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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(shi)利用(yong)現代電力電子技(ji)術(shu),控制開(kai)(kai)關晶(jing)體管開(kai)(kai)通和關斷的時間比率,維(wei)(wei)持穩定(ding)輸出電壓的一種電源。廣泛運用(yong)在(zai)(zai)工業(ye)、軍事、科研、通訊(xun)、醫療及多種家(jia)用(yong)電器中。開(kai)(kai)關電源的發展與應(ying)用(yong)在(zai)(zai)節約(yue)能源、節約(yue)資源及保護環境方面都(dou)具(ju)有重(zhong)要的意義。下面我們就來看看開(kai)(kai)關電源電路圖與維(wei)(wei)修技(ji)巧(qiao)。

開關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的主要電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)是(shi)由輸(shu)(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)磁干擾濾(lv)波(bo)器(EMI)、整(zheng)流濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、功率變換電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、PWM控制器電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、輸(shu)(shu)出(chu)整(zheng)流濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)組成。輔助電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)有輸(shu)(shu)入過(guo)欠(qian)壓保(bao)(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、輸(shu)(shu)出(chu)過(guo)欠(qian)壓保(bao)(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、輸(shu)(shu)出(chu)過(guo)流保(bao)(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)、輸(shu)(shu)出(chu)短路(lu)(lu)(lu)(lu)保(bao)(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)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(dian)后觀察電(dian)源是否有燒(shao)保險及(ji)個別(bie)元件冒煙(yan)等現象,若有要(yao)及(ji)時切(qie)斷供電(dian)進行檢(jian)修(xiu)。

測量高壓濾波電容兩(liang)端有無300伏(fu)輸(shu)出,若無應(ying)重(zhong)點查整流二極(ji)管、濾波電容等。

測量(liang)高頻變壓器次級(ji)線圈有(you)無(wu)輸出,若(ruo)無(wu)應(ying)重點(dian)查開關管是否損壞,是否起振,保(bao)護電路(lu)是否動作等(deng)(deng),若(ruo)有(you)則(ze)應(ying)重點(dian)檢查各輸出側的整流二極管、濾(lv)波電容、三通穩(wen)壓管等(deng)(deng)。

如果電源啟動一下(xia)就停止,則該(gai)電源處于(yu)保護(hu)狀(zhuang)態下(xia),可(ke)直接測(ce)量PWM芯片保護(hu)輸入腳的電壓(ya),如果電壓(ya)超出(chu)規定值(zhi),則說明電源處于(yu)保護(hu)狀(zhuang)態下(xia),應重點檢查產生保護(hu)的原因。

總(zong)之,開(kai)關(guan)電(dian)(dian)源(yuan)電(dian)(dian)路有易有難,功率有大有小,輸(shu)出電(dian)(dian)壓(ya)多種(zhong)多樣。只要按(an)照上述維(wei)修技巧,多動手進行開(kai)關(guan)電(dian)(dian)源(yuan)的(de)維(wei)修,就能(neng)迅速地排除(chu)開(kai)關(guan)電(dian)(dian)源(yuan)故障,達到事半功倍的(de)效(xiao)果。

斷電后看聞問量

看:打(da)開電(dian)源(yuan)的(de)外殼,檢查(cha)保險絲是(shi)否熔斷,再觀察電(dian)源(yuan)的(de)內(nei)部(bu)情況,如果發現電(dian)源(yuan)的(de)PCB板上(shang)有燒焦(jiao)處或元件(jian)破裂,則(ze)應(ying)重(zhong)點檢查(cha)此處元件(jian)及相關電(dian)路元件(jian)。

