NAD-M25-pwr-sm维修电路原理图.pdf
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1、SERVICE MANUAL SERVICE MANUAL M25 C/AH MODEL :M3SERVICE MANUAL NAD 2005 NAD ELECTRONICS INTERNATIONAL TORONTO M25 C/AH SEVEN CHANNEL AMPLIFIER M25 C/AH SEVEN CHANNEL AMPLIFIER SEVEN CHANNEL AMPLIFIER RadioFans.CN 收音机爱 好者资料库 CONTENTS FRONT PANEL/REAR PANELVIEW? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
2、 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?3 SPECIFICATIONS? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 4 ALIGNMENT PROCEDURE/ALIGNMENT POINTS? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?5-6 WIRING DIAGRA
3、M? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?7 SCHEMATIC DIAGRAM? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?8-16 PCB LAYOUT? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
4、 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 17-23 ELECTRICALPARTS LIST? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?24-40 EXPLODED VIEW? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
5、 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 41-44 EXPLODED VIEW PARTS LIST? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?45 PACKING DIAGRAM? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?46 SERV
6、ICE SAFETY PRECAUTIONS 1. Replacing the Fuses CAUTION: FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE OF FUSE. REFERENCE NO.PART NUMBERDESCRIPTION Rear Panel AH20-11203-10MDAT20AL/250V C20-12103-20MDAT10AL/250V AMP Board F101/F10220-12632-00T6.3AL/250V PSU Board F201-F
7、20420-12162-01T1.6AL/250V NOTE: *AH : North American version only *C: European version only 2. Safety-check out (North American model only) Before returning the product to the customer, make leakage current or resistance measurements to determine that exposed parts are acceptably insulated from the
8、supply circuit. Parts marked with the symbolare critical with regard to the risk of fire and electric shock.Replace only parts recommended by the manufacturer. - 2 - RadioFans.CN 收音机爱 好者资料库 FRONT PANEL / REAR PANEL VIEW FRONT PANEL CONTROLS 1. POWER SWITCH 2. POWER INDICATOR 3. SOFT CLIPPING INDICAT
9、OR 4. PROTECTION INDICATOR 1. AC INLET 2. INPUT JACK 3. LEVEL CONTROL 4. SPEAKER TERMINALS 5. AUTO TRIGGER SWITCH 6. 12V TRIGGER INPUT 7. SOFT CLIPPING SWITCH 8. MAINS FUSE 9. GROUND TERMINAL - 3 - RadioFans.CN 收音机爱 好者资料库 - 4 - SPECIFICATIONS CONTINUOUS AVERAGE POWER?160 W (22.0 dBW) OUTPUT INTO 8 O
10、HMS 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?180 W (maximum continuous power per channel). IHF dynamic power (Maximum short term power per channel) 8 ohms:?220 W (23.4 dBW) 4 oh
11、ms:?385 W (25.9 dBW) 2 ohms:?485 W (26.9 dBW) Damping factor180 (ref. 8 ohms 50Hz) Input ImpedanceR = 1 Mohms C = 180 pF Input sensitivity (for rated output into 8 ohms)1250mV+/-50mV Voltage gain29 dB Frequency response 20 Hz 20 kHz?0.2 dB - 3dB at 3 Hz/70 kHz Signal / Noise ratio, A-weighted96 dB r
12、ef. 1 W 118 dB ref. 160W DIMENSIONS AND WEIGHTS Net Weight44.5 kg (98.0 Ib) Shipping Weight53 kg (116.7 Ib) Dimension (WHD)435 200 465.6mm RadioFans.CN 收音机爱 好者资料库 ALIGNMENT PROCEDURE A. THERMAL SENSE ADJUSTMENT This adjustment should be always done when the M25 is cool condition. (That means the tem
13、perature 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 that the Idling current heats up the unit excessively) At ambient temperature of 25 C degrees and when the unit is just turned on (still
14、 in cool condition), adjust the pot RV103(as marked as “Thermal Sense ADJ” in below drawing) for a voltage between the THERMAL TEST POINT and AGND to be 750mV+/-10mV. If the ambient temperature is different, the voltage setting should be changed by 20mV per degree difference. So at 20C degrees, the
15、voltage should be 850mV+/-10mV; and at 30C degrees, the voltage should be 650mV+/-10mV, etc. B. DC OFFSET VOLTAGE The DC OFFSET between OFFSET Test Point and AGND must be within 0+/-3mV. If its found to be out of this range, change the TL084BCD to one selected for low offset voltage to meet the requ
16、irement. C. IDLING CURRENT The idling current in the output stage of the poweramp should be set to 40mA+/-10mA per pnp-npn transistor pair( This means the mid point voltage is 17.6mV with down limit of 13.2mV and up limit of 22mV). The alignment procedure is: At first, adjust RV102 (Marked as “Idlin
17、g Current ADJ” in the drawing below) for a voltage of 17.6mV +/- 1mV between Test point 1 and 2. Then preheat the unit for 5 minutes, let idling current settled and then readjust to 17.6mV +/- 1mV. Pls note: 1.The idling current must be adjusted when all modules are assembled into the unit. 2.Though
18、 the idling current is set as 17.6mV +/-1mV during the adjustment, due to the influence of varied ambient temperature and mains voltage etc., the idling current will drift after some time. During the normal checking of idling current in the service field, its acceptable as long as the voltage is in
19、the range of 13.2mV22.0mV. D. ISC Current sense zero-set. The ISC current-sensing voltage at no signal should be 0mV+/-50mV. During factory alignment, it is set to 0mV+/-10mV . That is to adjust Pot RV104 (as marked as “ISC SENSE ADJ” in the below drawing) to get a voltage between the “ISC SENSE TES
20、T POINT” and AGND to be 0mV+/-10mV. (Pls note the ISC should be adjusted when all modules are plugged in. Its not possible to get 0mV +/-10mV if any of the modules are removed.) E. Fan Cut Off Point Adjustment Check the Fan sense voltage first. Turn Pot RV201 to the end clockwise and confirm TP2 of
21、J201 is in negative voltage. Run the unit to heat it up and drive the fan to start turning, - 5 - RadioFans.CN 收音机爱 好者资料库 for example, all 7 channels at 50W/4ohms 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 f
22、or 1 minute. Then run all 7 channels at 1kHz, 0.25W at 4 ohms load, monitor the voltage at TP1 of Pot RV201. Adjust RV201 to get the voltage from negative to positive to ensure that the Fans are turned off. Then run all 7 channels at 1kHz, 0.5W at 4 ohms load, monitor if the voltage at TP1 of Pot RV
23、201 is negative, if not, adjust Pot RV201 just to the point that TP1 changes from positive to negative (to get the fans just start turning). Finally, turn off the signal and monitor if fans stop turning within about 30s Max. - 6 - ISC SENSE ADJ RadioFans.CN 收音机爱 好者资料库 AGND ACINACIN ACOUTACOUT +5V+5V
24、 RELAYRELAY SC NPN SC PNP +18V -18V +70V -70V PROTECT SEN AC OFF +62V -62V -62V AGND AGND AGND ISC TRIG AGND +62V +18V -18V +70V -70V PROTECT SEN AC OFF SC NPN SC PNP +62V -62V -62V AGND AGND AGND ISC TRIG AGND +62V +18V -18V +70V -70V PROTECT SEN AC OFF SC NPN SC PNP +62V -62V -62V AGND AGND AGND I
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