2300功放电路图

2300功放电路图作用

2300是(shi)设(she)计(ji)供音响使用的功(gong)率(lv)(lv)放(fang)大(da)器，在5.7V电(dian)源电(dian)压(ya)(ya)时(shi)推动(dong)4Ω负载可(ke)以(yi)输出2Wx2(THD=1%)的功(gong)率(lv)(lv)。使用CMOS 工艺制(zhi)造，静态时(shi)耗电(dian)极(ji)低(di)，在音响特(te)性方面谐波失真率(lv)(lv)可(ke)低(di)0.03%，并具有单端(duan)(SE)以(yi)及桥接(jie)(BTL)两种不同输出模式可(ke)以(yi)选择，内建音量调整功(gong)能，仅须外(wai)部直(zhi)流电(dian)压(ya)(ya)即可(ke)控制(zhi)音量。在实装时(shi)外(wai)部元(yuan)件仅为精简(jian)易于使用，且具有过热保护功(gong)能，封装体积小，不占基板(ban)面积，最适宜供小型或携带(dai)型产品(pin)使用。

特点

MOS工艺制造

立(li)体声音源输入

输出功率(lv)2Wx2 (Vcc=6V，THD=1%，RL=4Ω)

谐波失真极低( 0.03%)，音质极佳

内含32阶音量控制器(qi)段(duan)

可(ke)切(qie)换SE（单端(duan)）以及(ji)BTL（桥接）两(liang)种输出模式

设有(you)冲击声抑制功(gong)能

设有节能( Shutdown)功能，启(qi)动后可进(jin)入省(sheng)电(dian)状态(lcc<0.7μA)

内建过(guo)热保护

应用范围

LCD荧幕（For TV）

可(ke)携式音(yin)响

多媒体(ti)音(yin)响喇叭

其他音响应(ying)用

2300功放电路及故障维修及安全检修方法

高保真(zhen)OCL、OTL功(gong)放(fang)电(dian)(dian)路(lu)(lu)，一(yi)(yi)般(ban)前级(ji)多采用(yong)差分(fen)放(fang)大输入(ru)，末级(ji)采用(yong)互补大功(gong)率(lv)对(dui)管输出，前后级(ji)之间直接(jie)耦合。它(ta)具(ju)有工作稳(wen)定(ding)、频(pin)率(lv)特(te)性(xing)好(hao)、失真(zhen)小(xiao)等(deng)优点，因而在(zai)近(jin)几年(nian)专业和(he)家(jia)用(yong)功(gong)放(fang)电(dian)(dian)路(lu)(lu)中得到广泛的(de)应用(yong)。但(dan)是，由于采用(yong)多管直接(jie)耦合，一(yi)(yi)旦某(mou)只元件(jian)变(bian)(bian)(bian)质或损坏(huai)，会造成(cheng)(cheng)整个(ge)电(dian)(dian)路(lu)(lu)工作点的(de)改变(bian)(bian)(bian)，轻则(ze)导致(zhi)声音小(xiao)而失真(zhen)，重则(ze)造成(cheng)(cheng)元器(qi)件(jian)大面积损坏(huai)，甚至烧毁扬声器(qi)系统。一(yi)(yi)点电(dian)(dian)压(ya)的(de)改变(bian)(bian)(bian)，会引(yin)起(qi)多点电(dian)(dian)压(ya)随之改变(bian)(bian)(bian)，这也(ye)给故障(zhang)的(de)判断(duan)和(he)检修(xiu)造成(cheng)(cheng)困难(nan)。与(yu)同(tong)行(xing)(xing)交流时(shi)(shi)还发(fa)现，在(zai)检修(xiu)此类功(gong)放(fang)时(shi)(shi)，如果故障(zhang)排除不(bu)彻底(di)，通电(dian)(dian)试(shi)机时(shi)(shi)往往引(yin)起(qi)新器(qi)件(jian)再次损坏(huai)，造成(cheng)(cheng)经济损失。因此笔者(zhe)在(zai)检修(xiu)实践(jian)中试(shi)行(xing)(xing)了一(yi)(yi)种安全检修(xiu)方(fang)法，通过实例(li)的(de)形式介(jie)绍给大家(jia)，以期与(yu)同(tong)行(xing)(xing)们交流。