聞(wen):聞(wen)一(yi)下電(dian)源內部是否(fou)有糊味,檢查(cha)是否(fou)有燒焦的元(yuan)器件。

問(wen)(wen):問(wen)(wen)一下電(dian)源(yuan)損壞的經過,是否對(dui)電(dian)源(yuan)進行違規操作。

量:沒通電(dian)(dian)(dian)(dian)前(qian),用(yong)(yong)(yong)(yong)萬用(yong)(yong)(yong)(yong)表(biao)量一下高壓(ya)電(dian)(dian)(dian)(dian)容(rong)(rong)兩(liang)端的(de)電(dian)(dian)(dian)(dian)壓(ya)先。如果是開(kai)關電(dian)(dian)(dian)(dian)源(yuan)不(bu)起振或開(kai)關管開(kai)路引起的(de)故障,則大多(duo)數情(qing)況下,高壓(ya)濾(lv)波(bo)電(dian)(dian)(dian)(dian)容(rong)(rong)兩(liang)端的(de)電(dian)(dian)(dian)(dian)壓(ya)未泄(xie)放(fang)悼,用(yong)(yong)(yong)(yong)萬用(yong)(yong)(yong)(yong)表(biao)測量AC電(dian)(dian)(dian)(dian)源(yuan)線兩(liang)端的(de)正反(fan)向電(dian)(dian)(dian)(dian)阻(zu)及電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)充電(dian)(dian)(dian)(dian)情(qing)況,電(dian)(dian)(dian)(dian)阻(zu)值不(bu)應(ying)過低,否則電(dian)(dian)(dian)(dian)源(yuan)內部可(ke)能存在短路。電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)應(ying)能充放(fang)電(dian)(dian)(dian)(dian)。脫開(kai)負載,分(fen)別(bie)測量各組輸出端的(de)對地(di)電(dian)(dian)(dian)(dian)阻(zu),正常時,表(biao)針應(ying)有電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)充放(fang)電(dian)(dian)(dian)(dian)擺動,最后(hou)指(zhi)示的(de)應(ying)為該路的(de)泄(xie)放(fang)電(dian)(dian)(dian)(dian)阻(zu)的(de)阻(zu)值。

開關電源常見故障檢修

1、保險絲熔斷

一般情況(kuang)下,保(bao)險絲熔(rong)斷(duan)說明開(kai)(kai)(kai)關(guan)電(dian)(dian)源的(de)(de)(de)內部電(dian)(dian)路存在短路或(huo)過流(liu)(liu)的(de)(de)(de)故障。由于(yu)開(kai)(kai)(kai)關(guan)電(dian)(dian)源工作(zuo)在高電(dian)(dian)壓(ya),大(da)(da)電(dian)(dian)流(liu)(liu)的(de)(de)(de)狀態下,直(zhi)流(liu)(liu)濾波和(he)變(bian)換(huan)振蕩電(dian)(dian)路在高壓(ya)狀態工作(zuo)時間(jian)(jian)太長,電(dian)(dian)壓(ya)變(bian)化相對大(da)(da)。電(dian)(dian)網(wang)電(dian)(dian)壓(ya)的(de)(de)(de)波動,浪涌都(dou)會引起電(dian)(dian)源內電(dian)(dian)流(liu)(liu)瞬(shun)間(jian)(jian)增大(da)(da)而(er)使保(bao)險絲熔(rong)斷(duan)。重點應(ying)檢(jian)查(cha)電(dian)(dian)源輸入端的(de)(de)(de)整流(liu)(liu)二極(ji)管,高壓(ya)濾波電(dian)(dian)解電(dian)(dian)容,開(kai)(kai)(kai)關(guan)功率管,UC3842本身及外(wai)圍(wei)元器件等(deng)。檢(jian)查(cha)一下這些元器件有無(wu)擊(ji)穿,開(kai)(kai)(kai)路,損(sun)壞,燒(shao)焦(jiao),炸裂等(deng)現象。

