眾所周知，日常生活中我們(men)使(shi)用(yong)功(gong)放機，時間久了(le)之后(hou)可(ke)能(neng)就(jiu)會出現(xian)各(ge)種各(ge)樣的(de)問(wen)題(ti)，那么，功(gong)放機出現(xian)問(wen)題(ti)的(de)情(qing)況下(xia)(xia)應該(gai)怎么解決呢？隔山如隔行(xing)，雖然不是(shi)(shi)所有的(de)人(ren)都(dou)能(neng)解決的(de)，但是(shi)(shi)了(le)解一些(xie)相(xiang)關方面的(de)知識會使(shi)你迎刃而解。下(xia)(xia)面介紹功(gong)放機的(de)三(san)種常見故障及維修(xiu)方法。

一、整機不工作

整機不工作的故(gu)障表現為通電后放大(da)器無任(ren)何(he)顯示，各功(gong)能(neng)鍵均失(shi)效，也無任(ren)何(he)聲音，像未通電時一樣。

檢修(xiu)時首(shou)先應(ying)(ying)檢查(cha)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)路(lu)。可用(yong)萬用(yong)表測(ce)量(liang)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)插(cha)頭兩端的(de)(de)直流電(dian)(dian)(dian)(dian)(dian)阻(zu)值(zhi)(電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)開關(guan)應(ying)(ying)接(jie)通)，正常時應(ying)(ying)有(you)數百歐姆的(de)(de)電(dian)(dian)(dian)(dian)(dian)阻(zu)值(zhi)。若(ruo)測(ce)得阻(zu)值(zhi)偏小許多，且電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變(bian)(bian)壓器(qi)(qi)嚴重發熱，說明電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變(bian)(bian)壓器(qi)(qi)的(de)(de)初級(ji)回路(lu)有(you)局部短路(lu)處；若(ruo)測(ce)得阻(zu)值(zhi)為(wei)大，應(ying)(ying)檢查(cha)保險絲(si)是否熔斷(duan)、變(bian)(bian)壓器(qi)(qi)初級(ji)繞組是否開路(lu)、電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)線與插(cha)頭之間(jian)有(you)無斷(duan)線。有(you)的(de)(de)機器(qi)(qi)增加了(le)溫度保護裝(zhuang)置，在(zai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變(bian)(bian)壓器(qi)(qi)的(de)(de)初級(ji)回路(lu)中接(jie)人了(le)電(dian)(dian)(dian)(dian)(dian)流保險絲(si)(通常安裝(zhuang)在(zai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變(bian)(bian)壓器(qi)(qi)內(nei)部，將變(bian)(bian)壓器(qi)(qi)外部的(de)(de)絕緣紙去(qu)掉(diao)即(ji)可見到)，它損壞后也會使電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變(bian)(bian)壓器(qi)(qi)初級(ji)回路(lu)開路(lu)。

國產 在線 | 日韓: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、噪聲大

放大(da)器的噪(zao)聲有交流(liu)聲、爆裂聲、感應噪(zao)聲和白噪(zao)聲等。

檢(jian)修時(shi)，應先判斷噪聲來自(zi)于前級還是來自(zi)于后(hou)級電(dian)路(lu)(lu)。可(ke)把前、后(hou)級的(de)(de)(de)信號連接(jie)插頭取下(xia)，若噪聲明顯(xian)變小，說明故障在前級電(dian)路(lu)(lu)；反之，故障在后(hou)級電(dian)路(lu)(lu)。交(jiao)流聲是指聽感(gan)低(di)沉(chen)、單調而穩定的(de)(de)(de)100Hz交(jiao)流哼聲，主要是電(dian)源部分濾波不良(liang)所致(zhi)，應著(zhu)重檢(jian)查電(dian)源整(zheng)流、濾波和穩壓元件(jian)有無損(sun)壞(huai)。前、后(hou)級放大電(dian)路(lu)(lu)電(dian)源端的(de)(de)(de)退耦電(dian)容虛焊或(huo)失(shi)效，也會產生(sheng)一(yi)種類(lei)似交(jiao)流聲的(de)(de)(de)低(di)頻振蕩噪聲。

