眾所周知，日常生(sheng)活中我們使用(yong)功放機，時間久了之后可能(neng)就會出現各(ge)種(zhong)各(ge)樣的(de)問(wen)題(ti)，那么(me)，功放機出現問(wen)題(ti)的(de)情(qing)況下應該怎么(me)解(jie)決呢？隔山如隔行(xing)，雖(sui)然(ran)不是(shi)(shi)所有的(de)人都能(neng)解(jie)決的(de)，但是(shi)(shi)了解(jie)一些相(xiang)關方(fang)面(mian)(mian)的(de)知識會使你(ni)迎刃(ren)而解(jie)。下面(mian)(mian)介紹功放機的(de)三種(zhong)常見故障及維修方(fang)法。

一、整(zheng)機(ji)不(bu)工(gong)作

整機不(bu)工(gong)作的故障表(biao)現為通電后放大器無任(ren)何顯示(shi)，各功能鍵(jian)均失(shi)效，也無任(ren)何聲音(yin)，像未通電時一樣。

檢(jian)(jian)修時首先(xian)應(ying)(ying)檢(jian)(jian)查電(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)路(lu)。可(ke)用萬用表測(ce)量電(dian)(dian)(dian)源(yuan)(yuan)插頭(tou)兩端的(de)(de)直流(liu)電(dian)(dian)(dian)阻值(zhi)(zhi)(電(dian)(dian)(dian)源(yuan)(yuan)開(kai)關應(ying)(ying)接(jie)通(tong))，正常(chang)時應(ying)(ying)有(you)(you)數百(bai)歐姆(mu)的(de)(de)電(dian)(dian)(dian)阻值(zhi)(zhi)。若測(ce)得(de)阻值(zhi)(zhi)偏(pian)小許(xu)多，且電(dian)(dian)(dian)源(yuan)(yuan)變(bian)壓(ya)(ya)(ya)(ya)器嚴(yan)重發熱，說明電(dian)(dian)(dian)源(yuan)(yuan)變(bian)壓(ya)(ya)(ya)(ya)器的(de)(de)初(chu)級(ji)回(hui)路(lu)有(you)(you)局部短路(lu)處(chu)；若測(ce)得(de)阻值(zhi)(zhi)為大，應(ying)(ying)檢(jian)(jian)查保險絲(si)是(shi)否熔斷、變(bian)壓(ya)(ya)(ya)(ya)器初(chu)級(ji)繞組是(shi)否開(kai)路(lu)、電(dian)(dian)(dian)源(yuan)(yuan)線與插頭(tou)之(zhi)間有(you)(you)無斷線。有(you)(you)的(de)(de)機(ji)器增加了溫度保護裝(zhuang)置，在電(dian)(dian)(dian)源(yuan)(yuan)變(bian)壓(ya)(ya)(ya)(ya)器的(de)(de)初(chu)級(ji)回(hui)路(lu)中接(jie)人了電(dian)(dian)(dian)流(liu)保險絲(si)(通(tong)常(chang)安(an)裝(zhuang)在電(dian)(dian)(dian)源(yuan)(yuan)變(bian)壓(ya)(ya)(ya)(ya)器內(nei)部，將變(bian)壓(ya)(ya)(ya)(ya)器外部的(de)(de)絕緣紙(zhi)去掉即可(ke)見到)，它(ta)損(sun)壞后(hou)也會(hui)使電(dian)(dian)(dian)源(yuan)(yuan)變(bian)壓(ya)(ya)(ya)(ya)器初(chu)級(ji)回(hui)路(lu)開(kai)路(lu)。

四虎國產精品永久一區:重慶音響工程公司稱若電源插頭兩端阻值正常，可通電測量電源電路各輸出電壓是否正常。對于采用系統控制微處理器或邏輯控制電路的放大器，應著重檢查該控制電路的供電電壓(通常為+5V)是否正常。如無+5V電壓，應測量三端穩壓集成電路7805的輸入端電壓是否正常，若輸入端電壓不正常，應檢查整流、濾波電路。若7805輸入端電壓正常，而輸出端無十5V電壓或電壓偏低，可斷開負載看+5V電壓能否恢復正常。若+5V電壓正常，則故障在負載電路；若+5V電壓仍不正常，則故障在7805本身。若系統控制電路的+5V供電電壓正常，應再檢查微處理器的時鐘及復位信號是否正常、鍵控與顯示驅動電路有無損壞。