維修方法:首先仔細查(cha)看電(dian)(dian)路板上(shang)面的(de)(de)各個(ge)元(yuan)(yuan)件(jian),看是(shi)(shi)否(fou)在這(zhe)些元(yuan)(yuan)件(jian)的(de)(de)外(wai)表(biao)(biao)有沒(mei)有被燒糊,有沒(mei)有電(dian)(dian)解液溢(yi)出,聞(wen)(wen)一(yi)聞(wen)(wen)有沒(mei)有異味。經看,聞(wen)(wen)之后(hou),再(zai)用萬用表(biao)(biao)進行(xing)檢查(cha)。首先測(ce)量(liang)(liang)一(yi)下(xia)(xia)電(dian)(dian)源輸入端(duan)的(de)(de)電(dian)(dian)阻(zu)(zu)值,若小于200K,則說明(ming)后(hou)端(duan)有局部(bu)短路現(xian)象,然后(hou)分別測(ce)量(liang)(liang)四只(zhi)整流(liu)(liu)二極(ji)管正(zheng),反向電(dian)(dian)阻(zu)(zu)和兩個(ge)限流(liu)(liu)電(dian)(dian)阻(zu)(zu)的(de)(de)阻(zu)(zu)值,看其有無短路或(huo)燒壞;然后(hou)再(zai)測(ce)量(liang)(liang)一(yi)下(xia)(xia)電(dian)(dian)源濾(lv)波電(dian)(dian)容是(shi)(shi)否(fou)能進行(xing)正(zheng)常充(chong)放電(dian)(dian),再(zai)就(jiu)測(ce)量(liang)(liang)一(yi)下(xia)(xia)開(kai)關功(gong)(gong)率管是(shi)(shi)否(fou)擊穿(chuan)損(sun)壞,以及(ji)UC3842本身,及(ji)周圍元(yuan)(yuan)件(jian)是(shi)(shi)否(fou)擊穿(chuan),燒壞等。需(xu)要說明(ming)的(de)(de)一(yi)點是(shi)(shi):因是(shi)(shi)在路測(ce)量(liang)(liang),有可能會使測(ce)量(liang)(liang)結果有誤(wu)(wu),造成誤(wu)(wu)判。因此(ci)必要時(shi)可把元(yuan)(yuan)器件(jian)焊下(xia)(xia)來再(zai)進行(xing)測(ce)量(liang)(liang)。如(ru)果仍然沒(mei)有上(shang)述情況則測(ce)量(liang)(liang)一(yi)下(xia)(xia)輸入電(dian)(dian)源線(xian)及(ji)輸出電(dian)(dian)源線(xian)是(shi)(shi)否(fou)內(nei)部(bu)短路。一(yi)般情況下(xia)(xia),熔斷器熔斷故障,整流(liu)(liu)二極(ji)管,電(dian)(dian)源濾(lv)波電(dian)(dian)容,開(kai)關功(gong)(gong)率管,UC3842是(shi)(shi)易損(sun)件(jian),損(sun)壞的(de)(de)概率可達95%以上(shang),一(yi)般著重檢查(cha)一(yi)下(xia)(xia)這(zhe)些元(yuan)(yuan)器件(jian),就(jiu)可很容易排除此(ci)類(lei)故障。

2、無直流電壓輸出或電壓輸出不穩定

如果保險絲是完好的(de),在(zai)有負(fu)載的(de)情(qing)況下(xia),各級直(zhi)流電壓(ya)無輸出(chu)。這種(zhong)情(qing)況主要(yao)是以下(xia)原因造成(cheng)的(de):電源中(zhong)出(chu)現開路(lu),短(duan)路(lu)現象,過壓(ya),過流保護電路(lu)出(chu)現故障,振蕩電路(lu)沒(mei)有工作,電源負(fu)載過重,高頻整流濾波(bo)電路(lu)中(zhong)整流二極管被擊穿,濾波(bo)電容漏電等。

維修方法:首先(xian),用(yong)(yong)萬用(yong)(yong)表(biao)測(ce)量(liang)(liang)一(yi)下高(gao)頻(pin)變壓(ya)器次級(ji)的(de)(de)(de)各個(ge)元器件(jian)是否有損壞。在排(pai)除了高(gao)頻(pin)整流(liu)二極(ji)管(guan)擊(ji)穿、負載短路(lu)的(de)(de)(de)情(qing)況后(hou),然(ran)后(hou)在測(ce)量(liang)(liang)各輸(shu)出(chu)端的(de)(de)(de)直流(liu)電(dian)壓(ya),如(ru)果(guo)這(zhe)時輸(shu)出(chu)仍為零,則可以肯(ken)定是電(dian)源(yuan)(yuan)的(de)(de)(de)控(kong)制電(dian)路(lu)出(chu)了故(gu)障(zhang)。控(kong)制電(dian)路(lu)的(de)(de)(de)兩部分是集成(cheng)開(kai)(kai)關電(dian)源(yuan)(yuan)控(kong)制器和過壓(ya)保護(hu)電(dian)路(lu)。最后(hou)用(yong)(yong)萬用(yong)(yong)表(biao)靜態測(ce)量(liang)(liang)高(gao)頻(pin)濾波(bo)電(dian)路(lu)中整流(liu)二極(ji)管(guan)及低壓(ya)濾波(bo)電(dian)容是否損壞。如(ru)果(guo)確實相(xiang)關的(de)(de)(de)元件(jian)損壞,在更換好(hao)新的(de)(de)(de)完(wan)好(hao)的(de)(de)(de)元件(jian)后(hou),開(kai)(kai)機測(ce)試(shi),一(yi)般故(gu)障(zhang)即(ji)可排(pai)除。需要說(shuo)明的(de)(de)(de)是:電(dian)源(yuan)(yuan)輸(shu)出(chu)線(xian)(xian)斷線(xian)(xian)或(huo)開(kai)(kai)焊(han),虛焊(han)也會造成(cheng)這(zhe)種故(gu)障(zhang)。在維修時應注(zhu)意這(zhe)一(yi)點。

