Sony TVP-08, Руководство по обучению

Страница: 21 / 139

13
Vcc Switch (Power On)
Overview
When Power On is selected, IC1008 Main CPU sends a signal to the G
board to turn ON the Vcc switch. The Vcc voltage powers the Soft Start,
Oscillator and Driver circuits. There is a connection from the latch circuit
to shut OFF the set if there is a problem on the DC side of the power
supply. In addition, there is a connection from the Standby Source Volt-
age that will shut down the supply if the AC line voltage becomes to high.
Power ON
When Power ON is selected using either the remote or the front panel
switch, 5 volts is output from IC1008/56 O Relay. This voltage travels
from CN505/3 on the A board to CN6101/3 on the G board. It then goes
through R6112, R6121 and D6112, placing .6V at Q6104/B. This turns
Q6104 ON and causes Q6104/C to pull IC6104/2 to ground. This turns
the phototransistor inside IC6104 Vcc Switch ON. When this occurs,
current flows through the B-E junction of Q6001. When Q6001 turns
ON, it causes Q6011 VccSW to turn ON. This switches the Standby
voltage through Q6011 VccSW where it is called Vcc. Vcc turns RY6001
Power Relay ON, as well as powering the Soft Start, Oscillator and Driver
circuits.
DC Protect
The DC protection latch circuit is connected through D6111 to the power
ON line at the junction of R6112 and R6121. When the protection latch
is activated, it pulls the O Relay line LOW and turns power OFF by turn-
ing and holding Q6014 OFF.
AC Protect
The Standby Source voltage is monitored in case there is an overvoltage
problem on that line. If the voltage from the Standby Source voltage
goes too high, it will cause the voltage at the cathode of D6035 to rise
above 12.6 volts. The voltage at Q6013/B will be enough to turn it ON.
When this occurs, Q6013 conducts, causing Q6012 to conduct. This
action causes the Q6001 to turn OFF, thereby shutting down the set.