Circuit Explanation - Panasonic TH-42PX80U Service Manual

Circuit Explanation

The D board consists of a Video/Panel Control circuit, a Discharge Control circuit, and a
Microprocessor Control circuit.
The LVDS (Low Voltage Differential Signaling) signal from the A board is processed by the Video/Panel
Control circuit (IC9300 and IC9400).
The Discharge Control circuit outputs the Control Data, Sustain Data, and Scan Control Data. The
Control Data is used by the Data Drive Circuit boards (C boards). The Sustain Control Pulses are used
by the Sustain board and the Scan Control Pulses are used by the Scan board.
The Main CPU IC9003 has multiple functions. It provides the command to turn on/off the Power Supply
and the Panel Drive circuit within the D board. It also monitors a number of voltages and circuits
providing protection by shutting down the TV when an abnormality is detected. This condition is
communicated to the Main CPU in the A board. When this happens, the power LED blinks a specified
number of times indicating the circuit that has failed.
Supply voltages P15V, P5V, and STB5V from the power supply are used to drive the circuits on the D
board. Other voltages (1.2V, 2.5V, and 3.3V) derived from the P15V are used by the Video/Panel
Control ICs (IC9300 and IC9400) and the Discharge Control IC (IC9500).
The P15V is monitored by the Main CPU (IC9003) for missing voltage condition.
The P5V is used by the level shifter ICs, IC9802, IC9803, and IC9019. Their functions is to change the
Scan Control Pulses level from 3.3V to 5V before they are output to the SC board via connector D20.
The P5V is monitored by the Main CPU (IC9003) for voltage drop condition.
The STB5V is applied to a 3.3V regulator (IC9011). The 3.3V output by this IC is used as the supply
source (VCC) by the Main CPU IC9003.
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