一、開(kai)關電(dian)源一直(zhi)無(wu)電(dian)壓輸出的檢修技巧(qiao)

開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)一(yi)(yi)直(zhi)無(wu)電(dian)壓輸(shu)出是指開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)各輸(shu)出端，在按電(dian)源(yuan)(yuan)開(kai)(kai)(kai)關(guan)開(kai)(kai)(kai)機后(hou)一(yi)(yi)直(zhi)為(wei)0V，這種狀(zhuang)況是因(yin)為(wei)開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)未發(fa)生震蕩所致。進一(yi)(yi)步證明(ming)的辦法是測開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)100UF/400V電(dian)容(rong)關(guan)機后(hou)的電(dian)壓，若(ruo)300V之(zhi)后(hou)慢慢下降，則(ze)闡明(ming)開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)未發(fa)生振動(dong)。開(kai)(kai)(kai)關(guan)電(dian)源(yuan)(yuan)未發(fa)生振動(dong)的原因(yin)有：

(1)開關管集電極未得(de)到滿(man)足的作業電壓

(2)開(kai)關(guan)管(guan)基極未得到發動(dong)電壓和相(xiang)關(guan)電路(lu)漏(lou)電

(3)開關管(guan)正反饋元件(jian)失效(xiao)

判別毛(mao)病(bing)的辦(ban)法和過程

檢(jian)修這類(lei)毛(mao)病的(de)首要任務是判別毛(mao)病在(zai)上述三(san)個(ge)部(bu)位(wei)中的(de)哪個(ge)部(bu)位(wei)，具(ju)體辦(ban)法是測開關(guan)管集電(dian)極，基(ji)極電(dian)壓，可能(neng)有以(yi)下幾種(zhong)狀況：

(1)開(kai)關管(guan)集電(dian)(dian)(dian)極電(dian)(dian)(dian)壓為0V和(he)低于市電(dian)(dian)(dian)1.4倍(bei)，開(kai)關管(guan)沒有正(zheng)(zheng)常的(de)作(zuo)業(ye)電(dian)(dian)(dian)壓，如(ru)果有1.4倍(bei)的(de)電(dian)(dian)(dian)壓，闡(chan)明(ming)開(kai)關管(guan)集電(dian)(dian)(dian)極具有了正(zheng)(zheng)常的(de)作(zuo)業(ye)電(dian)(dian)(dian)壓，闡(chan)明(ming)AC220V及(ji)整流濾(lv)波電(dian)(dian)(dian)路(lu)作(zuo)業(ye)正(zheng)(zheng)常。

(2)開關(guan)(guan)管(guan)的基極(ji)電(dian)(dian)壓(ya)為0V(包含開機瞬(shun)間(jian)(jian))這種狀況闡(chan)明(ming)發動(dong)電(dian)(dian)路對(dui)開關(guan)(guan)管(guan)基極(ji)未提供發動(dong)(導通(tong))電(dian)(dian)壓(ya)，或基極(ji)與發射極(ji)之間(jian)(jian)相(xiang)關(guan)(guan)元件(jian)擊穿，應對(dui)發動(dong)電(dian)(dian)路和開關(guan)(guan)管(guan)發射極(ji)及(ji)相(xiang)關(guan)(guan)元件(jian)進(jin)行查看，若(ruo)電(dian)(dian)壓(ya)為0.6~0.7(包含開機瞬(shun)間(jian)(jian))，闡(chan)明(ming)發動(dong)電(dian)(dian)路和開關(guan)(guan)管(guan)發射極(ji)元件(jian)正常(chang)，若(ruo)在0.7V以上闡(chan)明(ming)發動(dong)電(dian)(dian)路正常(chang)，但開關(guan)(guan)管(guan)發射極(ji)或其元件(jian)斷路或阻值變大。

(3)開關管(guan)具(ju)有導通條件(jian)：開關管(guan)基(ji)極電(dian)壓為0.6~0.7V，集電(dian)極電(dian)壓大于250V，闡(chan)明(ming)開關管(guan)具(ju)有了作業條件(jian)，毛病在(zai)正反(fan)饋(kui)電(dian)路，包含(han)正反(fan)饋(kui)電(dian)阻，電(dian)容，續流二極管(guan)及開關變壓器正反(fan)饋(kui)繞組(zu)及其之間的銜接應制板。

