【萬能表】萬能表的使用方法 電工用(yong)的(de)萬能(neng)表(biao)的(de)使用(yong)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(dian)阻檔，指針表的表筆輸出電(dian)流相對數字表來說(shuo)要大很(hen)多，用R×1Ω檔可以(yi)使(shi)揚聲器發出響亮(liang)的“噠(da)”聲，用R×10kΩ檔甚至可以(yi)點亮(liang)發光二極管（LED）。

3、在電(dian)(dian)(dian)(dian)壓檔(dang)，指針表內阻(zu)相對數(shu)字表來說比較(jiao)小，測量(liang)精度相比較(jiao)差。某些高(gao)電(dian)(dian)(dian)(dian)壓微(wei)電(dian)(dian)(dian)(dian)流的(de)場(chang)合甚至無法測準，因為其(qi)內阻(zu)會(hui)對被測電(dian)(dian)(dian)(dian)路造成影(ying)響(xiang)（比如在測電(dian)(dian)(dian)(dian)視機顯(xian)像管的(de)加速級電(dian)(dian)(dian)(dian)壓時測量(liang)值(zhi)會(hui)比實際值(zhi)低(di)很多）。數(shu)字表電(dian)(dian)(dian)(dian)壓檔(dang)的(de)內阻(zu)很大，至少(shao)在兆歐級，對被測電(dian)(dian)(dian)(dian)路影(ying)響(xiang)很小。但極高(gao)的(de)輸(shu)出阻(zu)抗(kang)使其(qi)易受(shou)感應電(dian)(dian)(dian)(dian)壓的(de)影(ying)響(xiang)，在一(yi)些電(dian)(dian)(dian)(dian)磁干擾比較(jiao)強(qiang)的(de)場(chang)合測出的(de)數(shu)據(ju)可(ke)能是虛的(de)。

4、總之，在相對來說大(da)電(dian)流高電(dian)壓的模擬電(dian)路測(ce)量中適用指針表(biao)，比如(ru)電(dian)視機、音(yin)響功(gong)放。在低電(dian)壓小(xiao)電(dian)流的數字(zi)電(dian)路測(ce)量中適用數字(zi)表(biao)，比如(ru)BP機、手機等。不是絕對的，可根據情況(kuang)選(xuan)用指針表(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(dong)圈式話筒(tong)：用R×1Ω檔，任一表筆接一端，另一表筆點觸(chu)另一端，正常時會發出清(qing)脆響量的“噠”聲。如果(guo)(guo)不響，則是線圈斷了，如果(guo)(guo)響聲小而尖，則是有擦(ca)圈問(wen)題，也不能用。

2、測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)：用(yong)電(dian)(dian)(dian)(dian)(dian)阻檔，根(gen)據電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)選(xuan)擇適(shi)當的(de)(de)(de)量(liang)(liang)(liang)程，并(bing)注意測(ce)(ce)(ce)(ce)量(liang)(liang)(liang)時對(dui)于電(dian)(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)黑表筆要(yao)接電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)正極(ji)。①、估(gu)測(ce)(ce)(ce)(ce)微(wei)波(bo)法級電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)的(de)(de)(de)大(da)小：可(ke)(ke)憑經驗或(huo)參照(zhao)相同(tong)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)的(de)(de)(de)標(biao)準電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)，根(gen)據指(zhi)針(zhen)(zhen)擺動(dong)的(de)(de)(de)最大(da)幅度來(lai)判定(ding)。所參照(zhao)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)不(bu)(bu)必耐壓值也一(yi)(yi)(yi)樣(yang)(yang)，只(zhi)(zhi)要(yao)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)相同(tong)即(ji)可(ke)(ke)，例如(ru)估(gu)測(ce)(ce)(ce)(ce)一(yi)(yi)(yi)個100μF/250V的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)可(ke)(ke)用(yong)一(yi)(yi)(yi)個100μF/25V的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)來(lai)參照(zhao)，只(zhi)(zhi)要(yao)它們指(zhi)針(zhen)(zhen)擺動(dong)最大(da)幅度一(yi)(yi)(yi)樣(yang)(yang)，即(ji)可(ke)(ke)斷定(ding)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)一(yi)(yi)(yi)樣(yang)(yang)。