体重秤维修故障分析（型号上海友声XK3100-B2+）

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                    <section><section powered-by="gulangu"><section><section><p><img src="image/20201019/d4cbf6c3b44491d5e49de3bf7d23b53e_1.gif" /></p></section></section></section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><p>故障概述</p></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p>&nbsp; &nbsp; &nbsp;体重秤的故障表现为有时显示数值明显不准，很多时候第一反应会认为是传感器故障，实际上显示模块也可能存在问题。通过检查发现是数码管的某段 LED 灯不亮，本文主要分享体重秤的维修和数码管极性及引脚判断。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/09e57b1951e58c98b326c0e21f4e4460_2.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><section><section powered-by="gulangu"><section><section><p>故障分析及处理</p></section></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p>1、极性判断</p><p>&nbsp; &nbsp; &nbsp; 按发光二极管单元连接方式可分为共阳极数码管和共阴极数码管。共阳数码管是指将所有发光二极管的阳极接到一起形成公共阳极(COM)的数码管。共阴数码管是指将所有发光二极管的阴极接到一起形成公共阴极(COM)的数码管，共阴数码管在应用时应将公共极 COM 接到地线 GND 上，当某一字段发光二极管的阳极为高电平时，相应字段就点亮，当某一字段的阳极为低电平时，相应字段就不亮。</p><p>&nbsp; &nbsp; &nbsp; 如下图为一位的七段共阴数码管，例如要数码管显示一个数字 1，需将数码管的共阴极接低电平，b、c 端接高电平即可。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/9fa36dc52447cc9926af6787c0d9fb32_3.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>2、先拆下主板，由于其他位数码管显示正常，故数字芯片工作正常，暂不作故障检测。检查 PCB 上</p><p>焊盘是否存在虚焊，布线是否破损。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/0ec55d544defeba9a91e32e1d79b2150_4.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/1802323e6fffcbb757f95797e0f6892c_5.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>3、电路板除做工差之外未发现其他明显故障，拆下数码管使用万用表测试。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/cd0f6c5eda6f0d0b8b2f5591190ab50b_6.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>4、本次故障的数码管为 3 位数码管，通过引脚检测和极性判断，该数码管为共阴极数码管。参数</p><p>如下图所示，管脚号的区分：共 11 脚，从左至右逆时针数 1-12。</p><p>注意：应注意 6 脚为空，8、9、12 脚分别为 3 位数码管的公共脚。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/6bf4739d4b8d9b83a6eba6017501b089_7.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>5、采用二极管档，当表笔极性与 LED（即发光二极管）相符时 LED 被点亮。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/4309cea74eaafc1e07d37e71f78b4114_8.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>6、维修前，第 2 位数码管做下角“E”段 LED 可能故障，使用万用表测试第 1 脚（红表笔）和第9 脚（黑表笔）即可确认该段故障。下图演示检测方法，非“E”。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/3b8045368043821052bbe099a42fdab2_9.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p>7、最终根据以上判断，匹配同型号的数码管更换即可，更换后开机显示自检全部正常。</p></section></section></section><section powered-by="gulangu"><section><section><p><img src="image/20201019/d9f949a46764cadfd00a6376b93ee581_10.jpg" /></p></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p>欢</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>迎</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>关</p></section></section></section></section><section><section powered-by="gulangu"><section><section><p>注</p></section></section></section></section></section></section><section powered-by="gulangu"><section><section><p><br  /></p></section></section></section><section powered-by="gulangu"><section><section><section powered-by="gulangu"><section><section><p><img src="image/20201019/e0c78031c6486a6f79c41b031a063b91_11.jpg" /></p></section></section></section></section><section><section powered-by="gulangu"><section><section></section></section></section></section><section><section powered-by="gulangu"><section><section><p>关注我们</p><p>一起涨姿势！</p></section></section></section></section></section></section></section>