如何判(pan)斷電(dian)路(lu)集成(cheng)電(dian)路(lu)IC工作(zuo)狀態?電(dian)子(zi)元件的(de)判(pan)斷是對電(dian)路(lu)失效(xiao)針對的(de)必須項,在維修電(dian)子(zi)產品或電(dian)路(lu)時(shi)(shi)經(jing)常出現,換上新(xin)集成(cheng)電(dian)路(lu)而(er)故障依然(ran)存在的(de)現象,所(suo)以要對集成(cheng)電(dian)路(lu)作(zuo)出正確判(pan)斷才能(neng)減(jian)少損失,準確及時(shi)(shi)處理問題(ti)。
1、首(shou)先要掌握(wo)該(gai)電(dian)路(lu)中IC的用(yong)途(tu)、內部(bu)(bu)結構(gou)原理、主要電(dian)特性等(deng),必要時還要分析內部(bu)(bu)電(dian)原理圖。除(chu)了(le)這些,如果再有(you)各引腳對(dui)地直流(liu)電(dian)壓、波形、對(dui) 地正反向直流(liu)電(dian)阻(zu)值,那(nei)么,對(dui)檢查前判斷提供了(le)更有(you)利條件;
2、然后按故(gu)障現象判斷(duan)其(qi)部(bu)位(wei),再按部(bu)位(wei)查找故(gu)障元(yuan)件。有時(shi)需要多種判斷(duan)方法去證明該器件是(shi)否(fou)確屬損壞(huai);
3、一般對(dui)電(dian)(dian)路(lu)中IC的檢查判(pan)斷方(fang)法有(you)(you)(you)兩種(zhong):一是(shi)不在線判(pan)斷,即電(dian)(dian)路(lu)中IC未焊入印(yin)刷電(dian)(dian)路(lu)板(ban)的判(pan)斷。這種(zhong)方(fang)法在沒有(you)(you)(you)專用儀器設備的情(qing)況下(xia),要(yao)確定該(gai)電(dian)(dian)路(lu)中IC的質量(liang)好壞是(shi)很困(kun)難的,一般情(qing)況下(xia)可用直流電(dian)(dian)阻法測量(liang)各(ge)引腳對(dui) 應于接地腳間的正(zheng)反向(xiang)電(dian)(dian)阻值,并和完(wan)好集成(cheng)電(dian)(dian)路(lu)進行(xing)比較,也(ye)可以(yi)采用替 換(huan)法把可疑的集成(cheng)電(dian)(dian)路(lu)插到正(zheng)常設備同型號(hao)集成(cheng)電(dian)(dian)路(lu)的位置上來確定其好 壞。當然有(you)(you)(you)條件(jian)可利用集成(cheng)電(dian)(dian)路(lu)測試儀對(dui)主要(yao)參數進行(xing)定量(liang)檢驗,這樣使用 就更有(you)(you)(you)保證。
還有在線(xian)檢查判(pan)斷(duan),即集成(cheng)電路(lu)連接在印刷(shua)電路(lu)板上的(de)判(pan)斷(duan)方(fang)法。在線(xian)判(pan)斷(duan)是檢修集成(cheng)電路(lu)在電視、音響、錄像設備中最實用(yong)的(de)方(fang)法。以下分幾種情況進行闡述:
1、直流(liu)工作電(dian)(dian)(dian)壓(ya)測(ce)(ce)量法(fa):主要是(shi)測(ce)(ce)出(chu)各(ge)引腳對地的直流(liu)工作電(dian)(dian)(dian)壓(ya)值;然后與標(biao)稱(cheng)值相比較,依此來判斷集(ji)成電(dian)(dian)(dian)路的好(hao)壞。用電(dian)(dian)(dian)壓(ya)測(ce)(ce)量法(fa)來判斷集(ji)成電(dian)(dian)(dian)路的好(hao)壞是(shi)檢(jian)修中最常采用的方法(fa)之一,但要注意(yi)區別非故(gu)障性(xing)的電(dian)(dian)(dian)壓(ya)誤差。測(ce)(ce)量集(ji)成電(dian)(dian)(dian)路各(ge)引腳的直流(liu)工作電(dian)(dian)(dian)壓(ya)時,如遇到(dao)個(ge)別引腳的電(dian)(dian)(dian)壓(ya)與原(yuan)理(li)圖或維修技術資料中所標(biao)電(dian)(dian)(dian)壓(ya)值不(bu)符,不(bu)要急(ji)于(yu)斷定集(ji)成電(dian)(dian)(dian)路已損壞,應該(gai)先排除以下幾個(ge)因素后再確定。
1)所提供的(de)標稱電(dian)壓(ya)是(shi)(shi)否(fou)可靠(kao),因為(wei)有一些說明書,原(yuan)理圖(tu)等資(zi)料上所標的(de)數(shu)值與實際電(dian)壓(ya)有較大差(cha)別(bie),有時甚至是(shi)(shi)錯誤的(de)。此時,應多找一些有關(guan)資(zi)料進行(xing)對照(zhao),必要時分析內部原(yuan)理圖(tu)與外圍電(dian)路再進行(xing)理論(lun)上的(de)計算或估算來(lai)證(zheng)明電(dian)壓(ya)是(shi)(shi)否(fou)有誤。