实例1 一位同事检修一台日产雅马哈2300功放和调音台组合机时，发现两路功放的16只大功率对管、4只推动管全部击穿，两只音箱内的扬声器全部烧毁。按规格全部更换已损坏件后，在没连接前级调音台的情况下，通电试机，仅过几分钟，就见机内冒烟。停机检查，新换的大功率对管又损坏12只，两只音箱内扬声器再次烧毁，损失达两千多元。他不敢再修，求助于笔者修理。

有(you)了前(qian)车之鉴，笔(bi)者经慎重考虑，采(cai)取了一(yi)种稳妥安全的方法进(jin)行检修，排除(chu)了故障。

具体检修步骤如下：

(1)对照(zhao)实物，画出整机(ji)(功放部(bu)分(fen)电原(yuan)理(li)图(见(jian)图1)，弄清电路的工作原(yuan)理(li)和元器件参数。

(2)用电(dian)阻(zu)测量(liang)法对(dui)电(dian)路中所有元件进行一(yi)次在路测量(liang)，并(bing)将左、右电(dian)路测量(liang)结(jie)果对(dui)照(zhao)比较，找出(chu)损坏(huai)元器(qi)件。

注意：

1）为了提高(gao)在路测(ce)量精确度，测(ce)量电(dian)(dian)阻时(shi)用(yong)数(shu)(shu)字式万用(yong)表。由(you)于数(shu)(shu)字万用(yong)表内阻大，向(xiang)被测(ce)电(dian)(dian)路提供的电(dian)(dian)流小，不(bu)能(neng)使二极(ji)管、三极(ji)管PN结导(dao)通，相当于开路，可减小对(dui)电(dian)(dian)阻测(ce)量的影(ying)响。

2）测(ce)(ce)量(liang)二极管、三(san)极管时用(yong)指针式万用(yong)表。测(ce)(ce)量(liang)PN结正(zheng)(zheng)(zheng)向电(dian)阻(zu)(zu)时用(yong)R×1挡(dang)，既可向PN结提供(gong)较大的正(zheng)(zheng)(zheng)向电(dian)流，检查其正(zheng)(zheng)(zheng)向特性(xing)，又可减小(xiao)在(zai)路其它元(yuan)件对测(ce)(ce)试(shi)的影响。正(zheng)(zheng)(zheng)常情况下用(yong)1.5V电(dian)池(chi)供(gong)电(dian)的电(dian)阻(zu)(zu)挡(dang)测(ce)(ce)量(liang)PN结正(zheng)(zheng)(zheng)向电(dian)阻(zu)(zu)时，指针应偏转到电(dian)阻(zu)(zu)量(liang)程刻(ke)度(du)线(xian)的中(zhong)点(距0Ω1/2左右)，如果(guo)显(xian)(xian)示电(dian)阻(zu)(zu)较大，说明PN结正(zheng)(zheng)(zheng)向特性(xing)不良。测(ce)(ce)反向电(dian)阻(zu)(zu)时，用(yong)R×100或R×1k挡(dang)，显(xian)(xian)示电(dian)阻(zu)(zu)应略小(xiao)于测(ce)(ce)试(shi)两点间并(bing)联电(dian)阻(zu)(zu)。

3）测(ce)量电(dian)(dian)容(rong)器(qi)时(特别是电(dian)(dian)解电(dian)(dian)容(rong)器(qi))，也选用指针万用表(biao)，并根据(ju)容(rong)量大(da)小选择相(xiang)应的量程(cheng)，既可(ke)测(ce)量电(dian)(dian)容(rong)器(qi)在路电(dian)(dian)阻，又可(ke)根据(ju)指针摆(bai)动情况，估测(ce)电(dian)(dian)容(rong)器(qi)容(rong)量。

