實驗室凱氏定氮儀常見兩種故障的解決方法

　1、定(ding)時器的改制故障現(xian)象(xiang)
　　在有加堿(jian)指令時(shi)(shi)(shi)，加堿(jian)泵(beng)不(bu)工作。在儀器(qi)(qi)(qi)中(zhong)有四只相同(tong)(tong)的(de)(de)(de)（305）定時(shi)(shi)(shi)器(qi)(qi)(qi)，外型(xing)(xing)(xing)(xing)為插人式大11腳封裝(zhuang)，所以(yi)在需要更換時(shi)(shi)(shi)顯得方便，型(xing)(xing)(xing)(xing)號為SA46720,工作電(dian)(dian)壓為AC22OV,國內(nei)沒有相同(tong)(tong)產(chan)品，曾與儀器(qi)(qi)(qi)生產(chan)廠家(jia)聯(lian)系，這種型(xing)(xing)(xing)(xing)號廠家(jia)早已不(bu)生產(chan)了，經(jing)(jing)我們(men)拆開(kai)(kai)檢查(cha)，發現是定時(shi)(shi)(shi)器(qi)(qi)(qi)TE的(de)(de)(de)供電(dian)(dian)變(bian)壓器(qi)(qi)(qi)B,（220V/24碼燒壞，但定時(shi)(shi)(shi)電(dian)(dian)路(lu)完好，這種小型(xing)(xing)(xing)(xing)變(bian)壓器(qi)(qi)(qi)由于體積(ji)很(hen)小，國產(chan)小的(de)(de)(de)產(chan)品也不(bu)能裝(zhuang)人，以(yi)前我們(men)曾兒次重繞，由于休積(ji)小，電(dian)(dian)壓高，重繞后(hou)(hou)(hou)也維持不(bu)了多(duo)久，后(hou)(hou)(hou)來，我們(men)將其(qi)(qi)部分電(dian)(dian)路(lu)稍加改(gai)動(dong)后(hou)(hou)(hou)，即徹修復，見(jian)圖(tu)1,定時(shi)(shi)(shi)器(qi)(qi)(qi)（TE）的(de)(de)(de)電(dian)(dian)壓端是通(tong)過堿(jian)泵(beng)控制(zhi)開(kai)(kai)關K接(jie)人定時(shi)(shi)(shi)器(qi)(qi)(qi)管座的(de)(de)(de)2,10兩腳，插頭相應的(de)(de)(de)2,10兩腳接(jie)定時(shi)(shi)(shi)器(qi)(qi)(qi)內(nei)部的(de)(de)(de)電(dian)(dian)源變(bian)壓器(qi)(qi)(qi)B的(de)(de)(de)a、b、次級(ji)c、d經(jing)(jing)硅(gui)橋整流后(hou)(hou)(hou)給定時(shi)(shi)(shi)電(dian)(dian)路(lu)供電(dian)(dian)，其(qi)(qi)中(zhong)D為硅(gui)橋，R、C為租容濾(lv)波元件，Rw為時(shi)(shi)(shi)間設定，J為定時(shi)(shi)(shi)器(qi)(qi)(qi)輸出控制(zhi)繼電(dian)(dian)器(qi)(qi)(qi)，J1一(yi)1是J的(de)(de)(de)控制(zhi)觸(chu)頭，S為堿(jian)泵(beng)電(dian)(dian)機，當加堿(jian)時(shi)(shi)(shi)K閉合(he)，AC220V經(jing)(jing)管座接(jie)口進(jin)人B的(de)(de)(de)初(chu)級(ji)，次級(ji)電(dian)(dian)壓整流濾(lv)波后(hou)(hou)(hou)供給定時(shi)(shi)(shi)器(qi)(qi)(qi)電(dian)(dian)路(lu)，設定時(shi)(shi)(shi)間到后(hou)(hou)(hou)，繼電(dian)(dian)器(qi)(qi)(qi)吸(xi)合(he)，其(qi)(qi)觸(chu)頭l,4閉合(he)啟動(dong)加堿(jian)電(dian)(dian)機，開(kai)(kai)始執行(xing)加堿(jian)程序。
　　改(gai)(gai)制(zhi)方(fang)法：先準備一只(zhi)3w一sw,22OV盡4V的(de)(de)(de)小(xiao)型(xing)變(bian)壓器(qi)(qi)B（小(xiao)型(xing)錄音機電源變(bian)壓器(qi)(qi)也可），再將定(ding)(ding)(ding)時器(qi)(qi)內的(de)(de)(de)B拆除，將原(yuan)B的(de)(de)(de)二次線(xian)c、b兩(liang)(liang)端(duan)直接(jie)接(jie)人(ren)插頭的(de)(de)(de)2,10兩(liang)(liang)端(duan)，原(yuan)管座(zuo)上(shang)的(de)(de)(de)2,10兩(liang)(liang)端(duan)拆下，并將這(zhe)兩(liang)(liang)點直接(jie)接(jie)到B的(de)(de)(de)初級(ji)1,2兩(liang)(liang)端(duan)，B的(de)(de)(de)次級(ji)3,4兩(liang)(liang)端(duan)接(jie)管座(zuo)的(de)(de)(de)2,10兩(liang)(liang)端(duan)，將B利用原(yuan)定(ding)(ding)(ding)時器(qi)(qi)旁(pang)邊(bian)接(jie)線(xian)排的(de)(de)(de)固定(ding)(ding)(ding)螺絲就近固定(ding)(ding)(ding)，通過(guo)(guo)這(zhe)樣處理后，定(ding)(ding)(ding)時器(qi)(qi)已使(shi)用兒(er)年未出(chu)現過(guo)(guo)問題。