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Main MPU (Power On Commands)
Main MPU (Power On Commands)
The STB 5V output of the P board passes through the AP board and enters the A board when the unit is
plugged into the AC outlet. IC5702 of the A board converts the STB 5V to 3.3V to power the system control circuit.
Activation of the power switch causes transistor Q5712 to turn off and output STB 3.3V to pin 18 of the MPU. Upon
receiving the STB 3.3V, the MPU (IC1100) outputs the TV-SUB-ON command via pin 8 of connector A4/AP4. The TV-
SUB_ON command is routed to the P board to provide a ground connection for relay RL802 of the power supply board.
On the AP board, The TV_SUB_ON command is used to turn on a circuit (not shown in the diagram) on the A board
that provides STB_5V to relay RL802. As a result , the switch of relay RL802 on the P board closes to allow the output
of 105Vdc to the LCD panel. The TV_Main_ON signal issued by IC1100 appears on pin 6 of connector AP4/A4 to
enable the output of the sound+12V DC/DC converter. Pin 105 of IC1100 outputs the PANEL VCC command to the AP
board to turn on the 12V DC/DC converter. The 12V output is provided to the panel via the P board.
Caution: Measure the 105Vdc source between pin 1 and 3 of connector P3. Hot ground must be used.
18
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