本(ben)文(wen)將對開關電(dian)源中恒電(dian)流(liu)源電(dian)路的工作(zuo)原理及(ji)特點(dian)等進行分析，供讀者。

　　一、開關電源恒流源電路的(de)(de)(de)(de)(de)構(gou)(gou)成(cheng)及工作(zuo)原(yuan)理由(you)分(fen)立(li)元件組(zu)成(cheng)的(de)(de)(de)(de)(de)開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)中(zhong)(zhong)的(de)(de)(de)(de)(de)恒(heng)流(liu)(liu)源(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)路由(you)分(fen)立(li)元件組(zu)成(cheng)的(de)(de)(de)(de)(de)開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)采(cai)用恒(heng)流(liu)(liu)源(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)(de)彩電(dian)(dian)(dian)(dian)(dian)(dian)有(you)：長虹NC-2、NC- 3、A6等機心系列闈電(dian)(dian)(dian)(dian)(dian)(dian)。另外(wai)，東芝2929DH/DXH彩3開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)基(ji)本相同，也是(shi)(shi)(shi)采(cai)用恒(heng)流(liu)(liu)源(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)揠。，是(shi)(shi)(shi)這種開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)中(zhong)(zhong)的(de)(de)(de)(de)(de)振蕩和(he)恒(heng)流(liu)(liu)源(yuan)(yuan)原(yuan)理圖。振蕩‘路由(you)-⑨繞組(zu)是(shi)(shi)(shi)振蕩電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)(de)(de)(de)反饋支路。恒(heng)流(liu)(liu)源(yuan)(yuan)由(you)VQ820、R822、VD820、C821、R823、T803⑦~⑧和(he)⑦⑨繞組(zu)構(gou)(gou)成(cheng)。其工作(zuo)原(yuan)理是(shi)(shi)(shi)：在VQ83截(jie)止期(qi)間(jian)，T803的(de)(de)(de)(de)(de)⑧端(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)為正，⑨端(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)為負(fu)(fu)。⑨端(duan)(duan)的(de)(de)(de)(de)(de)負(fu)(fu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)經R823加(jia)(jia)到(dao)VQ820的(de)(de)(de)(de)(de)基(ji)極，使VQ820截(jie)止。T803⑧端(duan)(duan)的(de)(de)(de)(de)(de)正電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)通過VD820向C821充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，C821上充(chong)得的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)就成(cheng)為VQ820導(dao)(dao)通時所(suo)需的(de)(de)(de)(de)(de)工作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)。VQ83導(dao)(dao)通時，T803⑧端(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)變(bian)負(fu)(fu)，⑨端(duan)(duan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)由(you)負(fu)(fu)變(bian)正。⑧端(duan)(duan)的(de)(de)(de)(de)(de)負(fu)(fu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)加(jia)(jia)到(dao)VD820正極使其截(jie)止，⑨端(duan)(duan)的(de)(de)(de)(de)(de)正電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)經R823加(jia)(jia)到(dao)VQ820基(ji)極使其導(dao)(dao)通。VQ820導(dao)(dao)通后(hou)，流(liu)(liu)經VQ820集-射之間(jian)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)便成(cheng)為VQ83的(de)(de)(de)(de)(de)基(ji)極注人(ren)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)。VQ820的(de)(de)(de)(de)(de)導(dao)(dao)通電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)不(bu)受交流(liu)(liu)輸(shu)人(ren)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波動的(de)(de)(de)(de)(de)影響，其大小取決于C821上的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)和(he)電(dian)(dian)(dian)(dian)(dian)(dian)阻R822的(de)(de)(de)(de)(de)大小，所(suo)以，VQ83的(de)(de)(de)(de)(de)基(ji)極電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)同樣不(bu)受交流(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)波動的(de)(de)(de)(de)(de)影響，這就展寬了開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)對交流(liu)(liu)輸(shu)入電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)(de)(de)適應范圍。

　　恒(heng)流(liu)源電(dian)路6333等。采用STR-S6309組成開(kai)(kai)關電(dian)源的彩電(dian)有：康(kang)佳06系(xi)列），夏普25N42-E2、29FN1、29AW1及(ji)寬屏(ping)W288、W328，熊貓C64P2、2919，長城G8173MF、G8263、G8363，創維(wei)CTV-8259、CTV-8298.厚(hou)膜電(dian)路STR-S6308與STR-S6309內部電(dian)路結構基本(ben)相同，恒(heng)流(liu)源電(dian)路和原理完全(quan)相同。下面以STR-S6308厚(hou)膜電(dian)路組成的開(kai)(kai)關電(dian)源為例說(shuo)明其恒(heng)流(liu)源工作原理。