2)要區別所(suo)提供的(de)(de)(de)標稱(cheng)電(dian)壓(ya)(ya)(ya)的(de)(de)(de)性(xing)質,其(qi)電(dian)壓(ya)(ya)(ya)是屬哪種工作狀(zhuang)態的(de)(de)(de)電(dian)壓(ya)(ya)(ya)。因為(wei)集成(cheng)塊的(de)(de)(de)個別引(yin)腳隨著(zhu)注入信號的(de)(de)(de)不同(tong)而明顯(xian)變(bian)化,所(suo)以此時可改(gai)變(bian)波段或錄放開關的(de)(de)(de)位(wei)置,再觀察電(dian)壓(ya)(ya)(ya)是否(fou)正常(chang)。如后者為(wei)正常(chang),則說明標稱(cheng)電(dian)壓(ya)(ya)(ya)屬某種工作電(dian)壓(ya)(ya)(ya),而這工作電(dian)壓(ya)(ya)(ya)又是指在某一特定的(de)(de)(de)條件下而言(yan),即測試(shi)的(de)(de)(de)工作狀(zhuang)態不同(tong),所(suo)測電(dian)壓(ya)(ya)(ya)也不一樣。
3)要注意由于外圍(wei)電(dian)(dian)路可變(bian)(bian)元件引(yin)起的(de)(de)(de)(de)引(yin)腳(jiao)電(dian)(dian)壓(ya)(ya)變(bian)(bian)化。當測(ce)量出的(de)(de)(de)(de)電(dian)(dian)壓(ya)(ya)與標(biao)稱電(dian)(dian)壓(ya)(ya)不(bu)(bu)符(fu)(fu)時可能因(yin)為(wei)個(ge)別引(yin)腳(jiao)或(huo)與該引(yin)腳(jiao)相(xiang)關(guan)(guan)的(de)(de)(de)(de)外圍(wei)電(dian)(dian)路,連接的(de)(de)(de)(de)是一個(ge)阻值可變(bian)(bian)的(de)(de)(de)(de)電(dian)(dian)位(wei)(wei)器(qi)(qi)或(huo)者是開關(guan)(guan)(如音量電(dian)(dian)位(wei)(wei)器(qi)(qi)、亮度、對比度、錄像、快進、快倒、錄放開關(guan)(guan)、音頻調幅開關(guan)(guan)等)。這(zhe)些電(dian)(dian)位(wei)(wei)器(qi)(qi)和(he)開關(guan)(guan)所處(chu)的(de)(de)(de)(de)位(wei)(wei)置不(bu)(bu)同(tong)(tong),引(yin)腳(jiao)電(dian)(dian)壓(ya)(ya)會(hui)有(you)明顯不(bu)(bu)同(tong)(tong),所以當出現(xian)某一引(yin)腳(jiao)電(dian)(dian)壓(ya)(ya)不(bu)(bu)符(fu)(fu)時,要考慮引(yin)腳(jiao)或(huo)與該引(yin)腳(jiao)相(xiang)關(guan)(guan)聯的(de)(de)(de)(de)電(dian)(dian)位(wei)(wei)器(qi)(qi)和(he)開關(guan)(guan)的(de)(de)(de)(de)位(wei)(wei)置變(bian)(bian)化,可旋動(dong)或(huo)拔動(dong)開頭看引(yin)腳(jiao)電(dian)(dian)壓(ya)(ya)能否(fou)在標(biao)稱值附近(jin)。
4)要防止由(you)于測量造成的誤(wu)差(cha)(cha)。由(you)于萬用(yong)表(biao)表(biao)頭內阻(zu)不(bu)同或不(bu)同直(zhi)流電(dian)壓(ya)檔(dang)會造成誤(wu)差(cha)(cha)。一般原理(li)上所標的直(zhi)流電(dian)壓(ya)都以測試儀表(biao)的內阻(zu)大于20KΩ/V進行測試的。內阻(zu)小于20KΩ/V的萬用(yong)表(biao)進行測試時,將(jiang)會使被(bei)測結果低(di)于原來(lai)所標的電(dian)壓(ya)。另外,還應注意不(bu)同電(dian)壓(ya)檔(dang)上所測的電(dian)壓(ya)會有差(cha)(cha)別,尤其用(yong)大量程檔(dang),讀數偏(pian)差(cha)(cha)影響更顯著。
5)當測得(de)某一引腳電(dian)(dian)壓(ya)(ya)與正常值不(bu)符時,應根據(ju)該引腳電(dian)(dian)壓(ya)(ya)對IC正常工(gong)作(zuo)有無重要影響以及其(qi)他引腳電(dian)(dian)壓(ya)(ya)的(de)相應變化進行分析,才能(neng)判斷IC的(de)好(hao)壞。
6) 若(ruo)IC各引腳電壓(ya)正(zheng)常(chang),則(ze)一般認為(wei)IC正(zheng)常(chang);若(ruo)IC部(bu)分引腳電壓(ya)異常(chang),則(ze)應(ying)從(cong)偏離正(zheng)常(chang)值最大處入手,進口泵檢查外圍元(yuan)件有無故障,若(ruo)無故障,則(ze)IC很(hen)可能損壞。
