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开通有线电视网以后,可供收看的电视节目往往有十几套,仅有8个预选器的老式彩电未免“力不从心”。有关技术刊物近来发表过改造老式彩电预选器的方案,笔者曾照图“摩机”,发现有的改造方法将新增的调谐电位器全部并联接入,大大增加了调谐电压供给线路的负担,引起调谐电压的跌落;有的则新老预选器互相牵制太多,技术效果很不理想。笔者经几次摸索后,找到一种能克服上述毛病的改造方法,且新增元件少,工作稳定、可靠,互不牵制。新增预选器在性能不低于原机的预选器的前提下,使老式彩电的预选范围扩大了一倍。现以NP82机芯的改造为例,介绍如下:
After the opening of cable networks, there are often dozens of TV shows available for viewing, and only 8 pre-selected vintage TV sets are “beyond any control.” Relevant technical publications have recently published a program for transforming old-fashioned color TV preselection devices. According to the figure, the author has found that some modification methods incorporate all the new tuning potentiometers in parallel, greatly increasing the burden on the tuning voltage supply circuit, Causing the tuning voltage drop; while others old and new pre-selector to contain each other too much, the technical effect is not ideal. The author after several groping, find a way to overcome the above-mentioned problems of transformation, and add fewer components, work stable, reliable, not contain each other. The new preselector in the performance of not less than the original machine preselector premise, the pre-selected range of the old TV doubled. Now the transformation of NP82 movement as an example, introduced as follows: