一、開關電(dian)源一直(zhi)無(wu)電(dian)壓輸出的檢(jian)修技巧

開(kai)(kai)關(guan)電(dian)(dian)源(yuan)一(yi)直(zhi)無(wu)電(dian)(dian)壓(ya)輸(shu)出(chu)是指開(kai)(kai)關(guan)電(dian)(dian)源(yuan)各輸(shu)出(chu)端，在按電(dian)(dian)源(yuan)開(kai)(kai)關(guan)開(kai)(kai)機后一(yi)直(zhi)為0V，這種狀(zhuang)況是因為開(kai)(kai)關(guan)電(dian)(dian)源(yuan)未(wei)發(fa)生震蕩所致。進一(yi)步證明的(de)辦法是測開(kai)(kai)關(guan)電(dian)(dian)源(yuan)100UF/400V電(dian)(dian)容關(guan)機后的(de)電(dian)(dian)壓(ya)，若300V之后慢慢下(xia)降，則闡(chan)明開(kai)(kai)關(guan)電(dian)(dian)源(yuan)未(wei)發(fa)生振動。開(kai)(kai)關(guan)電(dian)(dian)源(yuan)未(wei)發(fa)生振動的(de)原(yuan)因有：

(1)開關管集電極未得到滿足的作業電壓(ya)

(2)開關管(guan)基極未得到發動電(dian)壓和相(xiang)關電(dian)路漏電(dian)

(3)開關管(guan)正反饋元件失效

判別毛病的辦法和(he)過程

檢修這類毛病(bing)的首要任(ren)務是判(pan)別毛病(bing)在上(shang)述(shu)三個部位(wei)中(zhong)的哪個部位(wei)，具(ju)體(ti)辦法是測開(kai)關管集電(dian)極(ji)，基極(ji)電(dian)壓，可能有以下幾(ji)種狀況：

(1)開關管集電(dian)(dian)(dian)(dian)極電(dian)(dian)(dian)(dian)壓(ya)為0V和低于市(shi)電(dian)(dian)(dian)(dian)1.4倍(bei)，開關管沒有正(zheng)常的(de)作業(ye)電(dian)(dian)(dian)(dian)壓(ya)，如果有1.4倍(bei)的(de)電(dian)(dian)(dian)(dian)壓(ya)，闡(chan)明(ming)開關管集電(dian)(dian)(dian)(dian)極具(ju)有了正(zheng)常的(de)作業(ye)電(dian)(dian)(dian)(dian)壓(ya)，闡(chan)明(ming)AC220V及整流濾波電(dian)(dian)(dian)(dian)路作業(ye)正(zheng)常。

(2)開(kai)(kai)(kai)關(guan)管的基極電(dian)(dian)壓(ya)(ya)為(wei)(wei)0V(包(bao)含開(kai)(kai)(kai)機(ji)瞬間)這種狀況闡明(ming)發(fa)動(dong)電(dian)(dian)路(lu)(lu)對開(kai)(kai)(kai)關(guan)管基極未提供發(fa)動(dong)(導(dao)通)電(dian)(dian)壓(ya)(ya)，或(huo)(huo)基極與(yu)發(fa)射極之間相關(guan)元件(jian)擊穿，應對發(fa)動(dong)電(dian)(dian)路(lu)(lu)和開(kai)(kai)(kai)關(guan)管發(fa)射極及相關(guan)元件(jian)進行查看，若電(dian)(dian)壓(ya)(ya)為(wei)(wei)0.6~0.7(包(bao)含開(kai)(kai)(kai)機(ji)瞬間)，闡明(ming)發(fa)動(dong)電(dian)(dian)路(lu)(lu)和開(kai)(kai)(kai)關(guan)管發(fa)射極元件(jian)正常(chang)，若在0.7V以上闡明(ming)發(fa)動(dong)電(dian)(dian)路(lu)(lu)正常(chang)，但開(kai)(kai)(kai)關(guan)管發(fa)射極或(huo)(huo)其元件(jian)斷路(lu)(lu)或(huo)(huo)阻值(zhi)變(bian)大。

(3)開關(guan)管具有導通條件(jian)：開關(guan)管基極(ji)電(dian)壓為(wei)0.6~0.7V，集電(dian)極(ji)電(dian)壓大于(yu)250V，闡明開關(guan)管具有了作業條件(jian)，毛病在正反(fan)饋(kui)電(dian)路，包含正反(fan)饋(kui)電(dian)阻(zu)，電(dian)容，續(xu)流(liu)二極(ji)管及開關(guan)變壓器正反(fan)饋(kui)繞(rao)組(zu)及其之間的銜(xian)接應制板(ban)。

