PANASONIC TC-L42D30 – LED LCD TV - POWER BOARD – LED DRIVER BOARD and MAIN BOARD CONNECTOR VOLTAGES.
Panasonic 42" LED-LCD TV
Universal remote control set-up codes to check with Panasonic TVs.
> A disconnected connector LD2
provides ‘One’ blink of power LED; after 9 seconds of Power ON.
> A disconnected connector LD4
provides ‘One’ blink of power LED; after 7 seconds of Power On.
> A disconnected LVDS connector
will provide ‘Ten’ blinks of power LED; after 5 seconds of Power On.
POWER SUPPLY REGULATOR [SMPS] BOARD
MAIN BOARD
Universal remote control set-up codes
0016 0032 0033 0049 0054 0075
0099 0101 0104 0107 0110 0119 0143 0151 0152 0161 0166 0207 0249 0304 0305 0306
0396 0420 0461 0611 0631 0633 0692
CLICK ON THE PICTURES TO ZOOM IN
STANDBY
POWER-1
When
the TV is plugged in, the AC voltage is applied to the standby circuit of the
power supply circuit to produce STB 5.8V.
The STB 5.8V is provided to the A board, via pin-15 of connector A02. The STB 5.8v is regulated to STB 5V and
applied to the application specific IC [ASIC]; IC5000, for conversion to STB
3.3V. the STB 3.3V energizes IC8001 to
prepare the internal microprocessor for program execution. The 3.3V from the voltage regulator is also
applied to the remote control receiver, and power LED on the K board through
Pin-3 connector a10 / KA10.
IF
THE STB 5.8V IS MISSING, THE TV WILL BE DEAD [No-Power].
STANDBY
POWER-2
When
the power button of the TV or or the remote control is pressed, the MPU
[IC8000] of the A board outputs the TV-Sub-On command to turn ON the
transistors Q2001 & Q2002; which provide STB5V to the photo-coupler located
on the power supply regulator board. The
STB 5V enters the power supply regulator board; via pin-9 of the connector P2. The TV-Sub-On command is also connected directly
to the power supply to turn on a transistor that provides ground connection to
the photo-coupler. When the
photo-coupler turns On, the switched mode supply goes in operation to create
+16V or and DC24V supplies. On the A
board, the +16V is regulated to numerous other voltages to power the A
board. The DC24V is applied to the T’Con
drive board; to power the circuit that controls the light output of the
back-light LEDs. However, the back-light
circuit is not yet turned on, because this only a self check operation.
A
& P BOARDS ARE TO BE EXCHAGED ONLY.
THE T’CON / LED DRIVE BOARD, IS PART OF THE LCD PANEL. IF DEFECTIVE, THE PANEL SHOULD BE REPLACED.
STANDBY
POWER-3
When
the TV is plugged in, AC is applied to the standby circuit in the power supply
to produce STB5V. The STB5v is provided
to the A board via pin-2 of connector P2.
The standby 5V from pin-2 of connector P2 is applied to the Analogue
ASIC [IC5000] to power the main CPU / peaks LDA3 [IC8000] on the A board. The IC5000 converts the STB5V to STB3.3V and
STB1.2v. These two voltages energize and
prepare the Microprocessor [CPU] for program execution. The STB3.3V from IC5000, besides being
applied to the SPU, is also applied to the remote control receiver and the
power LED on the K board through A1/K1 [pin-3].
When CPU receives 3.eV and 1.2V, it outputs the Sub-On command that is
provided to the P board. This command
triggers the switches on the P board and only lasts approximately 15
seconds. The function of this command is
to turn On the circuit that generates the F15V on the P board. The +16V from the P board is applied to the A
board through connector P2 [pins 4 trough 6].
This voltage is applie4d to several voltage regulators to generates the
SUB voltages used by the A board for a self-check operation.
IF
STANDBY 5V IS MISSING; THE TV WILL BE DEAD [No-Power].
BACLIGHT
CONTROL
When
IC8000 is satisfied of the presence of all mentioned sub-voltages, it provides
the backlight_On command to turn on the LED drive unit. This command enters the P board, via pin13 of
the connector P2 and travels to the LCD panel to turn ON the LED drive
circuit. The back-light control signal
PWM] is delivered to the LED drive circuit, via pin-1 of connector P4, to control
the brightness of the LEDs. The PWM
signal is dependent on user settings, and picture content. An artificial intelligence circuit is used to
manipulate the PWM signal for picture quality and reduced power consumption. The LED drive circuit in responsible for
controlling the amount of current that passes through the LEDs. To avoid catastrophic failures, when the LED
backlight control circuit is defective, the Back-light_SOS command is output to
IC8000 to trigger the shutdown of the TV.
The power LED blinks ONE time.
EYEWEAR
CONTROL SIGNAL
The
circuit than handles 3D processing of the LCD TV is located inside the LCD
panel. Neither block diagram nor a
schematic diagram is available for the basic understanding of the 3D operation. The one thing that is know is that the
eyewear sync signal developed inside the LCD panel, is output to the A board
via pin-42 of the SVDS cable [A15]. On
the A board, it enters IC5901 where it is used as a reference to create the
signal needed to synchronize the 3D glasses.
The output signal of IC5901 is provided to the LEDs of the V-Board for
infrared transmission to the eyewear. To
turn On the IR transmitter, IC8000 outputs the 3D_LED_ON command to grigger the
DC/DC converter IC5900 into outputting LED_DRV 5V.