　　是(shi)STR-6308厚膜電(dian)(dian)(dian)(dian)路(lu)(lu)組(zu)成的(de)(de)(de)(de)開關電(dian)(dian)(dian)(dian)源中(zhong)的(de)(de)(de)(de)振蕩和(he)(he)恒流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)路(lu)(lu)原(yuan)理(li)圖(tu)。圖(tu)中(zhong)，IC801內部的(de)(de)(de)(de)Q1是(shi)開關管，R803、R804是(shi)振蕩啟動(dong)(dong)電(dian)(dian)(dian)(dian)阻，C812、R807、T803①-②繞組(zu)是(shi)振蕩電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)(de)反饋支路(lu)(lu)。恒流(liu)(liu)(liu)源電(dian)(dian)(dian)(dian)路(lu)(lu)由(you)IC801內部的(de)(de)(de)(de)Q3、R2、R3、D2及外部的(de)(de)(de)(de)C814、D803、R806和(he)(he)T803①-②繞組(zu)構成。其恒流(liu)(liu)(liu)源工作原(yuan)理(li)為(wei)(wei)(wei)：在(zai)（1截(jie)止(zhi)(zhi)期間，T803②端電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)(wei)(wei)正(zheng)(zheng)，①端電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)為(wei)(wei)(wei)負(fu)(fu)。T803②端電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)通(tong)(tong)(tong)過(guo)IC801內部的(de)(de)(de)(de)D2向C814充(chong)電(dian)(dian)(dian)(dian)，其充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)路(lu)(lu)徑(jing)為(wei)(wei)(wei)：T803②④一(yi)814-803-803①。C814上(shang)充(chong)得(de)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)就成為(wei)(wei)(wei)Q3導(dao)(dao)(dao)通(tong)(tong)(tong)時(shi)所(suo)需要(yao)的(de)(de)(de)(de)工作電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。在(zai)Q1導(dao)(dao)(dao)通(tong)(tong)(tong)時(shi)，T803②端電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)由(you)正(zheng)(zheng)變負(fu)(fu)，①端電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)由(you)負(fu)(fu)變正(zheng)(zheng)。②端的(de)(de)(de)(de)負(fu)(fu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)加(jia)(jia)到D2的(de)(de)(de)(de)正(zheng)(zheng)極(ji)使其截(jie)止(zhi)(zhi)，①端的(de)(de)(de)(de)正(zheng)(zheng)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)加(jia)(jia)到IC801的(de)(de)(de)(de)⑤腳(jiao)，再通(tong)(tong)(tong)過(guo)其內部R3加(jia)(jia)到Q3的(de)(de)(de)(de)基(ji)(ji)極(ji)使其導(dao)(dao)(dao)通(tong)(tong)(tong)。Q3導(dao)(dao)(dao)通(tong)(tong)(tong)后，C814通(tong)(tong)(tong)過(guo)Q3放(fang)電(dian)(dian)(dian)(dian)，其放(fang)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)路(lu)(lu)徑(jing)為(wei)(wei)(wei)：C814正(zheng)(zheng)極(ji)->IC801dH3ce極(ji)->Qlbe極(ji)―IC801②―R806->C814負(fu)(fu)極(ji)。Q3導(dao)(dao)(dao)通(tong)(tong)(tong)后，流(liu)(liu)(liu)過(guo)Q3集射(she)之間的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)便成為(wei)(wei)(wei)（1的(de)(de)(de)(de)基(ji)(ji)極(ji)注人(ren)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)。因為(wei)(wei)(wei)Q3的(de)(de)(de)(de)導(dao)(dao)(dao)通(tong)(tong)(tong)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)不受(shou)交流(liu)(liu)(liu)輸人(ren)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)波動(dong)(dong)的(de)(de)(de)(de)影響(xiang)，只取決于C814上(shang)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)和(he)(he)電(dian)(dian)(dian)(dian)阻R806的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)阻大小，所(suo)以，開關管Q1的(de)(de)(de)(de)基(ji)(ji)極(ji)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)同樣不受(shou)交流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)波動(dong)(dong)的(de)(de)(de)(de)影響(xiang)，這就展(zhan)寬了開關電(dian)(dian)(dian)(dian)海對(dui)交流(liu)(liu)(liu)輸人(ren)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)(de)(de)(de)適應范(fan)圍。

