一、開關電源一直無電壓輸出的檢修技巧(qiao)

開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)一直(zhi)無電(dian)(dian)(dian)(dian)壓(ya)輸出(chu)是(shi)指開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)各輸出(chu)端，在按電(dian)(dian)(dian)(dian)源(yuan)開(kai)(kai)關(guan)(guan)開(kai)(kai)機(ji)后(hou)一直(zhi)為0V，這種狀況(kuang)是(shi)因為開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)未發生(sheng)(sheng)(sheng)震蕩(dang)所(suo)致(zhi)。進一步證明(ming)的(de)(de)辦法是(shi)測開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)100UF/400V電(dian)(dian)(dian)(dian)容關(guan)(guan)機(ji)后(hou)的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)，若(ruo)300V之(zhi)后(hou)慢慢下降，則闡(chan)明(ming)開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)未發生(sheng)(sheng)(sheng)振(zhen)動。開(kai)(kai)關(guan)(guan)電(dian)(dian)(dian)(dian)源(yuan)未發生(sheng)(sheng)(sheng)振(zhen)動的(de)(de)原(yuan)因有：

(1)開關管集電(dian)極未(wei)得(de)到滿足的作業(ye)電(dian)壓

(2)開關管基極未得到(dao)發動電(dian)(dian)壓和(he)相關電(dian)(dian)路漏電(dian)(dian)

(3)開關管正(zheng)反饋元件失效

判別毛病的辦(ban)法和過程

檢修這類毛病(bing)的首(shou)要任務(wu)是判別毛病(bing)在上述三個部(bu)位(wei)中的哪個部(bu)位(wei)，具體(ti)辦法(fa)是測開(kai)關管集電極，基極電壓，可(ke)能有以下幾種狀況：

(1)開關(guan)管(guan)集電(dian)(dian)極(ji)電(dian)(dian)壓(ya)為0V和低于市電(dian)(dian)1.4倍，開關(guan)管(guan)沒有正(zheng)常的作業電(dian)(dian)壓(ya)，如果有1.4倍的電(dian)(dian)壓(ya)，闡明(ming)開關(guan)管(guan)集電(dian)(dian)極(ji)具有了(le)正(zheng)常的作業電(dian)(dian)壓(ya)，闡明(ming)AC220V及(ji)整流濾(lv)波電(dian)(dian)路作業正(zheng)常。

(2)開(kai)關(guan)(guan)管的(de)基(ji)極(ji)(ji)電(dian)(dian)壓為0V(包含開(kai)機(ji)瞬間(jian))這種(zhong)狀況闡明發(fa)(fa)(fa)(fa)(fa)(fa)動(dong)電(dian)(dian)路對開(kai)關(guan)(guan)管基(ji)極(ji)(ji)未提供(gong)發(fa)(fa)(fa)(fa)(fa)(fa)動(dong)(導通(tong))電(dian)(dian)壓，或(huo)基(ji)極(ji)(ji)與發(fa)(fa)(fa)(fa)(fa)(fa)射(she)(she)極(ji)(ji)之間(jian)相(xiang)(xiang)關(guan)(guan)元(yuan)件擊穿，應對發(fa)(fa)(fa)(fa)(fa)(fa)動(dong)電(dian)(dian)路和開(kai)關(guan)(guan)管發(fa)(fa)(fa)(fa)(fa)(fa)射(she)(she)極(ji)(ji)及相(xiang)(xiang)關(guan)(guan)元(yuan)件進行查(cha)看(kan)，若電(dian)(dian)壓為0.6~0.7(包含開(kai)機(ji)瞬間(jian))，闡明發(fa)(fa)(fa)(fa)(fa)(fa)動(dong)電(dian)(dian)路和開(kai)關(guan)(guan)管發(fa)(fa)(fa)(fa)(fa)(fa)射(she)(she)極(ji)(ji)元(yuan)件正常，若在0.7V以(yi)上闡明發(fa)(fa)(fa)(fa)(fa)(fa)動(dong)電(dian)(dian)路正常，但開(kai)關(guan)(guan)管發(fa)(fa)(fa)(fa)(fa)(fa)射(she)(she)極(ji)(ji)或(huo)其(qi)元(yuan)件斷(duan)路或(huo)阻值(zhi)變大。