3、電源負載能力差

電(dian)源負載能力差是(shi)一(yi)個常見的故障,一(yi)般都是(shi)出現在老式或是(shi)工作時間(jian)長的電(dian)源中,主要原因是(shi)各元(yuan)器件老化(hua),開關管(guan)的工作不穩定(ding),沒有(you)及時進行散熱(re)等(deng)。此外還有(you)穩壓二極管(guan)發熱(re)漏電(dian),整流(liu)二極管(guan)損壞等(deng)。

維修(xiu)方法:用萬用表著重(zhong)檢查(cha)一下穩壓(ya)二(er)極管,高壓(ya)濾波電容,限流電阻有無變質等再仔細(xi)檢查(cha)一下電路板上的(de)所有焊(han)(han)點(dian)是否(fou)開(kai)焊(han)(han),虛接(jie)等。把開(kai)焊(han)(han)的(de)焊(han)(han)點(dian)重(zhong)新焊(han)(han)牢,更(geng)換(huan)變質的(de)元器件,一般故障即(ji)可排(pai)除。

4、無直流電壓輸出,但保險絲完好

這(zhe)種(zhong)現象說明開關電源未(wei)工作,或者工作后(hou)進入了保護(hu)狀(zhuang)態。

維(wei)(wei)修(xiu)方法(fa):首先(xian)應判(pan)斷一(yi)下開(kai)關(guan)(guan)電(dian)(dian)源的主控(kong)芯(xin)片(pian)UC3842是否處在(zai)工作狀態或(huo)已經損(sun)壞。判(pan)斷方法(fa)是這(zhe)樣的:加電(dian)(dian)測(ce)UC3842的第7腳(jiao)(jiao)對(dui)地(di)(di)電(dian)(dian)壓(ya),若(ruo)測(ce)第8腳(jiao)(jiao)有(you)(you)+5V電(dian)(dian)壓(ya),1,2,4,6腳(jiao)(jiao)也(ye)有(you)(you)不(bu)同的電(dian)(dian)壓(ya),則說明電(dian)(dian)路已起振,UC3842基(ji)本(ben)正常(chang);若(ruo)7腳(jiao)(jiao)電(dian)(dian)壓(ya)低,其余(yu)管(guan)(guan)腳(jiao)(jiao)無(wu)電(dian)(dian)壓(ya)或(huo)不(bu)波動(dong),則UC3842已損(sun)壞。UC3842芯(xin)片(pian)損(sun)壞最常(chang)見的是6,7腳(jiao)(jiao)對(dui)地(di)(di)擊穿,5,7腳(jiao)(jiao)對(dui)地(di)(di)擊穿和1,7腳(jiao)(jiao)對(dui)地(di)(di)擊穿。如果這(zhe)幾只腳(jiao)(jiao)都為擊穿,而開(kai)關(guan)(guan)電(dian)(dian)源還是不(bu)能正常(chang)啟動(dong),則UC3842必壞,應直(zhi)接(jie)更換。若(ruo)判(pan)斷芯(xin)片(pian)未壞,則就著重(zhong)檢查開(kai)關(guan)(guan)功率管(guan)(guan)的柵(zha)極(G極)的限流電(dian)(dian)阻是否開(kai)焊,虛接(jie),變(bian)值,變(bian)質(zhi)以及開(kai)關(guan)(guan)功率管(guan)(guan)本(ben)身是否性(xing)能不(bu)良。除此之(zhi)外(wai),電(dian)(dian)源輸出(chu)線也(ye)有(you)(you)可能斷線或(huo)接(jie)觸不(bu)良也(ye)會造成這(zhe)種故(gu)障。因此在(zai)維(wei)(wei)修(xiu)時也(ye)應注(zhu)意檢查一(yi)下。

