開關電源的三個“非常”故障及應對技巧
1,保險絲熔斷
一(yi)(yi)般情況(kuang)下(xia)，保險絲(si)熔(rong)斷說明電(dian)(dian)源(yuan)的(de)(de)(de)內部線(xian)路(lu)(lu)有(you)(you)(you)(you)問題(ti)。由于電(dian)(dian)源(yuan)工作在(zai)高電(dian)(dian)壓、大電(dian)(dian)流的(de)(de)(de)狀態下(xia)，電(dian)(dian)網電(dian)(dian)壓的(de)(de)(de)波動(dong)、浪涌都(dou)會引起(qi)電(dian)(dian)源(yuan)內電(dian)(dian)流瞬間增大而使(shi)保險絲(si)熔(rong)斷。重點(dian)應(ying)檢查(cha)電(dian)(dian)源(yuan)輸(shu)入端的(de)(de)(de)整流二極管，高壓濾波電(dian)(dian)解電(dian)(dian)容，逆變功率開(kai)關管等(deng)，檢查(cha)一(yi)(yi)下(xia)這(zhe)此元(yuan)器件有(you)(you)(you)(you)無擊(ji)穿(chuan)、開(kai)路(lu)(lu)、損壞(huai)等(deng)。如果(guo)(guo)確實是保險絲(si)熔(rong)斷，應(ying)該(gai)首先查(cha)看電(dian)(dian)路(lu)(lu)板上(shang)的(de)(de)(de)各(ge)個元(yuan)件，看這(zhe)些(xie)元(yuan)件的(de)(de)(de)外表有(you)(you)(you)(you)沒有(you)(you)(you)(you)被燒糊，有(you)(you)(you)(you)沒有(you)(you)(you)(you)電(dian)(dian)解液溢出(chu)，如果(guo)(guo)沒有(you)(you)(you)(you)發現(xian)上(shang)述情況(kuang)，則用萬用表測量開(kai)關管有(you)(you)(you)(you)無擊(ji)穿(chuan)短路(lu)(lu)。需要(yao)特別注意的(de)(de)(de)是：切不可(ke)在(zai)查(cha)出(chu)某元(yuan)件損壞(huai)時，更(geng)換后直接開(kai)機(ji)，這(zhe)樣很有(you)(you)(you)(you)可(ke)能由于其它高壓元(yuan)件仍有(you)(you)(you)(you)故(gu)障又(you)將更(geng)換的(de)(de)(de)元(yuan)件損壞(huai)，一(yi)(yi)定要(yao)對上(shang)述電(dian)(dian)路(lu)(lu)的(de)(de)(de)所有(you)(you)(you)(you)高壓元(yuan)件進行全(quan)面檢查(cha)測量后，才能徹底排除保險絲(si)熔(rong)斷的(de)(de)(de)故(gu)障。
2,無直(zhi)流電壓(ya)輸出或(huo)電壓(ya)輸出不(bu)穩定
如果(guo)保(bao)險絲是(shi)完好(hao)的(de)(de)，在(zai)(zai)有負載情(qing)況(kuang)下，各級直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)無輸(shu)(shu)出(chu)(chu)(chu)。這種(zhong)情(qing)況(kuang)主(zhu)要是(shi)以(yi)下原(yuan)因造(zao)成(cheng)的(de)(de)：電(dian)(dian)(dian)(dian)(dian)(dian)源中出(chu)(chu)(chu)現開(kai)路(lu)(lu)、短路(lu)(lu)現象，過壓(ya)、過流(liu)(liu)保(bao)護電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)出(chu)(chu)(chu)現故障(zhang)，輔助電(dian)(dian)(dian)(dian)(dian)(dian)源故障(zhang)，振蕩電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)沒有工(gong)作，電(dian)(dian)(dian)(dian)(dian)(dian)源負載過重，高(gao)(gao)頻整(zheng)(zheng)(zheng)流(liu)(liu)濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中整(zheng)(zheng)(zheng)流(liu)(liu)二極管(guan)被擊(ji)穿(chuan)，濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)漏電(dian)(dian)(dian)(dian)(dian)(dian)等(deng)。在(zai)(zai)用萬(wan)(wan)用表測量(liang)次級元件(jian)，排除了(le)(le)高(gao)(gao)頻整(zheng)(zheng)(zheng)流(liu)(liu)二極管(guan)擊(ji)穿(chuan)、負載短路(lu)(lu)的(de)(de)情(qing)況(kuang)后(hou)，如果(guo)這時(shi)輸(shu)(shu)出(chu)(chu)(chu)為零，則可以(yi)肯定是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)源的(de)(de)控制電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)出(chu)(chu)(chu)了(le)(le)故障(zhang)。若有部分電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)輸(shu)(shu)出(chu)(chu)(chu)說明前(qian)級電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)工(gong)作正常，故障(zhang)出(chu)(chu)(chu)在(zai)(zai)高(gao)(gao)頻整(zheng)(zheng)(zheng)流(liu)(liu)濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中。高(gao)(gao)頻濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)主(zhu)要由整(zheng)(zheng)(zheng)流(liu)(liu)二極管(guan)及(ji)低壓(ya)濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)組(zu)成(cheng)直流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)輸(shu)(shu)出(chu)(chu)(chu)，其(qi)中整(zheng)(zheng)(zheng)流(liu)(liu)二極管(guan)擊(ji)穿(chuan)會(hui)使該電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)無電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)輸(shu)(shu)出(chu)(chu)(chu)，濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)漏電(dian)(dian)(dian)(dian)(dian)(dian)會(hui)造(zao)成(cheng)輸(shu)(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)不穩等(deng)故障(zhang)。用萬(wan)(wan)用表靜態(tai)測量(liang)對(dui)應(ying)元件(jian)即可檢查出(chu)(chu)(chu)其(qi)損壞(huai)的(de)(de)元件(jian)。
3,電源負載能力差
電源負載能力差是一個常見的故障，一般都是出現在老式或工作時間長的電源中，主要原因是各元器件老化，開關管的工作不穩定，沒有及時進行散熱等。應重點檢查穩壓二極管是否發熱漏電，整流二極管損壞、高壓濾波電容損壞等。
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