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X7bservice manual download site
X7bservice manual download site
Seven, boot high level from A board CPU instructions, also added to the Q881 B pole, the tube conduction, C is very low level, after R818, added to the switch tube Q843 G, Q843 is A P channel MOS tube, when G is extremely low levels, the tube conduction, the output voltage of 18.5 V, audio amplifier circuit is added to A plate. Normal work, Q882 conduction, Q850 cutoff, IC851 1 foot voltage is 1.7 V2:3 v3:20 v5:6 vd882 D884 physical objects are two resistance, rather than the regulator tube. D891 standby power supply output voltage, when the normal boot, is 18.5 V voltage, which is 10 V voltage in the standby mode. In normal boot, IC890 REF end is 2.48 V, K side is 17 v. Q881 Q883 B is 0.6 V. X7bservice manual download site
X7bservice manual download site
Eight, main switch power supply circuit: after the mains voltage into the 220 P TV board, through the control of the power relay RL801, added to the input end of the rectifier bridge D802, C830, C842 filtering, get 300 v voltage, add to the main power switch transformer T801 P2 of the feet, through internal primary coil, through P1 pins, meet IC830 1 foot, IC830 is the main switching power supply integrated block, foot is the internal power switch tube 1 D. 2 foot switch tube S pole. 3 feet is IC830 grounding. One end of the 220 v ac input, after R802 start resistance, add to IC830 4 feet, for within IC830 oscillation circuit start-up phase of the power supply voltage. Inside the switch tube under the action of drive pulse, the on - off again and again -- -- -- -- -- -- close -- -- -- -- --, switch tube conduction, D current, flows through the switch of the transformer primary coil P1 - P2 side, the mains electrical energy stored in the transformer, and when the switch pipe cut-off, transformer through the secondary coil, supply power to the load. Pulse voltage of secondary coil S1, S2, via D810 rectifier, C814, C815 filtering, the output voltage is 24 v, the inverter power supply. V1 - V2 is feedback coil, coil grounding V2 end, the pulse voltage at the V1, via R833 added to D833 positive, after rectification, C833 filter, get 20 v voltage, power supply for IC830 4 feet 20 v. The pulse voltage at the V1, also after R833 - D840 R846 - D843 - add to IC830:7 feet, when the power to the transformer load release is to control switch tube IC830 conduction into the next cycle. To reduce the switch tube opening loss. IC inside the switch tube conduction, the switch tube, S current flows through the 0.15 euro, the resistance of the 0.12 euro R843, R844 to produce in the resistance of pulse voltage, the R845 add to the IC 5 feet, when the switch tube current is too large, add to 5 feet of pulse voltage is too high, IC will start internal overload protection, limit switch tube current value.
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