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開關電源故障檢查 開關電源維修方法

本文章由注冊用戶 沉靜時光 上傳提供 評論 發布 反饋 0
摘要:您知道開關電源故障如何維修嗎?開關電源的維修可分為斷電情況下,“看、聞、問、量”、加電檢測兩步進行。看:打開電源的外殼,檢查保險絲是否熔斷,再觀察電源的內部情況。聞:聞一下電源內部是否有糊味,檢查是否有燒焦的元器件。下面小編就詳細為您介紹開關電源維修技巧。

開關電源簡介

開關電源是利用(yong)現(xian)代電(dian)力電(dian)子技(ji)術,控(kong)制開關晶體管開通和關斷的時間比率(lv),維(wei)持穩定輸出電(dian)壓的一種(zhong)電(dian)源(yuan)。廣泛運用(yong)在(zai)(zai)工(gong)業、軍事、科研、通訊(xun)、醫療及多種(zhong)家(jia)用(yong)電(dian)器中。開關電(dian)源(yuan)的發展(zhan)與應(ying)用(yong)在(zai)(zai)節約能源(yuan)、節約資源(yuan)及保(bao)護環境方(fang)面(mian)都具有重要(yao)的意義(yi)。下面(mian)我們(men)就(jiu)來看看開關電(dian)源(yuan)電(dian)路圖與維(wei)修技(ji)巧。

開(kai)關電(dian)(dian)(dian)源的主要電(dian)(dian)(dian)路是由輸入(ru)電(dian)(dian)(dian)磁(ci)干擾濾(lv)(lv)波(bo)器(EMI)、整流濾(lv)(lv)波(bo)電(dian)(dian)(dian)路、功率(lv)變換電(dian)(dian)(dian)路、PWM控制器電(dian)(dian)(dian)路、輸出整流濾(lv)(lv)波(bo)電(dian)(dian)(dian)路組成。輔助電(dian)(dian)(dian)路有輸入(ru)過欠壓保護(hu)電(dian)(dian)(dian)路、輸出過欠壓保護(hu)電(dian)(dian)(dian)路、輸出過流保護(hu)電(dian)(dian)(dian)路、輸出短路保護(hu)電(dian)(dian)(dian)路等。

開關電源的維修步驟

加電檢測

該圖片由注冊用戶"沉靜時光"提供,版權聲明反饋

通電后觀察電源是否有(you)燒保(bao)險及個別元件冒煙等現象(xiang),若有(you)要及時切斷(duan)供電進行(xing)檢修(xiu)。

測量高壓濾波電容兩(liang)端有(you)無300伏輸出,若(ruo)無應重(zhong)點(dian)查整流(liu)二極管、濾波電容等。

測量高頻變壓器次級(ji)線圈有無(wu)輸(shu)出,若無(wu)應(ying)重點查開關管(guan)是(shi)否損壞,是(shi)否起振,保護電(dian)路是(shi)否動(dong)作等,若有則應(ying)重點檢(jian)查各輸(shu)出側的整流二極管(guan)、濾(lv)波電(dian)容、三(san)通穩壓管(guan)等。

如果電(dian)源(yuan)(yuan)啟動一下(xia)就停止(zhi),則(ze)該電(dian)源(yuan)(yuan)處(chu)于保(bao)(bao)(bao)護狀態下(xia),可直接測(ce)量(liang)PWM芯片保(bao)(bao)(bao)護輸入(ru)腳的電(dian)壓(ya),如果電(dian)壓(ya)超出規(gui)定(ding)值,則(ze)說明電(dian)源(yuan)(yuan)處(chu)于保(bao)(bao)(bao)護狀態下(xia),應(ying)重點檢查(cha)產生保(bao)(bao)(bao)護的原(yuan)因。

總之,開(kai)關電(dian)源電(dian)路(lu)有(you)(you)(you)易有(you)(you)(you)難,功率有(you)(you)(you)大有(you)(you)(you)小(xiao),輸出電(dian)壓多種多樣。只要按照(zhao)上述維修技巧,多動手(shou)進行開(kai)關電(dian)源的(de)(de)維修,就能(neng)迅(xun)速地排除開(kai)關電(dian)源故障,達到事半功倍的(de)(de)效果。

