一、開關電(dian)源一直無電(dian)壓(ya)輸出的檢(jian)修技巧

開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)一直(zhi)無電(dian)(dian)(dian)壓輸(shu)出是(shi)(shi)指開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)各輸(shu)出端，在(zai)按電(dian)(dian)(dian)源(yuan)(yuan)開(kai)(kai)(kai)關(guan)(guan)開(kai)(kai)(kai)機(ji)后一直(zhi)為0V，這種狀況是(shi)(shi)因為開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)未(wei)發(fa)生震蕩所致。進一步證明的辦法是(shi)(shi)測開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)100UF/400V電(dian)(dian)(dian)容關(guan)(guan)機(ji)后的電(dian)(dian)(dian)壓，若300V之后慢慢下降(jiang)，則闡明開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)未(wei)發(fa)生振動(dong)。開(kai)(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)源(yuan)(yuan)未(wei)發(fa)生振動(dong)的原因有(you)：

(1)開關管(guan)集電極未(wei)得(de)到滿足(zu)的作業電壓

(2)開(kai)關(guan)管基極未得到發動(dong)電壓和相關(guan)電路漏電

(3)開(kai)關管正(zheng)反饋元件失(shi)效(xiao)

判別毛病(bing)的辦法(fa)和過程

檢修(xiu)這類毛病的(de)首(shou)要任務(wu)是(shi)判別毛病在上(shang)述三個部位中(zhong)的(de)哪個部位，具體辦(ban)法是(shi)測開關管集電(dian)極，基(ji)極電(dian)壓(ya)，可能有以下(xia)幾(ji)種(zhong)狀況：

(1)開(kai)關(guan)管(guan)(guan)集電(dian)(dian)極電(dian)(dian)壓(ya)為0V和低于(yu)市電(dian)(dian)1.4倍，開(kai)關(guan)管(guan)(guan)沒有正(zheng)常(chang)的作(zuo)業(ye)電(dian)(dian)壓(ya)，如(ru)果有1.4倍的電(dian)(dian)壓(ya)，闡(chan)明(ming)開(kai)關(guan)管(guan)(guan)集電(dian)(dian)極具有了(le)正(zheng)常(chang)的作(zuo)業(ye)電(dian)(dian)壓(ya)，闡(chan)明(ming)AC220V及整流濾波電(dian)(dian)路作(zuo)業(ye)正(zheng)常(chang)。

(2)開(kai)(kai)關管(guan)的(de)基極(ji)(ji)電(dian)壓(ya)(ya)為(wei)0V(包含(han)開(kai)(kai)機瞬(shun)間(jian))這種狀況闡明發(fa)動(dong)(dong)電(dian)路(lu)(lu)對(dui)開(kai)(kai)關管(guan)基極(ji)(ji)未提供(gong)發(fa)動(dong)(dong)(導通)電(dian)壓(ya)(ya)，或(huo)基極(ji)(ji)與(yu)發(fa)射(she)(she)極(ji)(ji)之間(jian)相(xiang)關元件擊(ji)穿，應(ying)對(dui)發(fa)動(dong)(dong)電(dian)路(lu)(lu)和(he)開(kai)(kai)關管(guan)發(fa)射(she)(she)極(ji)(ji)及相(xiang)關元件進(jin)行查(cha)看(kan)，若(ruo)電(dian)壓(ya)(ya)為(wei)0.6~0.7(包含(han)開(kai)(kai)機瞬(shun)間(jian))，闡明發(fa)動(dong)(dong)電(dian)路(lu)(lu)和(he)開(kai)(kai)關管(guan)發(fa)射(she)(she)極(ji)(ji)元件正常，若(ruo)在0.7V以(yi)上闡明發(fa)動(dong)(dong)電(dian)路(lu)(lu)正常，但(dan)開(kai)(kai)關管(guan)發(fa)射(she)(she)極(ji)(ji)或(huo)其元件斷路(lu)(lu)或(huo)阻值變大。

(3)開關(guan)管(guan)具(ju)有導通(tong)條件(jian)：開關(guan)管(guan)基極電(dian)(dian)壓為0.6~0.7V，集電(dian)(dian)極電(dian)(dian)壓大于250V，闡明開關(guan)管(guan)具(ju)有了作業條件(jian)，毛(mao)病(bing)在正反(fan)(fan)饋電(dian)(dian)路，包含正反(fan)(fan)饋電(dian)(dian)阻(zu)，電(dian)(dian)容，續流二極管(guan)及開關(guan)變壓器正反(fan)(fan)饋繞組及其之間(jian)的銜接(jie)應制板。

