【萬能表】萬能表的使用方(fang)法(fa) 電(dian)工用(yong)的萬能表的使用(yong)方(fang)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(dian)阻(zu)檔，指針表的表筆輸出電(dian)流相對(dui)數字(zi)表來說要大很多，用R×1Ω檔可以(yi)(yi)使揚聲器發出響亮的“噠”聲，用R×10kΩ檔甚(shen)至可以(yi)(yi)點亮發光二(er)極(ji)管（LED）。

3、在(zai)(zai)(zai)電(dian)壓(ya)檔(dang)，指針表內阻(zu)相對(dui)數(shu)(shu)字表來說比(bi)較小，測量精度相比(bi)較差。某些高(gao)電(dian)壓(ya)微電(dian)流的場合甚至無法測準，因為其內阻(zu)會(hui)對(dui)被(bei)測電(dian)路造成影響(xiang)（比(bi)如在(zai)(zai)(zai)測電(dian)視(shi)機顯像管(guan)的加速級(ji)電(dian)壓(ya)時測量值(zhi)會(hui)比(bi)實際(ji)值(zhi)低很(hen)(hen)多(duo)）。數(shu)(shu)字表電(dian)壓(ya)檔(dang)的內阻(zu)很(hen)(hen)大，至少在(zai)(zai)(zai)兆(zhao)歐級(ji)，對(dui)被(bei)測電(dian)路影響(xiang)很(hen)(hen)小。但(dan)極高(gao)的輸出阻(zu)抗(kang)使(shi)其易受感應電(dian)壓(ya)的影響(xiang)，在(zai)(zai)(zai)一些電(dian)磁干擾(rao)比(bi)較強的場合測出的數(shu)(shu)據可能是虛的。

4、總之，在相對來說大電(dian)(dian)流高電(dian)(dian)壓(ya)的(de)(de)模擬(ni)電(dian)(dian)路測量中適用(yong)指(zhi)針表(biao)，比(bi)如電(dian)(dian)視機、音(yin)響功放(fang)。在低電(dian)(dian)壓(ya)小(xiao)電(dian)(dian)流的(de)(de)數字(zi)電(dian)(dian)路測量中適用(yong)數字(zi)表(biao)，比(bi)如BP機、手(shou)機等。不是絕對的(de)(de)，可根據(ju)情況選(xuan)用(yong)指(zhi)針表(biao)和數字(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、動圈式話筒：用R×1Ω檔，任一(yi)表筆(bi)接一(yi)端，另(ling)一(yi)表筆(bi)點觸另(ling)一(yi)端，正常時(shi)會發出清脆響量的“噠”聲。如(ru)果不(bu)響，則是(shi)線圈斷了，如(ru)果響聲小而尖，則是(shi)有擦圈問(wen)題，也不(bu)能用。

2、測(ce)電(dian)容(rong)(rong)(rong)(rong)：用(yong)電(dian)阻檔(dang)(dang)(dang)，根據(ju)電(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)選擇適當的(de)(de)量(liang)(liang)(liang)程，并(bing)注(zhu)意測(ce)量(liang)(liang)(liang)時(shi)對(dui)(dui)(dui)(dui)于電(dian)解電(dian)容(rong)(rong)(rong)(rong)黑表筆要(yao)接電(dian)容(rong)(rong)(rong)(rong)正(zheng)極(ji)。①、估(gu)測(ce)微波法(fa)級電(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)的(de)(de)大(da)小：可(ke)憑經驗或(huo)參(can)照(zhao)相同(tong)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)的(de)(de)標(biao)準(zhun)電(dian)容(rong)(rong)(rong)(rong)，根據(ju)指(zhi)針(zhen)(zhen)擺動(dong)的(de)(de)最(zui)大(da)幅(fu)度來判定。所(suo)參(can)照(zhao)的(de)(de)電(dian)容(rong)(rong)(rong)(rong)不(bu)(bu)必耐壓值(zhi)也一(yi)(yi)(yi)樣(yang)(yang)，只(zhi)要(yao)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)相同(tong)即可(ke)，例如估(gu)測(ce)一(yi)(yi)(yi)個100μF/250V的(de)(de)電(dian)容(rong)(rong)(rong)(rong)可(ke)用(yong)一(yi)(yi)(yi)個100μF/25V的(de)(de)電(dian)容(rong)(rong)(rong)(rong)來參(can)照(zhao)，只(zhi)要(yao)它(ta)們指(zhi)針(zhen)(zhen)擺動(dong)最(zui)大(da)幅(fu)度一(yi)(yi)(yi)樣(yang)(yang)，即可(ke)斷定容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)一(yi)(yi)(yi)樣(yang)(yang)。②、估(gu)測(ce)皮法(fa)級電(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)大(da)小：要(yao)用(yong)R×10kΩ檔(dang)(dang)(dang)，但只(zhi)能測(ce)到(dao)1000pF以上的(de)(de)電(dian)容(rong)(rong)(rong)(rong)。