斷電后看聞問量

看:打開(kai)電源的外殼,檢查保險絲是否熔斷,再(zai)觀(guan)察電源的內部情(qing)況,如果發現電源的PCB板上有燒焦處(chu)或(huo)元(yuan)件破裂,則(ze)應重點檢查此處(chu)元(yuan)件及相關電路元(yuan)件。

聞(wen):聞(wen)一下電源內(nei)部是(shi)否有(you)(you)糊味,檢查是(shi)否有(you)(you)燒焦(jiao)的(de)元(yuan)器件。

問(wen):問(wen)一下電源(yuan)(yuan)損壞的(de)經(jing)過,是否對(dui)電源(yuan)(yuan)進行違規操作。

量(liang):沒通電(dian)(dian)(dian)前,用萬用表量(liang)一下高壓(ya)(ya)電(dian)(dian)(dian)容(rong)(rong)兩端的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)先。如果是開關電(dian)(dian)(dian)源(yuan)不起振或(huo)開關管開路引(yin)起的(de)(de)故障,則大多數情況(kuang)下,高壓(ya)(ya)濾波電(dian)(dian)(dian)容(rong)(rong)兩端的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)未泄(xie)放(fang)悼,用萬用表測量(liang)AC電(dian)(dian)(dian)源(yuan)線兩端的(de)(de)正(zheng)反向電(dian)(dian)(dian)阻及電(dian)(dian)(dian)容(rong)(rong)器(qi)(qi)充電(dian)(dian)(dian)情況(kuang),電(dian)(dian)(dian)阻值不應過低,否則電(dian)(dian)(dian)源(yuan)內部可能(neng)存在短路。電(dian)(dian)(dian)容(rong)(rong)器(qi)(qi)應能(neng)充放(fang)電(dian)(dian)(dian)。脫開負(fu)載,分別測量(liang)各組輸出端的(de)(de)對地電(dian)(dian)(dian)阻,正(zheng)常時,表針應有電(dian)(dian)(dian)容(rong)(rong)器(qi)(qi)充放(fang)電(dian)(dian)(dian)擺動,最后指示的(de)(de)應為該(gai)路的(de)(de)泄(xie)放(fang)電(dian)(dian)(dian)阻的(de)(de)阻值。

開關電源常見故障檢修

1、保險絲熔斷

一般情況下,保(bao)險絲熔(rong)斷說明開(kai)(kai)關(guan)電(dian)源(yuan)的內部(bu)電(dian)路(lu)(lu)存在短路(lu)(lu)或過流(liu)的故障。由于開(kai)(kai)關(guan)電(dian)源(yuan)工作(zuo)在高(gao)電(dian)壓,大(da)(da)電(dian)流(liu)的狀(zhuang)態下,直流(liu)濾(lv)(lv)波(bo)和變換振蕩(dang)電(dian)路(lu)(lu)在高(gao)壓狀(zhuang)態工作(zuo)時間太長,電(dian)壓變化(hua)相對大(da)(da)。電(dian)網電(dian)壓的波(bo)動,浪涌都會引(yin)起(qi)電(dian)源(yuan)內電(dian)流(liu)瞬間增大(da)(da)而(er)使保(bao)險絲熔(rong)斷。重點應檢查(cha)電(dian)源(yuan)輸入端的整流(liu)二極管,高(gao)壓濾(lv)(lv)波(bo)電(dian)解(jie)電(dian)容,開(kai)(kai)關(guan)功率(lv)管,UC3842本身(shen)及(ji)外圍元(yuan)(yuan)器件(jian)等。檢查(cha)一下這些元(yuan)(yuan)器件(jian)有無擊穿,開(kai)(kai)路(lu)(lu),損(sun)壞,燒焦(jiao),炸裂(lie)等現象(xiang)。

