【萬能(neng)表(biao)】萬能(neng)表(biao)的(de)使用方法(fa) 電(dian)工用的萬能表(biao)的使(shi)用方法

一、指針表和數字表的選用：

1、指針表讀取精度較差，但指針擺動的過程比較直觀，其擺動速度幅度有時也能比較客觀地反映了被測量的大小（比如測電視機數據總線（SDL）在傳送數據時的輕微抖動）；數字表讀數直觀，但數字變化的過程看起來很雜亂，不太容易觀看。

2、指針表內一般有兩塊電池，一塊低電壓的1.5V，一塊是高電壓的9V或15V，其黑表筆相對紅表筆來說是正端。數字表則常用一塊6V或9V的電池。在電阻(zu)檔，指針表的(de)表筆(bi)輸出(chu)電流相對數字表來(lai)說要大很多，用R×1Ω檔可以(yi)使揚聲器發(fa)出(chu)響亮的(de)“噠”聲，用R×10kΩ檔甚至(zhi)可以(yi)點亮發(fa)光(guang)二(er)極管（LED）。

3、在(zai)電(dian)(dian)壓(ya)檔，指(zhi)針表(biao)內阻(zu)相對(dui)(dui)(dui)數字表(biao)來(lai)說比(bi)較小，測(ce)量(liang)精度(du)相比(bi)較差。某些高(gao)電(dian)(dian)壓(ya)微電(dian)(dian)流(liu)的(de)場合甚至無法測(ce)準(zhun)，因(yin)為其內阻(zu)會(hui)對(dui)(dui)(dui)被測(ce)電(dian)(dian)路(lu)造成影(ying)(ying)響（比(bi)如(ru)在(zai)測(ce)電(dian)(dian)視機顯像管(guan)的(de)加速級電(dian)(dian)壓(ya)時測(ce)量(liang)值會(hui)比(bi)實(shi)際(ji)值低很多）。數字表(biao)電(dian)(dian)壓(ya)檔的(de)內阻(zu)很大，至少在(zai)兆歐級，對(dui)(dui)(dui)被測(ce)電(dian)(dian)路(lu)影(ying)(ying)響很小。但極高(gao)的(de)輸出(chu)阻(zu)抗(kang)使(shi)其易受(shou)感應電(dian)(dian)壓(ya)的(de)影(ying)(ying)響，在(zai)一些電(dian)(dian)磁干擾比(bi)較強(qiang)的(de)場合測(ce)出(chu)的(de)數據可能是虛(xu)的(de)。

4、總之，在相對來說大電(dian)(dian)流高(gao)電(dian)(dian)壓(ya)(ya)的(de)模擬電(dian)(dian)路(lu)(lu)測(ce)量(liang)(liang)中適用指(zhi)針表(biao)，比(bi)如電(dian)(dian)視機(ji)、音(yin)響功(gong)放。在低電(dian)(dian)壓(ya)(ya)小電(dian)(dian)流的(de)數(shu)字(zi)電(dian)(dian)路(lu)(lu)測(ce)量(liang)(liang)中適用數(shu)字(zi)表(biao)，比(bi)如BP機(ji)、手機(ji)等。不是(shi)絕對的(de)，可根(gen)據情(qing)況選用指(zhi)針表(biao)和數(shu)字(zi)表(biao)。

二、測量技巧（如不作說明，則指用的是指針表）：

1、測喇叭、耳機、動圈(quan)(quan)式話筒：用R×1Ω檔，任一(yi)表筆接一(yi)端(duan)，另一(yi)表筆點觸另一(yi)端(duan)，正常(chang)時會發出清脆響(xiang)量(liang)的“噠”聲(sheng)。如果不響(xiang)，則是線圈(quan)(quan)斷了，如果響(xiang)聲(sheng)小而尖，則是有擦圈(quan)(quan)問題，也(ye)不能用。