5、有直流電壓輸出,但輸出電壓過高

這種(zhong)故(gu)障往(wang)往(wang)來自于穩壓取(qu)(qu)樣和穩壓控(kong)(kong)制電(dian)路(lu)出現故(gu)障所(suo)致(zhi)。在(zai)開關(guan)電(dian)源中(zhong),直(zhi)流輸出、取(qu)(qu)樣電(dian)阻、誤(wu)差取(qu)(qu)樣放大(da)器(如LM324,LM358等(deng))、光耦合器(PC817)、電(dian)源控(kong)(kong)制芯片(UC3842)等(deng)電(dian)路(lu)共同構成了(le)一(yi)個閉合的控(kong)(kong)制環路(lu),任何(he)一(yi)處出問題都會導致(zhi)輸出電(dian)壓升高。

維修方(fang)法:由于(yu)開關(guan)電(dian)(dian)(dian)源中有過(guo)壓(ya)(ya)保護(hu)電(dian)(dian)(dian)路(lu),輸出(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)過(guo)高首(shou)先會使(shi)過(guo)壓(ya)(ya)保護(hu)電(dian)(dian)(dian)路(lu)動作。因此對于(yu)這種故障的(de)維修,我們可(ke)以通過(guo)斷開過(guo)壓(ya)(ya)保護(hu)電(dian)(dian)(dian)路(lu),使(shi)過(guo)壓(ya)(ya)保護(hu)電(dian)(dian)(dian)路(lu)不起作用(yong),在這時,測量(liang)開機瞬間的(de)電(dian)(dian)(dian)源主電(dian)(dian)(dian)壓(ya)(ya)。如果測量(liang)值(zhi)比正常值(zhi)高出(chu)(chu)IV以上,說明輸出(chu)(chu)電(dian)(dian)(dian)壓(ya)(ya)過(guo)高。我們應著重檢(jian)查取樣(yang)電(dian)(dian)(dian)阻是否變值(zhi)或(huo)損(sun)壞(huai),精密穩(wen)壓(ya)(ya)放大器(qi)(TL431)或(huo)光耦合器(qi)(PC817)性(xing)能不良(liang),變質(zhi)或(huo)損(sun)壞(huai);其中精密穩(wen)壓(ya)(ya)放大器(qi)(TL431)極(ji)易損(sun)壞(huai),我們可(ke)用(yong)下述方(fang)法對精密穩(wen)壓(ya)(ya)放大器(qi)(TL431)作出(chu)(chu)好壞(huai)的(de)判(pan)別:將TL431的(de)參考(kao)端(Ref)與(yu)它的(de)陰(yin)極(ji)(Cathode)相連,串10k的(de)電(dian)(dian)(dian)阻,接入5V電(dian)(dian)(dian)壓(ya)(ya),若陽(yang)極(ji)(Anode)與(yu)陰(yin)極(ji)之(zhi)間為(wei)2、5V,并且等(deng)待片刻還仍(reng)然為(wei)2、5V,則為(wei)好管,否則為(wei)壞(huai)管。

6、有直流電壓輸出,但輸出直流電壓過低

對于這種故(gu)障(zhang)現象,根據維修(xiu)經(jing)驗可知,除穩壓控制電路會引起輸出電壓過(guo)低外(wai),還有(you)一些原因會引起輸出電壓過(guo)低,主要(yao)有(you)以下幾點:


① 開關電(dian)源負(fu)載(zai)(zai)有短路(lu)(lu)故障(zhang)。此(ci)時,應斷開開關電(dian)源電(dian)路(lu)(lu)的所(suo)有負(fu)載(zai)(zai),以區分(fen)是開關電(dian)源電(dian)路(lu)(lu)還是負(fu)載(zai)(zai)電(dian)路(lu)(lu)有故障(zhang)。若(ruo)斷開負(fu)載(zai)(zai)電(dian)路(lu)(lu)電(dian)壓輸(shu)出正常,說明(ming)是負(fu)載(zai)(zai)過重;若(ruo)仍不(bu)正常,說明(ming)開關電(dian)源電(dian)路(lu)(lu)有故障(zhang)。

