一(yi)、開關電源(yuan)一(yi)直無電壓輸(shu)出(chu)的檢修技(ji)巧

開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)一直無(wu)電(dian)(dian)壓輸出是指開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)各輸出端，在按電(dian)(dian)源(yuan)(yuan)開關(guan)(guan)(guan)開機(ji)(ji)后(hou)一直為0V，這種狀況是因為開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)未(wei)發生震蕩所致。進一步證明的辦法是測開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)100UF/400V電(dian)(dian)容關(guan)(guan)(guan)機(ji)(ji)后(hou)的電(dian)(dian)壓，若(ruo)300V之后(hou)慢慢下(xia)降，則(ze)闡明開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)未(wei)發生振動(dong)(dong)。開關(guan)(guan)(guan)電(dian)(dian)源(yuan)(yuan)未(wei)發生振動(dong)(dong)的原因有(you)：

(1)開關管集電(dian)極未得到滿足的作業電(dian)壓

(2)開關(guan)管基極未得到發動電(dian)(dian)壓(ya)和相關(guan)電(dian)(dian)路漏電(dian)(dian)

(3)開關管正反饋元件失效

判別毛病的(de)辦法和(he)過程

檢修這類(lei)毛病的首要任務是判別毛病在上述三個(ge)部位中的哪個(ge)部位，具體辦法是測開(kai)關管集電極(ji)(ji)，基(ji)極(ji)(ji)電壓，可能(neng)有以(yi)下幾(ji)種狀(zhuang)況：

(1)開關(guan)管集(ji)電(dian)極電(dian)壓為0V和低于市電(dian)1.4倍，開關(guan)管沒有(you)(you)正常(chang)的(de)作(zuo)業(ye)電(dian)壓，如果有(you)(you)1.4倍的(de)電(dian)壓，闡(chan)明(ming)開關(guan)管集(ji)電(dian)極具(ju)有(you)(you)了(le)正常(chang)的(de)作(zuo)業(ye)電(dian)壓，闡(chan)明(ming)AC220V及整流(liu)濾波電(dian)路作(zuo)業(ye)正常(chang)。

(2)開(kai)關(guan)(guan)(guan)(guan)管的基(ji)極(ji)電(dian)(dian)(dian)壓(ya)為0V(包(bao)含(han)開(kai)機(ji)瞬(shun)間)這種狀(zhuang)況闡(chan)明發(fa)動(dong)電(dian)(dian)(dian)路對(dui)開(kai)關(guan)(guan)(guan)(guan)管基(ji)極(ji)未提(ti)供發(fa)動(dong)(導通)電(dian)(dian)(dian)壓(ya)，或(huo)基(ji)極(ji)與發(fa)射極(ji)之間相關(guan)(guan)(guan)(guan)元件(jian)擊(ji)穿(chuan)，應(ying)對(dui)發(fa)動(dong)電(dian)(dian)(dian)路和(he)開(kai)關(guan)(guan)(guan)(guan)管發(fa)射極(ji)及相關(guan)(guan)(guan)(guan)元件(jian)進行查看，若電(dian)(dian)(dian)壓(ya)為0.6~0.7(包(bao)含(han)開(kai)機(ji)瞬(shun)間)，闡(chan)明發(fa)動(dong)電(dian)(dian)(dian)路和(he)開(kai)關(guan)(guan)(guan)(guan)管發(fa)射極(ji)元件(jian)正(zheng)常(chang)，若在0.7V以上闡(chan)明發(fa)動(dong)電(dian)(dian)(dian)路正(zheng)常(chang)，但開(kai)關(guan)(guan)(guan)(guan)管發(fa)射極(ji)或(huo)其元件(jian)斷路或(huo)阻值(zhi)變大(da)。

(3)開關管具有導通條件：開關管基極(ji)電(dian)(dian)(dian)壓為0.6~0.7V，集電(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)壓大于(yu)250V，闡明開關管具有了(le)作(zuo)業(ye)條件，毛(mao)病在正反饋電(dian)(dian)(dian)路(lu)，包含正反饋電(dian)(dian)(dian)阻(zu)，電(dian)(dian)(dian)容(rong)，續(xu)流二極(ji)管及開關變壓器正反饋繞組及其之間的銜接(jie)應(ying)制板。

