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功放维修实例来源: 作者: 【大中小】浏览:33次评论:0条一台AV功放，交流哼声较大，开盖检查，断开前级到后级的信号线，交流声消失，说明故障在前级。
怀疑前级接地不良，重新接地后故障依旧。
检查前级电源电路，两只1000цF/25V的滤波电容紧靠在三端稳压KA7812、KA7912散热片旁，估计是由于电容容量变小造成滤波不良。
用两只2200цF/25V的电容更换后故障排除。
一台功放机，无声音输出。
检查继电器不吸合，L声道中点电压有30V左右，但功放管、推动管、激励管、差分管均正常。
检测各偏置电阻也正常。
拆下激励管2N5401 b-e极间容量为100pF 的消振电容测量阻值只有20k欧，用一只相同的电容更换后故障排除。
一台功放机开机无任何反应。
检查发现保险管已烧断。
检测功放管，电源整流二极管均正常。
怀疑电源保险管是由于瞬时过载引起烧断的，换上保险管通电开机马上又烧断，说明还存在短路故障，仔细检查发现一只10000цF/50V的电容已击穿短路，用一只好的10000цF/50V的电容更换后故障排除。
故障现象：一台KONES牌AV-112型功放机，右声道音量小且沙哑，左声道正常。
分析检修：把机后EQ端子连接插头拔掉后，将VCD音频信号从IN端子输入，故障不变，说明故障范围在右声道功率放大部分。
注：应先把VCD音频输出减至最小音量，再接通功放机电源，然后把VCD音量慢慢调大至1/3音量指示格，这样可以防止冲击功率放大电路。
仔细观察，发现该机采用STK3048A加双STK6153组合，重点检查右声道STK6153。
在路测右声道STK6153②、③脚之间正、反向阻值很大；⑨、10脚之间阻值也很大；②、⑤脚之间和⑦、10脚之间已无PN结特性，判断此STK6153已损坏。
测量⑦、⑨脚之间和③、⑤脚之间大功率管芯已损坏，⑦、10脚之间和②、⑤脚之间中功率管芯已损坏，④、10脚之间管芯已损坏，而①、②脚之间和①、④脚之间管芯良好，②、③脚之间和⑨、10脚之间的四只电阻已烧焦。
音频功放保护电路分析与维修浏览文章维修技术维修吧在音频放大器中一般都设有功能完善的保护电路，可以在功放输出管过载、输出端电位偏移时进行可靠的保护，还可以在开机时延迟接通扬声器，避免开机损坏扬声器和开机“嘭”声，关机时瞬时断开扬声器，可避免关机时的冲击。
一、分离元件保护电路图1所示是湖山BK2X100JMKⅡ-95型纯后级功率放大器功放保护电路。
放大器刚接通电源时，+56V电压通过R143对C116充电，约延迟4s，C116上电压充到9．5V左右时，稳压管V126导通而使V124、V125导通，继电器K101吸合，才能接通扬声器，避免开机时的电流冲击而保护扬声器。
v126、v129组成功放输出端的电位检测电路，当输出端的电位偏移时，通过一51k电阻R144，使V126或V129导通。
当输出端的电位是正偏移时，V129导通。
反之，当输出端的电位是负偏移时V126导通。
无论v126或V129中哪一个导通，C116正端电位为0V，稳压管V126截止，V124、V125截止，使继电器释放，断开扬声器，这样就完成了输出端电位偏移保护。
当功放因输出短路或负载过重时，输出管V134、v135射极电流大增，在R132、R133上产生的压降增大经R134、R135分压加至V118基极，使V118导通，使V127基极电位降低，v127导通，稳压管V126截止，V124、V125截止，继电器释放，断开扬声器，这样就完成了输出管的过载保护。
二、uPC1237保护电路图2所示是天逸AD-5100A型AV放大器功放保护电路。
J1、J2为接在功放输出端的继电器。
刚开机时，+56V电压经R57、R58对c29充电，几秒后，当C29充电到一定电压时，IC2(uPC1237)⑥脚内的开关电路接通，输出低电平，使J1、J2吸合，接通扬声器，实现开机延时保护功能。
当功放输出端直流电压因某种原因发生偏移，使IC2 2脚电压超过+0．7V，或低于-0．23V时，⑥脚内开关电路截止，输出高电平，使J1、J2释放，断开扬声器，实现功放输出端的直流电压偏移保护。
雅马哈贴片机_修机_调机的经验之谈1 SMT设备维修实例随着电子工业的飞速发展，SMT设备正得到越来越广泛的应用，但这些设备在使用过程中不可避免地会出现这样或那样的问题。
一般情况下使用厂家是与设备供应商联系维修，但往往会因为路途等原因耽误相当长时间而影响生产，而且设备维修花费、维修人员的旅途费等也将是一笔不小的开支。
因此，对于SMT工程技术人员来说，掌握一定的维修技术，就可以避免上述情况的出现。
在维修过程中，我们应找出设备故障产生的根本原因，这样我们在排除故障时才能做到有的放矢。
笔者将结合自己的几次维修典型事例，介绍SMT设备故障分析及排除方法，以供同行参考。
故障分析及排除故障一:托盘(TRAY)元件供料平台位置的调整工作过程:我们使用的高精度贴片机为松下MPA—G3，其托盘元件供料器与机器主体连为一体。
贴装托盘元件(如QFP)时，有一个专用吸头(TRAY HEAD)将元件从托盘中吸出并放在一个供料平台上，然后供料平台移到贴片头所在位置以供贴装头吸取贴装。
故障的产生及分析:我们发现贴装头(MOUNT HEAD)吸取元件时存在一定的偏差，吸嘴很难吸取到元件的正中心上，从而会对贴装造成一定的影响。
但若将机器工作方式改为直接取料，即MOUNT HEAD不通过供料平台而直接从托盘上吸取元件时，就不存在这种情况。
由此我们分析MOUNT HEAD与TRAY HEAD在供料台上吸取放置元件的位置不在一个轴上，从而造成吸取误差。
故障的排除:MOUNT HEAD与TRAY HEAD在供料平台上的吸取放置元件的位置可由机器参数(MACHINE DATA)来设定，我们以MOUNT HEAD在供料平台上吸取元件的位置为参考点，将TRAY HEAD在供料平台上放置元件的位置调整到与参考点位置重合即可。
在以后的生产过程中，就再未出现过托盘元件吸取不正的问题。
笔者利用这种方法也曾解决了另外一家单位设备中存在的相类似的问题。
故障二:部品贴装偏差大故障的产生:笔者曾使用过YAMAHA公司的中速贴片机YV1OO，该型机器以贴装片状元件为主。