② 輸出電(dian)壓端整流二極管、濾(lv)波電(dian)容失效(xiao)等(deng),可(ke)以(yi)通過(guo)代換法進行判(pan)斷。

③ 開關功率管(guan)的性(xing)能(neng)下降(jiang),必然導致開關管(guan)不能(neng)正常導通,使(shi)電源(yuan)的內阻增加,帶(dai)負載能(neng)力下降(jiang)。

④ 開(kai)關功率(lv)管(guan)的源極(S極),通常(chang)接一個阻值很(hen)小,但(dan)功率(lv)很(hen)大的電阻,作為過(guo)流保(bao)護檢測電阻,此(ci)電阻的阻值一般在0.2到0.8之間。此(ci)電阻如變值或開(kai)焊,接觸不良也會造成輸出電壓過(guo)低的故障。

高頻(pin)變壓(ya)(ya)器不良,不但造(zao)成輸(shu)出電壓(ya)(ya)下降,還會造(zao)成開關(guan)功率管激(ji)勵不足從而屢損開關(guan)管。

⑤ 高壓直流濾波電容不(bu)良,造成電源帶負載能(neng)力(li)差,一接負載輸出電壓便下降。

⑥ 電(dian)源輸(shu)出線接觸不(bu)良,有一(yi)定(ding)的接觸電(dian)阻,造成輸(shu)出電(dian)壓過(guo)低。

⑦ 電(dian)網電(dian)壓(ya)是否過低(di)。雖然開關(guan)電(dian)源(yuan)在低(di)壓(ya)下仍然可以(yi)輸出(chu)額定的電(dian)壓(ya)值,但當電(dian)網電(dian)壓(ya)低(di)于開關(guan)電(dian)源(yuan)的最低(di)電(dian)壓(ya)限定值時,也會使輸出(chu)電(dian)壓(ya)過低(di)。

維修(xiu)方法:對于(yu)這(zhe)種故障我們可(ke)以(yi)根(gen)據(ju)以(yi)上故障原(yuan)因(yin),來逐一(yi)(yi)(yi)進(jin)行排查(cha)(cha)。但在(zai)實際(ji)維修(xiu)時,可(ke)根(gen)據(ju)實際(ji)情(qing)況來進(jin)行排查(cha)(cha),不(bu)一(yi)(yi)(yi)定要(yao)逐一(yi)(yi)(yi)排查(cha)(cha)。首先用(yong)萬用(yong)表(biao)檢(jian)(jian)查(cha)(cha)一(yi)(yi)(yi)下(xia)高(gao)(gao)壓(ya)(ya)(ya)直流濾波電(dian)(dian)(dian)容是(shi)(shi)否(fou)(fou)變(bian)質(zhi),容量(liang)是(shi)(shi)否(fou)(fou)下(xia)降(jiang),能(neng)否(fou)(fou)正常充放電(dian)(dian)(dian)。如無(wu)以(yi)上現象,則測量(liang)一(yi)(yi)(yi)下(xia)開(kai)關功率管的(de)柵(zha)極(ji)(G極(ji))的(de)限流電(dian)(dian)(dian)阻以(yi)及源極(ji)(S極(ji))的(de)過流保(bao)護檢(jian)(jian)測電(dian)(dian)(dian)阻是(shi)(shi)否(fou)(fou)變(bian)值,變(bian)質(zhi)或(huo)開(kai)焊(han),接(jie)觸不(bu)良。經判別后,若無(wu)問題,我們就(jiu)檢(jian)(jian)查(cha)(cha)一(yi)(yi)(yi)下(xia)高(gao)(gao)頻(pin)變(bian)壓(ya)(ya)(ya)器的(de)鐵(tie)(tie)芯是(shi)(shi)否(fou)(fou)完好無(wu)損(sun)。因(yin)在(zai)日常生活使(shi)用(yong)中,不(bu)可(ke)避免的(de)重摔或(huo)重幢(chuang),使(shi)高(gao)(gao)頻(pin)變(bian)壓(ya)(ya)(ya)器的(de)鐵(tie)(tie)芯損(sun)壞。使(shi)高(gao)(gao)頻(pin)變(bian)壓(ya)(ya)(ya)器的(de)磁(ci)(ci)通量(liang),磁(ci)(ci)感應強度(du),以(yi)及磁(ci)(ci)路等(deng)都(dou)會受(shou)到很大(da)的(de)影響,造成傳輸(shu)(shu)的(de)效率,能(neng)量(liang)將會大(da)打(da)折扣。由于(yu)高(gao)(gao)頻(pin)變(bian)壓(ya)(ya)(ya)器為(wei)了(le)減(jian)小渦流,增(zeng)大(da)高(gao)(gao)頻(pin)交流電(dian)(dian)(dian)的(de)傳輸(shu)(shu)效率,它的(de)鐵(tie)(tie)芯是(shi)(shi)用(yong)軟磁(ci)(ci)鐵(tie)(tie)氧體制(zhi)作(zuo)而成的(de)。這(zhe)種磁(ci)(ci)性材料具有高(gao)(gao)的(de)導磁(ci)(ci)率,但質(zhi)脆,易碎。因(yin)此(ci)它的(de)損(sun)壞率也是(shi)(shi)很高(gao)(gao)的(de)。因(yin)此(ci)在(zai)維修(xiu)時千(qian)萬不(bu)要(yao)忘了(le)檢(jian)(jian)查(cha)(cha)此(ci)處,以(yi)免走彎路。除此(ci)之外(wai)還有可(ke)能(neng)就(jiu)是(shi)(shi)輸(shu)(shu)出(chu)濾波電(dian)(dian)(dian)容容量(liang)降(jiang)低,甚(shen)至失(shi)容或(huo)開(kai)焊(han),虛接(jie);電(dian)(dian)(dian)源輸(shu)(shu)出(chu)限流電(dian)(dian)(dian)阻變(bian)值或(huo)虛接(jie),電(dian)(dian)(dian)源輸(shu)(shu)出(chu)線虛接(jie)等(deng)。在(zai)實際(ji)維修(xiu)時,這(zhe)些因(yin)素都(dou)不(bu)要(yao)放過,都(dou)應檢(jian)(jian)查(cha)(cha)一(yi)(yi)(yi)下(xia),以(yi)保(bao)證(zheng)萬無(wu)一(yi)(yi)(yi)失(shi)。