②、估(gu)測(ce)(ce)(ce)(ce)皮法級電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)大(da)小：要(yao)用(yong)R×10kΩ檔，但只(zhi)(zhi)能測(ce)(ce)(ce)(ce)到1000pF以上(shang)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)。對(dui)1000pF或(huo)稍(shao)大(da)一(yi)(yi)(yi)點的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)，只(zhi)(zhi)要(yao)表針(zhen)(zhen)稍(shao)有擺動(dong)，即(ji)可(ke)(ke)認為容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)夠了。③、測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)是(shi)否漏電(dian)(dian)(dian)(dian)(dian)：對(dui)一(yi)(yi)(yi)千微(wei)法以上(shang)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)，可(ke)(ke)先用(yong)R×10Ω檔將其(qi)快速充電(dian)(dian)(dian)(dian)(dian)，并(bing)初(chu)步估(gu)測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)容(rong)(rong)(rong)(rong)(rong)量(liang)(liang)(liang)，然后(hou)改到R×1kΩ檔繼續測(ce)(ce)(ce)(ce)一(yi)(yi)(yi)會兒，這時指(zhi)針(zhen)(zhen)不(bu)(bu)應(ying)(ying)回返，而應(ying)(ying)停在或(huo)十分接近∞處，否則就(jiu)是(shi)有漏電(dian)(dian)(dian)(dian)(dian)現象。對(dui)一(yi)(yi)(yi)些幾十微(wei)法以下的(de)(de)(de)定(ding)時或(huo)振蕩電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)（比如(ru)彩電(dian)(dian)(dian)(dian)(dian)開關電(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)振蕩電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)），對(dui)其(qi)漏電(dian)(dian)(dian)(dian)(dian)特性要(yao)求非常高(gao)，只(zhi)(zhi)要(yao)稍(shao)有漏電(dian)(dian)(dian)(dian)(dian)就(jiu)不(bu)(bu)能用(yong)，這時可(ke)(ke)在R×1kΩ檔充完(wan)電(dian)(dian)(dian)(dian)(dian)后(hou)再改用(yong)R×10kΩ檔繼續測(ce)(ce)(ce)(ce)量(liang)(liang)(liang)，同(tong)樣(yang)(yang)表針(zhen)(zhen)應(ying)(ying)停在∞處而不(bu)(bu)應(ying)(ying)回返。

3、在(zai)(zai)路(lu)測(ce)(ce)二(er)(er)極管(guan)(guan)、三極管(guan)(guan)、穩壓管(guan)(guan)好壞(huai)(huai)：因為(wei)在(zai)(zai)實際電(dian)(dian)路(lu)中，三極管(guan)(guan)的(de)(de)(de)(de)偏置電(dian)(dian)阻(zu)(zu)(zu)或(huo)(huo)二(er)(er)極管(guan)(guan)、穩壓管(guan)(guan)的(de)(de)(de)(de)周邊電(dian)(dian)阻(zu)(zu)(zu)一般都比較大(da)(da)，大(da)(da)都在(zai)(zai)幾百(bai)幾千歐姆(mu)以(yi)(yi)上，這(zhe)樣，我們就(jiu)可(ke)以(yi)(yi)用(yong)(yong)萬(wan)用(yong)(yong)表的(de)(de)(de)(de)R×10Ω或(huo)(huo)R×1Ω檔(dang)來在(zai)(zai)路(lu)測(ce)(ce)量PN結(jie)的(de)(de)(de)(de)好壞(huai)(huai)。在(zai)(zai)路(lu)測(ce)(ce)量時(shi)，用(yong)(yong)R×10Ω檔(dang)測(ce)(ce)PN結(jie)應(ying)有較明顯的(de)(de)(de)(de)正(zheng)(zheng)反(fan)向特(te)(te)性(xing)(xing)（如果(guo)(guo)正(zheng)(zheng)反(fan)向電(dian)(dian)阻(zu)(zu)(zu)相(xiang)差不(bu)(bu)太(tai)明顯，可(ke)改用(yong)(yong)R×1Ω檔(dang)來測(ce)(ce)），一般正(zheng)(zheng)向電(dian)(dian)阻(zu)(zu)(zu)在(zai)(zai)R×10Ω檔(dang)測(ce)(ce)時(shi)表針(zhen)應(ying)指示在(zai)(zai)200Ω左右(you)，在(zai)(zai)R×1Ω檔(dang)測(ce)(ce)時(shi)表針(zhen)應(ying)指示在(zai)(zai)30Ω左右(you)（根據不(bu)(bu)同表型可(ke)能(neng)略有出入）。