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创维8218彩电开关电源原理图如图1所示。龙江54G—4型、创维8219型、创维8148型等电视机都采用此电路。此电源适应电压范围交流电140～260V能正常工作,使用元件较少,省去遥控供电的副电源,在待机状态整机耗电不到10W,同时也减少了故障机会。现以创维8218为例介绍几例常见故障。例1 故障现象:无图像,无伴音,但待机指示灯亮。从原理看待机指示灯亮说明主电源起振,待机电源是由主电源输出16V通过R_(626)经L_(7805)稳压后提供。先测D_(607)负极电压为+160V偏高50V,测Q_(605)e极电压为OV,说明Q_(605)未导通,按起动钮与节目上下钮均不能起动,测Q_(608)与Q_(607)控制电压正常,焊下Q_(605)
Skyworth 8218 color TV switching power supply schematic shown in Figure 1. Longjiang 54G-4 type, Skyworth 8219 type, Skyworth 8148-type TV are using this circuit. The power to adapt to the voltage range AC 140 ~ 260V can work properly, the use of fewer components, eliminating the need for remote control power supply, the standby power consumption less than 10W, but also reduce the chance of failure. Take Skyworth 8218 as an example to introduce a few common faults. Example 1 Symptom: no image, no sound, but the standby indicator light. From the principle of the standby indicator light on the main power start-up, the standby power supply is provided by the main power output 16V R_ (626) by L_ (7805) regulator. The first test D_ (607) negative voltage is + 160V high 50V, measured Q_ (605) e pole voltage OV, indicating Q_ (605) is not conducted, press the start button and the program can not be started up and down button, ) And Q_ (607) control voltage is normal, welding Q_ (605)