Daewoo DTA-14C4TFF Service Manual page 34

APPENDIX
FUNCTIONAL DESCRIPTION
9-1-4. Reset pulse circuit operations description
- When DC supply voltage from I823 regulator starts rising (from 0V to 1.2V), no current flows through D591 zener diode. So,
Q510 is in off mode.
Also V =Vcc/2 -Vcc = -Vcc/2 > -0.6V. So, Q511 is in off mode.
be Q511
Then, no voltage reaches I501 pin 60.
- When this voltage reaches 1.2 V, Q510 stays in off mode
but V = -0.6V. So, Q511 is switched on and starts driving DC supply voltage to I501 pin 60.
be Q511
- When the DC supply voltage reaches (2.4V +0.6V ) =3.0V, Q510 starts conducting but as the Q511 base-emitter voltage is the
same as the collector-emitter voltage of the saturated Q510, Q511 switches off and no voltage reaches I501 pin 60.
- If the DC supply voltage decreases below 3 V, Q510 switches off immediately. Q511 starts conducting, pulling I501 pin 60
high. At the same time, it discharges the reset capacitor C501. Discharging this capacitor is necessary to guarantee a defined
reset pulse duration.
9-2. TV normal run and stand-by mode operations
Depending on remote control commands, I501 microcontroller part pin 63 (power) is set to:
- high for normal run mode
- low for stand-by mode
9-2-1. TV on normal run mode
9-2-1-1. I501 microcontroller part pin 63 (power) effect
I501 microcontroller part pin 63 (power) is connected to the following circuit:
I810
CONTROLLED
RECTIFIER
LOW
R820
CONDUCT ING
6 V DC
R830
C830
LOW
Q807
Q808
HIGH
I501 microcontroller part pin 63 (POWER) effect
R829
LOW
Q809
12
11V DC
R870
D811
Q 811
HIGH
LOW
Q810
NOT
CONDUCTING
POWER
H IGH