一、開關電源一直無電壓(ya)輸出的檢修技巧(qiao)

開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)一(yi)直無電(dian)(dian)(dian)(dian)(dian)壓輸出(chu)是指開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)各輸出(chu)端，在(zai)按電(dian)(dian)(dian)(dian)(dian)源(yuan)開(kai)(kai)(kai)關(guan)(guan)(guan)開(kai)(kai)(kai)機(ji)后(hou)一(yi)直為0V，這種(zhong)狀況是因為開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)未(wei)發生震蕩所致(zhi)。進(jin)一(yi)步證明的(de)辦法是測開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)100UF/400V電(dian)(dian)(dian)(dian)(dian)容關(guan)(guan)(guan)機(ji)后(hou)的(de)電(dian)(dian)(dian)(dian)(dian)壓，若(ruo)300V之(zhi)后(hou)慢(man)慢(man)下降，則闡明開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)未(wei)發生振動。開(kai)(kai)(kai)關(guan)(guan)(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)未(wei)發生振動的(de)原(yuan)因有：

(1)開關管集電(dian)極未得到滿足(zu)的(de)作(zuo)業電(dian)壓

(2)開關管基(ji)極未得到發動電壓和相關電路漏電

(3)開關管正反饋元件失效

判別毛(mao)病的辦(ban)法和過(guo)程(cheng)

檢(jian)修這(zhe)類毛病(bing)的(de)(de)首要任務是判別(bie)毛病(bing)在(zai)上述三個部(bu)位(wei)中的(de)(de)哪個部(bu)位(wei)，具體(ti)辦法是測(ce)開關管集(ji)電(dian)極，基(ji)極電(dian)壓，可能(neng)有以下幾(ji)種狀況：

(1)開(kai)(kai)關管(guan)集(ji)電(dian)(dian)極電(dian)(dian)壓(ya)為0V和(he)低于市(shi)電(dian)(dian)1.4倍，開(kai)(kai)關管(guan)沒有正常的作(zuo)業電(dian)(dian)壓(ya)，如果有1.4倍的電(dian)(dian)壓(ya)，闡(chan)明開(kai)(kai)關管(guan)集(ji)電(dian)(dian)極具有了正常的作(zuo)業電(dian)(dian)壓(ya)，闡(chan)明AC220V及(ji)整(zheng)流(liu)濾波電(dian)(dian)路作(zuo)業正常。

(2)開(kai)關(guan)(guan)管的基極電壓為0V(包(bao)含(han)開(kai)機(ji)瞬(shun)間)這種(zhong)狀況(kuang)闡(chan)明(ming)發(fa)(fa)(fa)動電路(lu)(lu)對(dui)(dui)開(kai)關(guan)(guan)管基極未提供發(fa)(fa)(fa)動(導通(tong))電壓，或(huo)(huo)(huo)基極與發(fa)(fa)(fa)射(she)極之(zhi)間相關(guan)(guan)元件擊穿，應對(dui)(dui)發(fa)(fa)(fa)動電路(lu)(lu)和開(kai)關(guan)(guan)管發(fa)(fa)(fa)射(she)極及相關(guan)(guan)元件進行查(cha)看，若電壓為0.6~0.7(包(bao)含(han)開(kai)機(ji)瞬(shun)間)，闡(chan)明(ming)發(fa)(fa)(fa)動電路(lu)(lu)和開(kai)關(guan)(guan)管發(fa)(fa)(fa)射(she)極元件正常，若在0.7V以上闡(chan)明(ming)發(fa)(fa)(fa)動電路(lu)(lu)正常，但開(kai)關(guan)(guan)管發(fa)(fa)(fa)射(she)極或(huo)(huo)(huo)其(qi)元件斷路(lu)(lu)或(huo)(huo)(huo)阻值(zhi)變(bian)大。

(3)開關管(guan)具有導通條件(jian)：開關管(guan)基極(ji)電(dian)(dian)壓(ya)為0.6~0.7V，集電(dian)(dian)極(ji)電(dian)(dian)壓(ya)大(da)于250V，闡明(ming)開關管(guan)具有了作業條件(jian)，毛病在正反饋(kui)電(dian)(dian)路，包含(han)正反饋(kui)電(dian)(dian)阻(zu)，電(dian)(dian)容，續(xu)流二極(ji)管(guan)及開關變壓(ya)器正反饋(kui)繞組及其之間(jian)的銜接(jie)應制板。