感應(ying)(ying)噪(zao)(zao)聲(sheng)(sheng)是(shi)(shi)(shi)成(cheng)分較復雜(za)且刺耳的(de)(de)(de)交流聲(sheng)(sheng)，主要是(shi)(shi)(shi)前(qian)級電(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)的(de)(de)(de)轉換(huan)開關、電(dian)(dian)(dian)(dian)(dian)位(wei)器(qi)接(jie)地不良(liang)(liang)或(huo)(huo)信(xin)號連(lian)線屏蔽不良(liang)(liang)所致。爆裂聲(sheng)(sheng)是(shi)(shi)(shi)指(zhi)(zhi)間斷(duan)的(de)(de)(de)“劈(pi)啪”、“咔(ka)咔(ka)”聲(sheng)(sheng)，在(zai)前(qian)級電(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)，應(ying)(ying)檢(jian)查信(xin)號輸入插頭(tou)與插座、轉換(huan)開關、電(dian)(dian)(dian)(dian)(dian)位(wei)器(qi)等是(shi)(shi)(shi)否接(jie)觸不良(liang)(liang)，耦合電(dian)(dian)(dian)(dian)(dian)容(rong)有(you)無(wu)(wu)虛(xu)焊(han)、漏電(dian)(dian)(dian)(dian)(dian)等。后級放(fang)大電(dian)(dian)(dian)(dian)(dian)路(lu)應(ying)(ying)檢(jian)查繼電(dian)(dian)(dian)(dian)(dian)器(qi)觸點(dian)是(shi)(shi)(shi)否氧化、輸 入耦合電(dian)(dian)(dian)(dian)(dian)容(rong)有(you)無(wu)(wu)漏電(dian)(dian)(dian)(dian)(dian)或(huo)(huo)接(jie)觸不良(liang)(liang)。另外，后級電(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)的(de)(de)(de)差分輸入管(guan)或(huo)(huo)恒(heng)流管(guan)軟擊(ji)穿，也會產(chan)生類(lei)似(si)電(dian)(dian)(dian)(dian)(dian)火(huo)花(hua)的(de)(de)(de)“咔(ka)咔(ka)”噪(zao)(zao)聲(sheng)(sheng)。白噪(zao)(zao)聲(sheng)(sheng)是(shi)(shi)(shi)指(zhi)(zhi)無(wu)(wu)規則的(de)(de)(de)連(lian)續“沙(sha)沙(sha)”聲(sheng)(sheng)，通常(chang)是(shi)(shi)(shi)由前(qian)、后級放(fang)大電(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)的(de)(de)(de)輸入級晶體管(guan)、場效(xiao)應(ying)(ying)管(guan)或(huo)(huo)運放(fang)集(ji)成(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)(de)性能(neng)不良(liang)(liang)產(chan)生的(de)(de)(de)本底噪(zao)(zao)聲(sheng)(sheng)，檢(jian)修時，可用同(tong)規格的(de)(de)(de)元件代換(huan)試(shi)之。

三、音量輕

專業國產 在線 | 日韓: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)上各部分均正常，應判(pan)斷(duan)出(chu)(chu)(chu)故(gu)障是在(zai)前(qian)級(ji)還是在(zai)后級(ji)電(dian)路(lu)。對于某一個聲道(dao)音輕(qing)(qing)，可將(jiang)其(qi)前(qian)級(ji)電(dian)路(lu)輸(shu)出(chu)(chu)(chu)的(de)(de)信(xin)(xin)號交換輸(shu)入到另一聲道(dao)的(de)(de)后級(ji)電(dian)路(lu)，若(ruo)音箱的(de)(de)聲音大小不變，則故(gu)障在(zai)后級(ji)電(dian)路(lu)；反(fan)之，故(gu)障在(zai)前(qian)級(ji)電(dian)路(lu)。后級(ji)放大電(dian)路(lu)造成的(de)(de)音輕(qing)(qing)，主要(yao)有輸(shu)出(chu)(chu)(chu)功(gong)率不足和增益不夠(gou)兩種原因(yin)。可用適當加(jia)大輸(shu)入信(xin)(xin)號(例如將(jiang)收錄機(ji)輸(shu)出(chu)(chu)(chu)給揚聲器的(de)(de)信(xin)(xin)號直接加(jia)至(zhi)后級(ji)功(gong)放電(dian)路(lu)的(de)(de)輸(shu)入端，改變收錄機(ji)的(de)(de)音量，觀察功(gong)放輸(shu)出(chu)(chu)(chu)的(de)(de)變化(hua))的(de)(de)方法來判(pan)斷(duan)是哪種原因(yin)引起的(de)(de)。