2、測(ce)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)：用(yong)(yong)電(dian)(dian)(dian)阻檔(dang)，根據電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)選擇適當的(de)量(liang)(liang)程，并(bing)注意(yi)測(ce)量(liang)(liang)時(shi)對于電(dian)(dian)(dian)解電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)黑(hei)表筆要(yao)接電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)正(zheng)極。①、估(gu)測(ce)微波法級電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)的(de)大(da)(da)(da)小：可(ke)憑經驗或參(can)照相同容(rong)(rong)(rong)(rong)量(liang)(liang)的(de)標準電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)，根據指(zhi)針擺(bai)動(dong)的(de)最大(da)(da)(da)幅(fu)度來判定(ding)(ding)。所參(can)照的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)不(bu)必耐壓值(zhi)也一(yi)(yi)(yi)樣(yang)，只要(yao)容(rong)(rong)(rong)(rong)量(liang)(liang)相同即(ji)可(ke)，例如估(gu)測(ce)一(yi)(yi)(yi)個100μF/250V的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)可(ke)用(yong)(yong)一(yi)(yi)(yi)個100μF/25V的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)來參(can)照，只要(yao)它們指(zhi)針擺(bai)動(dong)最大(da)(da)(da)幅(fu)度一(yi)(yi)(yi)樣(yang)，即(ji)可(ke)斷定(ding)(ding)容(rong)(rong)(rong)(rong)量(liang)(liang)一(yi)(yi)(yi)樣(yang)。②、估(gu)測(ce)皮法級電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)大(da)(da)(da)小：要(yao)用(yong)(yong)R×10kΩ檔(dang)，但只能測(ce)到1000pF以上(shang)的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)。對1000pF或稍(shao)大(da)(da)(da)一(yi)(yi)(yi)點(dian)的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)，只要(yao)表針稍(shao)有(you)擺(bai)動(dong)，即(ji)可(ke)認(ren)為容(rong)(rong)(rong)(rong)量(liang)(liang)夠了。③、測(ce)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)是否漏(lou)(lou)電(dian)(dian)(dian)：對一(yi)(yi)(yi)千(qian)微法以上(shang)的(de)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)，可(ke)先用(yong)(yong)R×10Ω檔(dang)將其快(kuai)速充(chong)電(dian)(dian)(dian)，并(bing)初步估(gu)測(ce)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)，然后(hou)改到R×1kΩ檔(dang)繼續測(ce)一(yi)(yi)(yi)會兒，這時(shi)指(zhi)針不(bu)應(ying)回返，而(er)應(ying)停在(zai)或十分(fen)接近∞處(chu)，否則就是有(you)漏(lou)(lou)電(dian)(dian)(dian)現(xian)象。對一(yi)(yi)(yi)些幾十微法以下的(de)定(ding)(ding)時(shi)或振蕩(dang)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)（比(bi)如彩電(dian)(dian)(dian)開關電(dian)(dian)(dian)源的(de)振蕩(dang)電(dian)(dian)(dian)容(rong)(rong)(rong)(rong)），對其漏(lou)(lou)電(dian)(dian)(dian)特(te)性(xing)要(yao)求非常高(gao)，只要(yao)稍(shao)有(you)漏(lou)(lou)電(dian)(dian)(dian)就不(bu)能用(yong)(yong)，這時(shi)可(ke)在(zai)R×1kΩ檔(dang)充(chong)完電(dian)(dian)(dian)后(hou)再(zai)改用(yong)(yong)R×10kΩ檔(dang)繼續測(ce)量(liang)(liang)，同樣(yang)表針應(ying)停在(zai)∞處(chu)而(er)不(bu)應(ying)回返。

