眾所(suo)(suo)周知，日常(chang)生(sheng)活中我們使用(yong)功(gong)(gong)放(fang)機(ji)，時間(jian)久了(le)之后(hou)可能就會出(chu)現各種各樣(yang)的(de)問題，那么，功(gong)(gong)放(fang)機(ji)出(chu)現問題的(de)情況下應該怎么解(jie)決呢？隔山(shan)如隔行，雖然不(bu)是所(suo)(suo)有的(de)人都能解(jie)決的(de)，但(dan)是了(le)解(jie)一些(xie)相關方面的(de)知識會使你迎刃(ren)而解(jie)。下面介紹功(gong)(gong)放(fang)機(ji)的(de)三(san)種常(chang)見故障及維修方法。

一、整機不工作(zuo)

       整機不工作的(de)故障(zhang)表現為通電(dian)后放大器無任(ren)何顯示，各功(gong)能鍵(jian)均失效，也(ye)無任(ren)何聲音，像未通電(dian)時一樣(yang)。

檢(jian)修(xiu)時(shi)首先應檢(jian)查電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)路。可(ke)用萬用表測量電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)插頭兩端(duan)的(de)直流電(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)值(zhi)(電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)開關(guan)應接(jie)通)，正常時(shi)應有數(shu)百歐姆的(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)值(zhi)。若測得(de)阻(zu)(zu)值(zhi)偏(pian)小許多，且電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)變(bian)(bian)壓(ya)器(qi)嚴(yan)重發熱，說明電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)變(bian)(bian)壓(ya)器(qi)的(de)初級回路有局部(bu)短路處；若測得(de)阻(zu)(zu)值(zhi)為無(wu)窮大，應檢(jian)查保(bao)(bao)險(xian)絲(si)是否熔斷、變(bian)(bian)壓(ya)器(qi)初級繞組是否開路、電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)線與插頭之間有無(wu)斷線。有的(de)機器(qi)增加了溫度保(bao)(bao)護裝(zhuang)置，在電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)變(bian)(bian)壓(ya)器(qi)的(de)初級回路中接(jie)人了電(dian)(dian)(dian)(dian)(dian)(dian)流保(bao)(bao)險(xian)絲(si)(通常安裝(zhuang)在電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)變(bian)(bian)壓(ya)器(qi)內(nei)部(bu)，將變(bian)(bian)壓(ya)器(qi)外部(bu)的(de)絕緣紙去掉即可(ke)見到)，它(ta)損(sun)壞后也會使電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)變(bian)(bian)壓(ya)器(qi)初級回路開路。

       專業音響工程公司稱若(ruo)電(dian)(dian)(dian)(dian)(dian)(dian)源插(cha)頭兩(liang)端(duan)(duan)(duan)阻值正(zheng)(zheng)(zheng)常(chang)，可通電(dian)(dian)(dian)(dian)(dian)(dian)測量電(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)路各輸(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)是(shi)否(fou)正(zheng)(zheng)(zheng)常(chang)。對于采(cai)用系統控(kong)制(zhi)微處(chu)理器或邏輯控(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)放(fang)大器，應著重檢查該控(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(通常(chang)為+5V)是(shi)否(fou)正(zheng)(zheng)(zheng)常(chang)。如無(wu)+5V電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，應測量三端(duan)(duan)(duan)穩壓(ya)(ya)(ya)集成電(dian)(dian)(dian)(dian)(dian)(dian)路7805的(de)輸(shu)入端(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)是(shi)否(fou)正(zheng)(zheng)(zheng)常(chang)，若(ruo)輸(shu)入端(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不正(zheng)(zheng)(zheng)常(chang)，應檢查整流(liu)、濾波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路。若(ruo)7805輸(shu)入端(duan)(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)正(zheng)(zheng)(zheng)常(chang)，而輸(shu)出端(duan)(duan)(duan)無(wu)十5V電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)或電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)偏(pian)低，可斷(duan)開負載(zai)看+5V電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)能否(fou)恢復正(zheng)(zheng)(zheng)常(chang)。若(ruo)+5V電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)正(zheng)(zheng)(zheng)常(chang)，則故障在負載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)路；若(ruo)+5V電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)仍不正(zheng)(zheng)(zheng)常(chang)，則故障在7805本身(shen)。若(ruo)系統控(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)+5V供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)正(zheng)(zheng)(zheng)常(chang)，應再檢查微處(chu)理器的(de)時鐘及復位信號(hao)是(shi)否(fou)正(zheng)(zheng)(zheng)常(chang)、鍵控(kong)與顯示驅動電(dian)(dian)(dian)(dian)(dian)(dian)路有無(wu)損壞(huai)。

