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机型:华强牌2195型彩电故障现象:出现水平一条亮线。分析与检修:据用户讲,该机经他人几次维修均没能排除故障。该机场扫描电路如图1所示。只要 N101(LA7680)的(32)脚输出的场同步脉冲作为触发信号,加到 N451的②脚,经内部场脉冲输入电路整形后,触发单稳态电路,产生一个宽度由③脚外接定时元件决定的场频脉冲,给⑥脚外接的电容 C455充、放电,形成锯齿波电压,再经内部反馈控制、放大后由(12)脚输出,驱动场偏转线圈,完成场扫描工作。
Model: Huaqiang brand 2195 TV Fault phenomenon: a bright line appears. Analysis and Maintenance: According to the user, the aircraft by several other maintenance failed to eliminate the fault. The airport scanning circuit shown in Figure 1. As long as the field sync pulse output by the (32) pin of N101 (LA7680) is used as the trigger signal and added to pin 2 of N451, the monostable circuit is triggered by the internal field pulse input circuit to generate a pulse width The decision field frequency pulse, to C ⑥ pin external capacitor C455 charge and discharge, forming a sawtooth voltage, and then by the internal feedback control, amplified by the (12) pin output drive field deflection coil to complete field scanning.