第 1 页共2 页维修手记机器型号：YV100X-S故障描述：生产进行中当机，提示L018：I/O CMU ERROR! 重启后OK,但高速运行中会当机.维修过程:一. 确定出故障的大概部件.1. 根据VIOS 提示,初步确认为HEAD I/O BOARD 引起故障.2. 与其它机器对调I/O BOARD 确定此片I/O BOARD 存在故障.排除机器本身的故障.3. I/O 板分主副板,对调后确认主板有问题.*此段目的已达到,初步确认为I/O 板之主板存在异常!排除法可用于同型号机器多种情况.可以很快找出大概故障部件.去掉测量线路之苦.二.确认故障范围1.既然故障已确定在I/O 板的主板之上,首先应搞清其输入输出的情况.通过查相关资料,了解到此板共有13 个连接器,但本机仅使用10 个,其功能如下:CN2: DC 24 1N CN5:EMG.CNX1: 与SYSTEM BOARD 通信(I/O2)CN13: LIGHT(控制相机光源)CN10: HEAD DOWN SENSORCN8: SL. DOWN SENSORCN7: DOWN HEADCN4: R.UP / DOWN / SAFATY SENSORCN9: VACUUM SENSOR可以看出唯一与外界通信的是CNX1 ,现在仅插X1 开机.自检OK.归零OK.到3/3/B5,MOVE RANDOM→X1→100→RUN. 3S 后当机,重复二次依然出现相同故障.依此判定其余未插的连接器不存在问题.现重点排查这4 个连接器是否存在接触不良的问题.X1 不太可能存在接触不良,因为它在副板上,再用排除法一一拨掉4.开机,均有故障出现.但不是L018.排除中不小心手碰了一下机板.突然发现副板上的5VLED 闪了一下.再碰,发现LED 有闪断的现象.是否可能为主/副板连接器接触不良呢?3.连接不良?清洁!无效;更换?找不到配件.只有使用最狠的一招.用线直接焊!60*2=120 30 分钟后完成!装好之后,竟然故障依旧!!!第 2 页共2 页4.排除此连接器的问题,还原连接器!5.在第2 步排除掉5,唯独没排除CN2. CN2 怎么排除?焊上去啰!在操作时由于晕了头未关电就顺手拨下CN2 了,不经意发现屏幕显示L018 !!!莫非电源部分有问题.7.联想到碰.高速会当机,会不会是由于在剧烈情况下电源部份的元件的瞬间接触不良而产生的呢?8.当I/O 板正常时,D23 常亮D22 启动前慢闪,启动OK 后快闪.LED2 常亮.9.取下机板分析.此板电源部份组件不多,将组件焊点加锡一遍后故障依旧.测量元件.经对比后也没发现有什么问题.10.转到正面,取下X1 (小心,此东东比较难拆). 发现在它的掩盖之后还有一个二极管.太小,本人近视,用放大镜观察,终于发现传说中的假焊.此发现纯属巧合,鬼子的东西也有假焊??加锡焊接先!11.装机,开机,祈祷,启动OK!归零OK!! 3/3/B5 正常.运行10 分钟OK!12.初出判定故障排除!三.总结1.解决此问题还有一个办法.就是换I/O 板!2.充分运用排除法,操作中胆大心细!3.具体操作中要一步步做好相关记录!。
DA CONVERTER Owner’s ManualEKeep This Manual For Future Reference.FCC INFORMATION (U.S.A.)1. IMPORTANT NOTICE: DO NOT MODIFY THIS UNIT!This product, when installed as indicated in the instructions contained in this manual, meets FCCrequirements. Modifications not expressly approved by Yamaha may void your authority, granted by the FCC, to use the product.2. IMPORTANT: When connecting this product to accessories and/or another product use only high quality shielded cables. Cable/s supplied with this product MUSTbe used. Follow all installation instructions. Failure to follow instructions could void your FCC authorization to use this product in the USA.3. NOTE: This product has been tested and found to comply with the requirements listed in FCC Regulations, Part 15 for Class “B” digital devices. Compliance withthese requirements provides a reasonable level of assurance that your use of this product in a residential environment will not result in harmful interference with other electronic devices. This equipment generates/uses radio frequencies and, if not installed and used according to the instructions found in the users manual, may cause interference harmful to the operation of other electronic devices. Compliance with FCC regulations does not guarantee that interference will not occur in all installations. If this product is found to be the source of interference, which can be determined by turning the unit “OFF” and “ON”, please try to eliminate the problem by using one of the following measures:Relocate either this product or the device that is being affected by the interference.Utilize power outlets that are on different branch (circuit breaker or fuse) circuits or install AC line filter/s.In the case of radio or TV interference, relocate/reorient the antenna. If the antenna lead-in is 300 ohm ribbon lead, change the lead-in to coaxial type cable.If these corrective measures do not produce satisfactory results, please contact the local retailer authorized to distribute this type of product. If you can not locate the appropriate retailer, please contact Yamaha Corporation of America, Electronic Service Division, 6600 Orangethorpe Ave, Buena Park, CA 90620The above statements apply ONLY to