Careful observation, instant boot standby light blinks a few times to lit and dark.nKwservice manual download site

     According to the characteristics of the movement, the standby indicator is on, indicating that the switching power supply is not working. But instantaneous power standby light blinks a few times and dark, the machine has started signs may start conditions are not met due to enter protected.nKwservice manual download site

     Boot, measuring CPU (IC1102) 6 feet power control terminal voltage is 0V (see photo), when the boot is high 4.4V, 39-pin CPU power supply terminal voltage measurement is 4.3V (icon 4.4V), basic normal. 6 feet instantly monitor the CPU when you press the power switch has a 0.2V voltage immediately dropped to 0V, the output power signal has been described CPU, but the duration is too short, can not be measured multimeter to 4.4V high level. Determine fault in the power supply protection circuit.nKwservice manual download site

     To understand the aircraft power supply protection circuit works, we must first understand the process of opening and standby operation. Standby power directly from the machine 300V DC power rectifier filtered through concatenation electronic regulator circuit for the CPU power. When turned on, when you press the main power switch, 300V DC voltage rectified filtered directly added to Q810 collector, through R809, R810 Q810 base to provide a bias voltage. After conducting the voltage Q810 through R815, D1135, the light emitting diode D813 two routes. Q811 R813 applied all the way through the base, Q811 IC801 conduction of Q1 through the base-emitter short-circuit switch, the switching power supply does not work, the ratio of the switching power supply start-up process is faster; D814 in another way by the two C811 end formation voltage of about 5V respectively to the 39-pin power supply terminal of the CPU, 8-pin reset terminal and the remote receiver 3 feet. Meanwhile, the voltage is applied through R1124 S801 (main switch) P5 contacts. When you press the main power switch S801 (main contacts not shown), with a single contact point linkage P5 momentary switch is turned on and then off, forming a power pulse. The pulse is applied through R1122 base Q1105, Q1105 and Q1104 instant turn-on, 18-pin output of the CPU key sweep pulse returned 16 feet by conduction Q1114 (P5 contacts are switched on at boot time, decided to boot TV the work of the state machine. If the contact is not instantaneous power is turned on when the main switch is pressed, the TV is in standby mode, but pressing the standby button on the remote control to open or selected digital keys can still boot) microprocessor receives later, from 6 feet high output (4.4V), was R850, R1150 added to the base of Q814, Q814 is turned on, Q810 off, standby indicator is off D813, Q811 off the main power supply IC801 start-up operation, the output + B (113V) and 17V voltage. After IC802 and IC1105 17V voltage regulator, the output voltage of 5V to the microprocessor and the remote receiver. At this point, the boot process is complete, the TV into the normal working condition. During standby power with the main power switch, microprocessor power supply provided by the capacitor C1143 (470μF), 6 feet high does not guarantee its fall. 6-pin output low standby CPU's, Q814 deadline, Q81O conduction, Q811 is turned on, the switch is turned off.

 4    1 2 3 4 Next Last