對(dui)(dui)(dui)(dui)1000pF或(huo)稍大(da)一(yi)(yi)(yi)點的(de)(de)電(dian)容(rong)(rong)(rong)(rong)，只(zhi)要(yao)表針(zhen)(zhen)稍有擺動(dong)，即可(ke)認(ren)為容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)夠了。③、測(ce)電(dian)容(rong)(rong)(rong)(rong)是否漏(lou)電(dian)：對(dui)(dui)(dui)(dui)一(yi)(yi)(yi)千微法(fa)以上的(de)(de)電(dian)容(rong)(rong)(rong)(rong)，可(ke)先用(yong)R×10Ω檔(dang)(dang)(dang)將其快速充(chong)電(dian)，并(bing)初步估(gu)測(ce)電(dian)容(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)量(liang)(liang)(liang)，然后改到(dao)R×1kΩ檔(dang)(dang)(dang)繼續測(ce)一(yi)(yi)(yi)會兒，這(zhe)(zhe)時(shi)指(zhi)針(zhen)(zhen)不(bu)(bu)應(ying)回返(fan)，而(er)應(ying)停在(zai)或(huo)十分接近∞處，否則就(jiu)是有漏(lou)電(dian)現(xian)象(xiang)。對(dui)(dui)(dui)(dui)一(yi)(yi)(yi)些(xie)幾十微法(fa)以下的(de)(de)定時(shi)或(huo)振蕩電(dian)容(rong)(rong)(rong)(rong)（比如彩電(dian)開關電(dian)源的(de)(de)振蕩電(dian)容(rong)(rong)(rong)(rong)），對(dui)(dui)(dui)(dui)其漏(lou)電(dian)特性要(yao)求非(fei)常高，只(zhi)要(yao)稍有漏(lou)電(dian)就(jiu)不(bu)(bu)能用(yong)，這(zhe)(zhe)時(shi)可(ke)在(zai)R×1kΩ檔(dang)(dang)(dang)充(chong)完(wan)電(dian)后再改用(yong)R×10kΩ檔(dang)(dang)(dang)繼續測(ce)量(liang)(liang)(liang)，同(tong)樣(yang)(yang)表針(zhen)(zhen)應(ying)停在(zai)∞處而(er)不(bu)(bu)應(ying)回返(fan)。

3、在(zai)(zai)(zai)路測(ce)(ce)二(er)極(ji)管(guan)、三極(ji)管(guan)、穩(wen)壓管(guan)好(hao)(hao)壞：因為在(zai)(zai)(zai)實際電路中(zhong)，三極(ji)管(guan)的(de)(de)(de)(de)(de)偏置電阻(zu)或(huo)(huo)二(er)極(ji)管(guan)、穩(wen)壓管(guan)的(de)(de)(de)(de)(de)周邊(bian)電阻(zu)一般都比較大(da)，大(da)都在(zai)(zai)(zai)幾百幾千歐姆以上，這(zhe)樣，我(wo)們就可(ke)(ke)以用(yong)(yong)萬用(yong)(yong)表的(de)(de)(de)(de)(de)R×10Ω或(huo)(huo)R×1Ω檔來在(zai)(zai)(zai)路測(ce)(ce)量PN結(jie)的(de)(de)(de)(de)(de)好(hao)(hao)壞。在(zai)(zai)(zai)路測(ce)(ce)量時(shi)(shi)，用(yong)(yong)R×10Ω檔測(ce)(ce)PN結(jie)應(ying)有較明顯的(de)(de)(de)(de)(de)正(zheng)(zheng)(zheng)反(fan)向(xiang)特(te)性(xing)(xing)（如(ru)(ru)果(guo)正(zheng)(zheng)(zheng)反(fan)向(xiang)電阻(zu)相(xiang)差不太明顯，可(ke)(ke)改用(yong)(yong)R×1Ω檔來測(ce)(ce)），一般正(zheng)(zheng)(zheng)向(xiang)電阻(zu)在(zai)(zai)(zai)R×10Ω檔測(ce)(ce)時(shi)(shi)表針應(ying)指(zhi)示在(zai)(zai)(zai)200Ω左右(you)，在(zai)(zai)(zai)R×1Ω檔測(ce)(ce)時(shi)(shi)表針應(ying)指(zhi)示在(zai)(zai)(zai)30Ω左右(you)（根據不同表型可(ke)(ke)能略有出入）。如(ru)(ru)果(guo)測(ce)(ce)量結(jie)果(guo)正(zheng)(zheng)(zheng)向(xiang)阻(zu)值(zhi)太大(da)或(huo)(huo)反(fan)向(xiang)阻(zu)值(zhi)太小，都說明這(zhe)個(ge)PN結(jie)有問題(ti)，這(zhe)個(ge)管(guan)子(zi)也就有問題(ti)了。這(zhe)種方法對于(yu)維修時(shi)(shi)特(te)別有效，可(ke)(ke)以非常(chang)(chang)快速地找(zhao)出壞管(guan)，甚至可(ke)(ke)以測(ce)(ce)出尚未(wei)完全(quan)壞掉但特(te)性(xing)(xing)變(bian)壞的(de)(de)(de)(de)(de)管(guan)子(zi)。比如(ru)(ru)當你用(yong)(yong)小阻(zu)值(zhi)檔測(ce)(ce)量某個(ge)PN結(jie)正(zheng)(zheng)(zheng)向(xiang)電阻(zu)過大(da)，如(ru)(ru)果(guo)你把它焊下來用(yong)(yong)常(chang)(chang)用(yong)(yong)的(de)(de)(de)(de)(de)R×1kΩ檔再測(ce)(ce)，可(ke)(ke)能還(huan)是(shi)正(zheng)(zheng)(zheng)常(chang)(chang)的(de)(de)(de)(de)(de)，其實這(zhe)個(ge)管(guan)子(zi)的(de)(de)(de)(de)(de)特(te)性(xing)(xing)已(yi)經變(bian)壞了，不能正(zheng)(zheng)(zheng)常(chang)(chang)工作(zuo)或(huo)(huo)不穩(wen)定了。