在上(shang)述(shu)方法(fa)进行在路测量后，该组(zu)合机(ji)有12只大(da)功(gong)率输出管(guan)击穿，5只发射极(ji)电(dian)阻烧断，推动(dong)管(guan)有两只漏(lou)电(dian)，扬声(sheng)(sheng)器(qi)保护电(dian)路失效。将上(shang)述(shu)元件全部更换新件，修复扬声(sheng)(sheng)器(qi)保护电(dian)路后，进入关键的通电(dian)试机(ji)阶段。

采用三步安全通电试机法进行通电试机

第一步

1）使(shi)用假(jia)负(fu)载。首先为(wei)了不损坏(huai)扬声器(qi)和大功率管，试机(ji)前(qian)不接扬声器(qi)系统，在推挽输出端与(yu)地之间(即图1中(zhong)的(de)C点与(yu)D点之间)接一只(zhi)20～50Ω/20～50W线绕电(dian)阻做假(jia)负(fu)载。

2）其(qi)次(ci)，使末(mo)级功(gong)(gong)放管脱离电(dian)路。断开末(mo)级大(da)(da)功(gong)(gong)率管的(de)任意两个电(dian)极或事(shi)先不安装大(da)(da)功(gong)(gong)率管Q212～Q219。保(bao)留推(tui)动管Q210、Q211做互补(bu)推(tui)挽输出(如果推(tui)动管发(fa)射极与中点之间(jian)无(wu)发(fa)射极电(dian)阻，应临时(shi)加(jia)装两只100～270Ω、0.5W以(yi)上电(dian)阻，试机(ji)后(hou)拆除)。

3）使(shi)用调(diao)压(ya)(ya)(ya)(ya)(ya)器，从最低(di)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)开始(shi)检查(cha)。接(jie)着(zhe)在功放电(dian)(dian)(dian)源(yuan)220V输入端串接(jie)一(yi)(yi)台(tai)调(diao)压(ya)(ya)(ya)(ya)(ya)器，从50V开始(shi)向(xiang)功放供电(dian)(dian)(dian)，并监测输出端中(zhong)点(dian)(dian)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)(C点(dian)(dian)与D点(dian)(dian)之间的电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya))。对OCL电(dian)(dian)(dian)路来说(shuo)，这一(yi)(yi)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)应(ying)为0V±0.5V，对OTL电(dian)(dian)(dian)路来说(shuo)应(ying)为电(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)的一(yi)(yi)半。如(ru)(ru)果(guo)中(zhong)点(dian)(dian)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)不符合正常(chang)值(zhi)，应(ying)立即(ji)停机检查(cha)。此时由于供电(dian)(dian)(dian)较低(di)，一(yi)(yi)般不会造成元(yuan)(yuan)器件(jian)损(sun)坏。如(ru)(ru)果(guo)中(zhong)点(dian)(dian)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)正常(chang)，可逐(zhu)渐提高电(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)，一(yi)(yi)边(bian)监测中(zhong)点(dian)(dian)电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)，一(yi)(yi)边(bian)观察有无变(bian)色(se)、冒烟元(yuan)(yuan)件(jian)，同时用手摸(mo)推动(dong)管(guan)温度(du)。如(ru)(ru)果(guo)市电(dian)(dian)(dian)升(sheng)到正常(chang)值(zhi)，通(tong)(tong)电(dian)(dian)(dian)半小(xiao)时输出端电(dian)(dian)(dian)压(ya)(ya)(ya)(ya)(ya)保持不变(bian)，推动(dong)管(guan)无温度(du)上升(sheng)或元(yuan)(yuan)器件(jian)无变(bian)质变(bian)色(se)，则表明(ming)安全通(tong)(tong)电(dian)(dian)(dian)试机法第一(yi)(yi)步操作(zuo)结束，可进行下一(yi)(yi)步操作(zuo)。

