眾所(suo)(suo)周(zhou)知，日常(chang)生活中我(wo)們使(shi)(shi)用(yong)功放(fang)機，時間久了之(zhi)后(hou)可能就會(hui)出(chu)現各(ge)種各(ge)樣的問題(ti)(ti)，那么(me)，功放(fang)機出(chu)現問題(ti)(ti)的情況(kuang)下(xia)應該怎么(me)解(jie)決(jue)呢？隔(ge)山如隔(ge)行，雖然不是所(suo)(suo)有的人(ren)都能解(jie)決(jue)的，但是了解(jie)一些相(xiang)關方面的知識會(hui)使(shi)(shi)你迎刃而(er)解(jie)。下(xia)面介紹功放(fang)機的三種常(chang)見故障(zhang)及維(wei)修方法。

一、整機不工作

整機不工作(zuo)的(de)故障表現(xian)為通電后放大器無(wu)任何顯(xian)示，各(ge)功能鍵均(jun)失效，也(ye)無(wu)任何聲音，像(xiang)未(wei)通電時一樣。

檢(jian)修時首先(xian)應(ying)(ying)檢(jian)查電源(yuan)電路(lu)。可用(yong)萬用(yong)表(biao)測(ce)量電源(yuan)插(cha)頭(tou)兩端的(de)(de)(de)直流電阻值(電源(yuan)開關應(ying)(ying)接通)，正常(chang)(chang)時應(ying)(ying)有數(shu)百歐姆(mu)的(de)(de)(de)電阻值。若(ruo)測(ce)得阻值偏小許多，且(qie)電源(yuan)變(bian)(bian)壓器嚴重發熱，說明(ming)電源(yuan)變(bian)(bian)壓器的(de)(de)(de)初級(ji)回(hui)路(lu)有局部短路(lu)處；若(ruo)測(ce)得阻值為大，應(ying)(ying)檢(jian)查保(bao)險(xian)絲是(shi)否熔(rong)斷、變(bian)(bian)壓器初級(ji)繞組是(shi)否開路(lu)、電源(yuan)線(xian)與插(cha)頭(tou)之間有無斷線(xian)。有的(de)(de)(de)機(ji)器增加了(le)溫度保(bao)護(hu)裝置，在電源(yuan)變(bian)(bian)壓器的(de)(de)(de)初級(ji)回(hui)路(lu)中接人了(le)電流保(bao)險(xian)絲(通常(chang)(chang)安(an)裝在電源(yuan)變(bian)(bian)壓器內(nei)部，將變(bian)(bian)壓器外部的(de)(de)(de)絕緣紙去掉即(ji)可見到(dao))，它(ta)損壞(huai)后(hou)也會使電源(yuan)變(bian)(bian)壓器初級(ji)回(hui)路(lu)開路(lu)。

四虎影視884a精品國產四虎: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

放大器的噪聲(sheng)(sheng)有交流聲(sheng)(sheng)、爆裂聲(sheng)(sheng)、感應噪聲(sheng)(sheng)和(he)白噪聲(sheng)(sheng)等。

檢修時(shi)，應先判(pan)斷噪聲(sheng)(sheng)(sheng)來自于前級還(huan)是(shi)來自于后級電(dian)路。可(ke)把前、后級的(de)(de)信(xin)號連接(jie)插頭取下，若(ruo)噪聲(sheng)(sheng)(sheng)明顯變小，說明故障在(zai)(zai)前級電(dian)路；反(fan)之，故障在(zai)(zai)后級電(dian)路。交(jiao)(jiao)流(liu)聲(sheng)(sheng)(sheng)是(shi)指聽(ting)感(gan)低沉、單調而穩定的(de)(de)100Hz交(jiao)(jiao)流(liu)哼聲(sheng)(sheng)(sheng)，主要是(shi)電(dian)源(yuan)部分濾(lv)波(bo)不良所致，應著(zhu)重檢查電(dian)源(yuan)整(zheng)流(liu)、濾(lv)波(bo)和穩壓(ya)元(yuan)件(jian)有無損壞。前、后級放(fang)大電(dian)路電(dian)源(yuan)端的(de)(de)退耦電(dian)容虛焊或失(shi)效，也(ye)會(hui)產生一種類似交(jiao)(jiao)流(liu)聲(sheng)(sheng)(sheng)的(de)(de)低頻振蕩噪聲(sheng)(sheng)(sheng)。