二、噪聲大

       放大(da)器(qi)的噪聲(sheng)有交(jiao)流聲(sheng)、爆裂(lie)聲(sheng)、感(gan)應噪聲(sheng)和(he)白噪聲(sheng)等。

檢(jian)修時，應先判斷噪(zao)聲來(lai)自(zi)于(yu)前級(ji)還(huan)是來(lai)自(zi)于(yu)后級(ji)電路(lu)。可把(ba)前、后級(ji)的信號連(lian)接(jie)插頭取(qu)下，若噪(zao)聲明顯變小(xiao)，說明故(gu)障(zhang)在(zai)(zai)前級(ji)電路(lu)；反(fan)之，故(gu)障(zhang)在(zai)(zai)后級(ji)電路(lu)。交流聲是指聽感低沉(chen)、單(dan)調而(er)穩定(ding)的100Hz交流哼聲，主要是電源部分(fen)濾(lv)波不良所致，應著重檢(jian)查電源整流、濾(lv)波和穩壓(ya)元件有無損壞。前、后級(ji)放(fang)大(da)電路(lu)電源端(duan)的退耦電容虛焊或失效，也會產生一(yi)種(zhong)類似交流聲的低頻振蕩噪(zao)聲。

       感應(ying)噪聲(sheng)(sheng)是(shi)成分(fen)較復雜且(qie)刺耳的交(jiao)流聲(sheng)(sheng)，主要(yao)是(shi)前級(ji)電(dian)路(lu)中(zhong)的轉換開關(guan)、電(dian)位器(qi)接(jie)地不(bu)良或(huo)信號連(lian)線(xian)屏(ping)蔽不(bu)良所致(zhi)。爆裂聲(sheng)(sheng)是(shi)指間斷的“劈(pi)啪”、“咔(ka)(ka)咔(ka)(ka)”聲(sheng)(sheng)，在前級(ji)電(dian)路(lu)中(zhong)，應(ying)檢(jian)(jian)查(cha)信號輸入插頭與插座(zuo)、轉換開關(guan)、電(dian)位器(qi)等(deng)是(shi)否接(jie)觸不(bu)良，耦(ou)合電(dian)容有(you)無(wu)(wu)虛焊、漏(lou)電(dian)等(deng)。后級(ji)放(fang)(fang)大電(dian)路(lu)應(ying)檢(jian)(jian)查(cha)繼電(dian)器(qi)觸點(dian)是(shi)否氧(yang)化、輸 入耦(ou)合電(dian)容有(you)無(wu)(wu)漏(lou)電(dian)或(huo)接(jie)觸不(bu)良。另(ling)外，后級(ji)電(dian)路(lu)中(zhong)的差分(fen)輸入管(guan)或(huo)恒流管(guan)軟擊(ji)穿，也會(hui)產(chan)生類似電(dian)火花的“咔(ka)(ka)咔(ka)(ka)”噪聲(sheng)(sheng)。白噪聲(sheng)(sheng)是(shi)指無(wu)(wu)規則的連(lian)續“沙沙”聲(sheng)(sheng)，通常是(shi)由前、后級(ji)放(fang)(fang)大電(dian)路(lu)中(zhong)的輸入級(ji)晶(jing)體管(guan)、場效應(ying)管(guan)或(huo)運放(fang)(fang)集成電(dian)路(lu)的性(xing)能(neng)不(bu)良產(chan)生的本(ben)底噪聲(sheng)(sheng)，檢(jian)(jian)修時，可用同規格的元(yuan)件代換試之。

三、音量輕

       專(zhuan)業音(yin)響工(gong)程公司稱(cheng)所謂音(yin)輕故障，是(shi)指音(yin)頻信號在放大(da)傳輸過程中，因某個(ge)放大(da)級放大(da)量變化或在某個(ge)環節被(bei)衰減(jian)，使放大(da)器的(de)增益(yi)下(xia)降或輸出功率(lv)變小。檢(jian)修時，首先(xian)應檢(jian)查信號源和音(yin)箱是(shi)否(fou)正(zheng)常，可(ke)用替換的(de)辦法來檢(jian)查。然后(hou)檢(jian)查各類(lei)轉換開關和控制電位器，看音(yin)量能(neng)否(fou)變大(da)。

