As, ac fuses in good condition, but no 5 v output, the P82 (1) the foot P83 6 feet no 142 v output (a + B), (2) (1) the feet nor 16 v and 15 v output. By measuring the power supplies are no short-circuit phenomenon, which showed that the fault in the switching power supply part. Carefully check the switch power supply, found a thin gap IC802 has blasted off, Q804, D824, R807, R814, R826 have been damaged. In addition, also check IC803 and D803. Otherwise after change, higher power supply voltage is out of control and the secondary cause greater losses. As D803 have also been damaged. Finally, check the Q807. IC802 model for STR S6708, is a new type of power thick film integrated block, there are two sold on the market. One is three rows of pins, and PCB hole one-to-one correspondence, convenient installation, welding is easy, but the price is very expensive. Is another two rows of pins, with pointed nose pliers before installation to its plastic is three rows pin, a row of pins can just scrape through the flat PCB hole, welding is important to note don't empty welding, but the price is very cheap. Both can be used, don't worry about it. Q804 models for 2 sc1984zf, the following parameters: BVcbo = 100 v, Icm = 3 a, PCM = 30 w, Hfe = 50 ~ 2000, the measured average at around 700, darlington tube, such as do not easily bought, also can use other types of pipe, such as 2 sd1276a sd1277a and 2 or 2 sd1275a substitution is also very good, and the price is cheaper. D824 models for MA4062 - H, is 6.2 V zener diode, no special requirements, but must pay attention to choose voltage value is above 6 V, the voltage value lower switching power supply wouldn't start up. D803 models for TLP621GR - LF2, photoelectric coupler, all components after welding, general boot can work normally. But not this time, after the boot flash lights on or off, the measured voltage boot after a + B up and down at once. Found that after carefully check, and use alcohol to clean PCB D631 one side welding very discreet, good welding after troubleshooting, boot up grating. But don't think have strange phenomenon appeared, this time a boot is AV state, and automatically to full volume. And analog to choose any one, are automatically to maximum, even by the remote control to be cut down, but a let go let go of the button and automatically to maximum, and dysfunction of the remote control. Why these strange phenomenon? After tested the microprocessor, jade-like stone 瑠 feet, yao, both to 0 V, normal should be 4.8 V, 4.8 V and 3.6 V, jade-like stone feet 瑠 feet are 0 V, explain P82 (1) the foot 5 V did not add to the motherboard. Via checking, so he found P82 poor contact, trying to contact good after all, the remote control all function returned to normal, the fault completely ruled out. The power supply section because of the big screen color television in overhaul is to remove repair alone, it removed when will P82 P83 two press type, and has set off a wiring row, separated from the mainboard. Completed with the mainboard lap after testing for many times, P82, bad P83 is very easy to lap and notice carefully when please recovery. Also, when repair this power source in P82 (2) the Q806 the base and ground between about 3 k Ω temporarily by one resistance, or switching power supply will not work properly. After repair, don't forget to get off this resistance.

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