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故障现象:通电开机后,无图像。检修方法:出现此类故障时,首先观察屏幕有无海信字符显示,若无海信字符显示,但屏幕微亮,则说明背光灯电路工作正常,可能是逻辑电路存在故障所致。在开机状态下,检测LCD屏逻辑板的供电电压是否正常(正常应为12V)。若正常,则检查VD015是否点亮。若不亮,则说明供电异常,应检查+5V电压是否正常。若电压偏低,则检测NE551(LM2576)①脚(输入端)电压是否正常(正常应为12V)。若正常,则检测其②脚(输出端)电压是否正常。若电压偏低,
Symptom: power on, no image. Maintenance methods: such failures, the first screen to see whether Hisense character display, if no Hisense character display, but the screen is bright, then the backlight circuit is working properly, the logic circuit may be due to failure. In the boot state, check the LCD screen logic board power supply voltage is normal (normal should be 12V). If normal, then check VD015 is lit. If not, then the power supply anomalies, should check the +5 V voltage is normal. If the voltage is low, then test NE551 (LM2576) ① feet (input) voltage is normal (normal should be 12V). If normal, then test its ② feet (output) voltage is normal. If the voltage is low,