Analysis and repair; the measured output voltage of the switch power supply is only 10V, which is 15V lower than the standby voltage, indicating that there is a problem with the switch power supply. The voltage across C909 is measured to be 285V, which is normal. The voltage at pin 8 of STR6309 is much lower than the normal value, so it is determined that the fault lies in the voltage stabilizing circuit. Checking the voltages of each pole of Q901 in the voltage stabilizing circuit and the voltages of each pin of IC901, it is found that the voltages of most pins of IC901 differ greatly from the normal values, but the voltage difference between pins 1 and 2 is only 0.7V, and there is almost no voltage difference between pins 3 and 4. When the voltage difference between pins 1 and 2 is higher than 1.1V, IC902 will conduct and the voltage difference between pins 3 and 4 will decrease. However, the actual measurement data is opposite, suspecting that IC902 and ZD902 are faulty. After inspection, it was found that ZD902 had broken down. Source of information: Beijing Changhong TV Repair Center http://blog.163.com/changhong_dianshi/. After turning on the Changhong TV, it cannot work properly, showing three non-existent phenomena. Repair method: Replace ZD902 to eliminate the fault.