7)對于動態接收裝(zhuang)置(zhi),如(ru)電視機,在(zai)有無信號(hao)時,IC各引(yin)腳(jiao)電壓(ya)是不(bu)同(tong)的。如(ru)發(fa)現引(yin)腳(jiao)電壓(ya)不(bu)該(gai)變(bian)(bian)化的反而(er)變(bian)(bian)化大(da),該(gai)隨(sui)信號(hao)大(da)小和(he)可調元件(jian)不(bu)同(tong)位置(zhi)而(er)變(bian)(bian)化的反而(er)不(bu)變(bian)(bian)化,就可確定IC損壞(huai)。
8)對于多(duo)種工作(zuo)方式(shi)的(de)裝置,如錄像機(ji),在(zai)不同工作(zuo)方式(shi)下,IC各引腳電壓也是(shi)不同的(de)。
以上幾點(dian)就是(shi)(shi)在電(dian)(dian)路中(zhong)IC沒有(you)故障(zhang)(zhang)的情況(kuang)下,由于某種原因而(er)使所測(ce)(ce)(ce)結果與標稱(cheng)值不(bu)同(tong),所以總的來說,在進行集成(cheng)塊直流(liu)電(dian)(dian)壓或直流(liu)電(dian)(dian)阻測(ce)(ce)(ce)試時(shi)要(yao)規定一(yi)個測(ce)(ce)(ce)試條件,尤(you)其是(shi)(shi)要(yao)作為實測(ce)(ce)(ce)經驗數據記錄時(shi)更要(yao)注意這一(yi)點(dian)。通常把各電(dian)(dian)位(wei)(wei)器(qi)旋(xuan)到機械中(zhong)間位(wei)(wei)置,信號源采用一(yi)定場強下的標準(zhun)信號,當然,如能再記錄各功能開關位(wei)(wei)置,那(nei)就更有(you)代表(biao)性。如果排(pai)除以上幾個因素后,所測(ce)(ce)(ce)的個別引腳電(dian)(dian)壓還是(shi)(shi)不(bu)符標稱(cheng)值時(shi),需進一(yi)步分(fen)析原因,但(dan)不(bu)外乎(hu)兩種可能。一(yi)是(shi)(shi)集成(cheng)電(dian)(dian)路本(ben)身故障(zhang)(zhang)引起;二是(shi)(shi)集成(cheng)塊外圍電(dian)(dian)路造成(cheng)。分(fen)辨出(chu)這兩種故障(zhang)(zhang)源,也(ye)是(shi)(shi)修理集成(cheng)電(dian)(dian)路家電(dian)(dian)設備的關鍵。
2、交流工作電(dian)(dian)(dian)壓測(ce)(ce)量(liang)法(fa):為了掌(zhang)握IC交流信號的變(bian)化情況,可(ke)以(yi)用(yong)帶有(you)dB插孔的萬(wan)(wan)用(yong)表(biao)(biao)對IC的交流工作電(dian)(dian)(dian)壓進行(xing)近似測(ce)(ce)量(liang)。檢測(ce)(ce)時萬(wan)(wan)用(yong)表(biao)(biao)置于(yu)交流電(dian)(dian)(dian)壓擋(dang),正表(biao)(biao)筆(bi)插入(ru)dB插孔;對于(yu)無dB插孔的萬(wan)(wan)用(yong)表(biao)(biao),需要在(zai)正表(biao)(biao)筆(bi)串接(jie)一只0.1~0.5uF隔(ge)直電(dian)(dian)(dian)容。該法(fa)適(shi)用(yong)于(yu)工作頻率比較(jiao)低的IC,如電(dian)(dian)(dian)視(shi)機(ji)的視(shi)頻放大級、場掃描電(dian)(dian)(dian)路等(deng)。由于(yu)這些電(dian)(dian)(dian)路的固有(you)頻率不(bu)同,波形不(bu)同,所(suo)(suo)以(yi)所(suo)(suo)測(ce)(ce)的數據是近似值,或(huo)者作為有(you)無。
如何(he)判(pan)斷(duan)電(dian)(dian)路集成(cheng)(cheng)電(dian)(dian)路IC工(gong)作狀(zhuang)態?內容就(jiu)到這里,ic集成(cheng)(cheng)電(dian)(dian)路能夠集成(cheng)(cheng)電(dian)(dian)容、電(dian)(dian)阻、等(deng)這種線(xian)路,測試方法都在上述文中(zhong)了,ic在損壞后或(huo)者淘汰后很(hen)多(duo)人都喜(xi)歡花更多(duo)的時間(jian)維(wei)修或(huo)者扔(reng)掉(diao),那么扔(reng)掉(diao)或(huo)者處理(li)不當(dang)的ic會對(dui)大氣造成(cheng)(cheng)污染,不妨選擇超(chao)興勝進行(xing)電(dian)(dian)子回(hui)收,減少損失。