WILL NOT ONLY VOID THE WAR
2、RANTY, BUTMAY LEAD TO YOUR BEING LIABLE FOR ANY RESULTINGPROPERTY DAMAGE OR USER INJURY.SERVICE WORK SHOULD BE PERFORMED ONLY AFTER YOUARE THOROUGHLY FAMILIAR WITH ALL OF THE FOLLOWINGSAFETY CHECKS AND SERVICING GUIDELINES. TO DOOTHERWISE, INCREASES THE RISK OF POTENTIAL HAZARDSAND INJURY TO THE USE
3、R. WHILE SERVICING, USE AN ISOLATION TRANSFORMER FORPROTECTION FROM AC LINE SHOCK.SAFETY CHECKSAFTER THE ORIGINAL SERVICE PROBLEM HAS BEENCORRECTED. A CHECK SHOULD BE MADE OF THEFOLLOWING.SUBJECT : FIRE & SHOCK HAZARD1. BE SURE THAT ALL COMPONENTS ARE POSITIONED INSUCH A WAY AS TO AVOID POSSIBILITY
4、OF ADJACENTCOMPONENT SHORTS. THIS IS ESPECIALLY IMPORTANTON THOSE MODULES WHICH ARE TRANSPORTED TO ANDFROM THE REPAIR SHOP. 2. NEVER RELEASE A REPAIR UNLESS ALL PROTECTIVEDEVICES SUCH AS INSULATORS, BARRIERS, COVERS,SHIELDS, STRAIN RELIEFS, POWER SUPPLY CORDS, ANDOTHER HARDWARE HAVE BEEN REINSTALLED
5、 PERORIGINAL DESIGN. BE SURE THAT THE SAFETY PURPOSEOF THE POLARIZED LINE PLUG HAS NOT BEEN DEFEATED.3. SOLDERING MUST BE INSPECTED TO DISCOVER POSSIBLECOLD SOLDER JOINTS, SOLDER SPLASHES OR SHARPSOLDER POINTS. BE CERTAIN TO REMOVE ALL LOOSEFOREIGN PARTICLES.4. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE
6、ORDETERIORATION TO PARTS AND COMPONENTS. FORFRAYED LEADS, DAMAGED INSULATION (INCLUDING ACCORD). AND REPLACE IF NECESSARY FOLLOW ORIGINALLAYOUT, LEAD LENGTH AND DRESS.5. NO LEAD OR COMPONENT SHOULD TOUCH A RECEIVINGTUBE OR A RESISTOR RATED AT 1 WATT OR MORE. LEADTENSION AROUND PROTRUDING METAL SURFA
7、CES MUSTBE AVOIDED.6. ALL CRITICAL COMPONENTS SUCH AS FUSES,FLAMEPROOF RESISTORS, CAPACITORS, ETC. MUST BEREPLACED WITH EXACT FACTORY TYPES, DO NOT USEREPLACEMENT COMPONENTS OTHER THAN THOSESPECIFIED OR MAKE UNRECOMMENDED CIRCUITMODIFICATIONS.7. AFTER RE-ASSEMBLY OF THE SET ALWAYS PERFORM ANAC LEAKA
8、GE TEST ON ALL EXPOSED METALLIC PARTS OFTHE CABINET, (THE CHANNEL SELECTOR KNOB, ANTENNATERMINALS. HANDLE AND SCREWS) TO BE SURE THE SETIS SAFET TO OPERATE WITHOUT DANGER OF ELECTRICALSHOCK. DO NOT USE A LINE ISOLATION TRANSFORMERDURING THIS TEST USE AN AC VOLTMETER, HAVING 5000OHMS PER VOLT OR MORE
9、 SENSITIVITY, IN THEFOLLOWING MANNER; CONNECT A 1500 OHM 10 WATTRESISTOR, PARALLELED BY A .15 MFD, 150V AC TYPECAPACITOR BETWEEN A KNOWN GOOD EARTH GROUND(WATER PIPE, CONDUIT, ETC.) AND THE EXPOSEDMETALLIC PARTS, ONE AT A TIME. MEASURE THE AC VOLTAGE ACROSS THE COMBINATIONOF 1500 OHM RESISTOR AND .1
10、5 MFD CAPACITOR. REVERSE THE AC PLUG AND REPEAT AC VOLTAGEMEASUREMENTS FOR EACH EXPOSED METALLIC PART. VOLTAGE MEASURE MUST NOT EXCEED 75 VOLTS R.M.S.THIS CORRESPONDS TO 0.5 MILLIAMP AC ANY VALUEEXCEEDING THIS LIMIT CONSTITUTES A POTENTIALSHOCK HAZARD AND MUST BE CORRECTED IMMEDIATELY.SUBJECT : GRAP
11、HIC SYMBOLSSUBJECT : TIPS ON PROPER INSTALLATION1. NEVER INSTALL ANY PRODUCT IN A CLOSED-IN RECESS,CUBBYHOLE OR CLOSELY FITTING SHELF SPACE. OVEROR CLOSE TO HEAT DUCT, OR IN THE PATH OF HEATEDAIR FLOW.2. AVOID CONDITIONS OF HIGH HUMIDITY SUCH AS:OUTDOOR PATIO INSTALLATIONS WHERE DEW IS AFACTOR, NEAR
12、 STEAM RADIATORS WHERE STEAMLEAKAGE IS A FACTOR, ETC.3. AVOID PLACEMENT WHERE DRAPERIES MAY OBSTRUCTREAR VENTING. THE CUSTOMER SHOULD ALSO AVOID THEUSE OF DECORATIVE SCARVES OR OTHER COVERINGSWHICH MIGHT OBSTRUCT VENTILATION.4. WALL AND SHELF MOUNTED INSTALLATIONS USING ACOMMERCAL MOUNTING KIT MUST
13、FOLLOW THE FACTORYAPPROVED MOUNTING INSTRUCTIONS A PRODUCTMOUNTED TO A SHELF OR PLATFORM MUST RETAIN ITSORIGINAL FEET (OR THE EQUIVALENT THICKNESS INSPACERS) TO PROVIDE ADEQUATE AIR FLOW ACROSSTHE BOTTOM, BOLTS OR SCREWS USED FOR FASTENERSMUST NOT TOUCH ANY PARTS OR WIRING. PERFORMLEAKAGE TEST ON CU
