Overall System Description - Sony KDS-50A2000 Training Manual

Overall System Description

Reference Figures 4-1 & 4-2
The power supply system for the 2006 SXRD-A rear projection televisions
consists of the Standby (STBY) 5V Power Supply, Main Power Supply,
and the Power Factor Control (PFC) circuit. Aside from various regulator
circuits, all power supply circuits are contained on the G-Board.
Both the Standby 5V and Main Power Supplies are switch-mode power
supplies. The configuration and operation using the MCZ3000 converter
IC is similar to previous models.
The AC (110V) is supply through the main fuse F6001 and an AC line
filter and is applied directly to the AC Relay RY6004 and the Standby 5V
converter IC6101. Consequently, as long as the TV is plugged into the
AC outlet the Standby 5V circuit is activated and supplying STBY 5V to
TV Microprocessor (A1-Board), IR Sensor (H2-Board), and the Fan Drive
circuit as shown in Figure 2-2. The TV Microprocessor and IR Sensor
are therefore placed in standby mode waiting for an "ON" command from
the remote control or the ON/OFF main unit button.
The reason STBY 5V is supplied to the fan drive circuit is to enable the
lamp cooling fans to run for a predetermined time (~2 mins) after shut-off
and provide a steady reduction in the lamp temperature.
In the standby mode the AC Relay, Inrush Relay, Main Power Supply
IC6100, and PFC are off. These circuits are activated with the TV Power
"ON" command. The TV Microprocessor IC8003 on the A1-Board
receives the "ON" command and outputs a high "AC_Relay" signal to turn
the rest of the Power Supply circuits ON.
The AC Relay is turned on directly by the "AC_Relay". The Main Power
Supply IC6100 is turned on through the PH6400 switching circuit.
Approximately 18V is supplied from the Standby 5V supply to these
circuits. The 18V is used as the Main Power Converter VCC.
Also note that the switched 18V from the Standby 5V circuit is used to turn
ON the PFC circuit. The PFC circuit's primary purpose is to make the
TVP-23
power supply circuits look like a purely resistive load to the external AC
power network (current and voltage are in-phase). In reality the internal
switch-mode power supply circuit is a highly inductive load (current and
voltage are 90 degrees out-of-phase), which causes distortions and
inefficiencies in the AC power network when connected directly to the AC
power network.
The PFC circuit works basically like a switch-mode power supply (SMPS)
in that it converts the rectified AC into a pulse train using a switching (or
chopper) circuit. The pulses are then filtered (or smoothed) and the result
is a regulated DC output.
The PFC circuit differs from a SMPS in that it has the added function of
ensuring that the current drawn from the AC power network is in-phase
with the AC power network voltage. When this condition is achieved the
AC power network current is effectively and efficiently used along with
the voltage to produce the necessary device power consumption.
The Main Power Supply circuit IC6100 develops and supplies all other
operating voltages (380V, 14V, 11V, 9V, 6.5V, and 16.5V) throughout the
television as shown on Figure 2-1. The Main Power Supply is not active
until an "ON" command is received and the AC relay is closed. To activate
the AC Relay 5V is supplied through the Thermostat (CN6005/pins 1 & 3)
to one side of the relay coil and the "AC-Relay" (0.6V) signal (CN6902) is
applied to a transistor Q6402, which supplies a ground to the other side
of the relay coil. The AC Relay switch closes and passes AC voltage,
initially, through the Inrush resistor (limiting the initial current surge) and to
the Main Converter IC6100.
Once the Main Power supply is up and running the secondary voltages
are developed. Notice that regulated 6.5V is fed back to the Inrush relay.
This 6.5V activates the relay, which then bypasses the Inrush resistor
(effectively removing the resistor from the circuit). The Inrush resistor is
only needed in the circuit, at first, to limit the instantaneous AC current
surge on initial power-on. In normal operation, both the AC Relay and the
Inrush relay are ON.
To activate the SW9V regulator IC6401 the TV microprocessor IC7002
supplies the "REC-ON" signal at CN6502/pin 37.
4. Power Supply System
31