Chapter 1 - Features and Circuit Descriptions
CTV-41 4
Circuit Description
Various differences in circuitry occur in the WAX3 chassis line based on
panel size and display features. Virtually all video processing is the same
among the different designs and centers around the BU1 board. From this
point it becomes a matter of what LCD panel size is used, HDMI versus
analog front video inputs and the design of the power supply dedicated to
that model.
The circuit descriptions to follow will differentiate between the models
based primarily on LCD panel size since this will determine what type of
power supply and backlight inverter boards will be used. The KDL32XBR4
and KDL40D3000 are the only models in this chassis line that has an
upgrade in video features including a third HDMI input and High Frame
Rate circuits and panel. This will be described in a separate block
diagram.
Overall Block Diagrams
26 and 32-inch S-Line Models
In Figure 1-1 the overall block diagram of the circuit layout utilized in the
KDL26A3000 and KDL32S3000 is shown. A brief description for each of
the major circuit boards will be given.
Backlight Inverter
These smaller panels use a single inverter/balancer assembly that is part
of the LCD panel in order to provide ballast control for the fluorescent
backlights. 24VDC is provided by the power supply (G1D for the 26” or
G1H for the 32”). This 24 volt source powers the individual inverters to
generate the high voltage (4.5KV to 5KV) necessary to light the fluorescent
backlight lamps. Additional lines for on/off control and inverter failure
feedback are on the same DC voltage connector from the power supply
and are routed to the BU1 board for control and monitoring by the Main
Micro.
The inverter board also contains circuits to monitor the current draw of
each individual backlight lamp. If a lamp were to fail or weaken with age,
or if one or more of the inverters were to fail, an error command will be
detected by the Main Micro on the BU1 board and shut the unit down and
blink the front power LED in groups of 6.
Power Supply
2 power supplies reside on the G board. The 23” model power supplies
are designated G1D whereas the 32” is G1H. Both supplies are relatively
the same aside from current capacity and layout of their protect circuits. A
standby supply runs constantly whenever AC power is applied to provide
12VDC for the main relay and power for the main switching supply.
Standby 3.3 volts is also generated to power the Main Micro on the BU1
board and other circuits that are required to run constantly such as the
remote IR receiver. The main switching regulator provides the majority of
the voltages used within the unit. Further details of the power supplies will
be discussed later in this chapter.
BU1 Board
This board has been redesigned to take on virtually all of the circuits that
were found on 3 boards in last year’s chassis designs. The tuner and ATI
Micro were on separate boards in previous designs but have now been
integrated on the same board with the video process circuits.
Other than the front video inputs applied to the U1 board, all analog and
HDMI input connectors are part of the BU1 board. The Main TV Micro
resides on this board and is responsible for virtually all of the operational
functions of the unit.
Audio switching, digital signal processing and amplification are also
located here. The audio exits the BU1 board to drive the speakers, optical
output, L/R analog out and headphones. Another important feature of the
audio circuits is that all audio sources selected will be output from the
optical transmitter. This was not true in previous Sony designs in which
the optical out only functioned when a digital tuner signal was received.
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