4、測(ce)電阻：重(zhong)要(yao)(yao)的是要(yao)(yao)選好(hao)量程，當指針指示于(yu)1/3～2/3滿(man)量程時(shi)測(ce)量精度(du)最高，讀數最準確。要(yao)(yao)注意的是，在(zai)用R×10k電阻檔(dang)測(ce)兆歐級的大阻值電阻時(shi)，不可將手指捏在(zai)電阻兩(liang)端，這樣人體電阻會使(shi)測(ce)量結果偏小(xiao)。

5、測(ce)(ce)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)二(er)極管(guan)(guan)：我們通常所用(yong)(yong)到的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)一(yi)(yi)(yi)般都(dou)大于1.5V，而指(zhi)(zhi)(zhi)針表(biao)(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)R×1k以下的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)檔是(shi)(shi)(shi)用(yong)(yong)表(biao)(biao)(biao)(biao)內的(de)(de)(de)(de)(de)(de)1.5V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)，這(zhe)樣(yang)，用(yong)(yong)R×1k以下的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)檔測(ce)(ce)量穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)就(jiu)(jiu)如(ru)同(tong)測(ce)(ce)二(er)極管(guan)(guan)一(yi)(yi)(yi)樣(yang)，具有完全的(de)(de)(de)(de)(de)(de)單向導電(dian)(dian)(dian)(dian)(dian)(dian)(dian)性。但(dan)指(zhi)(zhi)(zhi)針表(biao)(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)R×10k檔是(shi)(shi)(shi)用(yong)(yong)9V或(huo)(huo)15V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)，在用(yong)(yong)R×10k測(ce)(ce)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)小(xiao)于9V或(huo)(huo)15V的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)時(shi)，反向阻(zu)值(zhi)(zhi)就(jiu)(jiu)不(bu)會是(shi)(shi)(shi)∞，而是(shi)(shi)(shi)有一(yi)(yi)(yi)定阻(zu)值(zhi)(zhi)，但(dan)這(zhe)個阻(zu)值(zhi)(zhi)還是(shi)(shi)(shi)要大大高于穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)正向阻(zu)值(zhi)(zhi)的(de)(de)(de)(de)(de)(de)。如(ru)此(ci)，我們就(jiu)(jiu)可以初(chu)步估測(ce)(ce)出(chu)(chu)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)好(hao)(hao)壞。但(dan)是(shi)(shi)(shi)，好(hao)(hao)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)還要有個準確(que)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)，業余條件下怎么估測(ce)(ce)出(chu)(chu)這(zhe)個穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)呢(ni)？不(bu)難(nan)，再去找一(yi)(yi)(yi)塊(kuai)(kuai)指(zhi)(zhi)(zhi)針表(biao)(biao)(biao)(biao)來(lai)就(jiu)(jiu)可以了(le)。