3、在(zai)(zai)(zai)(zai)路測(ce)二極(ji)(ji)管(guan)、三極(ji)(ji)管(guan)、穩壓(ya)管(guan)好壞(huai)：因為在(zai)(zai)(zai)(zai)實際電(dian)(dian)路中，三極(ji)(ji)管(guan)的(de)偏置電(dian)(dian)阻(zu)或(huo)二極(ji)(ji)管(guan)、穩壓(ya)管(guan)的(de)周邊(bian)電(dian)(dian)阻(zu)一般(ban)都(dou)比(bi)較大(da)，大(da)都(dou)在(zai)(zai)(zai)(zai)幾百(bai)幾千歐姆以(yi)(yi)上，這樣，我們就可(ke)(ke)以(yi)(yi)用(yong)萬用(yong)表(biao)的(de)R×10Ω或(huo)R×1Ω檔(dang)來在(zai)(zai)(zai)(zai)路測(ce)量PN結(jie)(jie)的(de)好壞(huai)。在(zai)(zai)(zai)(zai)路測(ce)量時，用(yong)R×10Ω檔(dang)測(ce)PN結(jie)(jie)應有較明顯的(de)正(zheng)(zheng)反(fan)向(xiang)特性（如(ru)(ru)果(guo)正(zheng)(zheng)反(fan)向(xiang)電(dian)(dian)阻(zu)相差不(bu)(bu)太明顯，可(ke)(ke)改用(yong)R×1Ω檔(dang)來測(ce)），一般(ban)正(zheng)(zheng)向(xiang)電(dian)(dian)阻(zu)在(zai)(zai)(zai)(zai)R×10Ω檔(dang)測(ce)時表(biao)針應指示在(zai)(zai)(zai)(zai)200Ω左右，在(zai)(zai)(zai)(zai)R×1Ω檔(dang)測(ce)時表(biao)針應指示在(zai)(zai)(zai)(zai)30Ω左右（根據不(bu)(bu)同表(biao)型(xing)可(ke)(ke)能略有出入）。如(ru)(ru)果(guo)測(ce)量結(jie)(jie)果(guo)正(zheng)(zheng)向(xiang)阻(zu)值太大(da)或(huo)反(fan)向(xiang)阻(zu)值太小(xiao)，都(dou)說明這個(ge)PN結(jie)(jie)有問題(ti)，這個(ge)管(guan)子也(ye)就有問題(ti)了(le)。這種方法對(dui)于維修時特別有效，可(ke)(ke)以(yi)(yi)非常(chang)快速地找(zhao)出壞(huai)管(guan)，甚至可(ke)(ke)以(yi)(yi)測(ce)出尚未完全(quan)壞(huai)掉但特性變(bian)(bian)壞(huai)的(de)管(guan)子。比(bi)如(ru)(ru)當你用(yong)小(xiao)阻(zu)值檔(dang)測(ce)量某個(ge)PN結(jie)(jie)正(zheng)(zheng)向(xiang)電(dian)(dian)阻(zu)過大(da)，如(ru)(ru)果(guo)你把它焊(han)下(xia)來用(yong)常(chang)用(yong)的(de)R×1kΩ檔(dang)再測(ce)，可(ke)(ke)能還是正(zheng)(zheng)常(chang)的(de)，其實這個(ge)管(guan)子的(de)特性已經變(bian)(bian)壞(huai)了(le)，不(bu)(bu)能正(zheng)(zheng)常(chang)工作或(huo)不(bu)(bu)穩定了(le)。

4、測電(dian)阻：重要(yao)的是(shi)要(yao)選好(hao)量(liang)(liang)程，當指(zhi)針指(zhi)示于1/3～2/3滿量(liang)(liang)程時(shi)測量(liang)(liang)精度(du)最高，讀(du)數最準確。要(yao)注意(yi)的是(shi)，在用(yong)R×10k電(dian)阻檔測兆歐級的大阻值(zhi)電(dian)阻時(shi)，不可將手(shou)指(zhi)捏在電(dian)阻兩端，這樣人體電(dian)阻會使(shi)測量(liang)(liang)結果(guo)偏小。

