眾所周知，日常(chang)生活中我們使用功放機，時(shi)間久了之后(hou)可能(neng)就(jiu)會(hui)出現(xian)各種(zhong)各樣的問(wen)題，那么，功放機出現(xian)問(wen)題的情(qing)況下(xia)(xia)應(ying)該怎么解(jie)決呢？隔山如隔行，雖然(ran)不是所有(you)的人都能(neng)解(jie)決的，但是了解(jie)一些相(xiang)關(guan)方面(mian)的知識會(hui)使你迎(ying)刃而(er)解(jie)。下(xia)(xia)面(mian)介紹功放機的三種(zhong)常(chang)見故障(zhang)及維修方法。

一、整機(ji)不工作

整機不(bu)工作(zuo)的故障表(biao)現為(wei)通電后放大器無(wu)任(ren)何顯示，各功能鍵均失效，也無(wu)任(ren)何聲(sheng)音，像未(wei)通電時一樣。

檢修(xiu)時(shi)首先(xian)應檢查電(dian)(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)(dian)路(lu)(lu)。可(ke)用萬用表測量電(dian)(dian)(dian)(dian)源(yuan)(yuan)插(cha)頭兩端的(de)(de)(de)直流(liu)電(dian)(dian)(dian)(dian)阻值(電(dian)(dian)(dian)(dian)源(yuan)(yuan)開(kai)(kai)關應接通)，正常時(shi)應有數百歐姆的(de)(de)(de)電(dian)(dian)(dian)(dian)阻值。若測得(de)阻值偏小許多(duo)，且電(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)器(qi)(qi)嚴(yan)重(zhong)發(fa)熱，說(shuo)明電(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)器(qi)(qi)的(de)(de)(de)初(chu)級(ji)回(hui)(hui)路(lu)(lu)有局部短路(lu)(lu)處；若測得(de)阻值為大，應檢查保險絲(si)(si)是(shi)否(fou)熔斷(duan)、變壓(ya)器(qi)(qi)初(chu)級(ji)繞組(zu)是(shi)否(fou)開(kai)(kai)路(lu)(lu)、電(dian)(dian)(dian)(dian)源(yuan)(yuan)線(xian)與插(cha)頭之間有無斷(duan)線(xian)。有的(de)(de)(de)機器(qi)(qi)增加了溫度保護裝置，在電(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)器(qi)(qi)的(de)(de)(de)初(chu)級(ji)回(hui)(hui)路(lu)(lu)中接人了電(dian)(dian)(dian)(dian)流(liu)保險絲(si)(si)(通常安(an)裝在電(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)器(qi)(qi)內部，將(jiang)變壓(ya)器(qi)(qi)外部的(de)(de)(de)絕緣(yuan)紙去掉即(ji)可(ke)見(jian)到(dao))，它損壞后也會使電(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)器(qi)(qi)初(chu)級(ji)回(hui)(hui)路(lu)(lu)開(kai)(kai)路(lu)(lu)。

國產精品影視: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(zao)聲(sheng)大(da)

放大器的噪(zao)聲(sheng)有交流聲(sheng)、爆裂聲(sheng)、感應噪(zao)聲(sheng)和白噪(zao)聲(sheng)等。

檢修(xiu)時，應先(xian)判斷噪(zao)聲來自于前級(ji)還是(shi)來自于后級(ji)電路(lu)(lu)。可(ke)把(ba)前、后級(ji)的(de)信號(hao)連(lian)接插頭(tou)取下，若噪(zao)聲明顯變小(xiao)，說明故障(zhang)在前級(ji)電路(lu)(lu)；反(fan)之，故障(zhang)在后級(ji)電路(lu)(lu)。交(jiao)流(liu)聲是(shi)指聽感低(di)沉(chen)、單調而穩(wen)定(ding)的(de)100Hz交(jiao)流(liu)哼聲，主要是(shi)電源(yuan)部(bu)分濾(lv)波不良所致，應著重檢查電源(yuan)整流(liu)、濾(lv)波和穩(wen)壓(ya)元件(jian)有無損壞。前、后級(ji)放大(da)電路(lu)(lu)電源(yuan)端的(de)退耦(ou)電容虛焊或失效，也會產生一種(zhong)類似(si)交(jiao)流(liu)聲的(de)低(di)頻振蕩噪(zao)聲。

