|
r5kservice manual download site
r5kservice manual download site
(6) mains rectifier R817, R818 overvoltage detection circuit by the sampling circuit, voltage regulator tube D820, D821, triode Q803 and peripheral components. Because it USES wide power supply circuit, in order to adapt to AC110V and AC220V mains supply, adopted by thyristor Q801 and triode Q853, Q854 and its peripheral components of full wave and voltage doubling rectifying circuit switch (not painted) in figure 1: AC110V for mains, Q801 conduction, the rectifier filter circuit work in doubler rectifier state, mains is AC220V, Q801 cut-off, work to make rectification filter circuit Yu Quanbo commutation state. r5kservice manual download site
r5kservice manual download site
Main switch power supply, power grid rectifier filter circuit is normal, its the middle of the filter capacitor C818, C819 should be the half of the rectifier voltage. When the mains is AC220V, C818 the anode voltage of 300 v, C819 the anode voltage of 150 v or so. The voltage by R817 and R818 partial pressure of bead voltage is lower than the voltage value of the voltage regulator tube D820 10 v, D820 cut-off, Q803 partial cut-off, does not affect the switch power; If Q801 switching circuit failure, when the mains is AC220V wrongly into doubler rectifier state, it will cause the output voltage is too high, puncture of switch power supply components. But at this point, the C819 anode voltage will be increased, the voltage after R817 and R818 pressure is greater than 10 v, will D820 breakdown, the breakdown voltage is divided into two after the road, all the way provide positive bias voltage for Q805 Q803 conduction, will power thick film circuit IC801 VCC (STRM6529F04) 5 feet by D822, light coupling D819 R846 plant's leds can guide, through the photoelectric coupling, light activated triode saturated conductivity, the switch machine control tube Q852 base on high power between low, causing Q852 cut-off, relay RL801 disconnect, cut off to tend to the power grid, the television to enter standby protection. r5kservice manual download site
6 Home Previous 1 2 3 4 5 6 Next Last |