開關電源瞬間有電壓出檢修技巧

1）、瞬間電壓輸出毛病原(yuan)因

這種(zhong)(zhong)毛病(bing)在按(an)下發(fa)(fa)動(dong)開(kai)關的(de)瞬間，開(kai)關電(dian)(dian)源某個(ge)或(huo)各個(ge)輸(shu)出(chu)(chu)端(duan)電(dian)(dian)壓有一個(ge)小(xiao)的(de)電(dian)(dian)壓輸(shu)出(chu)(chu)，然后降為0V，這種(zhong)(zhong)狀(zhuang)況闡(chan)明開(kai)關電(dian)(dian)源在加(jia)電(dian)(dian)的(de)初始(shi)發(fa)(fa)生了振動(dong)，但后因為過壓，過流維護引(yin)起(qi)停振，或(huo)開(kai)關機(ji)接口電(dian)(dian)路加(jia)電(dian)(dian)初始(shi)為開(kai)機(ji)狀(zhuang)況，但隨CPU清零的(de)完畢(bi)而(er)轉入待機(ji)狀(zhuang)況，引(yin)發(fa)(fa)這種(zhong)(zhong)狀(zhuang)況的(de)原(yuan)因有：

(1)開關電(dian)(dian)源因故(gu)輸出電(dian)(dian)壓(ya)比(bi)標準值高(gao)10V而(er)引起(qi)過壓(ya)維護

(2)負載過(guo)流(liu)引起(qi)維(wei)護動作

(3)維(wei)護電路(lu)自身(shen)的誤動作

(4)遙控系統因故執(zhi)行待機指令

2）、判(pan)別(bie)毛病辦法與過程

（1）假負載法

（2）測量維護元件是否擊(ji)穿

（3）斷開法

（4）降壓法

3）、各功用電(dian)路的檢測辦法

經過上(shang)述辦法判別毛病在開關電源的(de)哪個(ge)部分(fen)后，對各個(ge)部分(fen)的(de)查(cha)看辦法如下：

（1）對(dui)脈寬調制電(dian)(dian)(dian)(dian)路和正反(fan)(fan)饋電(dian)(dian)(dian)(dian)路的(de)查(cha)看。對(dui)正反(fan)(fan)饋電(dian)(dian)(dian)(dian)路中(zhong)的(de)電(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)直接(jie)替(ti)換現在(zai)開(kai)關電(dian)(dian)(dian)(dian)源的(de)正反(fan)(fan)饋電(dian)(dian)(dian)(dian)路中(zhong)的(de)振動電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)有兩種，一(yi)是(shi)0。016UF0。039UF膽電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)，其(qi)毛病(bing)率(lv)很低，檢修這種電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)可以掃除，另一(yi)種是(shi)10UF左(zuo)右的(de)電(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)，毛病(bing)率(lv)使用數(shu)年后有可能，檢修時直接(jie)替(ti)換此電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)。

（2）替換脈寬調制(zhi)電(dian)(dian)(dian)路作業(ye)電(dian)(dian)(dian)壓形成中的電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)

在手中無溝通調壓器的狀況下，對于(yu)過壓維護毛病，為(wei)了安(an)全起見(jian)可先替換脈寬調制電路作(zuo)業(ye)電壓形成電路中的易損件，即濾波(bo)電容（幾微法到100UF不等的電解電容），看開關電源是否康復正常。

開關電(dian)源輸出電(dian)壓低檢(jian)修技(ji)巧(qiao)

1、開關(guan)電源輸出電壓低(di)的原因

（1）220V溝通電(dian)壓輸(shu)入電(dian)路(lu)和整流濾波電(dian)路(lu)對開關管(guan)提供的作(zuo)業電(dian)壓不(bu)夠(gou)，超出(chu)脈(mo)寬調制電(dian)路(lu)的控制范圍。

（2）負(fu)載電路存(cun)在過流引起開(kai)關(guan)電源(yuan)負(fu)載加重而導致輸出電壓(ya)下降。

（3）開/關機(ji)(ji)接口電(dian)路處于(yu)待(dai)機(ji)(ji)狀(zhuang)(zhuang)況，令開關電(dian)源作業于(yu)低頻(pin)振動狀(zhuang)(zhuang)況其輸出電(dian)壓為待(dai)機(ji)(ji)狀(zhuang)(zhuang)況下的(de)度數(shu)。此類毛病僅(jin)應于(yu)無準(zhun)備(bei)電(dian)源，CPU準(zhun)備(bei)狀(zhuang)(zhuang)況下的(de)作業電(dian)壓由開關電(dian)源提供的(de)機(ji)(ji)型(xing)。