開關電(dian)源瞬(shun)間有電(dian)壓(ya)出檢修技巧

1）、瞬間(jian)電壓輸出毛病原因

這種毛病在按(an)下發(fa)動(dong)開(kai)關的(de)瞬間(jian)，開(kai)關電(dian)源某個或各個輸出端電(dian)壓(ya)有一個小的(de)電(dian)壓(ya)輸出，然(ran)后(hou)降(jiang)為(wei)0V，這種狀(zhuang)(zhuang)況(kuang)闡明開(kai)關電(dian)源在加電(dian)的(de)初(chu)始(shi)(shi)發(fa)生(sheng)了振動(dong)，但后(hou)因為(wei)過壓(ya)，過流維護(hu)引起停振，或開(kai)關機(ji)接口電(dian)路加電(dian)初(chu)始(shi)(shi)為(wei)開(kai)機(ji)狀(zhuang)(zhuang)況(kuang)，但隨CPU清零的(de)完畢(bi)而轉入待(dai)機(ji)狀(zhuang)(zhuang)況(kuang)，引發(fa)這種狀(zhuang)(zhuang)況(kuang)的(de)原因有：

(1)開關電源因故輸出電壓(ya)比標準值高10V而(er)引起過壓(ya)維(wei)護

(2)負載過流引起維護動作(zuo)

(3)維護(hu)電路自身的誤動作

(4)遙(yao)控(kong)系統因故(gu)執行待機指令

2）、判別毛病辦法(fa)與過(guo)程

（1）假負載法

（2）測(ce)量維(wei)護元件是否擊穿(chuan)

（3）斷開法

（4）降壓法

3）、各(ge)功用電路(lu)的檢測辦(ban)法

經過上述辦法判別毛(mao)病在開關電源的哪個部分后，對(dui)各(ge)個部分的查看辦法如(ru)下：

（1）對脈寬調制電(dian)(dian)(dian)(dian)路和正(zheng)反(fan)饋(kui)電(dian)(dian)(dian)(dian)路的(de)查看。對正(zheng)反(fan)饋(kui)電(dian)(dian)(dian)(dian)路中(zhong)的(de)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)直接替換(huan)現在(zai)開關電(dian)(dian)(dian)(dian)源的(de)正(zheng)反(fan)饋(kui)電(dian)(dian)(dian)(dian)路中(zhong)的(de)振動電(dian)(dian)(dian)(dian)容(rong)有兩種(zhong)，一(yi)是0。016UF0。039UF膽(dan)電(dian)(dian)(dian)(dian)容(rong)，其毛病(bing)率很低，檢修這種(zhong)電(dian)(dian)(dian)(dian)容(rong)可以掃除，另一(yi)種(zhong)是10UF左右的(de)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)，毛病(bing)率使(shi)用數年后有可能，檢修時(shi)直接替換(huan)此電(dian)(dian)(dian)(dian)容(rong)。

（2）替(ti)換脈(mo)寬調制電(dian)路作(zuo)業電(dian)壓形成中的電(dian)解電(dian)容

在(zai)手中無溝通調壓(ya)器的(de)狀況下(xia)，對于過壓(ya)維護毛(mao)病，為了安全(quan)起(qi)見可先(xian)替換(huan)脈寬調制(zhi)電(dian)(dian)路作業電(dian)(dian)壓(ya)形成電(dian)(dian)路中的(de)易損件，即(ji)濾波電(dian)(dian)容(rong)（幾微(wei)法到100UF不等的(de)電(dian)(dian)解(jie)電(dian)(dian)容(rong)），看開關(guan)電(dian)(dian)源(yuan)是(shi)否康復(fu)正常(chang)。

開關電源輸出電壓低檢修技巧

1、開關電源輸出電壓低的原因

（1）220V溝(gou)通電壓輸入(ru)電路和(he)整流濾波(bo)電路對開(kai)關管提(ti)供的作業電壓不夠，超出脈寬調制電路的控(kong)制范圍。

（2）負載電路存在過流引起開關電源(yuan)負載加(jia)重而導致(zhi)輸出電壓下降。

（3）開(kai)/關(guan)(guan)機(ji)接口電(dian)(dian)路(lu)處于待機(ji)狀(zhuang)況，令開(kai)關(guan)(guan)電(dian)(dian)源作業(ye)于低頻振動狀(zhuang)況其輸(shu)出電(dian)(dian)壓為待機(ji)狀(zhuang)況下的(de)度數。此類毛病僅應于無準備電(dian)(dian)源，CPU準備狀(zhuang)況下的(de)作業(ye)電(dian)(dian)壓由(you)開(kai)關(guan)(guan)電(dian)(dian)源提供的(de)機(ji)型。