创维5t10机心彩电开关电源常见故障检修（A common troubleshooting service for the 5t10 machine heart color switch power supply）.doc

创维5t10机心彩电开关电源常见故障检修（A common troubleshooting service for the 5t10 machine heart color switch power supply） This paper takes 5T series machine heart as an example, and its switch power schematic diagram is shown in the attached drawing, and its common troubleshooting and testing key points are introduced below. 1. Automatic shutdown automatically. (1) the power indicator will be on when the fault occurs. When the fault appears, observe the power indicator light, indicating that the switching power supply is in the state of standby intermittent oscillation. For the native heart, the failure rate of standby circuit itself is relatively low, and the components such as Q601 and ZD601 should be mainly checked. At this time, the Q603 c pole can be disconnected. If + B terminal voltage is normal, the judgment is basically correct. Q601 caused the fault to be one of its common diseases due to its severe heat and poor performance. The power tube can be replaced by C3582 and other composite power tube in maintenance, but not in the ordinary triode. It is worth noting that after the load is broken, the voltage of each circuit will rise to normal value, which can easily be misjudged as the working anomaly of the line circuit. The glitch was particularly common in the early 29NF Canon and 29NL phantom models. It can be seen from the schematic diagram that the Q601 e and b pole voltage of the normal working hours are closed. Only when the lower standby and mains voltage drop, constituting the T601 {6} - {5} winding D603, D618 rectifier C609 filter provided by the voltage drops below 6.8 V, Q601 is only partial conduction (unsaturated conductivity), for IC601 {9} feet providing stream power. Therefore, the work of Q601 depends to some extent on the high and low voltage of IC601 {9}. But because the working voltage of different synfuels fiasco heart line circuit (B + 110 v, 120 v, 130 v, 120 v four), can make IC601 {9} feet have different reference voltage. Such as 5 t10 machine he