如果(guo)(guo)測(ce)(ce)量結(jie)果(guo)(guo)正(zheng)(zheng)向阻(zu)(zu)(zu)值(zhi)太(tai)大(da)(da)或(huo)(huo)反(fan)向阻(zu)(zu)(zu)值(zhi)太(tai)小，都說明這(zhe)個(ge)PN結(jie)有問(wen)題，這(zhe)個(ge)管(guan)(guan)子也就(jiu)有問(wen)題了(le)(le)。這(zhe)種方法對于(yu)維修(xiu)時(shi)特(te)(te)別有效，可(ke)以(yi)(yi)非常(chang)快速地找出壞(huai)(huai)管(guan)(guan)，甚至可(ke)以(yi)(yi)測(ce)(ce)出尚未完全(quan)壞(huai)(huai)掉但特(te)(te)性(xing)(xing)變(bian)壞(huai)(huai)的(de)(de)(de)(de)管(guan)(guan)子。比如當你用(yong)(yong)小阻(zu)(zu)(zu)值(zhi)檔(dang)測(ce)(ce)量某個(ge)PN結(jie)正(zheng)(zheng)向電(dian)(dian)阻(zu)(zu)(zu)過大(da)(da)，如果(guo)(guo)你把它(ta)焊下來用(yong)(yong)常(chang)用(yong)(yong)的(de)(de)(de)(de)R×1kΩ檔(dang)再測(ce)(ce)，可(ke)能(neng)還(huan)是正(zheng)(zheng)常(chang)的(de)(de)(de)(de)，其(qi)實這(zhe)個(ge)管(guan)(guan)子的(de)(de)(de)(de)特(te)(te)性(xing)(xing)已(yi)經變(bian)壞(huai)(huai)了(le)(le)，不(bu)(bu)能(neng)正(zheng)(zheng)常(chang)工作(zuo)或(huo)(huo)不(bu)(bu)穩定了(le)(le)。

4、測電阻(zu)：重要(yao)的(de)是要(yao)選好(hao)量(liang)程(cheng)，當(dang)指針指示(shi)于1/3～2/3滿量(liang)程(cheng)時測量(liang)精度最高，讀數最準確。要(yao)注意的(de)是，在用R×10k電阻(zu)檔測兆(zhao)歐級的(de)大(da)阻(zu)值電阻(zu)時，不可將手指捏在電阻(zu)兩(liang)端，這樣人(ren)體電阻(zu)會使(shi)測量(liang)結果偏小。

5、測(ce)(ce)(ce)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)二極管(guan)：我(wo)們通(tong)常(chang)所用(yong)(yong)(yong)到的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)一(yi)般都大于(yu)(yu)1.5V，而指(zhi)(zhi)針(zhen)(zhen)表(biao)的(de)(de)(de)(de)(de)(de)(de)R×1k以(yi)下的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻檔是(shi)用(yong)(yong)(yong)表(biao)內的(de)(de)(de)(de)(de)(de)(de)1.5V電(dian)(dian)(dian)(dian)(dian)池供電(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)(de)，這(zhe)樣(yang)(yang)，用(yong)(yong)(yong)R×1k以(yi)下的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)阻檔測(ce)(ce)(ce)量穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)就(jiu)如(ru)同測(ce)(ce)(ce)二極管(guan)一(yi)樣(yang)(yang)，具(ju)有完全的(de)(de)(de)(de)(de)(de)(de)單向(xiang)導電(dian)(dian)(dian)(dian)(dian)性。但(dan)指(zhi)(zhi)針(zhen)(zhen)表(biao)的(de)(de)(de)(de)(de)(de)(de)R×10k檔是(shi)用(yong)(yong)(yong)9V或15V電(dian)(dian)(dian)(dian)(dian)池供電(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)(de)，在用(yong)(yong)(yong)R×10k測(ce)(ce)(ce)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)小(xiao)于(yu)(yu)9V或15V的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)時，反(fan)向(xiang)阻值(zhi)(zhi)(zhi)就(jiu)不會(hui)是(shi)∞，而是(shi)有一(yi)定阻值(zhi)(zhi)(zhi)，但(dan)這(zhe)個阻值(zhi)(zhi)(zhi)還(huan)是(shi)要大大高(gao)(gao)于(yu)(yu)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)正(zheng)向(xiang)阻值(zhi)(zhi)(zhi)的(de)(de)(de)(de)(de)(de)(de)。