維修方法(fa):首(shou)先仔(zi)細(xi)查(cha)看電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)板上面的各個元件(jian),看是(shi)否在(zai)這(zhe)些(xie)元件(jian)的外表有(you)(you)沒有(you)(you)被燒(shao)糊,有(you)(you)沒有(you)(you)電(dian)(dian)(dian)(dian)解液溢出,聞(wen)一(yi)(yi)(yi)聞(wen)有(you)(you)沒有(you)(you)異味。經看,聞(wen)之后(hou),再(zai)用萬用表進行(xing)檢查(cha)。首(shou)先測(ce)(ce)量(liang)一(yi)(yi)(yi)下電(dian)(dian)(dian)(dian)源(yuan)輸(shu)入(ru)端的電(dian)(dian)(dian)(dian)阻(zu)(zu)值(zhi),若(ruo)小(xiao)于200K,則(ze)說明(ming)后(hou)端有(you)(you)局(ju)部短(duan)路(lu)(lu)(lu)現象,然(ran)后(hou)分別測(ce)(ce)量(liang)四只(zhi)整流(liu)二極(ji)管正,反向電(dian)(dian)(dian)(dian)阻(zu)(zu)和兩個限流(liu)電(dian)(dian)(dian)(dian)阻(zu)(zu)的阻(zu)(zu)值(zhi),看其(qi)有(you)(you)無(wu)短(duan)路(lu)(lu)(lu)或燒(shao)壞(huai)(huai)(huai);然(ran)后(hou)再(zai)測(ce)(ce)量(liang)一(yi)(yi)(yi)下電(dian)(dian)(dian)(dian)源(yuan)濾波電(dian)(dian)(dian)(dian)容是(shi)否能(neng)進行(xing)正常充放電(dian)(dian)(dian)(dian),再(zai)就測(ce)(ce)量(liang)一(yi)(yi)(yi)下開關功(gong)率(lv)管是(shi)否擊(ji)穿損壞(huai)(huai)(huai),以及(ji)UC3842本身(shen),及(ji)周圍元件(jian)是(shi)否擊(ji)穿,燒(shao)壞(huai)(huai)(huai)等。需要說明(ming)的一(yi)(yi)(yi)點是(shi):因是(shi)在(zai)路(lu)(lu)(lu)測(ce)(ce)量(liang),有(you)(you)可(ke)能(neng)會使(shi)測(ce)(ce)量(liang)結果(guo)有(you)(you)誤(wu),造成誤(wu)判。因此必(bi)要時可(ke)把元器件(jian)焊下來再(zai)進行(xing)測(ce)(ce)量(liang)。如果(guo)仍然(ran)沒有(you)(you)上述情(qing)況則(ze)測(ce)(ce)量(liang)一(yi)(yi)(yi)下輸(shu)入(ru)電(dian)(dian)(dian)(dian)源(yuan)線及(ji)輸(shu)出電(dian)(dian)(dian)(dian)源(yuan)線是(shi)否內部短(duan)路(lu)(lu)(lu)。一(yi)(yi)(yi)般情(qing)況下,熔斷(duan)(duan)器熔斷(duan)(duan)故障(zhang),整流(liu)二極(ji)管,電(dian)(dian)(dian)(dian)源(yuan)濾波電(dian)(dian)(dian)(dian)容,開關功(gong)率(lv)管,UC3842是(shi)易損件(jian),損壞(huai)(huai)(huai)的概(gai)率(lv)可(ke)達95%以上,一(yi)(yi)(yi)般著重檢查(cha)一(yi)(yi)(yi)下這(zhe)些(xie)元器件(jian),就可(ke)很容易排除此類故障(zhang)。

2、無直流電壓輸出或電壓輸出不穩定

如果保(bao)險絲是完(wan)好的,在有負載(zai)的情況(kuang)下,各級直流(liu)電(dian)壓(ya)無輸出(chu)。這種情況(kuang)主(zhu)要是以下原(yuan)因造成的:電(dian)源中出(chu)現(xian)開路,短(duan)路現(xian)象,過壓(ya),過流(liu)保(bao)護電(dian)路出(chu)現(xian)故障(zhang),振蕩電(dian)路沒有工作,電(dian)源負載(zai)過重,高頻整(zheng)流(liu)濾(lv)(lv)波(bo)電(dian)路中整(zheng)流(liu)二極管被擊穿,濾(lv)(lv)波(bo)電(dian)容漏電(dian)等。