(3)開(kai)關管具(ju)有導通(tong)條(tiao)件(jian)：開(kai)關管基極電(dian)(dian)(dian)壓(ya)為0.6~0.7V，集(ji)電(dian)(dian)(dian)極電(dian)(dian)(dian)壓(ya)大于250V，闡明開(kai)關管具(ju)有了作業條(tiao)件(jian)，毛病在正(zheng)反(fan)饋(kui)電(dian)(dian)(dian)路，包含正(zheng)反(fan)饋(kui)電(dian)(dian)(dian)阻，電(dian)(dian)(dian)容，續流二極管及開(kai)關變壓(ya)器(qi)正(zheng)反(fan)饋(kui)繞組及其之(zhi)間的銜接應制板。

開關電(dian)源瞬間(jian)有電(dian)壓出檢(jian)修技巧

1）、瞬間電壓輸出(chu)毛病原因(yin)

這種(zhong)毛病在(zai)按(an)下發動開(kai)關的(de)瞬間，開(kai)關電(dian)(dian)源某個(ge)或各個(ge)輸出(chu)端(duan)電(dian)(dian)壓有一個(ge)小(xiao)的(de)電(dian)(dian)壓輸出(chu)，然后降為(wei)0V，這種(zhong)狀況闡明開(kai)關電(dian)(dian)源在(zai)加電(dian)(dian)的(de)初(chu)始發生了振動，但后因(yin)為(wei)過(guo)壓，過(guo)流維護引起停(ting)振，或開(kai)關機(ji)接口(kou)電(dian)(dian)路加電(dian)(dian)初(chu)始為(wei)開(kai)機(ji)狀況，但隨CPU清(qing)零的(de)完畢而(er)轉(zhuan)入待機(ji)狀況，引發這種(zhong)狀況的(de)原因(yin)有：

(1)開關電源因故輸出電壓比標準值高10V而引起過壓維護

(2)負(fu)載(zai)過流引起(qi)維護動(dong)作

(3)維護電路自身的誤(wu)動作

(4)遙(yao)控系統因故執(zhi)行待(dai)機指令

2）、判別毛病辦(ban)法與過程

（1）假負載法

（2）測量(liang)維護(hu)元(yuan)件是否擊穿

（3）斷開法

（4）降壓法

3）、各功用(yong)電路的(de)檢測辦法

經(jing)過上述(shu)辦(ban)法判別毛(mao)病(bing)在開關電源(yuan)的哪個部分后，對(dui)各個部分的查(cha)看辦(ban)法如下：

（1）對脈寬調制(zhi)電路和(he)正反(fan)饋(kui)電路的(de)查看(kan)。對正反(fan)饋(kui)電路中(zhong)的(de)電解電容(rong)(rong)(rong)直(zhi)接(jie)替換現在開(kai)關電源的(de)正反(fan)饋(kui)電路中(zhong)的(de)振(zhen)動電容(rong)(rong)(rong)有(you)兩種(zhong)，一是0。016UF0。039UF膽電容(rong)(rong)(rong)，其毛(mao)病(bing)(bing)率很低，檢修這種(zhong)電容(rong)(rong)(rong)可以(yi)掃除，另一種(zhong)是10UF左右的(de)電解電容(rong)(rong)(rong)，毛(mao)病(bing)(bing)率使用數(shu)年后有(you)可能，檢修時直(zhi)接(jie)替換此電容(rong)(rong)(rong)。

（2）替換(huan)脈寬調制(zhi)電(dian)路作業電(dian)壓形成中的電(dian)解電(dian)容

在手(shou)中無溝通(tong)調壓(ya)器的狀況下(xia)，對于(yu)過(guo)壓(ya)維護毛病，為了(le)安全(quan)起見可(ke)先替換脈寬(kuan)調制電(dian)路作業電(dian)壓(ya)形成電(dian)路中的易損(sun)件，即濾波電(dian)容（幾微法到100UF不等的電(dian)解(jie)電(dian)容），看(kan)開關電(dian)源是否康復正常。

開關電源輸出電壓低檢(jian)修(xiu)技巧

1、開關電(dian)源輸出電(dian)壓低的原因

（1）220V溝通電壓輸入電路(lu)和整流濾波電路(lu)對開關(guan)管提(ti)供的作業電壓不(bu)夠，超出脈寬調(diao)制(zhi)(zhi)電路(lu)的控制(zhi)(zhi)范圍。

（2）負載電路存在(zai)過流引起開關電源負載加重而(er)導致輸出電壓下降。

（3）開(kai)/關機接(jie)口(kou)電路處(chu)于待機狀況，令開(kai)關電源作(zuo)業于低(di)頻振(zhen)動狀況其輸(shu)出電壓為待機狀況下的度(du)數(shu)。此類毛病僅(jin)應于無準備(bei)電源，CPU準備(bei)狀況下的作(zuo)業電壓由開(kai)關電源提供的機型。