若(ruo)加大(da)(da)(da)輸(shu)入信(xin)號(hao)后(hou)，輸(shu)出(chu)的(de)(de)聲音(yin)(yin)足夠大(da)(da)(da)，說明功放(fang)(fang)輸(shu)出(chu)功率(lv)足夠，只(zhi)是(shi)增(zeng)益降低，應著重檢(jian)查繼電(dian)(dian)(dian)(dian)(dian)器觸點有無(wu)接觸電(dian)(dian)(dian)(dian)(dian)阻(zu)增(zeng)大(da)(da)(da)、輸(shu)入耦合電(dian)(dian)(dian)(dian)(dian)容(rong)容(rong)量(liang)減小、隔離電(dian)(dian)(dian)(dian)(dian)阻(zu)阻(zu)值增(zeng)大(da)(da)(da)、負反饋電(dian)(dian)(dian)(dian)(dian)容(rong)容(rong)量(liang)變小或(huo)開(kai)路、負反饋電(dian)(dian)(dian)(dian)(dian)阻(zu)阻(zu)值增(zeng)大(da)(da)(da)或(huo)開(kai)路等現象。若(ruo)加大(da)(da)(da)輸(shu)入信(xin)號(hao)后(hou)，輸(shu)出(chu)的(de)(de)聲音(yin)(yin)出(chu)現失(shi)真(zhen)，音(yin)(yin)量(liang)并(bing)無(wu)顯著增(zeng)大(da)(da)(da)，說明后(hou)級(ji)放(fang)(fang)大(da)(da)(da)器的(de)(de)輸(shu)出(chu)功率(lv)不(bu)(bu)足，應先(xian)檢(jian)查放(fang)(fang)大(da)(da)(da)器的(de)(de)正(zheng)、負供電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓是(shi)否偏低(若(ruo)只(zhi)是(shi)一個聲道音(yin)(yin)輕，可(ke)不(bu)(bu)必檢(jian)查電(dian)(dian)(dian)(dian)(dian)源供電(dian)(dian)(dian)(dian)(dian))、功率(lv)管(guan)或(huo)集成(cheng)電(dian)(dian)(dian)(dian)(dian)路的(de)(de)性能(neng)是(shi)否變差(cha)、發射極電(dian)(dian)(dian)(dian)(dian)阻(zu)阻(zu)值有無(wu)變大(da)(da)(da)等。前級(ji)電(dian)(dian)(dian)(dian)(dian)路中轉換開(kai)關、電(dian)(dian)(dian)(dian)(dian)位器所造成(cheng)的(de)(de)音(yin)(yin)輕，采(cai)用(yong)(yong)直觀檢(jian)查較易發現，可(ke)對其進行(xing)清(qing)洗或(huo)更換。如(ru)懷疑某信(xin)號(hao)耦合電(dian)(dian)(dian)(dian)(dian)容(rong)失(shi)效，可(ke)用(yong)(yong)同值電(dian)(dian)(dian)(dian)(dian)容(rong)并(bing)聯試之；放(fang)(fang)大(da)(da)(da)管(guan)或(huo)運放(fang)(fang)集成(cheng)電(dian)(dian)(dian)(dian)(dian)路性能(neng)不(bu)(bu)良，也可(ke)用(yong)(yong)代換法檢(jian)查。另(ling)外，負反饋元件(jian)有問(wen)題，也會造成(cheng)電(dian)(dian)(dian)(dian)(dian)路增(zeng)益下降。