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Samsung 32in LCD LA32A650A1FXXY

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    #1

    Samsung 32in LCD LA32A650A1FXXY

    hi guys, i used the search function and couldn't find anything useful, if you know of something please post a link.

    i have an older samsung 32in Lcd:
    Model: LA32A650A1F
    Model code: LA32A650A1FXXY
    Type: LA32A650
    Power board: BN-4400208A
    Main board: BN94-01767A

    Problem is the Tv takes up to 6 power button led flashes to turn on, if it even turns on at all, the 5v standby voltage is solid the whole time, but when switching on the other voltages 12 and 24etc, they turn on and off (cycling about 1-2seconds) seemingly with the flashing led, when it finally turns on the power board voltages are stable and correct, i've disconnected all the other boards other than the main board and problem persists, i've disconnected everything except mains power and used the 1k resistor across pin 1 and 3 on the power board to power it on and all (5,12,24etc) the voltages are stable straight away.

    Only thing i noticed is if i leave the backlight board connected and manually power the power board with the resistor the backlights don't turn on, it must get a signal from elsewhere.

    I've removed and tested every cap on the power board and back light board, all test good via capacitance meter and esr meter. I have an oscilloscope for testing, but a beginner at that also, Id appreciate any advice.
    Attached Files
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    #2
    Re: Samsung 32in LCD LA32A650A1FXXY

    see if one of the pins is labeled blu-on, bl-on, add another resistor there and you should get the backlights on, if working.

    Comment

      #3
      Re: Samsung 32in LCD LA32A650A1FXXY

      Thanks for the tip nomoresonys, i'll check it tonight
      Attached Files

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        #4
        Re: Samsung 32in LCD LA32A650A1FXXY

        when i connect b/l and Det5v on the power board the backlight turns on immediately and all voltages appear stable, i have found a tiny cap on the mainboard that's measuring 6ohms on the ESR meter, but having trouble decoding 8B 1 50J, i have recorded some voltages for the the cycling issue starts for tomorrows test, it's not repeatable other than waiting a day. thanks for your help
        Attached Files

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          #5
          Re: Samsung 32in LCD LA32A650A1FXXY

          update: i took the 1uf 50v cap off the board and measured in spec, put it back on.

          i did notice that the on/off pin on the power board which is the same pin i bridge from 5v with the 1k resistor, it measures 3.3v when the tv is on, but cycles when the tv is in the faulty cycling mode from almost zero to 3v (this connector goes to the main board), kind of leads me to
          think the main board is faulty here, what’s your opinion?
          Last edited by michael1973; 02-13-2023, 04:22 AM.

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            #6
            Re: Samsung 32in LCD LA32A650A1FXXY

            yes, I think you are correct, sure seems to be the mainboard at fault.

            Comment

              #7
              Re: Samsung 32in LCD LA32A650A1FXXY

              i was able to get the same tv and swapping boards im able to confirm it was the main board at fault, im looking for a thermal camera to try and narrow the specific fault on the board further

              Comment

                #8
                Re: Samsung 32in LCD LA32A650A1FXXY

                Ok, now that you have a working board you can compare some voltages between the two boards, should make it a lot easier to sort out.

                Comment

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