如(ru)此(ci)，我(wo)們就(jiu)可以(yi)初步(bu)估測(ce)(ce)(ce)出(chu)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)好壞。但(dan)是(shi)，好的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)還(huan)要有個準確的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)，業余條(tiao)件下怎么估測(ce)(ce)(ce)出(chu)這(zhe)個穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)呢？不難，再去找一(yi)塊(kuai)指(zhi)(zhi)針(zhen)(zhen)表(biao)來就(jiu)可以(yi)了(le)。方(fang)法是(shi)：先將一(yi)塊(kuai)表(biao)置(zhi)于(yu)(yu)R×10k檔，其黑、紅表(biao)筆分別接(jie)在穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)陰極和陽極，這(zhe)時就(jiu)模擬出(chu)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)實際工作(zuo)狀(zhuang)態(tai)，再取另一(yi)塊(kuai)表(biao)置(zhi)于(yu)(yu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)檔V×10V或V×50V（根據穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)）上，將紅、黑表(biao)筆分別搭接(jie)到剛才那塊(kuai)表(biao)的(de)(de)(de)(de)(de)(de)(de)的(de)(de)(de)(de)(de)(de)(de)黑、紅表(biao)筆上，這(zhe)時測(ce)(ce)(ce)出(chu)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)就(jiu)基本(ben)上是(shi)這(zhe)個穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)。說“基本(ben)上”，是(shi)因為(wei)(wei)第一(yi)塊(kuai)表(biao)對穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)偏(pian)置(zhi)電(dian)(dian)(dian)(dian)(dian)流(liu)相(xiang)對正(zheng)常(chang)使用(yong)(yong)(yong)時的(de)(de)(de)(de)(de)(de)(de)偏(pian)置(zhi)電(dian)(dian)(dian)(dian)(dian)流(liu)稍(shao)小(xiao)些，所以(yi)測(ce)(ce)(ce)出(chu)的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)會(hui)稍(shao)偏(pian)大一(yi)點，但(dan)基本(ben)相(xiang)差不大。這(zhe)個方(fang)法只可估測(ce)(ce)(ce)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)小(xiao)于(yu)(yu)指(zhi)(zhi)針(zhen)(zhen)表(biao)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)。如(ru)果(guo)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)管(guan)的(de)(de)(de)(de)(de)(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)值(zhi)(zhi)(zhi)太高(gao)(gao)，就(jiu)只能用(yong)(yong)(yong)外加(jia)電(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)(de)(de)(de)方(fang)法來測(ce)(ce)(ce)量了(le)（這(zhe)樣(yang)(yang)看來，我(wo)們在選用(yong)(yong)(yong)指(zhi)(zhi)針(zhen)(zhen)表(biao)時，選用(yong)(yong)(yong)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)(ya)為(wei)(wei)15V的(de)(de)(de)(de)(de)(de)(de)要比9V的(de)(de)(de)(de)(de)(de)(de)更適用(yong)(yong)(yong)些）。

