Panasonic Lx-600, Technical Information

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10
Power On Sequence
1.The Standby 7V (STB_7V) is generated on the P board (non- serviceable) when AC power
is applied. This can be measured on Pin 3 of Connector AP4/A4.
2.The STB_7V is regulated to 3.3 V on the Main board and applied to the Main Video and
Audio Controller IC4002.
3.Power on command by the remote control is not possible until the main power switch is
activated. When the Main Power Switch (AP Board) is activated, a active low ALL_OFF
signal is provided to the base of Q1151 via pin 7 of the connector AP4/A4. As a result
Q1151 turns on and a low is applied to the Key Scan Power input pin of IC4002. This
causes the unit to turn on, display a raster and become fully operational. The remote
control commands are now received and processed by the main unit. To continue
having full access via the remote control, the unit must be powered off by the remote
control, not by the power switch located on the main unit.
4.The Sub-On signal is issued by IC4002 on pin 8 of connector AP4. This signal is
responsible for pulling the contacts on the AC relay on the Power Board.
5.The Main_On signal is issued by IC4002 and provided to the AP board via pin 6 of
connector AP4/A4. It enables the Main 9V, Main 5V, and the Sound 18V (Not Shown in
the diagram) secondary power sources of the AP board. The Main_On signal is also
responsible for enabling the Main 3.3V regulator needed to power IC4004.
6.IC4004 provides the Panel_On signal that enables the Panel 12V regulator on the AP
board. It also provides the Inverter_On signal that enables the DC to AC inverter
circuitry on the LCD Panel.
7.The Inverter PWM signal and Current signal control the output voltage of the DC to AC
inverters that is used to power the CCFLTs. Increasing the on time of the INV_PWM
signal, which can be seen on pin 5 of connector A5, will increase the brightness of the
backlighting on the LCD Panel.
8.The INV_SOS signal is issued by the logic that resides on the LCD Panel if there is a
problem with the panel of inverter power supply.