Standby Power; Primary Power; Led Inverter; Protection - Sony KDL46XBR10 Training Manual

Monitor Power
Figure 6-2 illustrates a block diagram of the power supply located on the
GD1 board used in the monitor. It is similar to power supplies found in most
Sony televisions. A dedicated standby switching regulator provides power
for the devices that must remain running constantly. A main switching
supply is activated at turn-on along with an additional inverter to supply
power for the LED backlights.

Standby Power

When in standby mode, the main relay RY6000 is open. AC power is
applied to the bridge rectifier D6002 through current limit resistor R6002.
The PFC circuit is inactive at this time so the rectified 160V is distributed
to the standby, primary and LED drive power supplies. Only the standby
is functional at this time.
Regulated 3.3V is provided for the QTM board via CN6253 pin 3. An
unregulated 15V source (PRI_VCC) is generated on the primary side of
T6200 of the standby supply. This voltage is used to provide a power
source to turn on the main relay and the primary switching supply.

Primary Power

When the unit is turned on, a high command (3.3V) enters at CN6253 pin
1. This high passes through inverter Q6350, photo coupler PH6301 and
inverter Q6304 to turn on switch Q6203. PRI_VCC is now available to turn
on main relay RY6000, the PFC circuit and the primary power supply.
The DC voltage exiting the PFC circuit rises to approximately 390V. The
primary switching supply outputs a regulated 12V and unregulated 12V
for the audio circuits which is sent to the QTM board.
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Chapter 6 - Power Supplies and Protection

LED Inverter

A dedicated switching supply is used to provide variable power for the
groups of series connected LED backlights located along the lower
edge of the LCD panel. This power supply is turned on by a backlight on
command (not shown). Operation of this power supply is discussed in a
separate section in this chapter.

Protection

The GD1 board contains circuits to monitor temperature, voltage and
current conditions. The PFC circuit is monitored for excessive temperature
and voltage by IC6300. If either of these exceeds specified limits, IC6300
pulls down the power on command, causing the main relay to open along
with stopping the PFC and primary supply.
If the regulated 12V source from the primary supply exceeds the specified
limit (15V), the latch circuit consisting of Q6251 and Q6253 is activated.
This pulls down the power on command turning off the PFC and primary
supply as described in the previous paragraph.
The regulated 12V source is monitored by the QTM board. If this voltage
is lost, the unit will shut down and display groups of 5 blinks on the power/
standby LED. Activation of any of the protect circuits on the GD1 board
will cause this symptom.
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