感應噪(zao)(zao)聲是(shi)(shi)成分(fen)較復(fu)雜且(qie)刺耳的(de)(de)(de)交(jiao)流聲，主要是(shi)(shi)前級(ji)電(dian)(dian)路(lu)(lu)中的(de)(de)(de)轉(zhuan)換開關、電(dian)(dian)位(wei)器接地(di)不良或(huo)信號連(lian)線(xian)屏蔽不良所致。爆裂(lie)聲是(shi)(shi)指(zhi)間斷的(de)(de)(de)“劈啪”、“咔咔”聲，在前級(ji)電(dian)(dian)路(lu)(lu)中，應檢查(cha)信號輸(shu)入插頭與(yu)插座、轉(zhuan)換開關、電(dian)(dian)位(wei)器等(deng)是(shi)(shi)否(fou)接觸不良，耦(ou)合電(dian)(dian)容有無(wu)(wu)虛焊、漏(lou)電(dian)(dian)等(deng)。后級(ji)放大電(dian)(dian)路(lu)(lu)應檢查(cha)繼電(dian)(dian)器觸點是(shi)(shi)否(fou)氧化、輸(shu) 入耦(ou)合電(dian)(dian)容有無(wu)(wu)漏(lou)電(dian)(dian)或(huo)接觸不良。另外，后級(ji)電(dian)(dian)路(lu)(lu)中的(de)(de)(de)差分(fen)輸(shu)入管或(huo)恒流管軟(ruan)擊穿，也會產生(sheng)類似電(dian)(dian)火花的(de)(de)(de)“咔咔”噪(zao)(zao)聲。白噪(zao)(zao)聲是(shi)(shi)指(zhi)無(wu)(wu)規則的(de)(de)(de)連(lian)續(xu)“沙(sha)沙(sha)”聲，通常是(shi)(shi)由前、后級(ji)放大電(dian)(dian)路(lu)(lu)中的(de)(de)(de)輸(shu)入級(ji)晶體管、場效應管或(huo)運放集成電(dian)(dian)路(lu)(lu)的(de)(de)(de)性能不良產生(sheng)的(de)(de)(de)本底噪(zao)(zao)聲，檢修時，可用(yong)同規格的(de)(de)(de)元(yuan)件代(dai)換試之。

三、音量(liang)輕

專業四虎影視884a精品國產四虎: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)(ruo)以上(shang)各部分(fen)均正(zheng)常，應(ying)判(pan)斷(duan)出(chu)故(gu)障是在前級(ji)還是在后(hou)級(ji)電(dian)路(lu)(lu)(lu)。對于某一個聲道音輕，可將其前級(ji)電(dian)路(lu)(lu)(lu)輸(shu)(shu)(shu)出(chu)的(de)信號交換輸(shu)(shu)(shu)入到另一聲道的(de)后(hou)級(ji)電(dian)路(lu)(lu)(lu)，若(ruo)(ruo)音箱的(de)聲音大小不(bu)變，則故(gu)障在后(hou)級(ji)電(dian)路(lu)(lu)(lu)；反之(zhi)，故(gu)障在前級(ji)電(dian)路(lu)(lu)(lu)。后(hou)級(ji)放大電(dian)路(lu)(lu)(lu)造成(cheng)的(de)音輕，主(zhu)要有輸(shu)(shu)(shu)出(chu)功(gong)率不(bu)足和(he)增益(yi)不(bu)夠兩種原(yuan)因。可用(yong)適(shi)當(dang)加大輸(shu)(shu)(shu)入信號(例如將收錄機輸(shu)(shu)(shu)出(chu)給揚聲器(qi)的(de)信號直接加至后(hou)級(ji)功(gong)放電(dian)路(lu)(lu)(lu)的(de)輸(shu)(shu)(shu)入端，改變收錄機的(de)音量，觀察(cha)功(gong)放輸(shu)(shu)(shu)出(chu)的(de)變化)的(de)方法來(lai)判(pan)斷(duan)是哪種原(yuan)因引起的(de)。