二(er)、噪聲大

放大器的噪(zao)(zao)聲(sheng)(sheng)有交流(liu)聲(sheng)(sheng)、爆裂聲(sheng)(sheng)、感應噪(zao)(zao)聲(sheng)(sheng)和白(bai)噪(zao)(zao)聲(sheng)(sheng)等。

檢修(xiu)時，應(ying)先判斷噪聲(sheng)來自(zi)于前級還是(shi)來自(zi)于后級電(dian)(dian)(dian)路。可(ke)把(ba)前、后級的信號(hao)連接(jie)插頭取下，若噪聲(sheng)明(ming)顯(xian)變小，說明(ming)故障在前級電(dian)(dian)(dian)路；反(fan)之，故障在后級電(dian)(dian)(dian)路。交(jiao)流聲(sheng)是(shi)指聽(ting)感低沉、單調(diao)而穩定的100Hz交(jiao)流哼聲(sheng)，主要是(shi)電(dian)(dian)(dian)源部(bu)分濾波不(bu)良(liang)所(suo)致，應(ying)著重檢查電(dian)(dian)(dian)源整(zheng)流、濾波和穩壓(ya)元件有無(wu)損壞。前、后級放(fang)大電(dian)(dian)(dian)路電(dian)(dian)(dian)源端(duan)的退耦電(dian)(dian)(dian)容虛焊(han)或失效，也會產生(sheng)一種類似交(jiao)流聲(sheng)的低頻振蕩噪聲(sheng)。

感應噪聲(sheng)是(shi)成分較復雜且刺耳的(de)交流聲(sheng)，主要是(shi)前級(ji)(ji)(ji)電(dian)(dian)路(lu)(lu)(lu)中的(de)轉換(huan)(huan)開(kai)(kai)關、電(dian)(dian)位(wei)器(qi)接(jie)地不(bu)良(liang)或信號(hao)連線屏(ping)蔽不(bu)良(liang)所致。爆裂(lie)聲(sheng)是(shi)指間(jian)斷的(de)“劈啪”、“咔咔”聲(sheng)，在(zai)前級(ji)(ji)(ji)電(dian)(dian)路(lu)(lu)(lu)中，應檢查信號(hao)輸入插頭與插座、轉換(huan)(huan)開(kai)(kai)關、電(dian)(dian)位(wei)器(qi)等(deng)是(shi)否(fou)接(jie)觸不(bu)良(liang)，耦合電(dian)(dian)容有無(wu)虛焊(han)、漏電(dian)(dian)等(deng)。后(hou)級(ji)(ji)(ji)放大電(dian)(dian)路(lu)(lu)(lu)應檢查繼電(dian)(dian)器(qi)觸點是(shi)否(fou)氧化(hua)、輸 入耦合電(dian)(dian)容有無(wu)漏電(dian)(dian)或接(jie)觸不(bu)良(liang)。另(ling)外，后(hou)級(ji)(ji)(ji)電(dian)(dian)路(lu)(lu)(lu)中的(de)差(cha)分輸入管(guan)或恒流管(guan)軟擊(ji)穿，也會產(chan)生類似(si)電(dian)(dian)火花的(de)“咔咔”噪聲(sheng)。白噪聲(sheng)是(shi)指無(wu)規(gui)則(ze)的(de)連續(xu)“沙(sha)沙(sha)”聲(sheng)，通常(chang)是(shi)由(you)前、后(hou)級(ji)(ji)(ji)放大電(dian)(dian)路(lu)(lu)(lu)中的(de)輸入級(ji)(ji)(ji)晶體(ti)管(guan)、場效(xiao)應管(guan)或運放集成電(dian)(dian)路(lu)(lu)(lu)的(de)性能不(bu)良(liang)產(chan)生的(de)本底噪聲(sheng)，檢修(xiu)時，可用同規(gui)格的(de)元件代換(huan)(huan)試之。

三、音量輕

專業四虎國產精品永久一區:音響工程公司稱所謂音輕故障，是指音頻信號在放大傳輸過程中，因某個放大級放大量變化或在某個環節被衰減，使放大器的增益下降或輸出功率變小。檢修時，首先應檢查信號源和音箱是否正常，可用替換的辦法來檢查。然后檢查各類轉換開關和控制電位器，看音量能否變大。