感應噪(zao)聲(sheng)是(shi)(shi)成分較復雜且刺耳的(de)(de)交(jiao)流(liu)聲(sheng)，主要是(shi)(shi)前(qian)(qian)級(ji)(ji)電(dian)(dian)路中的(de)(de)轉(zhuan)換開關(guan)、電(dian)(dian)位器接(jie)(jie)地不(bu)(bu)良或信號連線(xian)屏蔽(bi)不(bu)(bu)良所致。爆(bao)裂(lie)聲(sheng)是(shi)(shi)指間斷的(de)(de)“劈啪(pa)”、“咔咔”聲(sheng)，在前(qian)(qian)級(ji)(ji)電(dian)(dian)路中，應檢(jian)查信號輸入(ru)(ru)插頭(tou)與插座、轉(zhuan)換開關(guan)、電(dian)(dian)位器等(deng)是(shi)(shi)否接(jie)(jie)觸(chu)(chu)不(bu)(bu)良，耦(ou)合電(dian)(dian)容有無虛(xu)焊、漏(lou)電(dian)(dian)等(deng)。后級(ji)(ji)放(fang)大電(dian)(dian)路應檢(jian)查繼電(dian)(dian)器觸(chu)(chu)點是(shi)(shi)否氧化(hua)、輸 入(ru)(ru)耦(ou)合電(dian)(dian)容有無漏(lou)電(dian)(dian)或接(jie)(jie)觸(chu)(chu)不(bu)(bu)良。另外，后級(ji)(ji)電(dian)(dian)路中的(de)(de)差分輸入(ru)(ru)管(guan)或恒(heng)流(liu)管(guan)軟擊穿，也會產(chan)生類似電(dian)(dian)火花的(de)(de)“咔咔”噪(zao)聲(sheng)。白噪(zao)聲(sheng)是(shi)(shi)指無規(gui)則(ze)的(de)(de)連續“沙沙”聲(sheng)，通(tong)常是(shi)(shi)由前(qian)(qian)、后級(ji)(ji)放(fang)大電(dian)(dian)路中的(de)(de)輸入(ru)(ru)級(ji)(ji)晶體(ti)管(guan)、場效應管(guan)或運放(fang)集成電(dian)(dian)路的(de)(de)性能不(bu)(bu)良產(chan)生的(de)(de)本(ben)底噪(zao)聲(sheng)，檢(jian)修時，可用(yong)同規(gui)格的(de)(de)元件代換試(shi)之。

三(san)、音量輕

專業國產精品影視: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(ruo)以(yi)上各部(bu)分均正常，應判斷(duan)出故障是(shi)在前級(ji)(ji)(ji)還(huan)是(shi)在后(hou)級(ji)(ji)(ji)電路(lu)。對于某一個聲(sheng)(sheng)(sheng)道(dao)音輕，可(ke)將其(qi)前級(ji)(ji)(ji)電路(lu)輸(shu)(shu)(shu)出的(de)(de)(de)信號交換輸(shu)(shu)(shu)入(ru)到另一聲(sheng)(sheng)(sheng)道(dao)的(de)(de)(de)后(hou)級(ji)(ji)(ji)電路(lu)，若(ruo)音箱的(de)(de)(de)聲(sheng)(sheng)(sheng)音大小不變(bian)，則故障在后(hou)級(ji)(ji)(ji)電路(lu)；反(fan)之，故障在前級(ji)(ji)(ji)電路(lu)。后(hou)級(ji)(ji)(ji)放(fang)(fang)大電路(lu)造成(cheng)的(de)(de)(de)音輕，主要有輸(shu)(shu)(shu)出功率不足和增益不夠兩種原因。可(ke)用(yong)適當加(jia)大輸(shu)(shu)(shu)入(ru)信號(例如將收錄機輸(shu)(shu)(shu)出給揚聲(sheng)(sheng)(sheng)器的(de)(de)(de)信號直接加(jia)至后(hou)級(ji)(ji)(ji)功放(fang)(fang)電路(lu)的(de)(de)(de)輸(shu)(shu)(shu)入(ru)端，改變(bian)收錄機的(de)(de)(de)音量(liang)，觀察(cha)功放(fang)(fang)輸(shu)(shu)(shu)出的(de)(de)(de)變(bian)化)的(de)(de)(de)方法來判斷(duan)是(shi)哪種原因引起的(de)(de)(de)。

