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机型:HITAGHI(CAP—161D)型彩电故障现象:有伴音,无光栅。检修:开机检查时,发现高压帽处放电打火,观察显像管灯丝点亮,测加速极电压为280V,测视放板中的三个视放管集电极电压(在亮度电位器开到最大位置时)均为180V左右,说明视放管截止。试将加速极电压调高后,屏幕上出现绿蓝色带回扫线的光栅,说明故障出在解码电路。这时偶然发现ABL(自动亮度限制)电路中R322(47kΩ)电阻已烧焦炭化(相关电路见图1),在其上面并接一个47kΩ电阻,故障依旧。又看图1中R322与D301、R321及IC501的(15)脚相接,并
Model: HITAGHI (CAP-161D) type TV Fault phenomenon: a sound, no grating. Maintenance: boot check, found that high pressure cap discharge sparks, observe the picture tube filament light, the measured acceleration pole voltage is 280V, viewing the board in the three viewing tube collector voltage (brightness potentiometer open to the maximum position When) are about 180V, indicating the tube as the deadline. Try accelerating the pole voltage, the screen appears green and blue back to the line of the grating, indicating that the fault lies in the decoding circuit. Then accidentally found ABL (automatic brightness limit) circuit R322 (47kΩ) resistance charred charcoal (related circuit shown in Figure 1), and in the above and then a 47kΩ resistor, the fault still. Also see Figure 1 R322 and D301, R321 and IC501 (15) feet phase, and