Daewoo KR14E5/DTA-14V3VM Service Manual page 32

9-1-2. TV start-up and microcontroller initialisation
- When SW801 power switch is pushed, main AC voltage is applied to T801 transformer (after rectification by D801...D804
diodes). Then, T801 SMPS transformer starts operating and supplies DC voltage to I823 (3.3V regulator).
- This regulator provides 3.3V DC voltage to I501 microcontroller power supply pins (pins 54, 56, 61) and to the reset pulse cir-
cuit which provides reset pulse to I501 microcontroller reset pin (pin 60).
- Then, the microcontroller starts its initialisation. Its power pin (pin 63) is set to high which allows delivery of power supply volt-
ages (110/123V, 8V, 5V...). At this step, all IC' s start working but no picture appears on screen: I501 IC doesn' t provide horizon-
tal drive voltage.
- Then, the microcontroller consults I702 EEPROM via I2C bus to know the last TV set mode (normal run mode or stand-by
mode ) before switching off.
. If the TV set was on normal run mode before switching off, the microcontroller delivers horizontal drive voltage at pin 33 and
picture appears on screen.
. If the TV set was on stand-by mode before switching off, the microcontroller switches TV set to stand-by mode, decreasing
power pin voltage (pin 63). This matter will be explained in paragraph 2.2.
9-1-3 Reset pulse circuit:
from I823
pin 3
DC supply voltage
I823 pin 3
R591
220 W
R592
10k W
D591
DZ2.4
0V
reset pulse 0V
I501 pin 60
Reset pulse circuit and corresponding waveforms
Q510
R594
Q511
10K W
R593
10K W
3.0V
1.2V
3.0V
1.2V
11
APPENDIX
FUNCTIONAL DESCRIPTION
+ C501
50V
10 mF
to I501
pin 60
3.3V