若(ruo)加大(da)輸(shu)入信(xin)號后，輸(shu)出(chu)的聲(sheng)(sheng)音足夠(gou)大(da)，說明(ming)功(gong)(gong)放(fang)(fang)輸(shu)出(chu)功(gong)(gong)率(lv)足夠(gou)，只是(shi)增(zeng)益降低，應著(zhu)重檢查(cha)(cha)繼電(dian)(dian)(dian)(dian)器觸點有(you)無接(jie)觸電(dian)(dian)(dian)(dian)阻(zu)增(zeng)大(da)、輸(shu)入耦(ou)合電(dian)(dian)(dian)(dian)容(rong)容(rong)量減小(xiao)、隔離電(dian)(dian)(dian)(dian)阻(zu)阻(zu)值增(zeng)大(da)、負(fu)(fu)反饋(kui)電(dian)(dian)(dian)(dian)容(rong)容(rong)量變(bian)(bian)小(xiao)或(huo)開(kai)(kai)路(lu)(lu)、負(fu)(fu)反饋(kui)電(dian)(dian)(dian)(dian)阻(zu)阻(zu)值增(zeng)大(da)或(huo)開(kai)(kai)路(lu)(lu)等現(xian)象(xiang)。若(ruo)加大(da)輸(shu)入信(xin)號后，輸(shu)出(chu)的聲(sheng)(sheng)音出(chu)現(xian)失真，音量并無顯著(zhu)增(zeng)大(da)，說明(ming)后級(ji)放(fang)(fang)大(da)器的輸(shu)出(chu)功(gong)(gong)率(lv)不足，應先檢查(cha)(cha)放(fang)(fang)大(da)器的正、負(fu)(fu)供電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓是(shi)否(fou)偏(pian)低(若(ruo)只是(shi)一(yi)個(ge)聲(sheng)(sheng)道音輕，可(ke)(ke)不必檢查(cha)(cha)電(dian)(dian)(dian)(dian)源供電(dian)(dian)(dian)(dian))、功(gong)(gong)率(lv)管或(huo)集成電(dian)(dian)(dian)(dian)路(lu)(lu)的性(xing)能(neng)是(shi)否(fou)變(bian)(bian)差、發射極(ji)電(dian)(dian)(dian)(dian)阻(zu)阻(zu)值有(you)無變(bian)(bian)大(da)等。前級(ji)電(dian)(dian)(dian)(dian)路(lu)(lu)中轉換開(kai)(kai)關、電(dian)(dian)(dian)(dian)位器所(suo)造成的音輕，采用(yong)直觀檢查(cha)(cha)較易(yi)發現(xian)，可(ke)(ke)對其進行清洗或(huo)更換。如懷(huai)疑某(mou)信(xin)號耦(ou)合電(dian)(dian)(dian)(dian)容(rong)失效，可(ke)(ke)用(yong)同值電(dian)(dian)(dian)(dian)容(rong)并聯試之；放(fang)(fang)大(da)管或(huo)運放(fang)(fang)集成電(dian)(dian)(dian)(dian)路(lu)(lu)性(xing)能(neng)不良，也可(ke)(ke)用(yong)代換法(fa)檢查(cha)(cha)。另外，負(fu)(fu)反饋(kui)元件有(you)問題(ti)，也會造成電(dian)(dian)(dian)(dian)路(lu)(lu)增(zeng)益下降。