眾所(suo)(suo)周知，日(ri)常(chang)生活中我(wo)們使(shi)用功放(fang)機(ji)，時(shi)間久(jiu)了(le)之后可能就會出現各(ge)種各(ge)樣的(de)問題(ti)，那(nei)么，功放(fang)機(ji)出現問題(ti)的(de)情況下應該(gai)怎么解(jie)決(jue)呢？隔山(shan)如(ru)隔行，雖(sui)然不是所(suo)(suo)有(you)的(de)人都能解(jie)決(jue)的(de)，但是了(le)解(jie)一些相關方(fang)面的(de)知識(shi)會使(shi)你迎刃而解(jie)。下面介紹功放(fang)機(ji)的(de)三種常(chang)見故障(zhang)及維修方(fang)法。

一、整機不(bu)工(gong)作

整(zheng)機(ji)不工作(zuo)的故障表現(xian)為通(tong)電(dian)后放大器(qi)無任何顯(xian)示(shi)，各功能鍵均(jun)失效，也無任何聲(sheng)音，像未通(tong)電(dian)時一(yi)樣(yang)。

檢修時(shi)首先應檢查電(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)。可(ke)用(yong)萬用(yong)表測(ce)量電(dian)(dian)(dian)(dian)(dian)(dian)源插頭(tou)兩端的(de)(de)直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)阻值(zhi)(電(dian)(dian)(dian)(dian)(dian)(dian)源開關應接通)，正常(chang)時(shi)應有數百歐姆的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)阻值(zhi)。若測(ce)得阻值(zhi)偏小許多，且電(dian)(dian)(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)嚴重發熱(re)，說明電(dian)(dian)(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)的(de)(de)初(chu)級(ji)回路(lu)(lu)(lu)有局部(bu)短路(lu)(lu)(lu)處；若測(ce)得阻值(zhi)為大，應檢查保(bao)險絲是否熔斷(duan)、變(bian)壓(ya)器(qi)(qi)(qi)初(chu)級(ji)繞(rao)組是否開路(lu)(lu)(lu)、電(dian)(dian)(dian)(dian)(dian)(dian)源線(xian)與插頭(tou)之間有無斷(duan)線(xian)。有的(de)(de)機器(qi)(qi)(qi)增加了溫(wen)度保(bao)護裝置，在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)的(de)(de)初(chu)級(ji)回路(lu)(lu)(lu)中接人了電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)保(bao)險絲(通常(chang)安裝在(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)內部(bu)，將變(bian)壓(ya)器(qi)(qi)(qi)外部(bu)的(de)(de)絕緣紙(zhi)去掉即(ji)可(ke)見到)，它損壞后也會(hui)使電(dian)(dian)(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)初(chu)級(ji)回路(lu)(lu)(lu)開路(lu)(lu)(lu)。

香蕉視頻app下載: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(zao)聲大

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

檢修時，應先判斷噪聲(sheng)來自(zi)于前(qian)級(ji)還是來自(zi)于后級(ji)電(dian)路(lu)。可把前(qian)、后級(ji)的信號連接插頭(tou)取下，若噪聲(sheng)明(ming)顯(xian)變小，說明(ming)故障(zhang)在前(qian)級(ji)電(dian)路(lu)；反之，故障(zhang)在后級(ji)電(dian)路(lu)。交(jiao)流(liu)(liu)聲(sheng)是指聽感低沉、單調而穩定的100Hz交(jiao)流(liu)(liu)哼(heng)聲(sheng)，主要是電(dian)源部分濾(lv)波(bo)不(bu)良所致(zhi)，應著(zhu)重檢查電(dian)源整流(liu)(liu)、濾(lv)波(bo)和穩壓(ya)元件有(you)無損壞。前(qian)、后級(ji)放大電(dian)路(lu)電(dian)源端(duan)的退耦電(dian)容(rong)虛焊或失效，也會(hui)產生(sheng)一種類似交(jiao)流(liu)(liu)聲(sheng)的低頻振(zhen)蕩噪聲(sheng)。