those products distributed by Yamaha Corporation of America or its subsidiaries.WARNING: THIS APPARATUS MUST BE EARTHEDIMPORTANTTHE WIRES IN THIS MAINS LEAD ARE COLOURED INACCORDANCE WITH THE FOLLOWING CODE:GREEN-AND-YELLOW : EARTHBLUE : NEUTRALBROWN : LIVEAs the colours of the wires in the mains lead of this apparatus maynot correspond with the coloured markings identifying the terminals inyour plug, proceed as follows:The wire which is coloured GREEN and YELLOW must beconnected to the terminal in the plug which is marked by the letter Eor by the safety earth symbol or coloured GREEN and YELLOW.The wire which is coloured BLUE must be connected to the terminalwhich is marked with the letter N or coloured BLACK.The wire which is coloured BROWN must be connected to theterminal which is marked with the letter L or coloured RED.* This applies only to products distributed by YAMAHA KEMBLEMUSIC (U.K.) LTD.i Important InformationPlease read before operating the DA824Warnings•Do not subject the DA824 to extreme temperatures, humidity, direct sunlight, or dust, which could be a potential fire or electrical shock hazard.•Do not allow water to enter the DA824 or allow it to become wet. Fire or electrical shock may result.•Connect the power cord only to an AC outlet of the type stated in this Owner’s Manual or as marked on the DA824. Failure to do so is a fire and electrical shock hazard.•Hold the power-cord plug when disconnecting from an AC outlet. Never pull the cord.A power cord damaged through pulling is a potential fire and electrical shock hazard.•Do not touch the power plug with wet hands. Doing so is a potential electrical shock hazard.•Do not place heavy objects, including the DA824, on top of the power cord. A damaged power cord is a fire and electrical shock hazard. In particular, be careful not to placeheavy objects on a power cord covered by a carpet.•Do not scratch, bend, twist, pull, or heat the power cord. A damaged power cord is a fire and electrical shock hazard.•If the power cord is damaged (e.g., cut or a bare wire is exposed), ask your dealer for a replacement. Using the DA824 with a damaged power cord is a fire and electrical shockhazard.•Do not plug several devices into the same AC outlet. This may overload the AC outlet, and could be a fire or electrical shock hazard. It may also affect the performance of someequipment.•If you notice any abnormality, such as smoke, odor, or noise, or if a foreign object or liquid gets inside the DA824, turn it off immediately. Remove the power cord from theAC outlet and consult your dealer for repair. Using the DA824 in this condition is a fireand electrical shock hazard.•Do not place small objects on top of the DA824. Metal objects falling inside the DA824 is a fire and electrical shock hazard.•If a foreign object or water gets inside the DA824, turn it off immediately. Remove the power cord from the AC outlet and consult your dealer for repair. Using the DA824 inthis condition is a potential fire and electrical shock hazard.