維(wei)修方(fang)法(fa):首先,用(yong)萬用(yong)表(biao)測量一下高頻(pin)變壓(ya)器(qi)次級的(de)各(ge)個元器(qi)件是(shi)否有損壞(huai)。在(zai)(zai)排除(chu)了高頻(pin)整流二極(ji)管擊穿(chuan)、負載(zai)短路(lu)(lu)的(de)情況后,然后在(zai)(zai)測量各(ge)輸(shu)出端的(de)直流電(dian)(dian)(dian)壓(ya),如果這(zhe)時輸(shu)出仍為零,則可以(yi)肯定是(shi)電(dian)(dian)(dian)源(yuan)的(de)控(kong)(kong)制(zhi)電(dian)(dian)(dian)路(lu)(lu)出了故(gu)(gu)(gu)障。控(kong)(kong)制(zhi)電(dian)(dian)(dian)路(lu)(lu)的(de)兩部(bu)分是(shi)集成開關電(dian)(dian)(dian)源(yuan)控(kong)(kong)制(zhi)器(qi)和過壓(ya)保(bao)護電(dian)(dian)(dian)路(lu)(lu)。最后用(yong)萬用(yong)表(biao)靜(jing)態測量高頻(pin)濾波電(dian)(dian)(dian)路(lu)(lu)中整流二極(ji)管及低壓(ya)濾波電(dian)(dian)(dian)容是(shi)否損壞(huai)。如果確實(shi)相關的(de)元件損壞(huai),在(zai)(zai)更(geng)換好新的(de)完(wan)好的(de)元件后,開機測試,一般(ban)故(gu)(gu)(gu)障即可排除(chu)。需(xu)要說(shuo)明的(de)是(shi):電(dian)(dian)(dian)源(yuan)輸(shu)出線斷線或(huo)開焊(han),虛焊(han)也會造(zao)成這(zhe)種故(gu)(gu)(gu)障。在(zai)(zai)維(wei)修時應注(zhu)意這(zhe)一點。

3、電源負載能力差

電源(yuan)負(fu)載能力差是(shi)(shi)一個(ge)常(chang)見的故障,一般都是(shi)(shi)出現在老式或是(shi)(shi)工作時(shi)間長(chang)的電源(yuan)中,主(zhu)要原因是(shi)(shi)各元器件老化,開關(guan)管(guan)(guan)的工作不穩(wen)定,沒有及時(shi)進行散熱等(deng)。此外(wai)還有穩(wen)壓二(er)(er)極管(guan)(guan)發熱漏電,整流二(er)(er)極管(guan)(guan)損壞(huai)等(deng)。

維修方法:用萬用表著重檢查一下(xia)穩壓(ya)二極(ji)管,高壓(ya)濾波(bo)電(dian)(dian)(dian)容,限(xian)流電(dian)(dian)(dian)阻有無變質(zhi)(zhi)等(deng)再仔細(xi)檢查一下(xia)電(dian)(dian)(dian)路板上的(de)(de)所(suo)有焊(han)點是(shi)否(fou)開焊(han),虛(xu)接等(deng)。把開焊(han)的(de)(de)焊(han)點重新焊(han)牢,更換變質(zhi)(zhi)的(de)(de)元器件,一般故障即可排除。

