Circuit Operation When A6 And A7 Are Removed - Panasonic TH-42PX80U Service Manual

Circuit Operation When A6 and A7 are Removed

The result obtained on previous generations when D3 was disconnected, can
now be obtained by disconnecting A6/P6 and A7/P7.
When these connectors are removed, the A, K, GH, and S boards are disabled.
Normally Pin 2 of connector A3 is grounded by Q4014-Q4015. When A6 and
A7 are disconnected pin 2 is no longer grounded. This allows for the 3.3V
regulator on the D board to output 3.3V to the Panel CPU (IC9003).
The Panel CPU (IC9003) outputs a command that is provided to 2 different
circuits.
The "Panel Main On" command (3.2V) is connected to pin 11 of connector P25
on the power supply turning on the circuit that generates Vsus, Vda, P15V, and
P5V.
The "Power On/Off" command (3.2) is connected to the Video/Panel Control
and Discharge circuit to output the panel drive control pulses.
This method of isolation is useful when troubleshooting problems where the A,
GH, K, or S board are suspected to be defective.
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