•Should the DA824 be dropped or the cabinet be damaged, turn off the power, remove the power plug from the AC outlet, and contact your dealer. If you continue using theunit without heeding this instruction, fire or electrical shock may result.•Do not remove the DA824’s cover. Y ou could receive an electrical shock. If you think internal inspection, maintenance, or repair is necessary, contact your dealer.•Do not attempt to modify the DA824. This is a potential fire and electrical shock haz-ard.•Do not block the DA824 ventilation slots. Blocking the ventilation slots is a potential fire hazard.DA824—Owner’s ManualiiCautions•Allow enough free space around the unit for normal ventilation. This should be: 10 cm at the sides, 15 cm behind, and 30 cm above. These distances should also be adoptedwhen rack-mounting the DA824. For normal ventilation during use, remove the rearof the rack or open a ventilation hole. If the airflow is not adequate, the DA824 will heatup inside and may cause a fire.•Use the DA824 in an environment where the temperature is between 10˚C and 35˚C (50˚F and 95˚F).•Turn off audio devices when connecting them to the DA824, and use only the cables specified in the relevant owner’s manuals.•If you plan not to use the DA824 for a long period of time, remove the power cord from the AC outlet. Leaving the DA824 connected is a potential fire hazard.•Do not use benzene, thinner, cleaning detergent, or a chemical cloth to clean the DA824. Use only a soft, dry cloth.•If the DA824 is stored in a cold place (e.g., overnight in a car), and then moved to a warmer environment, or the temperature rises sharply, condensation may form insidethe DA824, which may affect performance. In such cases, the DA824 should be allowedto acclimatize for about one hour before use.InterferenceThe DA824 uses high-frequency digital circuits that may cause interference on radioand television equipment located nearby. If interference is a problem, relocate theaffected equipment.DA824 Exclusion of Certain ResponsibilityManufacturer, importer, or dealer shall not be liable for any incidental damages includ-ing personal injury or any other damage caused by improper use or operation of theDA824.Y amaha cannot be held responsible for any loss of data or data damage due to improperuse or operation of the DA824.Package ContentsThe DA824 package should contain the following items. Contact your Y amaha dealer ifanything is missing.•DA824 DA Converter•This manualTrademarksADAT MultiChannel Optical Digital Interface is a trademark of Alesis Corporation.Tascam Digital Interface is a trademark and Tascam and T eac are registered trademarksof T eac Corporation. Y amaha is a trademark of Y amaha Corporation. All other trade-marks are the property of their respective holders and are hereby acknowledged.DA824—Owner’s ManualiiiCopyrightNo part of the DA824 software or this Owner’s Manual may be reproduced or distrib-uted in any form or by any means without the prior written authorization of Y amaha Corporation.