Samsung LN46E550F6FXZA no backlight

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  • Mr. Volt
    New Member
    • May 2016
    • 2
    • USA

    #1

    Samsung LN46E550F6FXZA no backlight

    When plugged in but turned off, the TV has a red led lit.
    When turned on you get the boot up tones and TV audio. The red LED blinks 5 times and goes out.
    There is no picture. However, performing the flashlight test shows the picture so I believe the backlight is not working.
    I can find no burned or damaged components on any of the four boards. Also I cannot find any puffy capacitors.
    Using the diode checker on my meter, I checked the diodes, bridge rectifier and some of the transistors on the power board and they all seem good.
    There is 170VDC on the 82uF 450V capacitor when the unit is plugged in but off.
    The voltage drops down to 166VDC when the TV is turned on.
    When turned on I measured the following voltages going to the Inverter board:

    12 LD 0.08VDC
    11 13V 12.7V
    10 CNT_PRT 12.7VDC
    9 OVP 0VDC
    8 GND GND
    3 Low 0VDC / 0VAC
    1 High 0VDC / 0VAC

    BackLight Inverter Board
    K$27-D056264-L$ABX213S063601D
    Samsung 27-D056264 (T87I154-00) Backlight Inverter

    Power Board
    146F1_BHS
    BN44-00441A
    Rev 1.2
    Date: 11.03.15

    I am capable of soldering most components and measuring voltages.
    I thought I read somewhere you can disconnect the the main board to test the backlight but I
    have not tried that because I was not sure if that was ok to do.

    Are there any steps you can suggest to narrow down the fault?

    Thank you in advance for your help.

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