UN55F8000 LED TV SMPS Power-Up Sequence

The UN55F8000 powers-up in the following sequence:

• 5.3VDC on the A5V pin when the AC cord is connected.
• The MicroPROCESSOR on the Main PCB actively looks for the user to press Power.
• When Power is pressed, the MicroProcessor sends a “High” voltage (0- 3.5VDC transition) to the SMPS via
the PWR_ON/OFF pin, to activate the rest of voltages.
• Note: The SMPS may be “forced on” by simply disconnecting the wire harness between the SMPS and
Main PCB .
• Upon the 0-3.5VDC transition on the PWR_ON/OFF pin, the following voltages are activated on

  • Vamp ≈ 18VDC
  • B13V ≈ 13VDC
  • B5V ≈ 5VDC
    • Approximately two seconds later, 5VDC is applied to the BLU_ON/OFF pin.
    • Once the BLU_ON/OFF pin is activated, the LED arrays will turn on .
    • CNL80A and CNL802B supply high voltage to the LED arrays.
    • The “positive” pins will carry a steady voltage of 35VDC.
    • The “negative” pins will carry a voltage which will vary between 1 and 10VDC depending on how
    bright the section of the screen needs to be:
  • 1Vdc = Brighter screen
  • 10Vdc = Darker screen

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