14、STOMIZED INSTALLATIONS.5. CAUTION CUSTOMERS AGAINST THE MOUNTING OF APRODUCT ON SLOPING SHELF OR A TILTED POSITION,UNLESS THE PRODUCT IS PROPERLY SECURED.6. A PRODUCT ON A ROLL-ABOUT CART SHOULD BE STABLEON ITS MOUNTING TO THE CART. CAUTION THECUSTOMER ON THE HAZARDS OF TRYING TO ROLL A CARTWITH SMA
15、LL CASTERS ACROSS THRESHOLDS OR DEEPPILE CARPETS.7. CAUTION CUSTOMERS AGAINST THE USE OF A CART ORSTAND WHICH HAS NOT BEEN LISTED BY UNDERWRITERSLABORATORIES, INC. FOR USE WITH THEIR SPECIFICMODEL OF TELEVISION RECEIVER OR GENERICALLYAPPROVED FOR USE WITH T.V.S OF THE SAME ORLARGER SCREEN SIZE.8. CA
16、UTION CUSTOMERS AGAINST THE USE OF EXTENSIONCORDS, EXPLAIN THAT A FOREST OF EXTENSIONSSPROUTING FROM A SINGLE OUTLET CAN LEAD TODISASTROUS CONSEQUENCES TO HOME AND FAMILY.THE LIGHTNING FLASH WITH ARROWHEAD SYMBOL, WITHIN ANEQUILATERAL TRIANGLE, IS INTENDED TO ALERT THE USER TO THEPRESENCE OF UNINSUL
17、ATED “DANGEROUS VOLTAGE” WITHIN THEPRODUCTS ENCLOSURE THAT MAY BE OF SUFFICIENT MAGNITUDE TOCONSTITUTE A RISK OF ELECTRIC SHOCK.THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE ISINTENDED TO ALERT THE USER TO THE PRESENCE OF IMPORTANTOPERATING AND MAINTENANCE (SERVICING) INSTRUCTIONS IN THELITER
18、ATURE ACCOMPANYING THE APPLIANCE.Page 2 of 28RadioFans.CN 收音机爱 好者资料库Page 3 of 28FM SECTION Frequency Range: 87.50 MHz to 108.00 MHz (50 kHz steps)Signal-to-Noise Ratio: 65dB (Mono) 60dB (Stereo)Presets:30AM SECTION Frequency Range: 522 kHz to 1620 kHz (9 kHz steps) Signal-to-Noise Ratio: 35dB Preset
19、s:DAB SECTION Band lll: 174MHz - 240MHzBand L : 1452MHz - 1492MHzMax signal: -3dBmSensitivity: -96dBmAdjacent Channel Rejection: 35dBPresets: ? ?Display:2-line by 16-character DOT Matrix Audio Output Stereo:2.5V P-P48kHz sample rate, 16 bit sample resolutionOptical S/PDIF: IEC60958 Compliant.48kHz s
20、ample rate, 24 bit sample resolutionGENERAL Power Requirement: 230-240V AC, 50Hz Power Consumption: 12W 0.8W(standby)DIMENSIONS (MAX) Width Height Depth: 435 x 86 x 318mm Weight: 30 996kg SPECIFICATIONSPage 4 of 28This unit is designed for trouble-free operation. Most problems users encounter are du
21、e to operating errors. If you have a problem, first check this listfor a possible solution. If the problem persists, consult your authorized Service Centre. SymptomCause/CorrectionNo lights appear when System Power button is pressed Unit is plugged into a live outlet. Make sure the outlet is active.
22、 No sound is heard Tune to an active station. Check for correct amplifier settings. Check the connections and wires. Sound distorts, particularly in stereo mode. Use a more directional antenna. Intermittent or continuous buzzing or hissingPlace the unit further away from these appliances. Install no
23、ise filters on the appliances. Display says No stations Available Check that antenna is connected. Ensure that DAB coverage exists in your area. Display has gone blank or says service off air This may occur if a broadcaster changes the label of a service or removes a labelwhilst you are listening to
24、 it. Try to retune to this station, using the Autotuneprocedure.Units operation or the displays seem abnormalTo correct this problem, first unplug the unit from the AC wall outlet and wait atleast three minutes. After the pause, reconnect the AC power cord and check theunits operation. Reset the C44
25、5 Tuner; press and hold the Menu/FM Mute Button for 5 seconds,until the Information Display shows FACTORY RESET. Note that when the systemis reset, all tuner presets will be lost and must be re-entered. Press the RESET switch lightly once or twice with a pencil or ballpoint pen as perexample below.I
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