       若以上各部分均正常(chang)，應判斷出(chu)(chu)故(gu)(gu)障是在(zai)前級(ji)(ji)還是在(zai)后級(ji)(ji)電(dian)路(lu)。對于某一(yi)個聲道音輕(qing)，可將(jiang)其(qi)前級(ji)(ji)電(dian)路(lu)輸(shu)(shu)出(chu)(chu)的(de)(de)信(xin)號交換輸(shu)(shu)入(ru)(ru)到另一(yi)聲道的(de)(de)后級(ji)(ji)電(dian)路(lu)，若音箱的(de)(de)聲音大(da)小不(bu)(bu)變，則故(gu)(gu)障在(zai)后級(ji)(ji)電(dian)路(lu)；反之，故(gu)(gu)障在(zai)前級(ji)(ji)電(dian)路(lu)。后級(ji)(ji)放大(da)電(dian)路(lu)造成的(de)(de)音輕(qing)，主要有(you)輸(shu)(shu)出(chu)(chu)功率不(bu)(bu)足和增益不(bu)(bu)夠兩(liang)種原因。可用適(shi)當加(jia)(jia)大(da)輸(shu)(shu)入(ru)(ru)信(xin)號(例如將(jiang)收錄機輸(shu)(shu)出(chu)(chu)給揚聲器的(de)(de)信(xin)號直接加(jia)(jia)至后級(ji)(ji)功放電(dian)路(lu)的(de)(de)輸(shu)(shu)入(ru)(ru)端，改變收錄機的(de)(de)音量，觀(guan)察功放輸(shu)(shu)出(chu)(chu)的(de)(de)變化)的(de)(de)方法來判斷是哪種原因引起的(de)(de)。

       若(ruo)加(jia)大(da)(da)(da)輸(shu)(shu)(shu)入(ru)信號(hao)后(hou)，輸(shu)(shu)(shu)出(chu)的聲(sheng)音(yin)(yin)(yin)足夠大(da)(da)(da)，說(shuo)明功(gong)放(fang)輸(shu)(shu)(shu)出(chu)功(gong)率足夠，只是(shi)增益(yi)降低(di)，應(ying)著重(zhong)檢(jian)查繼電(dian)(dian)器觸點有無接觸電(dian)(dian)阻(zu)(zu)(zu)增大(da)(da)(da)、輸(shu)(shu)(shu)入(ru)耦合(he)電(dian)(dian)容(rong)(rong)(rong)容(rong)(rong)(rong)量減小、隔離(li)電(dian)(dian)阻(zu)(zu)(zu)阻(zu)(zu)(zu)值增大(da)(da)(da)、負(fu)反(fan)饋(kui)電(dian)(dian)容(rong)(rong)(rong)容(rong)(rong)(rong)量變小或(huo)開路(lu)(lu)、負(fu)反(fan)饋(kui)電(dian)(dian)阻(zu)(zu)(zu)阻(zu)(zu)(zu)值增大(da)(da)(da)或(huo)開路(lu)(lu)等(deng)現象。若(ruo)加(jia)大(da)(da)(da)輸(shu)(shu)(shu)入(ru)信號(hao)后(hou)，輸(shu)(shu)(shu)出(chu)的聲(sheng)音(yin)(yin)(yin)出(chu)現失真，音(yin)(yin)(yin)量并無顯(xian)著增大(da)(da)(da)，說(shuo)明后(hou)級放(fang)大(da)(da)(da)器的輸(shu)(shu)(shu)出(chu)功(gong)率不足，應(ying)先檢(jian)查放(fang)大(da)(da)(da)器的正、負(fu)供(gong)電(dian)(dian)電(dian)(dian)壓是(shi)否(fou)偏(pian)低(di)(若(ruo)只是(shi)一個聲(sheng)道音(yin)(yin)(yin)輕(qing)，可(ke)不必檢(jian)查電(dian)(dian)源供(gong)電(dian)(dian))、功(gong)率管或(huo)集成(cheng)(cheng)電(dian)(dian)路(lu)(lu)的性能是(shi)否(fou)變差(cha)、發射極電(dian)(dian)阻(zu)(zu)(zu)阻(zu)(zu)(zu)值有無變大(da)(da)(da)等(deng)。前級電(dian)(dian)路(lu)(lu)中(zhong)轉換開關、電(dian)(dian)位器所造成(cheng)(cheng)的音(yin)(yin)(yin)輕(qing)，采用直(zhi)觀檢(jian)查較易(yi)發現，可(ke)對其(qi)進行清(qing)洗或(huo)更換。如懷疑某信號(hao)耦合(he)電(dian)(dian)容(rong)(rong)(rong)失效，可(ke)用同值電(dian)(dian)容(rong)(rong)(rong)并聯試之(zhi)；放(fang)大(da)(da)(da)管或(huo)運放(fang)集成(cheng)(cheng)電(dian)(dian)路(lu)(lu)性能不良(liang)，也(ye)可(ke)用代換法檢(jian)查。另外，負(fu)反(fan)饋(kui)元件有問(wen)題(ti)，也(ye)會造成(cheng)(cheng)電(dian)(dian)路(lu)(lu)增益(yi)下降。