若以(yi)上各部(bu)分均(jun)正常，應判(pan)斷(duan)出(chu)(chu)故障(zhang)是(shi)(shi)在(zai)前(qian)級還是(shi)(shi)在(zai)后級電(dian)路(lu)。對于某一(yi)個(ge)聲道音輕，可將其前(qian)級電(dian)路(lu)輸出(chu)(chu)的(de)信(xin)號(hao)交換輸入(ru)到另一(yi)聲道的(de)后級電(dian)路(lu)，若音箱的(de)聲音大(da)小(xiao)不變，則故障(zhang)在(zai)后級電(dian)路(lu)；反之，故障(zhang)在(zai)前(qian)級電(dian)路(lu)。后級放(fang)大(da)電(dian)路(lu)造成的(de)音輕，主要有輸出(chu)(chu)功(gong)(gong)率不足和增益(yi)不夠(gou)兩種原因。可用適當加大(da)輸入(ru)信(xin)號(hao)(例如(ru)將收錄機輸出(chu)(chu)給揚聲器的(de)信(xin)號(hao)直接加至(zhi)后級功(gong)(gong)放(fang)電(dian)路(lu)的(de)輸入(ru)端，改變收錄機的(de)音量(liang)，觀察(cha)功(gong)(gong)放(fang)輸出(chu)(chu)的(de)變化)的(de)方法來判(pan)斷(duan)是(shi)(shi)哪種原因引起的(de)。

若加(jia)(jia)大(da)輸(shu)(shu)入信(xin)號(hao)后，輸(shu)(shu)出的(de)聲(sheng)音足夠大(da)，說明功放(fang)輸(shu)(shu)出功率足夠，只是(shi)增(zeng)(zeng)(zeng)益(yi)降(jiang)(jiang)低，應(ying)著(zhu)重(zhong)檢查繼電(dian)(dian)(dian)(dian)(dian)器(qi)(qi)觸點有(you)(you)無接觸電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)增(zeng)(zeng)(zeng)大(da)、輸(shu)(shu)入耦(ou)合(he)電(dian)(dian)(dian)(dian)(dian)容(rong)容(rong)量(liang)減(jian)小(xiao)、隔離(li)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值(zhi)(zhi)增(zeng)(zeng)(zeng)大(da)、負反(fan)(fan)饋(kui)(kui)電(dian)(dian)(dian)(dian)(dian)容(rong)容(rong)量(liang)變(bian)小(xiao)或(huo)開(kai)路(lu)、負反(fan)(fan)饋(kui)(kui)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值(zhi)(zhi)增(zeng)(zeng)(zeng)大(da)或(huo)開(kai)路(lu)等(deng)現象(xiang)。若加(jia)(jia)大(da)輸(shu)(shu)入信(xin)號(hao)后，輸(shu)(shu)出的(de)聲(sheng)音出現失(shi)真(zhen)，音量(liang)并(bing)無顯(xian)著(zhu)增(zeng)(zeng)(zeng)大(da)，說明后級(ji)放(fang)大(da)器(qi)(qi)的(de)輸(shu)(shu)出功率不(bu)足，應(ying)先檢查放(fang)大(da)器(qi)(qi)的(de)正、負供(gong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓是(shi)否偏低(若只是(shi)一個聲(sheng)道音輕，可不(bu)必檢查電(dian)(dian)(dian)(dian)(dian)源供(gong)電(dian)(dian)(dian)(dian)(dian))、功率管(guan)或(huo)集成(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)性能是(shi)否變(bian)差、發(fa)射極電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值(zhi)(zhi)有(you)(you)無變(bian)大(da)等(deng)。前級(ji)電(dian)(dian)(dian)(dian)(dian)路(lu)中轉換(huan)(huan)開(kai)關、電(dian)(dian)(dian)(dian)(dian)位(wei)器(qi)(qi)所造(zao)成(cheng)的(de)音輕，采用直觀檢查較易發(fa)現，可對其進行清洗或(huo)更換(huan)(huan)。如懷疑(yi)某信(xin)號(hao)耦(ou)合(he)電(dian)(dian)(dian)(dian)(dian)容(rong)失(shi)效，可用同值(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)容(rong)并(bing)聯試之(zhi)；放(fang)大(da)管(guan)或(huo)運放(fang)集成(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)性能不(bu)良，也可用代(dai)換(huan)(huan)法檢查。另外，負反(fan)(fan)饋(kui)(kui)元件有(you)(you)問題，也會造(zao)成(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)增(zeng)(zeng)(zeng)益(yi)下降(jiang)(jiang)。