Remove the standby lamp plugin E4, boot, image noise are back to normal, the machine keys and remote control also can be normal operation. Because standby lamp can light up, the normal standby lamp itself, the problem is still in the microprocessor circuit, standby or remote control circuit. Will recover standby lamp, boot, measuring 113 V output, measured on standby power supply + 5 V only from 3.2 V to 3.8 V and unstable, obviously, the microprocessor can't work normally. The voltage is added to the main power supply control tube Q811 base, Q811 conduction, forcing IC801 no 113 v output. Disconnect the standby control tube Q814, forcing on standby power supply + 5 v. Measuring D814 negative side or only from 3.2 V to 3.8 V, over-current protection tube Q812 emitter voltage measurement (R815) 0.64 V, prove the overload on standby power supply + 5 V. Disconnect D814 negative, namely load disconnect + 5 v, measuring its positive side + 5 v is back to normal, instructions on standby power supply + 5 v itself is normal, this also further prove that my judgment is right. Illustrate the heavy load to over-current protection tube Q812 in different degree of conducting state, control pipe Q810 emitter voltage on standby power supply, make the output voltage drop is 3.2 ~ 3.8 V. The following step by step to cut off the + 5 v of standby power supply load to judge the fault point. A total of three road load, namely IC1106 reset circuit, microprocessor IC1102 and remote control receiving circuit. The most convenient way to cut off the remote control receiving, first recover D814 negative side, and then remove the remote control receiving head E1 plugs. Switched on, the result image are normal voice, panel button also can normal operation. Suggesting that receives the head has a problem, replacement, fault all ruled out. In turn ask again, why remove the original standby lamp, with a receiving head, image noise is normal, normal panel buttons, and why the remote control is normal? Not receiving head is there a problem? Question is like this, remove the standby light, after the main power supply control tube Q811 base on standby power supply + 5 v don't come, at zero potential, Q811 cut-off, IC801 can normal output 113 v, the TV can work normally. Host + 12 v can be added to the input of IC1105 (1) feet, (2) feet can output a + 5 v, the microprocessor, reset circuit, receiving the first class all can normal work. To work is the decisive factor IC802 host + 12 v, and provided by the host IC1105 + 5 v power supply, its capacity is large enough. And this one special case is receiving head has not fully short circuit, only some degree of leakage, but limited capacity on standby power supply + 5 v, enough to bear, so as long as the standby lamp, also took the receiving head, it will light leakage is enough to come down on standby power supply + 5 v, standby power supply cannot work normally, the main power to build up, so will the remote control is failed. This fault is hard to understand, its reason lies in here.

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