若(ruo)加(jia)大(da)(da)(da)輸(shu)入信號后(hou)(hou)，輸(shu)出(chu)(chu)(chu)(chu)的(de)聲音(yin)足夠(gou)大(da)(da)(da)，說(shuo)明功放(fang)輸(shu)出(chu)(chu)(chu)(chu)功率(lv)足夠(gou)，只(zhi)是增(zeng)益(yi)降低，應著重檢(jian)(jian)(jian)查(cha)(cha)繼(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)觸點有(you)無接觸電(dian)(dian)(dian)(dian)(dian)(dian)阻增(zeng)大(da)(da)(da)、輸(shu)入耦(ou)合電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)容(rong)(rong)量(liang)減小、隔(ge)離電(dian)(dian)(dian)(dian)(dian)(dian)阻阻值(zhi)(zhi)增(zeng)大(da)(da)(da)、負反饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)容(rong)(rong)量(liang)變(bian)小或開(kai)(kai)路(lu)(lu)(lu)、負反饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)阻阻值(zhi)(zhi)增(zeng)大(da)(da)(da)或開(kai)(kai)路(lu)(lu)(lu)等(deng)(deng)現(xian)(xian)象。若(ruo)加(jia)大(da)(da)(da)輸(shu)入信號后(hou)(hou)，輸(shu)出(chu)(chu)(chu)(chu)的(de)聲音(yin)出(chu)(chu)(chu)(chu)現(xian)(xian)失真，音(yin)量(liang)并無顯著增(zeng)大(da)(da)(da)，說(shuo)明后(hou)(hou)級放(fang)大(da)(da)(da)器(qi)的(de)輸(shu)出(chu)(chu)(chu)(chu)功率(lv)不(bu)(bu)足，應先(xian)檢(jian)(jian)(jian)查(cha)(cha)放(fang)大(da)(da)(da)器(qi)的(de)正、負供電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)是否(fou)偏低(若(ruo)只(zhi)是一個聲道音(yin)輕，可不(bu)(bu)必檢(jian)(jian)(jian)查(cha)(cha)電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)供電(dian)(dian)(dian)(dian)(dian)(dian))、功率(lv)管或集成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)的(de)性能(neng)是否(fou)變(bian)差(cha)、發(fa)射極電(dian)(dian)(dian)(dian)(dian)(dian)阻阻值(zhi)(zhi)有(you)無變(bian)大(da)(da)(da)等(deng)(deng)。前(qian)級電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中轉換(huan)開(kai)(kai)關、電(dian)(dian)(dian)(dian)(dian)(dian)位器(qi)所造成(cheng)的(de)音(yin)輕，采用(yong)直觀檢(jian)(jian)(jian)查(cha)(cha)較(jiao)易發(fa)現(xian)(xian)，可對(dui)其進行清(qing)洗(xi)或更換(huan)。如懷疑(yi)某信號耦(ou)合電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)失效，可用(yong)同(tong)值(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)并聯(lian)試之；放(fang)大(da)(da)(da)管或運放(fang)集成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)性能(neng)不(bu)(bu)良(liang)，也(ye)可用(yong)代(dai)換(huan)法檢(jian)(jian)(jian)查(cha)(cha)。另(ling)外，負反饋(kui)元件有(you)問題，也(ye)會(hui)造成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)增(zeng)益(yi)下降。