5、測(ce)(ce)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)二極管(guan)：我們(men)通常(chang)所用(yong)(yong)(yong)到的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)一(yi)般都大(da)(da)于(yu)(yu)1.5V，而指(zhi)針表(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)(de)R×1k以(yi)下(xia)的(de)(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻檔(dang)是(shi)用(yong)(yong)(yong)表(biao)(biao)內的(de)(de)(de)(de)(de)(de)(de)(de)1.5V電(dian)(dian)(dian)(dian)池(chi)供電(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)(de)(de)，這(zhe)(zhe)樣，用(yong)(yong)(yong)R×1k以(yi)下(xia)的(de)(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻檔(dang)測(ce)(ce)量穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)就(jiu)(jiu)如同測(ce)(ce)二極管(guan)一(yi)樣，具有完全的(de)(de)(de)(de)(de)(de)(de)(de)單向(xiang)導電(dian)(dian)(dian)(dian)性。但(dan)指(zhi)針表(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)(de)R×10k檔(dang)是(shi)用(yong)(yong)(yong)9V或(huo)15V電(dian)(dian)(dian)(dian)池(chi)供電(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)(de)(de)，在用(yong)(yong)(yong)R×10k測(ce)(ce)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)小于(yu)(yu)9V或(huo)15V的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)時(shi)，反向(xiang)阻值(zhi)(zhi)(zhi)就(jiu)(jiu)不會(hui)是(shi)∞，而是(shi)有一(yi)定阻值(zhi)(zhi)(zhi)，但(dan)這(zhe)(zhe)個阻值(zhi)(zhi)(zhi)還是(shi)要(yao)大(da)(da)大(da)(da)高于(yu)(yu)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)正向(xiang)阻值(zhi)(zhi)(zhi)的(de)(de)(de)(de)(de)(de)(de)(de)。如此，我們(men)就(jiu)(jiu)可以(yi)初步估測(ce)(ce)出穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)好壞。但(dan)是(shi)，好的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)還要(yao)有個準確(que)的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)，業余條件下(xia)怎么(me)估測(ce)(ce)出這(zhe)(zhe)個穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)呢？不難，再去(qu)找一(yi)塊指(zhi)針表(biao)(biao)來(lai)就(jiu)(jiu)可以(yi)了。方法是(shi)：先將一(yi)塊表(biao)(biao)置于(yu)(yu)R×10k檔(dang)，其黑(hei)、紅(hong)(hong)表(biao)(biao)筆(bi)分(fen)別接(jie)在穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)陰極和陽極，這(zhe)(zhe)時(shi)就(jiu)(jiu)模擬出穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)實際(ji)工作(zuo)狀態(tai)，再取另一(yi)塊表(biao)(biao)置于(yu)(yu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)檔(dang)V×10V或(huo)V×50V（根據(ju)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)）上(shang)，將紅(hong)(hong)、黑(hei)表(biao)(biao)筆(bi)分(fen)別搭接(jie)到剛才那塊表(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)(de)的(de)(de)(de)(de)(de)(de)(de)(de)黑(hei)、紅(hong)(hong)表(biao)(biao)筆(bi)上(shang)，這(zhe)(zhe)時(shi)測(ce)(ce)出的(de)(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)就(jiu)(jiu)基本上(shang)是(shi)這(zhe)(zhe)個穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)。說“基本上(shang)”，是(shi)因為第(di)一(yi)塊表(biao)(biao)對穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)偏置電(dian)(dian)(dian)(dian)流相(xiang)對正常(chang)使用(yong)(yong)(yong)時(shi)的(de)(de)(de)(de)(de)(de)(de)(de)偏置電(dian)(dian)(dian)(dian)流稍小些(xie)，所以(yi)測(ce)(ce)出的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)會(hui)稍偏大(da)(da)一(yi)點(dian)，但(dan)基本相(xiang)差不大(da)(da)。這(zhe)(zhe)個方法只可估測(ce)(ce)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)小于(yu)(yu)指(zhi)針表(biao)(biao)高壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)。如果穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)太(tai)高，就(jiu)(jiu)只能用(yong)(yong)(yong)外加電(dian)(dian)(dian)(dian)源的(de)(de)(de)(de)(de)(de)(de)(de)方法來(lai)測(ce)(ce)量了（這(zhe)(zhe)樣看來(lai)，我們(men)在選用(yong)(yong)(yong)指(zhi)針表(biao)(biao)時(shi)，選用(yong)(yong)(yong)高壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為15V的(de)(de)(de)(de)(de)(de)(de)(de)要(yao)比(bi)9V的(de)(de)(de)(de)(de)(de)(de)(de)更(geng)適(shi)用(yong)(yong)(yong)些(xie)）。