感應(ying)噪(zao)聲是(shi)成分較(jiao)復(fu)雜(za)且刺耳的(de)(de)(de)交(jiao)流聲，主(zhu)要是(shi)前級(ji)(ji)(ji)電(dian)(dian)(dian)(dian)路(lu)中的(de)(de)(de)轉(zhuan)換開關(guan)、電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)接(jie)地不良(liang)(liang)(liang)或(huo)信號(hao)連線屏蔽不良(liang)(liang)(liang)所致。爆裂聲是(shi)指(zhi)間斷的(de)(de)(de)“劈啪”、“咔(ka)咔(ka)”聲，在前級(ji)(ji)(ji)電(dian)(dian)(dian)(dian)路(lu)中，應(ying)檢(jian)(jian)查(cha)信號(hao)輸入(ru)插(cha)頭與插(cha)座(zuo)、轉(zhuan)換開關(guan)、電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)等是(shi)否(fou)接(jie)觸(chu)不良(liang)(liang)(liang)，耦合電(dian)(dian)(dian)(dian)容有無虛(xu)焊、漏(lou)電(dian)(dian)(dian)(dian)等。后級(ji)(ji)(ji)放(fang)大電(dian)(dian)(dian)(dian)路(lu)應(ying)檢(jian)(jian)查(cha)繼電(dian)(dian)(dian)(dian)器(qi)觸(chu)點是(shi)否(fou)氧化、輸 入(ru)耦合電(dian)(dian)(dian)(dian)容有無漏(lou)電(dian)(dian)(dian)(dian)或(huo)接(jie)觸(chu)不良(liang)(liang)(liang)。另(ling)外，后級(ji)(ji)(ji)電(dian)(dian)(dian)(dian)路(lu)中的(de)(de)(de)差分輸入(ru)管(guan)(guan)或(huo)恒(heng)流管(guan)(guan)軟擊穿，也(ye)會產生類似電(dian)(dian)(dian)(dian)火花的(de)(de)(de)“咔(ka)咔(ka)”噪(zao)聲。白(bai)噪(zao)聲是(shi)指(zhi)無規(gui)則的(de)(de)(de)連續“沙沙”聲，通常是(shi)由前、后級(ji)(ji)(ji)放(fang)大電(dian)(dian)(dian)(dian)路(lu)中的(de)(de)(de)輸入(ru)級(ji)(ji)(ji)晶體(ti)管(guan)(guan)、場效應(ying)管(guan)(guan)或(huo)運放(fang)集成電(dian)(dian)(dian)(dian)路(lu)的(de)(de)(de)性能不良(liang)(liang)(liang)產生的(de)(de)(de)本底(di)噪(zao)聲，檢(jian)(jian)修時，可(ke)用同規(gui)格(ge)的(de)(de)(de)元件代換試之。

三(san)、音(yin)量輕

專業香蕉視頻app下載: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。

若以上各部分均正常，應判(pan)斷出(chu)故(gu)(gu)(gu)障是(shi)在(zai)前級(ji)(ji)(ji)還是(shi)在(zai)后(hou)(hou)級(ji)(ji)(ji)電(dian)路(lu)(lu)(lu)。對于某一(yi)(yi)個聲道音(yin)(yin)輕(qing)，可將其前級(ji)(ji)(ji)電(dian)路(lu)(lu)(lu)輸(shu)出(chu)的(de)(de)(de)信號(hao)交換輸(shu)入(ru)到(dao)另一(yi)(yi)聲道的(de)(de)(de)后(hou)(hou)級(ji)(ji)(ji)電(dian)路(lu)(lu)(lu)，若音(yin)(yin)箱的(de)(de)(de)聲音(yin)(yin)大小不(bu)(bu)變，則故(gu)(gu)(gu)障在(zai)后(hou)(hou)級(ji)(ji)(ji)電(dian)路(lu)(lu)(lu)；反之，故(gu)(gu)(gu)障在(zai)前級(ji)(ji)(ji)電(dian)路(lu)(lu)(lu)。后(hou)(hou)級(ji)(ji)(ji)放大電(dian)路(lu)(lu)(lu)造(zao)成(cheng)的(de)(de)(de)音(yin)(yin)輕(qing)，主要(yao)有(you)輸(shu)出(chu)功率不(bu)(bu)足和增益(yi)不(bu)(bu)夠兩(liang)種原(yuan)因(yin)。可用適(shi)當(dang)加大輸(shu)入(ru)信號(hao)(例如將收錄機輸(shu)出(chu)給揚(yang)聲器的(de)(de)(de)信號(hao)直(zhi)接加至后(hou)(hou)級(ji)(ji)(ji)功放電(dian)路(lu)(lu)(lu)的(de)(de)(de)輸(shu)入(ru)端，改(gai)變收錄機的(de)(de)(de)音(yin)(yin)量，觀(guan)察功放輸(shu)出(chu)的(de)(de)(de)變化(hua))的(de)(de)(de)方(fang)法來判(pan)斷是(shi)哪(na)種原(yuan)因(yin)引起(qi)的(de)(de)(de)。