　　二、開(kai)關中(zhong)楦流源(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)路(lu)(lu)的(de)(de)(de)(de)特點1.含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)與(yu)不含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)電(dian)(dian)路(lu)(lu)區別通過(guo)對(dui)含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)和(he)不含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)電(dian)(dian)路(lu)(lu)對(dui)比，就會發(fa)現，這兩類電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)振蕩反(fan)(fan)(fan)饋支(zhi)路(lu)(lu)的(de)(de)(de)(de)阻(zu)抗是(shi)不同的(de)(de)(de)(de)（反(fan)(fan)(fan)饋支(zhi)路(lu)(lu)主要由電(dian)(dian)阻(zu)和(he)電(dian)(dian)容(rong)(rong)串聯組成）。附表(biao)是(shi)這兩類電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)幾(ji)種機心彩(cai)電(dian)(dian)反(fan)(fan)(fan)饋電(dian)(dian)容(rong)(rong)和(he)反(fan)(fan)(fan)饋電(dian)(dian)阻(zu)的(de)(de)(de)(de)統計表(biao)。從統計表(biao)中(zhong)可以看出：含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)振蕩反(fan)(fan)(fan)饋電(dian)(dian)容(rong)(rong)小，阻(zu)抗大(da)，反(fan)(fan)(fan)饋電(dian)(dian)流小；不含恒(heng)(heng)流源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)開(kai)關電(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)振蕩反(fan)(fan)(fan)饋電(dian)(dian)容(rong)(rong)大(da)，阻(zu)抗小，反(fan)(fan)(fan)饋電(dian)(dian)流大(da)。

　　2.失效后(hou)機器的(de)故(gu)障表現(xian)開(kai)關電(dian)(dian)(dian)源中(zhong)(zhong)的(de)恒流電(dian)(dian)(dian)路(lu)失效后(hou)，注人開(kai)關管的(de)基(ji)極電(dian)(dian)(dian)流僅有振(zhen)蕩反饋支(zhi)路(lu)一(yi)路(lu)電(dian)(dian)(dian)流，只能(neng)維持開(kai)關管處于弱振(zhen)蕩狀態，開(kai)關電(dian)(dian)(dian)源的(de)負載能(neng)力(li)將會(hui)大大降低。遙控彩(cai)電(dian)(dian)(dian)在待電(dian)(dian)(dian)子世界老式(shi)彩(cai)電(dian)(dian)(dian)加(jia)裝哞技討嫡(di)t媒葙f鯰(nian)改(gai)良(liang)方(fang)鉉李超2.記(ji)錄(lu)數據安裝前測量并記(ji)錄(lu)彩(cai)電(dian)(dian)(dian)各模擬量的(de)電(dian)(dian)(dian)壓調節板±的(de)運放(fang)。農彩(cai)電(dian)(dian)(dian)中(zhong)(zhong)模擬量控制電(dian)(dian)(dian)壓的(de)兩(liang)個指(zhi)標(biao)彩(cai)電(dian)(dian)(dian)中(zhong)(zhong)有音量、亮度等模擬量控制電(dian)(dian)(dian)路(lu)，它們一(yi)般用調節電(dian)(dian)(dian)壓的(de)方(fang)式(shi)進(jin)行控制。在這種電(dian)(dian)(dian)路(lu)中(zhong)(zhong)，控制電(dian)(dian)(dian)壓有兩(liang)個指(zhi)標(biao)。

　　調(diao)節(jie)(jie)范圍設電(dian)(dian)位器調(diao)到上、下極限時(shi)，對應的(de)(de)觸(chu)頭電(dian)(dian)位分別為(wei)Vh、Vl，則(ze)控制電(dian)(dian)壓調(diao)節(jie)(jie)范圍AV=VH―VL.一般來說厶V越大控制范圍越寬(kuan)。但(dan)是，過(guo)大的(de)(de)AV會使調(diao)節(jie)(jie)精度(du)下降，影響圖像或(huo)伴音質量，嚴重時(shi)彩電(dian)(dian)不能(neng)正常工作。