第二步是(shi)接入大功率管(guan)，保持(chi)假负载，降(jiang)压供(gong)电(dian)(dian)，监测中(zhong)点(dian)(dian)。也(ye)就(jiu)是(shi)说，装上(shang)末级(ji)大功率管(guan)Q212～Q219，并(bing)按照从50V起逐渐升压的方法继续通电(dian)(dian)试(shi)机(ji)(ji)。必要时，应对(dui)整(zheng)机(ji)(ji)静态电(dian)(dian)流(liu)、中(zhong)点(dian)(dian)电(dian)(dian)压进(jin)行(xing)相应的调整(zheng)。如果(guo)中(zhong)点(dian)(dian)电(dian)(dian)压失常，应重点(dian)(dian)检查末级(ji)功放管(guan)及外围电(dian)(dian)路。直到中(zhong)点(dian)(dian)电(dian)(dian)压稳定(ding)，功放管(guan)不发(fa)热(re)为止。

第三步是拆去假负载，接入低档扬声器和信号源，正常供电试听。具体说，分别在图1中C、D间和E、D间接入低档扬声器试听。此时，即使电路发生故障，也仅仅是损坏价位较低的低档扬声器。通电试听半小时，中点电压应保持稳定，功放管温度应正常(不烫手)。有条件可进行指标的测试和调整。

如(ru)果在C、D间试听有声，在E、D间试听无声，则是扬声器(qi)保(bao)护(hu)电(dian)路(lu)故障，应检查修理相应保(bao)护(hu)电(dian)路(lu)。

该机(ji)(ji)采(cai)用上述方(fang)法使(shi)用调压(ya)(ya)(ya)器(qi)(qi)第(di)一(yi)步通电(dian)(dian)试(shi)机(ji)(ji)时，发(fa)现中(zhong)点(dian)(dian)C、D间(jian)电(dian)(dian)压(ya)(ya)(ya)偏高，且(qie)推(tui)动管Q210、Q211发(fa)热冒烟。立即停机(ji)(ji)，对(dui)(dui)电(dian)(dian)路元(yuan)件反复进(jin)行检(jian)测、对(dui)(dui)比，均未(wei)(wei)发(fa)现损(sun)坏变(bian)质(zhi)元(yuan)件。后(hou)来对(dui)(dui)照原理图仔细核对(dui)(dui)电(dian)(dian)路，发(fa)现差(cha)分(fen)输入(ru)(ru)(ru)级(ji)(ji)Q202的(de)基极上偏流对(dui)(dui)地电(dian)(dian)阻R210未(wei)(wei)与(yu)(yu)(yu)地线直接(jie)(jie)(jie)相(xiang)接(jie)(jie)(jie)，而是通过插(cha)头座与(yu)(yu)(yu)调音(yin)台地线相(xiang)连，再与(yu)(yu)(yu)电(dian)(dian)源的(de)地端构成回路。而在通电(dian)(dian)试(shi)机(ji)(ji)时，为了方(fang)便，未(wei)(wei)与(yu)(yu)(yu)调音(yin)台相(xiang)连，致使(shi)差(cha)分(fen)放(fang)大(da)(da)级(ji)(ji)Q202失去(qu)偏置电(dian)(dian)压(ya)(ya)(ya)，差(cha)分(fen)放(fang)大(da)(da)器(qi)(qi)失去(qu)平衡，经(jing)直接(jie)(jie)(jie)耦合，造成输出(chu)端中(zhong)点(dian)(dian)(C、D间(jian))电(dian)(dian)压(ya)(ya)(ya)偏高，烧毁互补大(da)(da)功率对(dui)(dui)管Q212～Q219。直接(jie)(jie)(jie)将(jiang)R210接(jie)(jie)(jie)地线A与(yu)(yu)(yu)功放(fang)地线B相(xiang)连，并对(dui)(dui)可(ke)能假焊虚接(jie)(jie)(jie)的(de)与(yu)(yu)(yu)调音(yin)台相(xiang)连的(de)插(cha)座进(jin)行补焊后(hou)，再按照第(di)一(yi)步通电(dian)(dian)试(shi)机(ji)(ji)，中(zhong)点(dian)(dian)电(dian)(dian)压(ya)(ya)(ya)恢复0V，且(qie)调节(jie)输入(ru)(ru)(ru)端电(dian)(dian)压(ya)(ya)(ya)中(zhong)点(dian)(dian)电(dian)(dian)压(ya)(ya)(ya)稳定。接(jie)(jie)(jie)入(ru)(ru)(ru)16只功放(fang)管进(jin)行第(di)二步通电(dian)(dian)半小(xiao)时，无异常现象。最后(hou)，去(qu)掉假负(fu)载，在C、D和E、D间(jian)接(jie)(jie)(jie)入(ru)(ru)(ru)低档扬声器(qi)(qi)和调音(yin)台，输入(ru)(ru)(ru)CD信号试(shi)听(ting)几小(xiao)时，中(zhong)点(dian)(dian)电(dian)(dian)压(ya)(ya)(ya)不变(bian)，功放(fang)管无明显温升。一(yi)切正常。该机(ji)(ji)交用户(hu)使(shi)用已(yi)二年，未(wei)(wei)再出(chu)现类似故障。此(ci)次(ci)安全维修(xiu)，未(wei)(wei)损(sun)坏一(yi)只元(yuan)件。