開關電源瞬間有電壓(ya)出(chu)檢修技巧

1）、瞬間電壓輸出毛病原因

這(zhe)種(zhong)毛病在按下(xia)發(fa)動開關的(de)瞬間，開關電(dian)(dian)源某(mou)個或(huo)(huo)各(ge)個輸出端電(dian)(dian)壓(ya)有一個小(xiao)的(de)電(dian)(dian)壓(ya)輸出，然(ran)后降為(wei)0V，這(zhe)種(zhong)狀(zhuang)(zhuang)況(kuang)(kuang)闡明開關電(dian)(dian)源在加電(dian)(dian)的(de)初(chu)(chu)始發(fa)生了振(zhen)動，但(dan)后因(yin)為(wei)過(guo)(guo)壓(ya)，過(guo)(guo)流維護(hu)引(yin)起停振(zhen)，或(huo)(huo)開關機接口電(dian)(dian)路加電(dian)(dian)初(chu)(chu)始為(wei)開機狀(zhuang)(zhuang)況(kuang)(kuang)，但(dan)隨CPU清(qing)零的(de)完畢而(er)轉入(ru)待機狀(zhuang)(zhuang)況(kuang)(kuang)，引(yin)發(fa)這(zhe)種(zhong)狀(zhuang)(zhuang)況(kuang)(kuang)的(de)原因(yin)有：

(1)開關電(dian)源因故輸出電(dian)壓比標準值(zhi)高10V而引起(qi)過壓維護

(2)負載過(guo)流引起維護動作(zuo)

(3)維護電路自身的誤動(dong)作

(4)遙控系(xi)統因故執行待機指令

2）、判別毛病辦(ban)法與過程(cheng)

（1）假負載法

（2）測量維護元件是(shi)否擊(ji)穿

（3）斷開法

（4）降壓法

3）、各功用(yong)電(dian)路的檢測(ce)辦法

經過(guo)上述辦法判(pan)別毛(mao)病在開關電源的哪個部(bu)分后，對各個部(bu)分的查看(kan)辦法如下(xia)：

（1）對脈寬調制電(dian)(dian)(dian)路(lu)和正反(fan)饋電(dian)(dian)(dian)路(lu)的(de)查看。對正反(fan)饋電(dian)(dian)(dian)路(lu)中的(de)電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)(rong)直(zhi)接替換現在開(kai)關電(dian)(dian)(dian)源的(de)正反(fan)饋電(dian)(dian)(dian)路(lu)中的(de)振(zhen)動電(dian)(dian)(dian)容(rong)(rong)有(you)兩種(zhong)，一是0。016UF0。039UF膽電(dian)(dian)(dian)容(rong)(rong)，其毛(mao)病(bing)(bing)率(lv)(lv)很低，檢(jian)修(xiu)這種(zhong)電(dian)(dian)(dian)容(rong)(rong)可以(yi)掃除，另一種(zhong)是10UF左(zuo)右(you)的(de)電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)(rong)，毛(mao)病(bing)(bing)率(lv)(lv)使用(yong)數年(nian)后有(you)可能(neng)，檢(jian)修(xiu)時直(zhi)接替換此電(dian)(dian)(dian)容(rong)(rong)。

（2）替換脈(mo)寬(kuan)調制(zhi)電(dian)路作業(ye)電(dian)壓(ya)形成中的電(dian)解電(dian)容

在(zai)手中(zhong)無溝通(tong)調(diao)壓(ya)器的(de)狀(zhuang)況下，對于過壓(ya)維護毛病，為了(le)安(an)全起見可先替(ti)換脈(mo)寬(kuan)調(diao)制電(dian)路(lu)作業電(dian)壓(ya)形(xing)成電(dian)路(lu)中(zhong)的(de)易(yi)損件，即濾波電(dian)容(rong)（幾微法(fa)到100UF不等的(de)電(dian)解電(dian)容(rong)），看開關電(dian)源(yuan)是否康復(fu)正常。

開關電源輸出電壓低檢修技(ji)巧

1、開關電源輸(shu)出電壓低的原因

（1）220V溝通(tong)電壓(ya)(ya)輸入電路(lu)和整流濾(lv)波電路(lu)對開關(guan)管(guan)提供的作業電壓(ya)(ya)不夠，超出(chu)脈(mo)寬調制電路(lu)的控制范圍。

（2）負(fu)載電路(lu)存在(zai)過流引起開關(guan)電源負(fu)載加(jia)重(zhong)而導致輸出電壓下降。

（3）開(kai)/關機(ji)接(jie)口(kou)電路處于(yu)待機(ji)狀(zhuang)(zhuang)況(kuang)，令開(kai)關電源(yuan)作業于(yu)低頻振動狀(zhuang)(zhuang)況(kuang)其輸出(chu)電壓為(wei)待機(ji)狀(zhuang)(zhuang)況(kuang)下的度(du)數。此類毛病僅應于(yu)無(wu)準備電源(yuan)，CPU準備狀(zhuang)(zhuang)況(kuang)下的作業電壓由(you)開(kai)關電源(yuan)提(ti)供的機(ji)型。