　　平均電(dian)位平均電(dian)位丫(ya)=丫(ya)11一￥1/2.丫(ya)的大小(xiao)直接(jie)影響控(kong)(kong)制(zhi)效(xiao)果。如(ru)飽(bao)(bao)和度控(kong)(kong)制(zhi)中，V過小(xiao)會造成圖像飽(bao)(bao)和度調(diao)(diao)不起來，色彩很淡。所以在加裝遙控(kong)(kong)時，AV和V應盡可能(neng)調(diao)(diao)整到設計水(shui)平。如(ru)有困難(nan)，以適當偏高為宜。

　　改良(liang)方法的(de)基本構想1.模擬量(liang)控(kong)(kong)制(zhi)電(dian)(dian)路的(de)特點老式(shi)彩電(dian)(dian)一般有(you)四個模擬量(liang)，如(ru)遙控(kong)(kong)板(ban)上(shang)有(you)四個相(xiang)應的(de)模擬量(liang)輸(shu)出電(dian)(dian)路，各由三只電(dian)(dian)阻(zu)(zu)：輸(shu)出電(dian)(dian)阻(zu)(zu)，上(shang)、下偏置電(dian)(dian)阻(zu)(zu)組成，在中(zhong)相(xiang)應的(de)電(dian)(dian)阻(zu)(zu)分別是R17、R18、R19.其中(zhong)，輸(shu)出電(dian)(dian)阻(zu)(zu)主(zhu)要控(kong)(kong)制(zhi)調節范(fan)圍，上(shang)、下偏置電(dian)(dian)阻(zu)(zu)主(zhu)要控(kong)(kong)制(zhi)平(ping)均電(dian)(dian)位。

　　2.現行的(de)調整(zheng)方法及(ji)改(gai)良安裝說明書及(ji)一般資(zi)料上介(jie)紹的(de)方法是，廢除(chu)彩(cai)電(dian)(dian)原有的(de)分壓調節電(dian)(dian)路，對遙控(kong)板上的(de)電(dian)(dian)阻進(jin)行調整(zheng)。這樣須(xu)調整(zheng)的(de)電(dian)(dian)阻一般有12只(zhi)。在實際(ji)工作中要選定并(bing)找(zhao)到(dao)相應的(de)電(dian)(dian)阻并(bing)不(bu)容易，調整(zheng)起(qi)來反反復(fu)復(fu)，耗時多，精度(du)差。

　　從上(shang)(shang)面的(de)分析中，我們不難(nan)發現(xian)：如果保留彩(cai)電(dian)(dian)上(shang)(shang)的(de)分壓(ya)電(dian)(dian)路就可以(yi)省掉遙控板上(shang)(shang)的(de)分壓(ya)電(dian)(dian)路，這樣需調整的(de)電(dian)(dian)阻由12只減(jian)為4只，大(da)大(da)減(jian)少(shao)了工(gong)作量，有利于提高調整精(jing)度。

　　實例-1803PD（S）彩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)安裝(zhuang)卓異Z9831遙控器為例，現介紹如(ru)下：1.準備材(cai)料找51kn、200kfl可調電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)各一只，按連接(jie)，引(yin)線長約30cm.備1/8W電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)若干。機(ji)狀(zhuang)態，行(xing)、場(chang)掃(sao)描(miao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)停(ting)(ting)止(zhi)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)，開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源處(chu)于輕負荷狀(zhuang)態，即使恒流(liu)有問題也看(kan)不出它的(de)(de)故障(zhang)表現。當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)視機(ji)處(chu)于正常收視狀(zhuang)態，特別(bie)是電(dian)(dian)(dian)(dian)(dian)(dian)(dian)視屏幕比(bi)較亮(liang)時，行(xing)、場(chang)掃(sao)描(miao)系(xi)統要消(xiao)耗較大的(de)(de)功(gong)率，恒流(liu)源失(shi)效了的(de)(de)開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源難以負擔這(zhe)一重任，開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源將會停(ting)(ting)止(zhi)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)。開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源停(ting)(ting)止(zhi)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)后，行(xing)、場(chang)掃(sao)描(miao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)因失(shi)去(qu)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)也自然停(ting)(ting)止(zhi)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)，這(zhe)時開(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源因失(shi)去(qu)負載又開(kai)始起(qi)振(zhen)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)，行(xing)、場(chang)掃(sao)描(miao)又得到(dao)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)再度工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)，開(kai)關管負擔加重又停(ting)(ting)止(zhi)工(gong)作(zuo)(zuo)(zuo)(zuo)(zuo)，周而復(fu)始，范圍，留作(zuo)(zuo)(zuo)(zuo)(zuo)調試標準。實測數(shu)據為：亮(liang)度：7.4彩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)改(gai)動關掉彩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源拔下插頭，將各模擬量的(de)(de)控制端由電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)器的(de)(de)中(zhong)心抽頭改(gai)接(jie)到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)器的(de)(de)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)端，并與遙控板上(shang)相應模擬量的(de)(de)輸出引(yin)線庫接(jie)，如(ru)所示。