開(kai)關電源瞬間有電壓出檢修(xiu)技巧

1）、瞬間電(dian)壓輸出(chu)毛病原因

這種(zhong)毛(mao)病(bing)在按(an)下發(fa)動開(kai)(kai)關的(de)瞬間(jian)，開(kai)(kai)關電(dian)(dian)源某個(ge)或(huo)各個(ge)輸出(chu)端電(dian)(dian)壓有一個(ge)小的(de)電(dian)(dian)壓輸出(chu)，然后降為(wei)0V，這種(zhong)狀(zhuang)況(kuang)闡(chan)明(ming)開(kai)(kai)關電(dian)(dian)源在加(jia)電(dian)(dian)的(de)初(chu)(chu)始發(fa)生(sheng)了振(zhen)(zhen)動，但后因(yin)為(wei)過壓，過流維(wei)護引(yin)起(qi)停振(zhen)(zhen)，或(huo)開(kai)(kai)關機(ji)(ji)接口(kou)電(dian)(dian)路加(jia)電(dian)(dian)初(chu)(chu)始為(wei)開(kai)(kai)機(ji)(ji)狀(zhuang)況(kuang)，但隨CPU清零(ling)的(de)完畢而轉(zhuan)入(ru)待機(ji)(ji)狀(zhuang)況(kuang)，引(yin)發(fa)這種(zhong)狀(zhuang)況(kuang)的(de)原(yuan)因(yin)有：

(1)開關電(dian)源因故輸出電(dian)壓比標準值(zhi)高(gao)10V而(er)引起過(guo)壓維護

(2)負載過流引起(qi)維護動作

(3)維護電(dian)路自身的(de)誤動作

(4)遙控(kong)系統因故執行待機指令

2）、判別毛(mao)病辦法與過程

（1）假負載法

（2）測量維護元件(jian)是否擊(ji)穿

（3）斷開法

（4）降壓法

3）、各功用電路的檢測辦法(fa)

經過上(shang)述辦(ban)法判別(bie)毛病(bing)在開關電源的哪(na)個(ge)部分后(hou)，對各個(ge)部分的查看辦(ban)法如下：

（1）對脈寬調制電(dian)(dian)(dian)(dian)路(lu)(lu)和正反饋(kui)(kui)電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)查看。對正反饋(kui)(kui)電(dian)(dian)(dian)(dian)路(lu)(lu)中的(de)(de)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)直(zhi)接替換(huan)現(xian)在(zai)開關電(dian)(dian)(dian)(dian)源的(de)(de)正反饋(kui)(kui)電(dian)(dian)(dian)(dian)路(lu)(lu)中的(de)(de)振動電(dian)(dian)(dian)(dian)容(rong)有(you)兩種(zhong)，一(yi)是0。016UF0。039UF膽電(dian)(dian)(dian)(dian)容(rong)，其毛(mao)病率(lv)很低，檢修這種(zhong)電(dian)(dian)(dian)(dian)容(rong)可(ke)以掃除，另一(yi)種(zhong)是10UF左右(you)的(de)(de)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)，毛(mao)病率(lv)使用數年后(hou)有(you)可(ke)能，檢修時直(zhi)接替換(huan)此電(dian)(dian)(dian)(dian)容(rong)。

（2）替換脈寬調制(zhi)電(dian)路作業電(dian)壓(ya)形(xing)成中的電(dian)解(jie)電(dian)容(rong)

在手(shou)中無溝(gou)通(tong)調壓器的狀況下(xia)，對(dui)于過壓維護毛病，為了安全起見可先替換脈寬調制電路作業電壓形成電路中的易損(sun)件，即濾波電容(rong)（幾(ji)微(wei)法到100UF不等的電解電容(rong)），看開關電源是否康復(fu)正常。

開關電源輸出電壓低檢(jian)修(xiu)技巧

1、開關電源輸出電壓低(di)的原因(yin)

（1）220V溝(gou)通電(dian)壓輸入電(dian)路(lu)(lu)和整流(liu)濾波(bo)電(dian)路(lu)(lu)對開(kai)關管提供的(de)作(zuo)業(ye)電(dian)壓不夠，超出脈寬(kuan)調制電(dian)路(lu)(lu)的(de)控制范(fan)圍。

（2）負載電路存(cun)在過流引(yin)起開關電源負載加(jia)重而(er)導致輸出電壓(ya)下降。

（3）開/關機接口(kou)電(dian)路處(chu)于(yu)(yu)(yu)待機狀況，令開關電(dian)源(yuan)作業于(yu)(yu)(yu)低(di)頻振(zhen)動(dong)狀況其輸出電(dian)壓(ya)為(wei)待機狀況下(xia)的(de)度(du)數(shu)。此(ci)類毛病(bing)僅應于(yu)(yu)(yu)無準(zhun)備電(dian)源(yuan)，CPU準(zhun)備狀況下(xia)的(de)作業電(dian)壓(ya)由開關電(dian)源(yuan)提供的(de)機型。