6、測(ce)(ce)三極管(guan)(guan)(guan)：通常我們(men)要用(yong)(yong)R×1kΩ檔(dang)(dang)(dang)，不(bu)(bu)(bu)(bu)(bu)管(guan)(guan)(guan)是(shi)NPN管(guan)(guan)(guan)還(huan)是(shi)PNP管(guan)(guan)(guan)，不(bu)(bu)(bu)(bu)(bu)管(guan)(guan)(guan)是(shi)小(xiao)功率、中功率、大(da)(da)功率管(guan)(guan)(guan)，測(ce)(ce)其(qi)be結(jie)(jie)cb結(jie)(jie)都應(ying)呈(cheng)現與二(er)極管(guan)(guan)(guan)完全(quan)相同的(de)(de)(de)單向導(dao)電(dian)(dian)(dian)性，反(fan)(fan)向電(dian)(dian)(dian)阻(zu)無窮(qiong)大(da)(da)，其(qi)正(zheng)(zheng)向電(dian)(dian)(dian)阻(zu)大(da)(da)約在(zai)10K左右。為(wei)進一步估測(ce)(ce)管(guan)(guan)(guan)子(zi)特(te)性的(de)(de)(de)好(hao)壞，必要時(shi)還(huan)應(ying)變換電(dian)(dian)(dian)阻(zu)檔(dang)(dang)(dang)位進行(xing)多次測(ce)(ce)量(liang)，方法是(shi)：置(zhi)R×10Ω檔(dang)(dang)(dang)測(ce)(ce)PN結(jie)(jie)正(zheng)(zheng)向導(dao)通電(dian)(dian)(dian)阻(zu)都在(zai)大(da)(da)約200Ω左右；置(zhi)R×1Ω檔(dang)(dang)(dang)測(ce)(ce)PN結(jie)(jie)正(zheng)(zheng)向導(dao)通電(dian)(dian)(dian)阻(zu)都在(zai)大(da)(da)約30Ω左右，（以上(shang)(shang)為(wei)47型表(biao)測(ce)(ce)得數據(ju)，其(qi)它型號表(biao)大(da)(da)概略(lve)有(you)不(bu)(bu)(bu)(bu)(bu)同，可(ke)多試測(ce)(ce)幾個好(hao)管(guan)(guan)(guan)總(zong)結(jie)(jie)一下(xia)(xia)，做到心中有(you)數）如果讀數偏大(da)(da)太多，可(ke)以斷(duan)定管(guan)(guan)(guan)子(zi)的(de)(de)(de)特(te)性不(bu)(bu)(bu)(bu)(bu)好(hao)。還(huan)可(ke)將表(biao)置(zhi)于R×10kΩ再測(ce)(ce)，耐(nai)壓(ya)再低的(de)(de)(de)管(guan)(guan)(guan)子(zi)（基(ji)本上(shang)(shang)三極管(guan)(guan)(guan)的(de)(de)(de)耐(nai)壓(ya)都在(zai)30V以上(shang)(shang)），其(qi)cb結(jie)(jie)反(fan)(fan)向電(dian)(dian)(dian)阻(zu)也應(ying)在(zai)∞，但(dan)(dan)其(qi)be結(jie)(jie)的(de)(de)(de)反(fan)(fan)向電(dian)(dian)(dian)阻(zu)可(ke)能會(hui)有(you)些，表(biao)針(zhen)(zhen)會(hui)稍(shao)有(you)偏轉(zhuan)（一般(ban)不(bu)(bu)(bu)(bu)(bu)會(hui)超過滿量(liang)程的(de)(de)(de)1/3，根據(ju)管(guan)(guan)(guan)子(zi)的(de)(de)(de)耐(nai)壓(ya)不(bu)(bu)(bu)(bu)(bu)同而(er)不(bu)(bu)(bu)(bu)(bu)同）。同樣(yang)，在(zai)用(yong)(yong)R×10kΩ檔(dang)(dang)(dang)測(ce)(ce)ec間(對(dui)NPN管(guan)(guan)(guan)）或(huo)ce間（對(dui)PNP管(guan)(guan)(guan)）的(de)(de)(de)電(dian)(dian)(dian)阻(zu)時(shi)，表(biao)針(zhen)(zhen)可(ke)能略(lve)有(you)偏轉(zhuan)，但(dan)(dan)這不(bu)(bu)(bu)(bu)(bu)表(biao)示(shi)管(guan)(guan)(guan)子(zi)是(shi)壞的(de)(de)(de)。但(dan)(dan)在(zai)用(yong)(yong)R×1kΩ以下(xia)(xia)檔(dang)(dang)(dang)測(ce)(ce)ce或(huo)ec間電(dian)(dian)(dian)阻(zu)時(shi)，表(biao)頭指示(shi)應(ying)為(wei)無窮(qiong)大(da)(da)，否則管(guan)(guan)(guan)子(zi)就是(shi)有(you)問題(ti)。應(ying)該說明一點(dian)的(de)(de)(de)是(shi)，以上(shang)(shang)測(ce)(ce)量(liang)是(shi)針(zhen)(zhen)對(dui)硅管(guan)(guan)(guan)而(er)言的(de)(de)(de)，對(dui)鍺(zang)管(guan)(guan)(guan)不(bu)(bu)(bu)(bu)(bu)適用(yong)(yong)。不(bu)(bu)(bu)(bu)(bu)過現在(zai)鍺(zang)管(guan)(guan)(guan)也很少見(jian)了。另外(wai)，所說的(de)(de)(de)“反(fan)(fan)向”是(shi)針(zhen)(zhen)對(dui)PN結(jie)(jie)而(er)言，對(dui)NPN管(guan)(guan)(guan)和PNP管(guan)(guan)(guan)方向實際上(shang)(shang)是(shi)不(bu)(bu)(bu)(bu)(bu)同的(de)(de)(de)。