4、無直流電壓輸出,但保險絲完好

這種現象說明開(kai)關電源未工作,或者工作后進入了(le)保護(hu)狀態。

維(wei)修方法:首先(xian)應(ying)判斷一下開(kai)(kai)關(guan)(guan)電(dian)(dian)源的(de)(de)(de)主控芯片(pian)(pian)UC3842是(shi)(shi)(shi)否處(chu)在(zai)工作狀態或(huo)已(yi)經損(sun)壞(huai)。判斷方法是(shi)(shi)(shi)這樣的(de)(de)(de):加電(dian)(dian)測UC3842的(de)(de)(de)第7腳對(dui)地(di)電(dian)(dian)壓,若測第8腳有(you)+5V電(dian)(dian)壓,1,2,4,6腳也(ye)有(you)不(bu)同(tong)的(de)(de)(de)電(dian)(dian)壓,則(ze)說明電(dian)(dian)路已(yi)起振,UC3842基(ji)本正(zheng)(zheng)常(chang);若7腳電(dian)(dian)壓低,其余管腳無電(dian)(dian)壓或(huo)不(bu)波動,則(ze)UC3842已(yi)損(sun)壞(huai)。UC3842芯片(pian)(pian)損(sun)壞(huai)最常(chang)見(jian)的(de)(de)(de)是(shi)(shi)(shi)6,7腳對(dui)地(di)擊穿,5,7腳對(dui)地(di)擊穿和1,7腳對(dui)地(di)擊穿。如(ru)果這幾只腳都為擊穿,而開(kai)(kai)關(guan)(guan)電(dian)(dian)源還(huan)是(shi)(shi)(shi)不(bu)能(neng)正(zheng)(zheng)常(chang)啟動,則(ze)UC3842必(bi)壞(huai),應(ying)直接更換。若判斷芯片(pian)(pian)未壞(huai),則(ze)就著重檢查開(kai)(kai)關(guan)(guan)功(gong)率管的(de)(de)(de)柵極(G極)的(de)(de)(de)限流電(dian)(dian)阻是(shi)(shi)(shi)否開(kai)(kai)焊(han),虛接,變(bian)值(zhi),變(bian)質以(yi)及開(kai)(kai)關(guan)(guan)功(gong)率管本身是(shi)(shi)(shi)否性(xing)能(neng)不(bu)良(liang)。除此之(zhi)外,電(dian)(dian)源輸出(chu)線也(ye)有(you)可能(neng)斷線或(huo)接觸不(bu)良(liang)也(ye)會(hui)造成這種(zhong)故障。因此在(zai)維(wei)修時(shi)也(ye)應(ying)注意檢查一下。

5、有直流電壓輸出,但輸出電壓過高

這種故障往(wang)(wang)往(wang)(wang)來自于穩壓取(qu)樣(yang)和穩壓控(kong)制(zhi)電(dian)(dian)路出(chu)現(xian)故障所致。在開關電(dian)(dian)源中,直流輸出(chu)、取(qu)樣(yang)電(dian)(dian)阻(zu)、誤差取(qu)樣(yang)放大(da)器(如LM324,LM358等)、光耦(ou)合(he)器(PC817)、電(dian)(dian)源控(kong)制(zhi)芯片(pian)(UC3842)等電(dian)(dian)路共同構成了(le)一(yi)個閉合(he)的控(kong)制(zhi)環路,任何一(yi)處出(chu)問題(ti)都(dou)會導致輸出(chu)電(dian)(dian)壓升高。

