Power Supply; Power Supply For Backlight System; Ld Board (Local Dimming); 3D Ir Emitter - Sony KDL-40NX725 Service Manual

POWER SUPPLY

There are different Power Supply Boards used in the models in this
manual. The type of board depends on the size of LCD panel. They
are:
● G4 (40")
● G6 (55" and 60")
● G7 is used exclusively in the 55" and 60" models and
dedicated to provide B+ for the LD board to control the LED
backlighting
There are 3 distinct sections on the power supply:
Standby Supply: Continuously operational as long as AC power is
applied, the standby supply generates 3.3V for the circuits requiring
power while the unit is turned off. An unregulated 19V line is present
to provide power to the main relay, PFC and main power supply at
turn-on.
Main Supply: Once the power supply receives a power-on command
from the CPU on the Main Board, the main switching supply is turned
on to provide a regulated 12V source and an regulated 24V source
for the LED power supply circuits.
Converter: Generates the B+ for the local dimming (LD board)
circuits to control the backlighting level.

POWER SUPPLY FOR BACKLIGHT SYSTEM

Power for the LED backlights is provided for the LD board via the G4
(40"). The 55" and 60" models utilize a separate converter circuit G7
due to the increased current requirements of the larger panel.
KDL-40NX725/55NX725/60NX725
SECTION 3 - CHASSIS OVERVIEW

LD BOARD (LOCAL DIMMING)

The LD Driver Board is controlled by the TCON/HFR Board to perform
overall backlight power-on, backlight level, and local dimming
functions. This board takes the 24V from the Power Supply Board (or
G7 Board for the 55" and 60" models) and develops the negative and
positive voltages to directly drive the LEDs in the panel assembly.
The negative voltage rail is pulse width modulated to control the on
time of the LED backlights. LED backlight brightness is controlled in
4 separate groups (quadrants).

3D IR EMITTER

Designated as the HEM2 Board, this board is the internal 3D IR
Emitter to synchronize the 3D shutter glasses..

WIRELESS LAN CARD

The wireless transmit/receive circuits are located on this board to
communicate with a wireless network.

SWITCH UNIT

This board contains the power, channel, and volume up/down and
menu buttons.
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