開關電源的常見故障及維修技巧之三
1,保險絲熔斷
一般情(qing)況下，保(bao)險絲熔斷(duan)說明電(dian)(dian)源(yuan)的(de)(de)內部線路(lu)有(you)(you)(you)問題。由于(yu)電(dian)(dian)源(yuan)工(gong)作在(zai)高電(dian)(dian)壓(ya)、大(da)電(dian)(dian)流的(de)(de)狀態下，電(dian)(dian)網電(dian)(dian)壓(ya)的(de)(de)波動、浪涌都會引起(qi)電(dian)(dian)源(yuan)內電(dian)(dian)流瞬間增大(da)而使(shi)保(bao)險絲熔斷(duan)。重(zhong)點應檢查(cha)(cha)電(dian)(dian)源(yuan)輸(shu)入端(duan)的(de)(de)整流二極管，高壓(ya)濾(lv)波電(dian)(dian)解電(dian)(dian)容(rong)，逆變功(gong)率開關(guan)管等，檢查(cha)(cha)一下這(zhe)此元器件(jian)有(you)(you)(you)無擊穿、開路(lu)、損壞等。如(ru)果確實是保(bao)險絲熔斷(duan)，應該首先查(cha)(cha)看(kan)電(dian)(dian)路(lu)板上(shang)(shang)(shang)的(de)(de)各(ge)個元件(jian)，看(kan)這(zhe)些元件(jian)的(de)(de)外表(biao)有(you)(you)(you)沒有(you)(you)(you)被(bei)燒糊，有(you)(you)(you)沒有(you)(you)(you)電(dian)(dian)解液溢出，如(ru)果沒有(you)(you)(you)發(fa)現上(shang)(shang)(shang)述情(qing)況，則用(yong)萬用(yong)表(biao)測量開關(guan)管有(you)(you)(you)無擊穿短路(lu)。需(xu)要(yao)特別(bie)注(zhu)意的(de)(de)是：切不可(ke)在(zai)查(cha)(cha)出某元件(jian)損壞時(shi)，更換(huan)后直接開機，這(zhe)樣很有(you)(you)(you)可(ke)能由于(yu)其(qi)它高壓(ya)元件(jian)仍(reng)有(you)(you)(you)故(gu)(gu)障又將更換(huan)的(de)(de)元件(jian)損壞，一定要(yao)對上(shang)(shang)(shang)述電(dian)(dian)路(lu)的(de)(de)所(suo)有(you)(you)(you)高壓(ya)元件(jian)進行全面檢查(cha)(cha)測量后，才能徹底(di)排除保(bao)險絲熔斷(duan)的(de)(de)故(gu)(gu)障。
2,無(wu)直(zhi)流電壓輸(shu)出(chu)或電壓輸(shu)出(chu)不穩(wen)定
如果保險絲(si)是(shi)完好(hao)的，在(zai)有負(fu)(fu)載情況下，各級直(zhi)流(liu)電(dian)壓(ya)無(wu)(wu)輸(shu)出(chu)(chu)(chu)(chu)。這種(zhong)情況主要是(shi)以下原因造成的：電(dian)源(yuan)中(zhong)(zhong)出(chu)(chu)(chu)(chu)現開路(lu)、短路(lu)現象，過壓(ya)、過流(liu)保護(hu)電(dian)路(lu)出(chu)(chu)(chu)(chu)現故障，輔助電(dian)源(yuan)故障，振蕩電(dian)路(lu)沒有工作，電(dian)源(yuan)負(fu)(fu)載過重，高頻(pin)(pin)整流(liu)濾(lv)波(bo)電(dian)路(lu)中(zhong)(zhong)整流(liu)二(er)(er)(er)極(ji)(ji)管(guan)被擊穿(chuan)，濾(lv)波(bo)電(dian)容漏電(dian)等(deng)。在(zai)用(yong)(yong)萬(wan)(wan)用(yong)(yong)表測量(liang)次(ci)級元(yuan)件(jian)，排(pai)除了(le)高頻(pin)(pin)整流(liu)二(er)(er)(er)極(ji)(ji)管(guan)擊穿(chuan)、負(fu)(fu)載短路(lu)的情況后，如果這時(shi)輸(shu)出(chu)(chu)(chu)(chu)為零，則可以肯(ken)定是(shi)電(dian)源(yuan)的控制電(dian)路(lu)出(chu)(chu)(chu)(chu)了(le)故障。若(ruo)有部分電(dian)壓(ya)輸(shu)出(chu)(chu)(chu)(chu)說明前(qian)級電(dian)路(lu)工作正常，故障出(chu)(chu)(chu)(chu)在(zai)高頻(pin)(pin)整流(liu)濾(lv)波(bo)電(dian)路(lu)中(zhong)(zhong)。高頻(pin)(pin)濾(lv)波(bo)電(dian)路(lu)主要由整流(liu)二(er)(er)(er)極(ji)(ji)管(guan)及低(di)壓(ya)濾(lv)波(bo)電(dian)容組成直(zhi)流(liu)電(dian)壓(ya)輸(shu)出(chu)(chu)(chu)(chu)，其中(zhong)(zhong)整流(liu)二(er)(er)(er)極(ji)(ji)管(guan)擊穿(chuan)會使該電(dian)路(lu)無(wu)(wu)電(dian)壓(ya)輸(shu)出(chu)(chu)(chu)(chu)，濾(lv)波(bo)電(dian)容漏電(dian)會造成輸(shu)出(chu)(chu)(chu)(chu)電(dian)壓(ya)不穩(wen)等(deng)故障。用(yong)(yong)萬(wan)(wan)用(yong)(yong)表靜態(tai)測量(liang)對應元(yuan)件(jian)即可檢查出(chu)(chu)(chu)(chu)其損(sun)壞的元(yuan)件(jian)。
3,電源負載能力差
電(dian)源負載(zai)能力差是一(yi)個(ge)常見的故障，一(yi)般都是出現在老式或工作時(shi)間長的電(dian)源中，主(zhu)要原因是各元器件(jian)老化，開(kai)關(guan)管的工作不穩(wen)定(ding)，沒(mei)有及時(shi)進行(xing)散(san)熱等。應(ying)重點檢查穩(wen)壓二極管是否發(fa)熱漏電(dian)，整(zheng)流二極管損壞、高壓濾(lv)波(bo)電(dian)容損壞等。
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