維修(xiu)方法(fa)(fa):由于開關(guan)電(dian)源(yuan)中有過(guo)(guo)壓(ya)(ya)(ya)(ya)保(bao)護(hu)電(dian)路,輸(shu)出(chu)電(dian)壓(ya)(ya)(ya)(ya)過(guo)(guo)高(gao)(gao)首先會(hui)使過(guo)(guo)壓(ya)(ya)(ya)(ya)保(bao)護(hu)電(dian)路動作。因此對(dui)于這(zhe)種(zhong)故障的(de)維修(xiu),我們(men)可以通過(guo)(guo)斷開過(guo)(guo)壓(ya)(ya)(ya)(ya)保(bao)護(hu)電(dian)路,使過(guo)(guo)壓(ya)(ya)(ya)(ya)保(bao)護(hu)電(dian)路不起作用,在這(zhe)時,測量開機瞬間的(de)電(dian)源(yuan)主電(dian)壓(ya)(ya)(ya)(ya)。如(ru)果測量值比正常值高(gao)(gao)出(chu)IV以上,說明輸(shu)出(chu)電(dian)壓(ya)(ya)(ya)(ya)過(guo)(guo)高(gao)(gao)。我們(men)應著重檢查取樣電(dian)阻是否(fou)變值或損(sun)壞(huai)(huai),精密(mi)穩(wen)壓(ya)(ya)(ya)(ya)放(fang)大(da)器(qi)(TL431)或光耦合器(qi)(PC817)性能不良,變質或損(sun)壞(huai)(huai);其中精密(mi)穩(wen)壓(ya)(ya)(ya)(ya)放(fang)大(da)器(qi)(TL431)極易損(sun)壞(huai)(huai),我們(men)可用下述方法(fa)(fa)對(dui)精密(mi)穩(wen)壓(ya)(ya)(ya)(ya)放(fang)大(da)器(qi)(TL431)作出(chu)好(hao)壞(huai)(huai)的(de)判別:將TL431的(de)參考(kao)端(Ref)與(yu)它的(de)陰(yin)極(Cathode)相連,串(chuan)10k的(de)電(dian)阻,接入5V電(dian)壓(ya)(ya)(ya)(ya),若(ruo)陽極(Anode)與(yu)陰(yin)極之(zhi)間為2、5V,并且等待(dai)片(pian)刻(ke)還仍然為2、5V,則為好(hao)管,否(fou)則為壞(huai)(huai)管。

6、有直流電壓輸出,但輸出直流電壓過低

對于這種故障現象(xiang),根(gen)據維修經(jing)驗可知,除穩壓控制電(dian)路會引起(qi)輸出電(dian)壓過低(di)外,還有一(yi)些原因(yin)會引起(qi)輸出電(dian)壓過低(di),主要(yao)有以下(xia)幾點(dian):


① 開(kai)關電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)負(fu)載有短路(lu)(lu)(lu)故障(zhang)(zhang)。此時,應斷開(kai)開(kai)關電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)的所有負(fu)載,以區分(fen)是(shi)開(kai)關電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)還是(shi)負(fu)載電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)有故障(zhang)(zhang)。若(ruo)斷開(kai)負(fu)載電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)電(dian)(dian)(dian)(dian)(dian)壓輸出正常(chang),說明(ming)是(shi)負(fu)載過重(zhong);若(ruo)仍不(bu)正常(chang),說明(ming)開(kai)關電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)有故障(zhang)(zhang)。

② 輸出電壓(ya)端整流二極(ji)管、濾波電容失效等(deng),可以通過代(dai)換法(fa)進行判斷。

③ 開關功(gong)率管的(de)性能(neng)下(xia)降,必然導致開關管不能(neng)正常導通,使電源的(de)內阻增加,帶負(fu)載能(neng)力下(xia)降。

④ 開關功率管的(de)源極(S極),通常接一個(ge)阻(zu)(zu)值(zhi)很小(xiao),但功率很大(da)的(de)電阻(zu)(zu),作為過流保護檢測電阻(zu)(zu),此電阻(zu)(zu)的(de)阻(zu)(zu)值(zhi)一般在0.2到(dao)0.8之間。此電阻(zu)(zu)如變值(zhi)或(huo)開焊(han),接觸(chu)不良也會造成輸出電壓過低的(de)故障。

高頻變壓(ya)器不(bu)良,不(bu)但造成輸出(chu)電壓(ya)下降,還(huan)會造成開關功(gong)率管(guan)激勵不(bu)足從(cong)而屢損(sun)開關管(guan)。

⑤ 高壓直流濾波電容不良,造(zao)成電源(yuan)帶負載(zai)能力(li)差(cha),一接(jie)負載(zai)輸出電壓便(bian)下降(jiang)。

⑥ 電源輸出線接觸不良,有一定的接觸電阻,造成輸出電壓過低(di)。

⑦ 電(dian)網(wang)(wang)電(dian)壓是否過低。雖然(ran)開(kai)(kai)關電(dian)源(yuan)在低壓下仍然(ran)可以輸出(chu)額(e)定(ding)的電(dian)壓值(zhi),但(dan)當電(dian)網(wang)(wang)電(dian)壓低于開(kai)(kai)關電(dian)源(yuan)的最(zui)低電(dian)壓限定(ding)值(zhi)時,也(ye)會使輸出(chu)電(dian)壓過低。

