System Control Block - Panasonic TC-26LX20 Technical Manual

The control signals responsible for the overall operation and control of both units are
shown in this diagram along with their designated termination points.
Main Power switch signal is derived from the power on switch, which is located on
the K board. The Main Micro (TV Microcontroller), located on the DG board, sees
this as a "key scan" input signal and issues a TV ON and AC_On to the control
circuitry within the Primary and secondary power supply.
DVD Power switch signal is derived from the DVD operation switch, located on the
DVD OP board. This signal is responsible for initiating the power on sequence for
the DVD operation. The Main Micro sees this as a "key scan" input signal.
Panel ON signal appears on pin 28 of the DG board connector DG2. This is
equivalent to an on/off switch for the LCD Panel.
Backlight ON /OFF (B/L On/Off) signal provides the enable for the DC to AC
backlight inverter power supply which is incorporated within the LCD Panel.
OSD Timing Compensator synchronizes the OSD with the incoming video.
System Shutdown
The Main Micro on the DG board is responsible for monitoring the various shutdown
conditions. The Main Micro monitors the SOS and main voltage (Zero X Detect)
detection signals via the DG2 connector.
LED Functions
o The Time Warp Led indicates that the DVD is recording at twice the normal
record mode (operator's choice)
o The SD LED indicates that the SD card is being accessed either for a read or
a write operation
o The DVD LED indicates that the DVD unit is being accessed either for a read
or a write operation
TV Data In/Out are DVD control lines used for playback and record.
DVD Play switches the audio monitor output from all audio inputs to the DVD
Output.
Wake Up provides Serial data communication between the DVD Micro and Main
Micro.
Fan Control is accomplished through the use of a fan control circuit located on the
DVD main circuit board. A PWM output signal from sub processor IC 7501 controls
the speed of the fan, based on the internal ambient temperature of the unit

System Control Block

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