6、測(ce)(ce)(ce)(ce)三(san)極(ji)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)：通常我們要用R×1kΩ檔(dang)(dang)，不(bu)(bu)(bu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)是(shi)(shi)(shi)(shi)(shi)NPN管(guan)(guan)(guan)(guan)(guan)(guan)(guan)還(huan)是(shi)(shi)(shi)(shi)(shi)PNP管(guan)(guan)(guan)(guan)(guan)(guan)(guan)，不(bu)(bu)(bu)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)是(shi)(shi)(shi)(shi)(shi)小(xiao)功率、中功率、大(da)(da)(da)(da)功率管(guan)(guan)(guan)(guan)(guan)(guan)(guan)，測(ce)(ce)(ce)(ce)其(qi)be結(jie)(jie)cb結(jie)(jie)都(dou)應呈現(xian)與二極(ji)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)完全相同(tong)的單向(xiang)(xiang)導電性，反向(xiang)(xiang)電阻(zu)(zu)(zu)無(wu)窮大(da)(da)(da)(da)，其(qi)正向(xiang)(xiang)電阻(zu)(zu)(zu)大(da)(da)(da)(da)約在(zai)(zai)10K左(zuo)右。為(wei)(wei)進(jin)一步估(gu)測(ce)(ce)(ce)(ce)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)特性的好(hao)(hao)壞(huai)，必要時還(huan)應變(bian)換電阻(zu)(zu)(zu)檔(dang)(dang)位進(jin)行多次測(ce)(ce)(ce)(ce)量(liang)(liang)，方法是(shi)(shi)(shi)(shi)(shi)：置R×10Ω檔(dang)(dang)測(ce)(ce)(ce)(ce)PN結(jie)(jie)正向(xiang)(xiang)導通電阻(zu)(zu)(zu)都(dou)在(zai)(zai)大(da)(da)(da)(da)約200Ω左(zuo)右；置R×1Ω檔(dang)(dang)測(ce)(ce)(ce)(ce)PN結(jie)(jie)正向(xiang)(xiang)導通電阻(zu)(zu)(zu)都(dou)在(zai)(zai)大(da)(da)(da)(da)約30Ω左(zuo)右，（以上(shang)為(wei)(wei)47型表(biao)(biao)測(ce)(ce)(ce)(ce)得數(shu)據，其(qi)它型號表(biao)(biao)大(da)(da)(da)(da)概略有(you)(you)(you)不(bu)(bu)(bu)同(tong)，可(ke)(ke)多試(shi)測(ce)(ce)(ce)(ce)幾個好(hao)(hao)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)總(zong)結(jie)(jie)一下，做(zuo)到心中有(you)(you)(you)數(shu)）如果讀(du)數(shu)偏(pian)大(da)(da)(da)(da)太多，可(ke)(ke)以斷定管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)的特性不(bu)(bu)(bu)好(hao)(hao)。還(huan)可(ke)(ke)將(jiang)表(biao)(biao)置于R×10kΩ再測(ce)(ce)(ce)(ce)，耐(nai)壓再低的管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)（基本(ben)上(shang)三(san)極(ji)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)的耐(nai)壓都(dou)在(zai)(zai)30V以上(shang)），其(qi)cb結(jie)(jie)反向(xiang)(xiang)電阻(zu)(zu)(zu)也(ye)應在(zai)(zai)∞，但其(qi)be結(jie)(jie)的反向(xiang)(xiang)電阻(zu)(zu)(zu)可(ke)(ke)能(neng)會有(you)(you)(you)些，表(biao)(biao)針(zhen)會稍有(you)(you)(you)偏(pian)轉（一般不(bu)(bu)(bu)會超過滿量(liang)(liang)程的1/3，根據管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)的耐(nai)壓不(bu)(bu)(bu)同(tong)而不(bu)(bu)(bu)同(tong)）。同(tong)樣，在(zai)(zai)用R×10kΩ檔(dang)(dang)測(ce)(ce)(ce)(ce)ec間(對(dui)(dui)(dui)NPN管(guan)(guan)(guan)(guan)(guan)(guan)(guan)）或ce間（對(dui)(dui)(dui)PNP管(guan)(guan)(guan)(guan)(guan)(guan)(guan)）的電阻(zu)(zu)(zu)時，表(biao)(biao)針(zhen)可(ke)(ke)能(neng)略有(you)(you)(you)偏(pian)轉，但這不(bu)(bu)(bu)表(biao)(biao)示管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)是(shi)(shi)(shi)(shi)(shi)壞(huai)的。但在(zai)(zai)用R×1kΩ以下檔(dang)(dang)測(ce)(ce)(ce)(ce)ce或ec間電阻(zu)(zu)(zu)時，表(biao)(biao)頭指示應為(wei)(wei)無(wu)窮大(da)(da)(da)(da)，否則管(guan)(guan)(guan)(guan)(guan)(guan)(guan)子(zi)(zi)(zi)(zi)就是(shi)(shi)(shi)(shi)(shi)有(you)(you)(you)問題。應該(gai)說(shuo)明一點的是(shi)(shi)(shi)(shi)(shi)，以上(shang)測(ce)(ce)(ce)(ce)量(liang)(liang)是(shi)(shi)(shi)(shi)(shi)針(zhen)對(dui)(dui)(dui)硅管(guan)(guan)(guan)(guan)(guan)(guan)(guan)而言的，對(dui)(dui)(dui)鍺(zang)(zang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)不(bu)(bu)(bu)適用。不(bu)(bu)(bu)過現(xian)在(zai)(zai)鍺(zang)(zang)管(guan)(guan)(guan)(guan)(guan)(guan)(guan)也(ye)很少見(jian)了(le)。另外，所說(shuo)的“反向(xiang)(xiang)”是(shi)(shi)(shi)(shi)(shi)針(zhen)對(dui)(dui)(dui)PN結(jie)(jie)而言，對(dui)(dui)(dui)NPN管(guan)(guan)(guan)(guan)(guan)(guan)(guan)和PNP管(guan)(guan)(guan)(guan)(guan)(guan)(guan)方向(xiang)(xiang)實際上(shang)是(shi)(shi)(shi)(shi)(shi)不(bu)(bu)(bu)同(tong)的。