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.

LED DRIVE BOARD

> 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.