实例2

马兰士(shi)PM－32功(gong)放，左路(lu)功(gong)放正常，右(you)路(lu)功(gong)放互补大(da)功(gong)率对管(guan)(guan)击穿，两个发射(she)极电(dian)阻烧断。该机主人(ren)(ren)，更换(huan)大(da)功(gong)率对管(guan)(guan)和电(dian)阻后通电(dian)试机，仅几分(fen)钟后，两个发射(she)极电(dian)阻烧红冒烟，总保险丝熔断。停机检(jian)查，新换(huan)上的大(da)功(gong)率对管(guan)(guan)再(zai)次击穿。该机主人(ren)(ren)无(wu)奈(nai)，将其送笔者(zhe)处(chu)检(jian)修(xiu)。

按照实例(li)1中介绍的安全检修法(fa)，首(shou)先(xian)绘制了末级功放电(dian)(dian)路(见图2)，弄清(qing)了电(dian)(dian)路连接和原(yuan)理。接着(zhe)用(yong)电(dian)(dian)阻测(ce)量(liang)法(fa)查找损坏(huai)元件(jian)，不但(dan)发现(xian)输出(chu)互补大功率(lv)对管(guan)Q762、Q764损坏(huai)，且发现(xian)与(yu)功率(lv)管(guan)相连的两只小(xiao)功率(lv)管(guan)Q702、Q704也(ye)同(tong)时损坏(huai)。全部损坏(huai)元器件(jian)由(you)同(tong)规格、型(xing)号(hao)新件(jian)更换后，用(yong)安全法(fa)通电(dian)(dian)试机。

