NAD-T975-pwr-sm维修电路原理图.pdf
《NAD-T975-pwr-sm维修电路原理图.pdf》由会员分享,可在线阅读,更多相关《NAD-T975-pwr-sm维修电路原理图.pdf(40页珍藏版)》请在收音机爱好者资料库上搜索。
1、? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? RadioFans.CN 收音机爱 好者资料库 CONTENTS FRONT PANEL/REAR PANELVIEW? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?3 SPECIFICATIONS? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
2、? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 4 ALIGNMENT PROCEDURE/ALIGNMENT POINTS? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 5-6 WIRING DIAGRAM? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?7 SCHEMATIC DIAGRAM
3、? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?8-15 PCB LAYOUT? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 16-23 ELECTRICALPARTS LIST? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
4、? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?24-37 EXPLODED VIEW? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 38 EXPLODED VIEW PARTS LIST? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
5、 ? ? ? ? ? ? ? ? ? ? ? ?39 PACKING DIAGRAM? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?40 SERVICE SAFETY PRECAUTIONS 1. Replacing the Fuses CAUTION: FOR CONTINUED PROTECTION AGAINST THE RISK OF FIRE REPLACE ONLY WITH SAME TYPE OF FU
6、SE. 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-F20420-12162-01T1.6AL/250V NOTE: *AH : North American version only *C: European version only 2. Safety-check out (North American model only
7、) 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 symbolare critical with regard to the risk of fire and electric shock.Replace only parts recommended
8、 by the manufacturer. - 2 - RadioFans.CN 收音机爱 好者资料库 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? - 3 - RadioFans.CN 收音机爱 好者资料库 - 4 - SPECIFICATIONS
9、 CONTINUOUS AVERAGE POWER?140 W (21.5 dBW) OUTPUT INTO 8 OHMS 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?170 W(22.3 dBW) (maximum continuous power per channel). IHF dynamic power
10、(Maximum short term power per channel) 8 ohms:?220 W (23.4 dBW) 4 ohms:?385 W (25.9 dBW) 2 ohms:?450 W (26.5 dBW) Damping factor300 (ref. 8 ohms 50Hz) Input ImpedanceR = 1 Mohms C = 180 pF Input sensitivity (for rated output into 8 ohms)1180mV+/-50mV Voltage gain29 dB Frequency response 20 Hz 20 kHz
11、?0.2 dB - 3dB at 3 Hz/100 kHz Signal / Noise ratio, A-weighted96 dB ref. 1 W 125 dB ref. 140W DIMENSIONS AND WEIGHTS Net Weight31 kg (68.0 Ib) Shipping Weight33 kg (72 Ib) Dimension (WHD)435 180 450mm RadioFans.CN 收音机爱 好者资料库 ALIGNMENT PROCEDURE (T975) A. THERMAL SENSE ADJUSTMENT This adjustment shou
12、ld be always done when the T975 is in a cool condition. (That means the temperature 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 the Idling current heating up the unit excessively) At ambie
13、nt temperature of 25 C degrees and when the unit is just turned on (still 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 settin
14、g should be changed by 20mV per degree C difference. So at 20C degrees, the 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,
15、 change the TL084BCD to one selected for low offset voltage to meet the requirement. 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
16、 22mV). The alignment procedure is: At first, adjust RV102 (Marked as “Idling 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 cur
17、rent must be adjusted when all modules are assembled into the unit. 2.Though 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 idlin
18、g current in the service field, its acceptable as long as the voltage is in the range of 13.2mV22.0mV. D. ISC SENSITIVITY The ISC sensing voltage range is 0mV+/-50mV. But, for the alignment process during production, we tighten the limit to 0mV+/-10mV. That is to adjust Pot RV104 (as marked as “ISC
19、SENSE ADJ” in the below drawing) to get a voltage between the “ISC SENSE TEST POINT” and AGND to be 0mV+/-10mV. (Please 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 F
20、an sense voltage first. Turn Pot RV201 (on the power supply board) to the end clockwise and confirm TP2 of J201 is negative voltage. Run the unit to heat it up and to start turning the fan. - 5 - RadioFans.CN 收音机爱 好者资料库 For example; all 7 channels at 50W/4 ohms for 10 minutes or 5 minutes or even le
21、ss (as long as the fan can starts turning). Turn off the signal but still keep the unit operating for 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
22、 off. Then run all 7 channels at 1kHz, 0.5W at 4 ohms load, monitor if the voltage at TP1 of Pot RV201 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 turnin
23、g within about 30s Maximum. - 6 - RadioFans.CN 收音机爱 好者资料库 AGND +62V +62V -62V -62V AGND AGND AGND ISCTRIG AC OFF SEN PROTECT -68V +68V -18V +18V SC PNP SC NPN AGND +62V +62V -62V -62V AGND AGND AGND ISCTRIG AC OFF SEN PROTECT -68V +68V -18V +18V SC PNP SC NPN AGND +62V +62V -62V -62V AGND AGND AGND
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- NAD T975 pwr sm 维修 电路 原理图