　　4遙控板調(diao)整拔下(xia)遙控板上各模(mo)擬量輸(shu)出(chu)端的(de)上下(xia)偏置電阻共8只，在其它加裝工作已完(wan)成的(de)情況(kuang)下(xia)，對各模(mo)擬量的(de)輸(shu)出(chu)電阻進行調(diao)整。以亮(liang)(liang)度控制(zhi)為例，具體步(bu)驟如下(xia)：⑴拔下(xia)輸(shu)出(chu)電阻R17，將(jiang)(jiang)51M1可調(diao)電阻焊上，通(tong)電并(bing)用遙控將(jiang)(jiang)亮(liang)(liang)度調(diao)到最小。如果(guo)熒(ying)光屏不亮(liang)(liang)，可用萬用表監測亮(liang)(liang)度控制(zhi)電壓，下(xia)降到不動(dong)為止。

　　（2）調(diao)(diao)整51kfi可(ke)調(diao)(diao)電阻(zu)使亮度(du)(du)控制電壓(ya)為(wei)7.4V.關(guan)機(ji)焊下(xia)可(ke)調(diao)(diao)電阻(zu)的一端(duan)，測(ce)得其(qi)阻(zu)值為(wei)37kfl.⑶重新焊上可(ke)調(diao)(diao)電阻(zu)并開機(ji)，用遙控器將亮度(du)(du)調(diao)(diao)到最大。調(diao)(diao)整可(ke)調(diao)(diao)電阻(zu)使亮度(du)(du)控制電壓(ya)為(wei)7.9V，關(guan)機(ji)焊下(xia)可(ke)調(diao)(diao)電阻(zu)，測(ce)得其(qi)阻(zu)值為(wei)40kft.在步驟(zou)⑵、⑶中。如果調(diao)(diao)整可(ke)調(diao)(diao)電阻(zu)達不到所需(xu)電壓(ya)，就將可(ke)調(diao)(diao)電阻(zu)由51kfl換成200M1后重試。

　　⑷一般來(lai)說(shuo)，選(xuan)擇偏(pian)小的(de)輸(shu)出電阻使調節范圍適(shi)當(dang)擴(kuo)大為宜，這里(li)選(xuan)R17=36kft.經(jing)測(ce)試亮度控制(zhi)電壓(ya)為7.3~8.IV，效(xiao)果很(hen)理想(xiang)。如果選(xuan)R17=33kft，效(xiao)果也不錯。其它三個模擬(ni)量(liang)輸(shu)出電阻的(de)選(xuan)擇方(fang)法與此相同，這里(li)不再(zai)贅(zhui)述(shu)。