© 2000 Y amaha Corporation. All rights reserved.DA824—Owner’s Manualiv ContentsContents1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Setting the Maximum Output Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Connecting the Power Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Turning On the Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2Touring the DA824 . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3Digital I/O Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 About Digital I/O Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Card Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Installing I/O Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4Hookup Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Basic AES/EBU Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Basic ADAT Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6AES/EBU Connection with Splitter Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Dual ADAT Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5Wordclocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 About Wordclocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Wordclock Hookup Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Wordclock Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 DA824—Owner’s ManualIntroduction1DA824—Owner’s Manual2Chapter 2—Touring the DA824DA824—Owner’s ManualRear Panel3DA824—Owner’s Manual4 Chapter 3—Digital I/O CardsDA824—Owner’s Manual 3 Digital I/O CardsAbout Digital I/O CardsFor digital input, the DA824 uses optional mini YGDAI (Y amaha General Digital Audio Interface) cards, which are available in all the popular digital audio interconnect for-mats, including AES/EBU, ADAT, and Tascam TDIF-1.The following digital I/O cards are currently available. See the Y amaha Professional Audio Web site at the following address for up-to-date news on mini YGDAI cards: <http://www.yamaha.co.jp/product/proaudio/homeenglish/>.MY8-AT—ADATThe MY8-AT card provides ADAT format digital I/O via two MultiChannel Optical Digital Interface connectors, and supports 16-, 20-, and 24-bit wordlengths. MY8-AE—AES/EBUThe MY8-AE card provides AES/EBU format digital I/O via a 25-pin D-sub connector, and supports 16-, 20-, and 24-bit wordlengths.MY8-TD—Tascam TDIF-1The MY8-TD card provides Tascam TDIF-1 format digital I/O via a 25-pin D-sub con-nector, and supports 16-, 20-, and 24-bit wordlengths. A BNC connector is provided for wordclock output.MY8-TD cards feature a device selector switch (EXT: 88/INT: 38) that should be set to match the device being connected. This should be set to “EXT: 88” when connecting a Tascam DA-88, or “INT: 38” when connecting a Tascam DA-38, DME32, or other device.Card SpecificationsThe following table provides specifications for the DA824-compatible I/O cards. CardFormat In Out Wordlength ConnectorsMY8-ATADAT I/O 8816, 20, 24Optical x2MY8-AEAES/EBU I/O 8816, 20, 2425-pin D-sub (cable not included)MY8-TD Tascam TDIF-1 I/O 8816, 20, 2425-pin D-sub,BNC wordclock outInstalling I/O Cards5DA824—Owner’s Manual6Chapter 4—Hookup ExamplesDA824—Owner’s ManualAES/EBU Connection with Splitter Cable7DA824—Owner’s Manual8Chapter 5—WordclocksDA824—Owner’s ManualWordclock Termination9DA824—Owner’s Manual10AppendixDA824—Owner’s ManualAppendixSpecificationsSampling rateMY8-AE, MY8-TD 39.69–50.88 kHz MY8-AT41.013–50.88 kHzDA conversion resolution 24-bit linear, 128-times oversampling Frequency response –3, +1 dB, 20 Hz–20 kHz Dynamic Range 11.Measured with a 6 dB/octave filter at 12.7 kHz; equivalent to a 20 kHz filter with infinitedB/octave attenuation.110 dB (typical)Gain Error ±1 dB @ 1 kHz THD 22. 