电(dian)容(rong)损坏引发的毛病(bing)在电(dian)子设备(bei)中(zhong)是最高(gao)的，其(qi)间(jian)特别(bie)以电(dian)解电(dian)容(rong)的损坏最为常见。电(dian)容(rong)损坏体(ti)现为：容(rong)量(liang)变(bian)小;彻(che)底失(shi)去容(rong)量(liang);漏电(dian);短(duan)路。

电容
毛病特色及(ji)修理

电(dian)(dian)容(rong)损(sun)坏(huai)引发的毛病(bing)在电(dian)(dian)子(zi)设备中是最高的，其间(jian)特别(bie)以电(dian)(dian)解电(dian)(dian)容(rong)的损(sun)坏(huai)最为常见。电(dian)(dian)容(rong)损(sun)坏(huai)体现(xian)为：容(rong)量变小(xiao);彻底失去(qu)容(rong)量;漏电(dian)(dian);短路。

电(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中所(suo)起的(de)(de)作用(yong)不(bu)同，引起的(de)(de)毛病也各有特色。在(zai)工控电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)板中，数字电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)占绝大多数，电(dian)(dian)(dian)(dian)(dian)容(rong)多用(yong)做电(dian)(dian)(dian)(dian)(dian)源(yuan)滤(lv)波(bo)，用(yong)做信号(hao)耦合和振荡电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)电(dian)(dian)(dian)(dian)(dian)容(rong)较少。用(yong)在(zai)开(kai)(kai)关电(dian)(dian)(dian)(dian)(dian)源(yuan)中的(de)(de)电(dian)(dian)(dian)(dian)(dian)解电(dian)(dian)(dian)(dian)(dian)容(rong)假如(ru)损坏(huai)，则开(kai)(kai)关电(dian)(dian)(dian)(dian)(dian)源(yuan)或(huo)许(xu)不(bu)起振，没有电(dian)(dian)(dian)(dian)(dian)压(ya)输(shu)出(chu);或(huo)者输(shu)出(chu)电(dian)(dian)(dian)(dian)(dian)压(ya)滤(lv)波(bo)欠(qian)好(hao)，电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)因(yin)电(dian)(dian)(dian)(dian)(dian)压(ya)不(bu)稳而发生逻辑(ji)混乱(luan)，体现为机(ji)器(qi)作业(ye)时(shi)(shi)好(hao)时(shi)(shi)坏(huai)或(huo)开(kai)(kai)不(bu)了机(ji)，假如(ru)电(dian)(dian)(dian)(dian)(dian)容(rong)并(bing)在(zai)数字电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)电(dian)(dian)(dian)(dian)(dian)源(yuan)正负极之间(jian)，毛病体现同上。

这(zhei)在(zai)电(dian)(dian)脑(nao)主板上(shang)体现特别显着，许多(duo)电(dian)(dian)脑(nao)用(yong)了几年就呈现有时(shi)(shi)开不(bu)了机，有时(shi)(shi)又能(neng)够(gou)开机的现象，打开机箱，往往能(neng)够(gou)看(kan)见有电(dian)(dian)解电(dian)(dian)容(rong)(rong)鼓包的现象，假如将电(dian)(dian)容(rong)(rong)拆下(xia)来量(liang)一(yi)下(xia)容(rong)(rong)量(liang)，发现比实(shi)践(jian)值要(yao)低许多(duo)。

电(dian)(dian)容(rong)的(de)寿数(shu)与环境(jing)温度直接有关，环境(jing)温度越(yue)高，电(dian)(dian)容(rong)寿数(shu)越(yue)短。这个(ge)规则不但适用电(dian)(dian)解电(dian)(dian)容(rong)，也适用其它电(dian)(dian)容(rong)。所以在寻找毛病(bing)电(dian)(dian)容(rong)时(shi)应要点(dian)检(jian)查(cha)和热源靠(kao)得比较(jiao)近(jin)的(de)电(dian)(dian)容(rong)，如(ru)散热片旁及大功(gong)率元器(qi)材旁的(de)电(dian)(dian)容(rong)，离其越(yue)近(jin)，损(sun)坏的(de)或许性就越(yue)大。