　　從上(shang)面(mian)的(de)(de)(de)(de)介紹(shao)(shao)中(zhong)不(bu)難發現(xian)這種方法有(you)三個優點：（1）不(bu)需(xu)對電(dian)(dian)(dian)(dian)路(lu)進行太多(duo)分(fen)析和了解。⑵需(xu)要調整電(dian)(dian)(dian)(dian)阻(zu)(zu)由12只變成4只，減少了工作量。⑶調整精度(du)便于(yu)(yu)控(kong)(kong)(kong)(kong)制，有(you)利于(yu)(yu)提高圖(tu)(tu)(tu)(tu)像(xiang)(xiang)(xiang)質量。必須說明(ming)的(de)(de)(de)(de)是(shi)，這里(li)介紹(shao)(shao)的(de)(de)(de)(de)；1一般性的(de)(de)(de)(de)方法，在(zai)實際工作中(zhong)應靈活運用(yong)。例如(ru)，在(zai)對本(ben)例的(de)(de)(de)(de)音量控(kong)(kong)(kong)(kong)制電(dian)(dian)(dian)(dian)路(lu)進行連接時(shi)(shi)(shi)，可將(jiang)遙控(kong)(kong)(kong)(kong)板(ban)上(shang)的(de)(de)(de)(de)三只電(dian)(dian)(dian)(dian)阻(zu)(zu)R11、R12、R13拔掉，將(jiang)電(dian)(dian)(dian)(dian)視(shi)(shi)機(ji)中(zhong)的(de)(de)(de)(de)R302移到遙控(kong)(kong)(kong)(kong)板(ban)上(shang)R11的(de)(de)(de)(de)位置(zhi)(zhi)，如(ru)所示，則音量控(kong)(kong)(kong)(kong)制電(dian)(dian)(dian)(dian)壓為(wei)0~5.6V，效果不(bu)錯。對于(yu)(yu)控(kong)(kong)(kong)(kong)制電(dian)(dian)(dian)(dian)壓為(wei)0~12V的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)路(lu)，如(ru)夏普NC-2T的(de)(de)(de)(de)色度(du)和對比(bi)度(du)控(kong)(kong)(kong)(kong)制電(dian)(dian)(dian)(dian)路(lu)，可將(jiang)遙控(kong)(kong)(kong)(kong)板(ban)輸(shu)出端的(de)(de)(de)(de)上(shang)、下(xia)偏置(zhi)(zhi)電(dian)(dian)(dian)(dian)阻(zu)(zu)拔掉，將(jiang)輸(shu)出電(dian)(dian)(dian)(dian)阻(zu)(zu)換成l~2kft即可使用(yong)。這時(shi)(shi)(shi)輸(shu)出電(dian)(dian)(dian)(dian)阻(zu)(zu)僅起限流作用(yong)，以保護遙控(kong)(kong)(kong)(kong)開(kai)(kai)關電(dian)(dian)(dian)(dian)源只能(neng)處于(yu)(yu)間(jian)歇振蕩狀態。表現(xian)在(zai)電(dian)(dian)(dian)(dian)視(shi)(shi)屏幕上(shang)的(de)(de)(de)(de)故障(zhang)現(xian)象是(shi)：電(dian)(dian)(dian)(dian)視(shi)(shi)屏幕亮(liang)(liang)(liang)度(du)高時(shi)(shi)(shi)，光柵會不(bu)斷地(di)收縮(suo)(suo)。或者當(dang)電(dian)(dian)(dian)(dian)視(shi)(shi)畫面(mian)較(jiao)暗時(shi)(shi)(shi)，圖(tu)(tu)(tu)(tu)像(xiang)(xiang)(xiang)尚能(neng)穩定(ding)住(zhu)。當(dang)電(dian)(dian)(dian)(dian)視(shi)(shi)畫面(mian)較(jiao)亮(liang)(liang)(liang)時(shi)(shi)(shi)，就會出現(xian)“光柵不(bu)停地(di)收縮(suo)(suo)――展(zhan)開(kai)(kai)一收縮(suo)(suo)”。這時(shi)(shi)(shi)你(ni)測(ce)量+B115V電(dian)(dian)(dian)(dian)壓，在(zai)光柵收縮(suo)(suo)瞬間(jian)會降至70V左右。該電(dian)(dian)(dian)(dian)視(shi)(shi)機(ji)在(zai)調機(ji)進行搜(sou)索(suo)時(shi)(shi)(shi)，搜(sou)索(suo)到的(de)(de)(de)(de)圖(tu)(tu)(tu)(tu)像(xiang)(xiang)(xiang)比(bi)較(jiao)暗時(shi)(shi)(shi)，可以正常搜(sou)索(suo)并存儲(chu)。搜(sou)索(suo)到的(de)(de)(de)(de)圖(tu)(tu)(tu)(tu)像(xiang)(xiang)(xiang)較(jiao)亮(liang)(liang)(liang)時(shi)(shi)(shi)，光柵來回閃動(dong)，圖(tu)(tu)(tu)(tu)像(xiang)(xiang)(xiang)不(bu)穩定(ding)，或同步不(bu)良，電(dian)(dian)(dian)(dian)視(shi)(shi)頻道不(bu)能(neng)存儲(chu)。

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