6 dB/octave filter @ 80 kHz.*Where dB represents a specific voltage, 0 dB is referenced to 0.775 V rms, 0 dBV is refer-enced to 1.00 V rms.0.05%, 20 Hz–20 kHz0.01% full scale output @ 1 kHz Hum & Noise Level 1–92 dB (typical)Crosstalk –70 dB between adjacent channels @ 1 kHz Signal Delay0.57 ms (digital input to analog output, fs = 48 kHz)IndicatorsPEAK 3 dB below full scale NOMINAL14 dB below full scale SIGNAL 34 dB below full scale LOCK Wordclock lock POWERPower on/offPower requirements U.S.A. & Canada 120 V AC, 60 Hz Europe 230 V AC, 50 Hz Power consumption 40 WDimensions (W × H × D)480 × 97.5 × 366.8 mm (18.9 x 3.84 x 14.44 inches)Weight7.5 kg (16.53 lbs)Free-air operating temperature 10˚ C to 35˚ C (50˚ F to 95˚ F)Storage temperature –20˚ C to 60˚ C (–4˚ F to 140˚ F)Power cord length 1.9 mSupplied AccessoriesOwner’s ManualSpecifications11DA824—Owner’s ManualAnalog OutputDigital I/OConnectionGAIN SWActual Source ImpedanceFor Use with NominalOutput Level ConnectorNominal Max. before clip OUTPUT 1–811.24-bit 128-times oversampling D/A converters.+24 dB 150 Ω lines600 Ω lines+10 dB (2.45 V)+24 dB (12.28 V)XLR-3-32 type (balanced)2&TRS phonejack (balanced)32.XLR-type connectors are electronically balanced (pin 1= ground, pin 2= hot, pin 3= cold).3.TRS phone jacks are electronically balanced (tip= hot, ring= cold, sleeve= ground).*Where dB represents a specific voltage, 0 dB is referenced to 0.775 V rms, 0 dBV is refer-enced to 1.00 V rms.+18 dB+4 dB (1.23 V)+18 dB (6.16 V)+15 dB +1 dB (0.87 V)+15 dB (4.36 V)+4 dBV–10 dBV (0.316 V)+4 dBV (1.58 V)Connection Format Level/ImpedanceConnector COM—RS232C 9-pin D-sub (male)WORD CLOCK IN —TTL, 75Ω (ON/OFF)BNC WORD CLOCK THRU —TTL, 75ΩBNC SLOTmini YGDAI——12AppendixDA824—Owner’s ManualYAMAHA CORPORATION V554060 R0 1 IP 20Pro Audio Division, #18/3P.O. Box 3, Hamamatsu, 430-8651, Japan 00 03 500 AP Printed in Japan。
通用2.1声道有源音箱电路图分析及维修方法（转）一、电源电路（图纸的最下面部分）：220V市电经过保险管（F），和开关S后进入变压器初级，变压器的次级输出双12V交流，双12V送入由VD1组成的桥式整流电路电路，经过桥式整流和C14，C15（3300UF/25V）的滤波后，输出的空载电压约为正负16V左右（根号2乘于12V），即A+为正16V，A-为负16V。
正负16V为三块功放芯片TDA2030，UTC2030提供电源。
另一路经过R21、R22的降压后，由B+，B-输出约正负12V为低音前置放大和低通滤波器IC4提供电源电压。
在本图纸当中，前置放大的供电并没有采用78/7912三端稳压电路，磨机爱好者在更换两个3300UF电容时，也可以考虑加入LM7812/7912为前置提供更为稳定的工作电压。
二、左右声道放大电路（卫星箱功放电路），因左右声道作原理完全一致。
这里我只以图纸的左声道为例，作个介绍。
如图：RIN为信号输入端，经过耦合电容C23进入音量电位器，（音量电位器由三个引脚，与C23连接的是输入端，输出端也叫滑动端、另一引脚为接地端），调整音量后信号进入由R1/C3组成的高音提升电路，此电路可以提升一定量的高频信号，使声音更加清晰。
尔后信号经过耦合电容C1进入左声道功放，型号为UTC2030的1脚，经过功率放大后，由2030的第四脚输出，推动卫星箱发声。
图中的R7为反馈电阻，R7/R9为决定2030芯片的放大倍数。
因此，调整R7的阻值，就可以调整放大倍数。
R11/C7为扬声器补偿网络。
三、超低音电路。
由左右声道经两个10K电阻R5、R6后至C11耦合电容，尔后信号进入IC4，型号为JRC4558的3脚，图中IC4A为超低音的前置放大器。
R201T将此放大器的放大倍数设置为6倍左右。
（R17/R18），经过前置放大后，才能保证足够大的驱动电压，获得足够大的音量。
4558的1脚为前置输出，经R19后进入由IC4B、C9、C10、R20组成的低通滤波器。