方法(fa)是(shi)(shi)(shi)：先將一(yi)(yi)(yi)塊(kuai)(kuai)表(biao)(biao)(biao)(biao)置于R×10k檔，其黑、紅(hong)表(biao)(biao)(biao)(biao)筆(bi)分別接(jie)在穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)陰極和陽極，這(zhe)時(shi)就(jiu)(jiu)模擬出(chu)(chu)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)實際工作狀態，再取另一(yi)(yi)(yi)塊(kuai)(kuai)表(biao)(biao)(biao)(biao)置于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)檔V×10V或(huo)(huo)V×50V（根據穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)）上(shang)(shang)，將紅(hong)、黑表(biao)(biao)(biao)(biao)筆(bi)分別搭接(jie)到剛才那塊(kuai)(kuai)表(biao)(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)的(de)(de)(de)(de)(de)(de)黑、紅(hong)表(biao)(biao)(biao)(biao)筆(bi)上(shang)(shang)，這(zhe)時(shi)測(ce)(ce)出(chu)(chu)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)就(jiu)(jiu)基本(ben)上(shang)(shang)是(shi)(shi)(shi)這(zhe)個穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)。說“基本(ben)上(shang)(shang)”，是(shi)(shi)(shi)因為第一(yi)(yi)(yi)塊(kuai)(kuai)表(biao)(biao)(biao)(biao)對穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)偏(pian)置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)相對正常使用(yong)(yong)時(shi)的(de)(de)(de)(de)(de)(de)偏(pian)置電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)稍小(xiao)些(xie)，所以測(ce)(ce)出(chu)(chu)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)會稍偏(pian)大一(yi)(yi)(yi)點，但(dan)基本(ben)相差(cha)不(bu)大。這(zhe)個方法(fa)只可估測(ce)(ce)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)小(xiao)于指(zhi)(zhi)(zhi)針表(biao)(biao)(biao)(biao)高壓(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)。如(ru)果穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)管(guan)(guan)的(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)太高，就(jiu)(jiu)只能(neng)用(yong)(yong)外加電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源的(de)(de)(de)(de)(de)(de)方法(fa)來(lai)測(ce)(ce)量了(le)（這(zhe)樣(yang)看來(lai)，我們在選(xuan)用(yong)(yong)指(zhi)(zhi)(zhi)針表(biao)(biao)(biao)(biao)時(shi)，選(xuan)用(yong)(yong)高壓(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)為15V的(de)(de)(de)(de)(de)(de)要比9V的(de)(de)(de)(de)(de)(de)更適用(yong)(yong)些(xie)）。

6、測(ce)(ce)(ce)(ce)三(san)極(ji)(ji)管(guan)(guan)(guan)(guan)(guan)：通(tong)常我們要用R×1kΩ檔，不(bu)(bu)管(guan)(guan)(guan)(guan)(guan)是(shi)(shi)(shi)(shi)(shi)NPN管(guan)(guan)(guan)(guan)(guan)還(huan)是(shi)(shi)(shi)(shi)(shi)PNP管(guan)(guan)(guan)(guan)(guan)，不(bu)(bu)管(guan)(guan)(guan)(guan)(guan)是(shi)(shi)(shi)(shi)(shi)小功率(lv)、中功率(lv)、大(da)(da)(da)功率(lv)管(guan)(guan)(guan)(guan)(guan)，測(ce)(ce)(ce)(ce)其be結(jie)(jie)cb結(jie)(jie)都應呈(cheng)現與(yu)二極(ji)(ji)管(guan)(guan)(guan)(guan)(guan)完全相同(tong)的(de)單向(xiang)(xiang)導電(dian)性(xing)，反向(xiang)(xiang)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)無窮(qiong)大(da)(da)(da)，其正向(xiang)(xiang)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)大(da)(da)(da)約在(zai)(zai)10K左右。