變頻器 R2B1N2N3N3A0A
用萬(wàn)能表檢測(cè)電路板
1.離線檢測(cè)
測(cè)出IC芯片各引腳對(duì)地之間的正,反電阻值.以此與好的IC芯片
進(jìn)行比較,從而找到故障點(diǎn).
2.在線檢測(cè)
1)直流電阻的檢測(cè)法
同離線檢測(cè).但要注意:
(a)要斷開(kāi)待測(cè)電路板上的電源;
(b)萬(wàn)能表內(nèi)部電壓不得大于6V;
(c)測(cè)量時(shí),要注意外圍的影響.如與IC芯片相連的電位器等.
2)直流工作電壓的測(cè)量法
測(cè)得IC芯片各腳直流電壓與正常值相比即可.但也要注意:
(a)萬(wàn)能表要有足夠大的內(nèi)阻,數(shù)字表為;
(b)各電位器旋到中間位置;
(c)表筆或探頭要采取防滑措施,可用自行車(chē)氣門(mén)芯套在筆頭上,
并應(yīng)長(zhǎng)出筆尖約5mm;
(d)當(dāng)測(cè)量值與正常值不相符時(shí),應(yīng)根據(jù)該引腳電壓,對(duì)IC芯片正
常值有無(wú)影響以及其它引腳電壓的相應(yīng)變化進(jìn)行分析;
(e)IC芯片引腳電壓會(huì)受外圍元器件的影響.當(dāng)外圍有漏電,短路,
開(kāi)路或變質(zhì)等;
(f)IC芯片部分引腳異常時(shí),則從偏離大的入手.先查外圍元器件,
若無(wú)故障,則IC芯片損壞;
(g)對(duì)工作時(shí)有動(dòng)態(tài)信號(hào)的電路板,有無(wú)信號(hào)IC芯片引腳電壓是不
同的.但若變化不正常則IC芯片可能已壞;
(h)對(duì)多種工作方式的設(shè)備,在不同工作方式時(shí)IC腳的電壓是不同
的.
3)交流工作電壓測(cè)試法
用帶有dB檔的萬(wàn)能表,對(duì)IC進(jìn)行交流電壓近似值的測(cè)量.若沒(méi)有dB
檔,則可在正表筆串入一只0.1-0.5μF隔離直流電容.該方法適用
于工作頻率比較低的IC.但要注意這些信號(hào)將受固有頻率,波形不
同而不同.所以所測(cè)數(shù)據(jù)為近似值,僅供參考.
4)總電流測(cè)量法
通過(guò)測(cè)IC電源的總電流,來(lái)判別IC的好壞.由于IC內(nèi)部大多數(shù)為直
流耦合,IC損壞時(shí)(如PN結(jié)擊穿或開(kāi)路)會(huì)引起后級(jí)飽和與截止,使
總電流發(fā)生變化.所以測(cè)總電流可判斷IC的好壞.在線測(cè)得回路電
阻上的電壓,即可算出電流值來(lái).
以上檢測(cè)方法,各有利弊.在實(shí)際應(yīng)用中將這些方法結(jié)合來(lái)運(yùn)用.運(yùn)用好了
就能維修好各種電路板。
變頻器 R2B1N2N3N3A0A
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事實(shí)上,正泰電器市值暴跌有跡可循。盡管并購(gòu)光伏資產(chǎn),“催肥”了正泰電器的營(yíng)收規(guī)模,但2018年以來(lái)其光伏業(yè)務(wù)的毛利率一直在下降,利潤(rùn)空間被壓縮。光伏組件業(yè)務(wù)在2021年的毛利率水平更是降至個(gè)位數(shù)。
玩不轉(zhuǎn)光伏業(yè)務(wù)后,正泰電器“斷臂”求生。今年4月底正泰電器宣布將光伏組件業(yè)務(wù)剝離只留有光伏電站業(yè)務(wù)。另一方面,正泰集團(tuán)卻在不斷加碼光伏業(yè)務(wù),但這與正泰電器無(wú)關(guān)。
脫掉光伏組件的外衣后,正泰電器現(xiàn)有業(yè)務(wù)又能否撐起這近600億市值?
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