曾经修(xiu)过一(yi)台X光探伤仪的(de)(de)电(dian)(dian)(dian)源，用户反映有(you)烟从电(dian)(dian)(dian)源里冒出(chu)来(lai)(lai)，拆开(kai)机(ji)箱后发(fa)现有(you)一(yi)只(zhi)1000uF/350V的(de)(de)大(da)电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)有(you)油质一(yi)样的(de)(de)东(dong)西流出(chu)来(lai)(lai)，拆下来(lai)(lai)一(yi)量(liang)容(rong)(rong)(rong)(rong)量(liang)只(zhi)要(yao)几(ji)十uF，还发(fa)现只(zhi)要(yao)这(zhei)只(zhi)电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)与整流桥的(de)(de)散热片离得(de)(de)最近(jin)，其(qi)它离得(de)(de)远(yuan)的(de)(de)就完好无缺，容(rong)(rong)(rong)(rong)量(liang)正常。别的(de)(de)有(you)瓷片电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)呈现短路的(de)(de)状况，也发(fa)现电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)离发(fa)热部件(jian)比较(jiao)(jiao)近(jin)。所以在(zai)检修(xiu)查找时应(ying)有(you)所侧重(zhong)。有(you)些电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)漏(lou)电(dian)(dian)(dian)比较(jiao)(jiao)严重(zhong)，用手指(zhi)触摸时甚至会烫手，这(zhei)种(zhong)电(dian)(dian)(dian)容(rong)(rong)(rong)(rong)有(you)必要(yao)替(ti)换。

在(zai)检修时(shi)好时(shi)坏的毛病时(shi)，排(pai)除(chu)了(le)接触不良的或许性以外，一般(ban)大部分便是电容损坏引起的毛病了(le)。所(suo)以在(zai)碰到此类(lei)毛病时(shi)，能够将(jiang)电容要点(dian)检查一下(xia)，换掉电容后(hou)往往令人惊喜。



电(dian)阻
损坏的特色与(yu)判别

常(chang)看见许多(duo)初学者在检修电路(lu)时在电阻上折腾，又是拆又是焊的，其(qi)实(shi)修得(de)多(duo)了，你只要了解了电阻的损坏特色，就不用大费(fei)周章。

电(dian)(dian)阻(zu)(zu)(zu)(zu)是电(dian)(dian)器设备中数量最多的元件，但不(bu)是损坏率最高(gao)的元件。电(dian)(dian)阻(zu)(zu)(zu)(zu)损坏以开路最常见(jian)(jian)，阻(zu)(zu)(zu)(zu)值变大较(jiao)罕(han)(han)见(jian)(jian)，阻(zu)(zu)(zu)(zu)值变小十(shi)分罕(han)(han)见(jian)(jian)。常见(jian)(jian)的有碳(tan)膜(mo)电(dian)(dian)阻(zu)(zu)(zu)(zu)、金属膜(mo)电(dian)(dian)阻(zu)(zu)(zu)(zu)、线绕电(dian)(dian)阻(zu)(zu)(zu)(zu)和保险电(dian)(dian)阻(zu)(zu)(zu)(zu)几种。

前两种电阻(zu)(zu)应用(yong)最广，其损坏(huai)的特色一(yi)是(shi)低(di)阻(zu)(zu)值(100Ω以下)和高(gao)(gao)阻(zu)(zu)值(100kΩ以上)的损坏(huai)率较(jiao)高(gao)(gao)，中心阻(zu)(zu)值(如几百欧到(dao)几十千欧)的很(hen)(hen)少损坏(huai);二是(shi)低(di)阻(zu)(zu)值电阻(zu)(zu)损坏(huai)时往往是(shi)烧焦(jiao)发(fa)黑，很(hen)(hen)简略发(fa)现，而高(gao)(gao)阻(zu)(zu)值电阻(zu)(zu)损坏(huai)时很(hen)(hen)少有(you)痕迹。

线绕电(dian)(dian)阻(zu)(zu)一(yi)(yi)般(ban)用作大电(dian)(dian)流(liu)限流(liu)，阻(zu)(zu)值(zhi)不(bu)大。圆柱形线绕电(dian)(dian)阻(zu)(zu)烧(shao)坏(huai)(huai)时有(you)(you)的会发(fa)黑(hei)或(huo)(huo)外表(biao)爆皮、裂纹(wen)，有(you)(you)的没(mei)(mei)(mei)有(you)(you)痕(hen)迹(ji)。水泥电(dian)(dian)阻(zu)(zu)是线绕电(dian)(dian)阻(zu)(zu)的一(yi)(yi)种，烧(shao)坏(huai)(huai)时或(huo)(huo)许会开裂，不(bu)然也没(mei)(mei)(mei)有(you)(you)可见痕(hen)迹(ji)。保(bao)险电(dian)(dian)阻(zu)(zu)烧(shao)坏(huai)(huai)时有(you)(you)的外表(biao)会炸掉一(yi)(yi)块(kuai)皮，有(you)(you)的也没(mei)(mei)(mei)有(you)(you)什么痕(hen)迹(ji)，但绝不(bu)会烧(shao)焦(jiao)发(fa)黑(hei)。依(yi)据以(yi)上特色，在(zai)检查电(dian)(dian)阻(zu)(zu)时可有(you)(you)所侧(ce)重，快速找出损坏(huai)(huai)的电(dian)(dian)阻(zu)(zu)。