為(wei)進一步估測(ce)(ce)(ce)(ce)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)特性(xing)的(de)好壞(huai)(huai)，必要時(shi)還(huan)應變換(huan)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)檔位進行多次測(ce)(ce)(ce)(ce)量，方法是(shi)(shi)(shi)(shi)(shi)：置R×10Ω檔測(ce)(ce)(ce)(ce)PN結(jie)(jie)正向(xiang)(xiang)導通(tong)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)都在(zai)(zai)大(da)(da)(da)約200Ω左右；置R×1Ω檔測(ce)(ce)(ce)(ce)PN結(jie)(jie)正向(xiang)(xiang)導通(tong)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)都在(zai)(zai)大(da)(da)(da)約30Ω左右，（以(yi)上為(wei)47型表(biao)(biao)(biao)測(ce)(ce)(ce)(ce)得數(shu)(shu)據(ju)，其它型號表(biao)(biao)(biao)大(da)(da)(da)概(gai)略有(you)不(bu)(bu)同(tong)，可(ke)多試(shi)測(ce)(ce)(ce)(ce)幾個(ge)好管(guan)(guan)(guan)(guan)(guan)總結(jie)(jie)一下，做到心中有(you)數(shu)(shu)）如果讀數(shu)(shu)偏大(da)(da)(da)太多，可(ke)以(yi)斷定管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)的(de)特性(xing)不(bu)(bu)好。還(huan)可(ke)將表(biao)(biao)(biao)置于R×10kΩ再測(ce)(ce)(ce)(ce)，耐(nai)壓再低的(de)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)（基本上三(san)極(ji)(ji)管(guan)(guan)(guan)(guan)(guan)的(de)耐(nai)壓都在(zai)(zai)30V以(yi)上），其cb結(jie)(jie)反向(xiang)(xiang)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)也應在(zai)(zai)∞，但(dan)其be結(jie)(jie)的(de)反向(xiang)(xiang)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)可(ke)能會有(you)些，表(biao)(biao)(biao)針(zhen)會稍有(you)偏轉(zhuan)（一般不(bu)(bu)會超過滿量程的(de)1/3，根(gen)據(ju)管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)的(de)耐(nai)壓不(bu)(bu)同(tong)而不(bu)(bu)同(tong)）。同(tong)樣(yang)，在(zai)(zai)用R×10kΩ檔測(ce)(ce)(ce)(ce)ec間(對NPN管(guan)(guan)(guan)(guan)(guan)）或(huo)ce間（對PNP管(guan)(guan)(guan)(guan)(guan)）的(de)電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)時(shi)，表(biao)(biao)(biao)針(zhen)可(ke)能略有(you)偏轉(zhuan)，但(dan)這不(bu)(bu)表(biao)(biao)(biao)示管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)是(shi)(shi)(shi)(shi)(shi)壞(huai)(huai)的(de)。但(dan)在(zai)(zai)用R×1kΩ以(yi)下檔測(ce)(ce)(ce)(ce)ce或(huo)ec間電(dian)阻(zu)(zu)(zu)(zu)(zu)(zu)時(shi)，表(biao)(biao)(biao)頭指示應為(wei)無窮(qiong)大(da)(da)(da)，否則管(guan)(guan)(guan)(guan)(guan)子(zi)(zi)就是(shi)(shi)(shi)(shi)(shi)有(you)問(wen)題(ti)。應該(gai)說(shuo)明一點的(de)是(shi)(shi)(shi)(shi)(shi)，以(yi)上測(ce)(ce)(ce)(ce)量是(shi)(shi)(shi)(shi)(shi)針(zhen)對硅管(guan)(guan)(guan)(guan)(guan)而言的(de)，對鍺管(guan)(guan)(guan)(guan)(guan)不(bu)(bu)適用。不(bu)(bu)過現在(zai)(zai)鍺管(guan)(guan)(guan)(guan)(guan)也很少見了。另外，所說(shuo)的(de)“反向(xiang)(xiang)”是(shi)(shi)(shi)(shi)(shi)針(zhen)對PN結(jie)(jie)而言，對NPN管(guan)(guan)(guan)(guan)(guan)和(he)PNP管(guan)(guan)(guan)(guan)(guan)方向(xiang)(xiang)實際上是(shi)(shi)(shi)(shi)(shi)不(bu)(bu)同(tong)的(de)。