維(wei)修方法:對(dui)于這種故(gu)障(zhang)我們可(ke)以(yi)(yi)根據(ju)以(yi)(yi)上故(gu)障(zhang)原因,來逐一(yi)(yi)(yi)進行排查(cha)(cha)(cha)。但(dan)在(zai)(zai)實際(ji)維(wei)修時(shi),可(ke)根據(ju)實際(ji)情況來進行排查(cha)(cha)(cha),不(bu)一(yi)(yi)(yi)定要逐一(yi)(yi)(yi)排查(cha)(cha)(cha)。首先用(yong)(yong)(yong)萬(wan)用(yong)(yong)(yong)表檢查(cha)(cha)(cha)一(yi)(yi)(yi)下(xia)(xia)高(gao)(gao)壓(ya)直(zhi)流(liu)濾波電(dian)(dian)(dian)容(rong)是(shi)否(fou)變(bian)(bian)質,容(rong)量(liang)是(shi)否(fou)下(xia)(xia)降(jiang),能否(fou)正常(chang)充放電(dian)(dian)(dian)。如無(wu)以(yi)(yi)上現象,則(ze)測量(liang)一(yi)(yi)(yi)下(xia)(xia)開關功(gong)率(lv)管的(de)(de)(de)(de)(de)柵極(ji)(G極(ji))的(de)(de)(de)(de)(de)限流(liu)電(dian)(dian)(dian)阻(zu)以(yi)(yi)及源極(ji)(S極(ji))的(de)(de)(de)(de)(de)過流(liu)保(bao)護檢測電(dian)(dian)(dian)阻(zu)是(shi)否(fou)變(bian)(bian)值,變(bian)(bian)質或(huo)(huo)開焊(han)(han),接(jie)觸不(bu)良。經判別后,若無(wu)問題,我們就檢查(cha)(cha)(cha)一(yi)(yi)(yi)下(xia)(xia)高(gao)(gao)頻(pin)變(bian)(bian)壓(ya)器(qi)的(de)(de)(de)(de)(de)鐵(tie)芯(xin)是(shi)否(fou)完好無(wu)損(sun)。因在(zai)(zai)日常(chang)生活使(shi)用(yong)(yong)(yong)中,不(bu)可(ke)避免的(de)(de)(de)(de)(de)重(zhong)摔或(huo)(huo)重(zhong)幢,使(shi)高(gao)(gao)頻(pin)變(bian)(bian)壓(ya)器(qi)的(de)(de)(de)(de)(de)鐵(tie)芯(xin)損(sun)壞。使(shi)高(gao)(gao)頻(pin)變(bian)(bian)壓(ya)器(qi)的(de)(de)(de)(de)(de)磁通量(liang),磁感應(ying)強度,以(yi)(yi)及磁路等都(dou)會受到(dao)很大(da)的(de)(de)(de)(de)(de)影響(xiang),造成傳輸(shu)(shu)的(de)(de)(de)(de)(de)效(xiao)率(lv),能量(liang)將會大(da)打折扣。由于高(gao)(gao)頻(pin)變(bian)(bian)壓(ya)器(qi)為了(le)減小渦流(liu),增(zeng)大(da)高(gao)(gao)頻(pin)交流(liu)電(dian)(dian)(dian)的(de)(de)(de)(de)(de)傳輸(shu)(shu)效(xiao)率(lv),它的(de)(de)(de)(de)(de)鐵(tie)芯(xin)是(shi)用(yong)(yong)(yong)軟(ruan)磁鐵(tie)氧體(ti)制作而成的(de)(de)(de)(de)(de)。這種磁性材料(liao)具有(you)高(gao)(gao)的(de)(de)(de)(de)(de)導磁率(lv),但(dan)質脆,易碎。因此它的(de)(de)(de)(de)(de)損(sun)壞率(lv)也是(shi)很高(gao)(gao)的(de)(de)(de)(de)(de)。因此在(zai)(zai)維(wei)修時(shi)千(qian)萬(wan)不(bu)要忘了(le)檢查(cha)(cha)(cha)此處,以(yi)(yi)免走彎路。除此之(zhi)外還有(you)可(ke)能就是(shi)輸(shu)(shu)出(chu)濾波電(dian)(dian)(dian)容(rong)容(rong)量(liang)降(jiang)低,甚至失(shi)容(rong)或(huo)(huo)開焊(han)(han),虛(xu)(xu)接(jie);電(dian)(dian)(dian)源輸(shu)(shu)出(chu)限流(liu)電(dian)(dian)(dian)阻(zu)變(bian)(bian)值或(huo)(huo)虛(xu)(xu)接(jie),電(dian)(dian)(dian)源輸(shu)(shu)出(chu)線虛(xu)(xu)接(jie)等。在(zai)(zai)實際(ji)維(wei)修時(shi),這些因素都(dou)不(bu)要放過,都(dou)應(ying)檢查(cha)(cha)(cha)一(yi)(yi)(yi)下(xia)(xia),以(yi)(yi)保(bao)證萬(wan)無(wu)一(yi)(yi)(yi)失(shi)。