由(you)于(yu)(yu)该机(ji)(ji)Q762、Q764采(cai)用(yong)达林顿复合互补大(da)(da)功(gong)率管(guan)(guan)(guan)(guan)，推动管(guan)(guan)(guan)(guan)与输(shu)出管(guan)(guan)(guan)(guan)复合在(zai)(zai)大(da)(da)功(gong)率管(guan)(guan)(guan)(guan)之中(zhong)(zhong)，无(wu)法(fa)采(cai)用(yong)第(di)一步通电(dian)(dian)(dian)(dian)法(fa)，故(gu)直接(jie)(jie)(jie)在(zai)(zai)图2中(zhong)(zhong)的(de)C、D之间接(jie)(jie)(jie)上(shang)假负(fu)载，用(yong)调压(ya)(ya)器降压(ya)(ya)后(hou)供电(dian)(dian)(dian)(dian)，C、D间中(zhong)(zhong)点(dian)电(dian)(dian)(dian)(dian)压(ya)(ya)接(jie)(jie)(jie)近(jin)0V。逐渐提高(gao)电(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)压(ya)(ya)，当电(dian)(dian)(dian)(dian)压(ya)(ya)升(sheng)(sheng)到100V时(shi)，发现两个发射极(ji)电(dian)(dian)(dian)(dian)阻(zu)开始冒(mao)烟(yan)(yan)、功(gong)放管(guan)(guan)(guan)(guan)明显升(sheng)(sheng)温。遂停机(ji)(ji)检(jian)查。中(zhong)(zhong)点(dian)电(dian)(dian)(dian)(dian)压(ya)(ya)基本(ben)正(zheng)常，说明上(shang)、下(xia)两臂的(de)电(dian)(dian)(dian)(dian)压(ya)(ya)和电(dian)(dian)(dian)(dian)流(liu)(liu)是(shi)相等(deng)且对(dui)称(cheng)的(de)；发射极(ji)电(dian)(dian)(dian)(dian)阻(zu)冒(mao)烟(yan)(yan)、功(gong)放管(guan)(guan)(guan)(guan)发热，说明流(liu)(liu)过功(gong)放管(guan)(guan)(guan)(guan)的(de)电(dian)(dian)(dian)(dian)流(liu)(liu)太大(da)(da)，造成(cheng)电(dian)(dian)(dian)(dian)流(liu)(liu)增(zeng)加(jia)，且上(shang)、下(xia)臂对(dui)称(cheng)增(zeng)加(jia)的(de)只能是(shi)上(shang)、下(xia)臂共用(yong)的(de)偏(pian)置电(dian)(dian)(dian)(dian)路。对(dui)该机(ji)(ji)偏(pian)流(liu)(liu)调整管(guan)(guan)(guan)(guan)Q754及其周围元(yuan)件(jian)(jian)进行在(zai)(zai)路测试(shi)，未发现元(yuan)件(jian)(jian)损坏(huai)变质。用(yong)放大(da)(da)镜观察线路板时(shi)，发现Q754基极(ji)焊点(dian)附(fu)近(jin)铜铂有(you)裂纹(wen)，经(jing)测量(liang)裂纹(wen)处不(bu)通。由(you)于(yu)(yu)该管(guan)(guan)(guan)(guan)基极(ji)开路，偏(pian)流(liu)(liu)调整管(guan)(guan)(guan)(guan)截(jie)止，等(deng)效为上(shang)、下(xia)臂输(shu)出管(guan)(guan)(guan)(guan)两基极(ji)间下(xia)偏(pian)流(liu)(liu)电(dian)(dian)(dian)(dian)阻(zu)增(zeng)大(da)(da)。造成(cheng)两管(guan)(guan)(guan)(guan)静(jing)态电(dian)(dian)(dian)(dian)流(liu)(liu)猛增(zeng)，将输(shu)出管(guan)(guan)(guan)(guan)烧毁(hui)。将裂纹(wen)连接(jie)(jie)(jie)后(hou)，再按安全通电(dian)(dian)(dian)(dian)试(shi)机(ji)(ji)法(fa)第(di)二(er)步通电(dian)(dian)(dian)(dian)试(shi)机(ji)(ji)，中(zhong)(zhong)点(dian)电(dian)(dian)(dian)(dian)压(ya)(ya)稳定，电(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)压(ya)(ya)升(sheng)(sheng)到额定值(zhi)也无(wu)大(da)(da)功(gong)率管(guan)(guan)(guan)(guan)温升(sheng)(sheng)和元(yuan)件(jian)(jian)冒(mao)烟(yan)(yan)现象。去(qu)掉假负(fu)载，接(jie)(jie)(jie)入低档扬声器试(shi)听，一切正(zheng)常。

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