7、散熱風扇不轉

這種(zhong)故(gu)障原因主要是(shi)(shi)由于(yu)(yu)控制風扇(shan)的三極(ji)管(8550或(huo)8050)損(sun)壞(huai),或(huo)者(zhe)風扇(shan)本身損(sun)壞(huai)或(huo)風葉被雜物(wu)卡住。但有些(xie)開關(guan)電源(yuan)中采用(yong)的是(shi)(shi)智能散熱,對于(yu)(yu)采用(yong)這種(zhong)方式散熱的開關(guan)電源(yuan),熱敏(min)電阻損(sun)壞(huai)的概率是(shi)(shi)很大的。

維修方法:首先(xian)用萬用表測(ce)量一(yi)(yi)(yi)下控制風(feng)扇(shan)的(de)(de)三極管(guan)是(shi)(shi)否損(sun)(sun)(sun)壞(huai),若測(ce)得此(ci)管(guan)未(wei)損(sun)(sun)(sun)壞(huai)那就有(you)可(ke)能(neng)是(shi)(shi)風(feng)扇(shan)本身損(sun)(sun)(sun)壞(huai)。可(ke)以把風(feng)扇(shan)從電(dian)路板上(shang)拔下來,另外(wai)接(jie)(jie)上(shang)一(yi)(yi)(yi)個12V的(de)(de)直(zhi)流電(dian)(注(zhu)意(yi)(yi)正負極),看是(shi)(shi)否轉動,并看有(you)無異物卡住。若擺動幾(ji)下風(feng)扇(shan)的(de)(de)電(dian)線,風(feng)扇(shan)就轉動,則說明電(dian)線內部有(you)斷線或接(jie)(jie)頭接(jie)(jie)觸(chu)不良。若仍不轉動,則風(feng)扇(shan)必(bi)壞(huai)。對于采用智能(neng)散熱(re)的(de)(de)開關電(dian)源來說,除按上(shang)述檢查外(wai),還應檢查一(yi)(yi)(yi)下熱(re)敏(min)電(dian)阻是(shi)(shi)否不良或損(sun)(sun)(sun)壞(huai),開焊等。但要注(zhu)意(yi)(yi)此(ci)熱(re)敏(min)電(dian)阻為(wei)負溫度系(xi)數(shu)的(de)(de)熱(re)敏(min)電(dian)阻,更換時應注(zhu)意(yi)(yi)。

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