依(yi)据以上列出的(de)特色，我们先(xian)能够(gou)(gou)观(guan)察(cha)一(yi)(yi)(yi)下电(dian)(dian)(dian)路(lu)板上低(di)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)有没有烧黑的(de)痕迹，再依(yi)据电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)损(sun)坏时绝(jue)大(da)多数开路(lu)或(huo)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)变大(da)以及高阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)简(jian)略损(sun)坏的(de)特色，我们就能够(gou)(gou)用万用表在电(dian)(dian)(dian)路(lu)板上先(xian)直(zhi)接量(liang)高阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)的(de)电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)两头的(de)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)，假(jia)如量(liang)得(de)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)比标(biao)称阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)大(da)，则(ze)这(zhei)个电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)肯定损(sun)坏(要注意等(deng)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)显现稳定后才下结论，因为电(dian)(dian)(dian)路(lu)中(zhong)有或(huo)许并联(lian)电(dian)(dian)(dian)容元件，有一(yi)(yi)(yi)个充放电(dian)(dian)(dian)进程)，假(jia)如量(liang)得(de)阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)比标(biao)称阻(zu)(zu)(zu)(zu)值(zhi)(zhi)(zhi)(zhi)小(xiao)，则(ze)一(yi)(yi)(yi)般不用理会它。这(zhei)样在电(dian)(dian)(dian)路(lu)板上每一(yi)(yi)(yi)个电(dian)(dian)(dian)阻(zu)(zu)(zu)(zu)都(dou)量(liang)一(yi)(yi)(yi)遍(bian)，即便(bian)“错杀”一(yi)(yi)(yi)千，也不会放过一(yi)(yi)(yi)个了。

运(yun)算扩大器
好坏判别

运算(suan)扩(kuo)大器好坏的(de)判别对相当多(duo)的(de)电子修理者有(you)必定的(de)难度，不(bu)只文化程度的(de)联系，在此与我们一起讨论一下(xia)，期望对我们有(you)所帮助。

抱负运(yun)算扩(kuo)大器具有(you)(you)“虚短(duan)”和“虚断”的特性，这(zhei)两(liang)个特性对(dui)分(fen)析线(xian)性运(yun)用的运(yun)放(fang)电路十分(fen)有(you)(you)用。为了保证(zheng)线(xian)性运(yun)用，运(yun)放(fang)有(you)(you)必要(yao)在(zai)闭环(负反馈(kui))下(xia)作业。假(jia)如(ru)没(mei)有(you)(you)负反馈(kui)，开环扩(kuo)大下(xia)的运(yun)放(fang)成为一个比较(jiao)器。假(jia)如(ru)要(yao)判(pan)别(bie)器材(cai)的好(hao)坏，先应分(fen)清(qing)楚(chu)器材(cai)在(zai)电路中是做(zuo)扩(kuo)大器用仍是做(zuo)比较(jiao)器用。

依(yi)据扩(kuo)大(da)器(qi)虚短的(de)原(yuan)理(li)，便(bian)是说假如这个运(yun)算扩(kuo)大(da)器(qi)作业(ye)正常(chang)的(de)话，其(qi)同(tong)向(xiang)输(shu)入(ru)端和反向(xiang)输(shu)入(ru)端电(dian)(dian)压(ya)(ya)必定相等，即便(bian)有差别(bie)也(ye)是mv级的(de)，当(dang)然在某些高输(shu)入(ru)阻(zu)抗(kang)电(dian)(dian)路中(zhong)，万(wan)用表(biao)的(de)内阻(zu)会对电(dian)(dian)压(ya)(ya)测验有点影响，但一般也(ye)不(bu)会超过0.2V，假如有0.5V以上的(de)差别(bie)，则扩(kuo)大(da)器(qi)必坏无疑!(我是用的(de)FLUKE179万(wan)用表(biao))

