500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/21/1096337354.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">开关是电源疑问,请教各位.
出于好奇,打开受雷击损坏的3COM交换机,主电源按个人经验应是3842+4N100反激、多路输出.在主电源前有部分电路不知有何作用,大致如图片所示,变压器大小与主电源变压器差不多,看不见有输出,功率管是IRF840,其中有一信号在主电源输出经光电偶合到IRF840前的IC.其它,因是贴片的不太清楚.好似这部分电路与主电源没有什么关系.各位能告知这部分电路的作用吗?
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