Ap Board Power Distribution - Panasonic LX600 Technical Information

AP Board Power Distribution

The AP Board is responsible for the regulation, distribution and
dissemination of all secondary voltages derived from the 24V and 10V
source supplies on the P Board. The 7V STBY voltage is present when
the unit is plugged into the AC outlet. When the main power switch is
activated, it is sensed on the main board by IC4002. A TV_SUB_ON
signal is subsequently issued in response, on pin 9 of connector AP4,
which activates the "Relay" signal on pin11 of connector AP2. This pulls
the contacts on the AC relay on the P board and allows for the output of
the 24V and 10V on that same connector. The TV_Main_ON signal
issued by IC4002, appears on pin 6 of connector AP4/A4 and provides
the output "Enable" for the 5V, 9V, and 20V switched mode power
supplies. Q7208 serves as a 24V detection line and provides an enable
for the Main_ on signal to function if 24V is detected. The panel 12V_On
signal provides the "Enable" for the Panel 12V logic and the enable for
the 24V inverters on the LCD Panel.
When a panel-on command is issued to turn on the Panel 12V switched
supply IC7212 located on the AP Board, transistor Q7805 turns on
causing Q7806 to turn off. As a result, the INV_ON pin of IC4004 on the
A board goes high. That same DC is applied to the LCD Panel's inverter
input on pin 3 of connector A5 also on the A board.
The over voltage protection circuitry affiliated with each of the regulators,
is responsible for monitoring for excessive or over voltage conditions, and
is designed to turn off the AC power by disabling the SUB_ON signal
needed to turn on the AC relay. All voltages are accessible and can be
measured either on the connectors or on the highlighted jumper
locations.
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