假(jia)(jia)如器(qi)(qi)材(cai)是做比较(jiao)器(qi)(qi)用(yong)(yong)，则答应(ying)同向(xiang)输(shu)入(ru)端(duan)和反(fan)向(xiang)输(shu)入(ru)端(duan)不等。同向(xiang)电(dian)压(ya)>反(fan)向(xiang)电(dian)压(ya)，则输(shu)出(chu)电(dian)压(ya)接(jie)近正的(de)最大值;同向(xiang)电(dian)压(ya)<反(fan)向(xiang)电(dian)压(ya)，则输(shu)出(chu)电(dian)压(ya)接(jie)近0V或负的(de)最大值(视(shi)乎双电(dian)源或单电(dian)源)。假(jia)(jia)如检(jian)测(ce)到(dao)电(dian)压(ya)不契合(he)这(zhei)个规则，则器(qi)(qi)材(cai)必(bi)坏无(wu)疑！这(zhei)样你(ni)不用(yong)(yong)运用(yong)(yong)代换法，不用(yong)(yong)拆下电(dian)路(lu)板上(shang)的(de)芯片就能够判别运算扩大器(qi)(qi)的(de)好坏了。

SMT元件
测验(yan)小窍门

有些贴片元(yuan)件十分细微，用(yong)普(pu)通万用(yong)表表笔(bi)测(ce)验检修时(shi)很(hen)不(bu)便利，一是(shi)简(jian)略(lve)造成短路(lu)，二是(shi)对涂有绝(jue)缘涂层的电(dian)路(lu)板不(bu)便接触(chu)到元(yuan)件管脚的金属部(bu)分。这里告知我们一个简(jian)便办法，会给检测(ce)带来不(bu)少便利。

取(qu)两(liang)枚最小号的缝衣(yi)针(zhen)(zhen)(zhen)，将(jiang)之与万用(yong)(yong)表笔(bi)靠(kao)紧，然后取(qu)一根多(duo)股电缆里的细(xi)铜线，用(yong)(yong)细(xi)铜线将(jiang)表笔(bi)和缝衣(yi)针(zhen)(zhen)(zhen)绑(bang)在一起(qi)，再(zai)用(yong)(yong)焊(han)锡焊(han)牢。这样用(yong)(yong)带有细(xi)微针(zhen)(zhen)(zhen)尖(jian)的表笔(bi)去测那(nei)些(xie)SMT元件(jian)的时(shi)分就再(zai)无短路之虞(yu)，并且针(zhen)(zhen)(zhen)尖(jian)能够(gou)刺破绝缘涂层，直捣关键部位，再(zai)也不用(yong)(yong)费心去刮那(nei)些(xie)膜(mo)膜(mo)了(le)。

公共电源
短路检修(xiu)
电路(lu)板修理(li)中，假(jia)如碰(peng)到公共(gong)电源短(duan)路(lu)的毛病(bing)往往头(tou)大，因(yin)为许多(duo)器(qi)材都(dou)共(gong)用(yong)同一电源，每一个用(yong)此(ci)电源的器(qi)材都(dou)有短(duan)路(lu)的嫌疑，假(jia)如板上元件不(bu)多(duo)，选用(yong)“锄(chu)大地”的方法终归能(neng)够找(zhao)到短(duan)路(lu)点，假(jia)如元件太多(duo)，“锄(chu)大地”能(neng)不(bu)能(neng)锄(chu)到状(zhuang)况(kuang)就(jiu)要靠运气了。在此(ci)引荐一比较(jiao)管用(yong)的办法，选用(yong)此(ci)法，事(shi)半功倍，往往能(neng)很快找(zhao)到毛病(bing)点。