應當(dang)(dang)(dang)注意的(de)(de)(de)是(shi)：如果原(yuan)機中其余兒(er)個定(ding)(ding)(ding)時器(qi)(qi)還未改(gai)(gai)過(guo)(guo)，那應當(dang)(dang)(dang)注意，改(gai)(gai)動過(guo)(guo)與未改(gai)(gai)動過(guo)(guo)的(de)(de)(de)定(ding)(ding)(ding)時器(qi)(qi)之間(jian)不可互換，否則會(hui)使(shi)工(gong)作不正常(chang)或(huo)者(zhe)燒壞，改(gai)(gai)動過(guo)(guo)后應當(dang)(dang)(dang)標(biao)上(shang)標(biao)記。
　　2、電流指示器(qi)的修復故障現象(xiang)
　　儀(yi)器(qi)(qi)(qi)(qi)(qi)每次開(kai)機(ji)簇餾時(shi)，其電(dian)(dian)流(liu)(liu)(liu)指(zhi)示(shi)(shi)(shi)(shi)讀(du)數(shu)不穩定(ding)，讀(du)數(shu)在(zai)(zai)1.5A與(yu)4A之(zhi)間隨機(ji)跳(tiao)動，檢(jian)(jian)查(cha)加熱器(qi)(qi)(qi)(qi)(qi)引(yin)線等均正(zheng)常，查(cha)電(dian)(dian)流(liu)(liu)(liu)指(zhi)示(shi)(shi)(shi)(shi)電(dian)(dian)路(lu)。其電(dian)(dian)路(lu)為(wei)二次互感(gan)方式，在(zai)(zai)加熱器(qi)(qi)(qi)(qi)(qi)電(dian)(dian)路(lu)中(zhong)串(chuan)接一(yi)只電(dian)(dian)流(liu)(liu)(liu)互感(gan)器(qi)(qi)(qi)(qi)(qi)B,B的二次回路(lu)經(jing)硅(gui)橋(qiao)整流(liu)(liu)(liu)，由(you)(you)R.Rw分流(liu)(liu)(liu)后(hou)(hou)由(you)(you)川產表(biao)顯示(shi)(shi)(shi)(shi)電(dian)(dian)流(liu)(liu)(liu)值(zhi)，經(jing)仔細(xi)(xi)分析，并檢(jian)(jian)查(cha)電(dian)(dian)路(lu)后(hou)(hou)用一(yi)只10A左(zuo)右的鉗型(xing)電(dian)(dian)流(liu)(liu)(liu)表(biao)卡人蒸(zheng)餾加熱器(qi)(qi)(qi)(qi)(qi)回路(lu)中(zhong)監測(ce)，發現(xian)當儀(yi)器(qi)(qi)(qi)(qi)(qi)上顯示(shi)(shi)(shi)(shi)的電(dian)(dian)流(liu)(liu)(liu)值(zhi)不穩定(ding)時(shi)，鉗型(xing)表(biao)電(dian)(dian)流(liu)(liu)(liu)讀(du)數(shu)并未變化，這說(shuo)明只是(shi)儀(yi)器(qi)(qi)(qi)(qi)(qi)電(dian)(dian)流(liu)(liu)(liu)指(zhi)示(shi)(shi)(shi)(shi)電(dian)(dian)路(lu)有問題，進一(yi)步檢(jian)(jian)查(cha)發現(xian)顯示(shi)(shi)(shi)(shi)電(dian)(dian)路(lu)中(zhong)校準微(wei)調(diao)Rw已(yi)由(you)(you)銀白色變為(wei)黑褐色，早已(yi)氧(yang)化，在(zai)(zai)調(diao)節(jie)Rw時(shi)，電(dian)(dian)流(liu)(liu)(liu)指(zhi)示(shi)(shi)(shi)(shi)跳(tiao)動較大，Rw廠家(jia)選用為(wei)簡易型(xing)，其觸頭暴(bao)露在(zai)(zai)外面，在(zai)(zai)長期的分析互作(zuo)中(zhong)很(hen)易遭(zao)到有害(hai)氣體的腐蝕(shi)，現(xian)選用國(guo)產封(feng)閉式認伙1型(xing)（IK/IW）代替(ti)后(hou)(hou)，電(dian)(dian)流(liu)(liu)(liu)顯示(shi)(shi)(shi)(shi)穩定(ding)，然后(hou)(hou)參(can)照鉗型(xing)表(biao)電(dian)(dian)流(liu)(liu)(liu)讀(du)數(shu)，仔細(xi)(xi)微(wei)調(diao)Rw使儀(yi)器(qi)(qi)(qi)(qi)(qi)電(dian)(dian)流(liu)(liu)(liu)值(zhi)與(yu)鉗型(xing)表(biao)保持一(yi)致(zhi)后(hou)(hou)，儀(yi)器(qi)(qi)(qi)(qi)(qi)指(zhi)示(shi)(shi)(shi)(shi)值(zhi)已(yi)校準，故(gu)障已(yi)排除(chu)。