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5-10 TV start-up, TV normal run and stand by mode operations<br />
5-10-1 TV start-up operations<br />
* Schematic diagram for start-up operations<br />
* TV start-up and microcontroller initialisation<br />
- When SW801 power switch is pushed, main AC voltage is applied to T801 transformer (after rectification by D801...<br />
D804 diodes). Then, T801 SMPS transformer starts operating and supplies DC voltage to I823 (5V regulator).<br />
- This regulator provides 5V / 3.3V DC voltage to I501 microcontroller power supply pins (pin 3 / pin 54) and to the<br />
reset pulse circuit which provides reset pulse to I501 microcontroller reset pin (pin 58).<br />
- Then, the microcontroller starts its initialisation. Its power pin (pin 1) is set to high which allows delivery of power<br />
supply voltages (123V, 8V, 5V...). At this step, all IC’s start working but no picture appears on screen: I501 IC<br />
doesn’t provide horizontal drive voltage.<br />
- Then, the microcontroller consults I702 EEPROM via I2C bus to know the last TV set mode (normal run mode or<br />
stand-by mode ) before switching off.<br />
- 59 -
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