Panasonic TH-65PX600U Service Manual page 23

Power Supply (Standby Circuit)
The STB5V from the P board is connected to the D board via connector D25. From there, it
is provided to the DG board via pin 29 of connector DG3.
On the DG board, the STB5V is connected to a 3.3V regulator, and a 1.5V regulator.
IC1110 provides the STB1.5V to the CPU IC1103 and the switching circuit consisting of
Q1140 and Q1141. The switching circuit outputs a high to turn on the STB3.3V regulator
(IC1111).
The 3.3V from IC1111 is provided to the CPU IC1103.
When IC1103 receives both 1.5V and 3.3V, it sends out a 3.2V command out of pin 216.
This command is provided to two different circuits and is given a different name in each of
these circuits. It first goes to pin 8 of connector DG20 under the name of "Tuner-Sub-ON"
and from there it goes to connector PA20 on the PA board to activate the protection circuit
of the PA board.
This command also goes to pin 27 of connector DG3 under the name of "F-STB-14V ON".
From there it goes to pin 13 of connector D25/P25 of the power supply circuit (P board).
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