若加大(da)(da)輸(shu)入信(xin)號(hao)(hao)后，輸(shu)出(chu)的(de)(de)(de)(de)聲(sheng)(sheng)音(yin)足(zu)夠大(da)(da)，說(shuo)明功(gong)放(fang)輸(shu)出(chu)功(gong)率足(zu)夠，只是(shi)增(zeng)(zeng)益(yi)降(jiang)低，應著重(zhong)檢(jian)查(cha)繼電(dian)(dian)(dian)器(qi)觸(chu)點有(you)無接觸(chu)電(dian)(dian)(dian)阻(zu)(zu)增(zeng)(zeng)大(da)(da)、輸(shu)入耦合(he)電(dian)(dian)(dian)容(rong)(rong)容(rong)(rong)量(liang)減小、隔離電(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值增(zeng)(zeng)大(da)(da)、負反饋電(dian)(dian)(dian)容(rong)(rong)容(rong)(rong)量(liang)變(bian)小或(huo)開(kai)路(lu)、負反饋電(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值增(zeng)(zeng)大(da)(da)或(huo)開(kai)路(lu)等現(xian)象。若加大(da)(da)輸(shu)入信(xin)號(hao)(hao)后，輸(shu)出(chu)的(de)(de)(de)(de)聲(sheng)(sheng)音(yin)出(chu)現(xian)失真，音(yin)量(liang)并(bing)無顯著增(zeng)(zeng)大(da)(da)，說(shuo)明后級放(fang)大(da)(da)器(qi)的(de)(de)(de)(de)輸(shu)出(chu)功(gong)率不(bu)足(zu)，應先檢(jian)查(cha)放(fang)大(da)(da)器(qi)的(de)(de)(de)(de)正、負供(gong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓是(shi)否偏低(若只是(shi)一個聲(sheng)(sheng)道(dao)音(yin)輕，可(ke)不(bu)必檢(jian)查(cha)電(dian)(dian)(dian)源供(gong)電(dian)(dian)(dian))、功(gong)率管(guan)或(huo)集成(cheng)(cheng)電(dian)(dian)(dian)路(lu)的(de)(de)(de)(de)性能(neng)是(shi)否變(bian)差、發(fa)射極電(dian)(dian)(dian)阻(zu)(zu)阻(zu)(zu)值有(you)無變(bian)大(da)(da)等。前級電(dian)(dian)(dian)路(lu)中轉換開(kai)關、電(dian)(dian)(dian)位器(qi)所造(zao)(zao)成(cheng)(cheng)的(de)(de)(de)(de)音(yin)輕，采用(yong)直觀(guan)檢(jian)查(cha)較易發(fa)現(xian)，可(ke)對其進行清洗(xi)或(huo)更換。如懷疑某信(xin)號(hao)(hao)耦合(he)電(dian)(dian)(dian)容(rong)(rong)失效，可(ke)用(yong)同值電(dian)(dian)(dian)容(rong)(rong)并(bing)聯(lian)試(shi)之；放(fang)大(da)(da)管(guan)或(huo)運(yun)放(fang)集成(cheng)(cheng)電(dian)(dian)(dian)路(lu)性能(neng)不(bu)良，也可(ke)用(yong)代(dai)換法檢(jian)查(cha)。另外，負反饋元(yuan)件(jian)有(you)問題，也會造(zao)(zao)成(cheng)(cheng)電(dian)(dian)(dian)路(lu)增(zeng)(zeng)益(yi)下降(jiang)。