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例1:长虹DT2000型倍频彩电,出现“三无”。经查开关电源的+125V电压输出正常,但末级视放供电也为+125(V正常应为200V)。进一步检查发现,显像管灯丝不亮,N00(5TDA9332H)集成块(17)脚无行启动电压,正常应为8.1V。该电压是由开关变压器T862(17)脚脉冲电压经RF889限流、VD896整流、V807(2SC3852)稳压后得到的,经查V807击穿,RF889烧断。更换V807、RF889后,故障排除。相关电路见图1所示。
Example 1: Changhong DT2000 type frequency doubling color TV, there “three no.” Check the switch power supply + 125V voltage output is normal, but the final stage power supply is also +125 (V normal should be 200V). Further examination found that the tube filament is not bright, N00 (5TDA9332H) block (17) foot no starting voltage, the normal should be 8.1V. The voltage is by the switching transformer T862 (17) pin voltage pulse by RF889 current limit, VD896 rectification, V807 (2SC3852) obtained after the regulator V807 punctured, RF889 blown. Replace V807, RF889, troubleshooting. Related circuit shown in Figure 1.