開關(guan)電(dian)(dian)源瞬間有電(dian)(dian)壓(ya)出檢修技巧

1）、瞬間(jian)電壓輸出毛病原因

這(zhe)種毛病在按下發動開(kai)關的(de)瞬間，開(kai)關電(dian)(dian)源某個(ge)(ge)或各個(ge)(ge)輸出端電(dian)(dian)壓(ya)有一(yi)個(ge)(ge)小的(de)電(dian)(dian)壓(ya)輸出，然后降(jiang)為0V，這(zhe)種狀況闡明開(kai)關電(dian)(dian)源在加電(dian)(dian)的(de)初始發生了振動，但(dan)后因為過壓(ya)，過流維護引起(qi)停(ting)振，或開(kai)關機接(jie)口(kou)電(dian)(dian)路(lu)加電(dian)(dian)初始為開(kai)機狀況，但(dan)隨CPU清(qing)零的(de)完畢而轉(zhuan)入待機狀況，引發這(zhe)種狀況的(de)原因有：

(1)開(kai)關(guan)電(dian)(dian)源因故輸出(chu)電(dian)(dian)壓比(bi)標準值(zhi)高(gao)10V而引(yin)起過壓維護

(2)負(fu)載過流引起維護動作

(3)維護電路自身的誤動作

(4)遙控系統因(yin)故執行待機指令

2）、判別毛(mao)病辦法與過(guo)程

（1）假負載法

（2）測量維護(hu)元件是否擊(ji)穿(chuan)

（3）斷開法

（4）降壓法

3）、各功用(yong)電路的(de)檢測辦法

經過上述(shu)辦(ban)法判別毛病在開關電源的哪個部(bu)分后，對各個部(bu)分的查看辦(ban)法如下(xia)：

（1）對脈寬(kuan)調制電(dian)(dian)(dian)路和正反(fan)饋電(dian)(dian)(dian)路的查(cha)看。對正反(fan)饋電(dian)(dian)(dian)路中(zhong)的電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容直接替換現(xian)在開關電(dian)(dian)(dian)源(yuan)的正反(fan)饋電(dian)(dian)(dian)路中(zhong)的振動(dong)電(dian)(dian)(dian)容有(you)兩種，一是0。016UF0。039UF膽電(dian)(dian)(dian)容，其毛病率(lv)很低(di)，檢修這種電(dian)(dian)(dian)容可以掃除，另(ling)一種是10UF左右的電(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)容，毛病率(lv)使(shi)用數年后有(you)可能，檢修時(shi)直接替換此電(dian)(dian)(dian)容。

（2）替換脈寬調制電(dian)路作業電(dian)壓形成中(zhong)的電(dian)解電(dian)容(rong)

在手中無溝(gou)通調壓(ya)器的(de)狀況(kuang)下(xia)，對于過壓(ya)維護毛病，為(wei)了安(an)全起見可先替換脈(mo)寬調制(zhi)電路作業電壓(ya)形成電路中的(de)易損(sun)件，即濾波電容（幾微法到(dao)100UF不等的(de)電解電容），看開關(guan)電源是否(fou)康復正常(chang)。

開關電源輸出(chu)電壓低檢修技巧

1、開關(guan)電(dian)源輸出電(dian)壓低的(de)原因

（1）220V溝(gou)通電(dian)(dian)(dian)壓輸入電(dian)(dian)(dian)路和整流(liu)濾波電(dian)(dian)(dian)路對(dui)開關管(guan)提供的作業電(dian)(dian)(dian)壓不夠，超出脈寬調制電(dian)(dian)(dian)路的控制范圍。

（2）負載電(dian)路存在過流引起開關電(dian)源負載加重而導致輸出電(dian)壓下降。

（3）開/關(guan)機接(jie)口電路處(chu)于待(dai)機狀況，令開關(guan)電源(yuan)作業于低頻振動狀況其(qi)輸(shu)出電壓(ya)為待(dai)機狀況下(xia)的(de)度數(shu)。此類毛病僅應于無準備(bei)(bei)電源(yuan)，CPU準備(bei)(bei)狀況下(xia)的(de)作業電壓(ya)由(you)開關(guan)電源(yuan)提供(gong)的(de)機型。