7、散熱風扇不轉

這種(zhong)故障原因主要是(shi)由(you)于控制風(feng)扇的(de)(de)三極管(guan)(8550或8050)損(sun)壞,或者(zhe)風(feng)扇本身損(sun)壞或風(feng)葉被雜(za)物卡住。但(dan)有些開(kai)關(guan)電(dian)源(yuan)(yuan)中采用的(de)(de)是(shi)智能散(san)熱,對于采用這種(zhong)方式(shi)散(san)熱的(de)(de)開(kai)關(guan)電(dian)源(yuan)(yuan),熱敏電(dian)阻損(sun)壞的(de)(de)概率是(shi)很大(da)的(de)(de)。

維(wei)修方法:首先(xian)用(yong)萬用(yong)表測(ce)量一(yi)下(xia)控制風(feng)(feng)扇(shan)(shan)(shan)(shan)的三(san)極管是否(fou)損(sun)壞(huai),若(ruo)測(ce)得此管未(wei)損(sun)壞(huai)那就有可(ke)能是風(feng)(feng)扇(shan)(shan)(shan)(shan)本身損(sun)壞(huai)。可(ke)以把風(feng)(feng)扇(shan)(shan)(shan)(shan)從電(dian)(dian)路(lu)板上(shang)拔下(xia)來,另外(wai)(wai)接上(shang)一(yi)個12V的直流電(dian)(dian)(注(zhu)意正負極),看(kan)是否(fou)轉動(dong),并(bing)看(kan)有無(wu)異物卡住。若(ruo)擺動(dong)幾下(xia)風(feng)(feng)扇(shan)(shan)(shan)(shan)的電(dian)(dian)線(xian),風(feng)(feng)扇(shan)(shan)(shan)(shan)就轉動(dong),則(ze)說明(ming)電(dian)(dian)線(xian)內部(bu)有斷線(xian)或接頭接觸不(bu)良(liang)。若(ruo)仍(reng)不(bu)轉動(dong),則(ze)風(feng)(feng)扇(shan)(shan)(shan)(shan)必壞(huai)。對于采用(yong)智(zhi)能散熱(re)的開(kai)關電(dian)(dian)源來說,除按(an)上(shang)述(shu)檢(jian)查外(wai)(wai),還應檢(jian)查一(yi)下(xia)熱(re)敏(min)電(dian)(dian)阻(zu)(zu)是否(fou)不(bu)良(liang)或損(sun)壞(huai),開(kai)焊等。但要注(zhu)意此熱(re)敏(min)電(dian)(dian)阻(zu)(zu)為負溫(wen)度系數(shu)的熱(re)敏(min)電(dian)(dian)阻(zu)(zu),更換時應注(zhu)意。

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很好,學習了,謝謝了
網友 (182.87.*.*)  09-25 21:46
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