Panasonic TH-65PX600U Service Manual page 21

Power Supply (Standby Circuit)
This is a sequence of events that take place during the standby operation.
The AC from connector P9 is filtered by the line filter L410 and then it is rectified by
the bridge rectifier D404. The DC from D404 is applied to the standby circuit (T410,
IC409) where 12V and 5V are developed.
The STB5V is applied to pin 1 of the Power MPU IC IC501 and pin 2 of the Reset IC,
IC502.
The STB5V is also applied to the source of Q537 and the STB12V is applied to the
gate of the transistor to turn it on. As a result, the STB5V comes out on pin 10 of
connector P25.
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