要有一(yi)个电(dian)(dian)(dian)(dian)(dian)压(ya)电(dian)(dian)(dian)(dian)(dian)流皆可调(diao)的电(dian)(dian)(dian)(dian)(dian)源(yuan)，电(dian)(dian)(dian)(dian)(dian)压(ya)0-30V，电(dian)(dian)(dian)(dian)(dian)流0-3A，此(ci)电(dian)(dian)(dian)(dian)(dian)源(yuan)不(bu)贵(gui)，300元左右(you)。将开路电(dian)(dian)(dian)(dian)(dian)压(ya)调(diao)到器(qi)(qi)(qi)材电(dian)(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)(dian)压(ya)水平，先将电(dian)(dian)(dian)(dian)(dian)流调(diao)至最小，将此(ci)电(dian)(dian)(dian)(dian)(dian)压(ya)加在电(dian)(dian)(dian)(dian)(dian)路的电(dian)(dian)(dian)(dian)(dian)源(yuan)电(dian)(dian)(dian)(dian)(dian)压(ya)点如74系列芯片的5V和(he)0V端，视乎短路程(cheng)度，渐渐将电(dian)(dian)(dian)(dian)(dian)流增大(da)，用手摸器(qi)(qi)(qi)材，当(dang)摸到某个器(qi)(qi)(qi)材发热显着，这个往往便是损坏(huai)的元件，可将之取下(xia)进一(yi)步丈(zhang)量确(que)认。当(dang)然操作(zuo)时电(dian)(dian)(dian)(dian)(dian)压(ya)必定不(bu)能超过器(qi)(qi)(qi)材的作(zuo)业电(dian)(dian)(dian)(dian)(dian)压(ya)，并且(qie)不(bu)能接反(fan)，不(bu)然会(hui)烧坏(huai)其它好的器(qi)(qi)(qi)材。

橡皮
处理大问(wen)题
工(gong)业(ye)(ye)控制用到的板(ban)(ban)卡(ka)(ka)越(yue)来越(yue)多(duo)(duo)，许(xu)多(duo)(duo)板(ban)(ban)卡(ka)(ka)选用金手(shou)指(zhi)(zhi)刺进(jin)插槽的方(fang)法(fa).因为工(gong)业(ye)(ye)现场环境恶劣，多(duo)(duo)尘、湿润(run)、多(duo)(duo)腐蚀气(qi)体(ti)的环境易使板(ban)(ban)卡(ka)(ka)产生接触不(bu)良(liang)毛病，许(xu)多(duo)(duo)朋(peng)友或许(xu)通过(guo)替换板(ban)(ban)卡(ka)(ka)的方(fang)法(fa)处理(li)了(le)(le)问题，但购买板(ban)(ban)卡(ka)(ka)的费(fei)用十分可观(guan)，特别某(mou)些进(jin)口设备的板(ban)(ban)卡(ka)(ka)。其实我们无妨运用橡(xiang)皮擦在(zai)金手(shou)指(zhi)(zhi)上(shang)(shang)重(zhong)复擦几下(xia)，将金手(shou)指(zhi)(zhi)上(shang)(shang)的污(wu)物清理(li)洁(jie)净后，再试机，没(mei)准就处理(li)了(le)(le)问题!办(ban)法(fa)简略(lve)又实用。

电气(qi)
毛病分析
各种(zhong)时(shi)好时(shi)坏电气毛病从概率大(da)小来(lai)讲大(da)约(yue)包(bao)括以下几(ji)种(zhong)状(zhuang)况(kuang)：

接触不良
板卡(ka)与插槽接触不良、缆线(xian)(xian)内部折(zhe)断时通时不通、线(xian)(xian)插头及接线(xian)(xian)端子接触欠(qian)好、元器材(cai)虚(xu)焊等皆属此类;

信号受搅扰
对数字电路而言，在特(te)定的状(zhuang)况条件下，毛病才会呈现，有或许确实是搅扰(rao)太(tai)大影响了(le)控(kong)制系统使其出错(cuo)，也有电路板个别元(yuan)件参数或整体体现参数呈现了(le)改变，使抗搅扰(rao)能力趋向(xiang)临界点，然后呈现毛病;

元器材热稳定(ding)性(xing)欠好
从很多的(de)修理(li)实践来看(kan)，其间首推电解电容(rong)的(de)热稳定性欠好(hao)，其次(ci)是(shi)其它电容(rong)、三(san)极(ji)管、二极(ji)管、IC、电阻等;

电(dian)路(lu)板上有(you)湿气、尘土等(deng)
湿(shi)气和(he)积尘(chen)会(hui)(hui)导电，具有(you)电阻(zu)效应，并且在(zai)热(re)胀冷缩的进程(cheng)中阻(zu)值还会(hui)(hui)改变(bian)，这(zhei)个电阻(zu)值会(hui)(hui)同其(qi)它元件有(you)并联作用，这(zhei)个作用比较强时就会(hui)(hui)改变(bian)电路(lu)参数，使毛病发生;

软件也是考虑要素之(zhi)一
电路中许多参数(shu)运用软(ruan)件来调整(zheng)，某些参数(shu)的裕量调得(de)太(tai)低，处于(yu)临界规模，当机器运行(xing)工况契合软(ruan)件断定毛(mao)病的理由时，那(nei)么报警就会(hui)呈现。
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