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lg 47LB585V help to identify ic please

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    #21
    Re: lg 47LB585V help to identify ic please

    ok thanks will do .i will post results

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      #22
      Re: lg 47LB585V help to identify ic please

      Well tiny tps54319 ic arrived
      removed s/c one
      checked all pins for s/c on board, prepared board
      fitted replacement , checked resistances
      i/p pins 1 and 2 had 5k to deck which was caused by zd2403 on 3.3v i/p
      powered up ,standby led ok 3.5v ok
      powered on no o/p from i/c no 1.5v on pins 10,11,12, no backlight
      no short on o/p
      so i suspect enable pin 15 not turning on
      this is proving to be a headache
      not giving up yet though
      trying to work out the start up sequence

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        #23
        Re: lg 47LB585V help to identify ic please

        The data sheet says "pull below 1.2V to disable" so I gues a voltage greater than 1.2V will enable it.
        Willing to help but I'm no expert.

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          #24
          Re: lg 47LB585V help to identify ic please

          The microcircuit may not fit well on the seat, it will not contact.

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            #25
            Re: lg 47LB585V help to identify ic please

            removed ic checked all print connections
            cleaned underside of ic, retinned the print
            refitted ic.
            same as before except i now have .2 volts on o/p pins
            before i had 0v on o/p
            enable pin has 3.2v on it
            im going to try another ic in case i used too much heat to flow the solder.
            (clutching at straws)

            i preheat the board underneath to approx 200 deg
            then fit chip
            then use s/station to melt solder and wait for flow
            i suppose something else on panel could have been damaged due to original faulty psu
            putting out more than 3v this is why the 5v zener failed

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              #26
              Re: lg 47LB585V help to identify ic please

              See the diagram for what else the standbay + 3.5v_ST bus powers

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                #27
                Re: lg 47LB585V help to identify ic please

                some progress .
                i supplied 1.5v to o/p and tv works ok
                so as Lotas said chip must not be seated correctly
                this has been my first time working with these sub minature ics
                i suppose practice makes perfect .ive ordered a couple more of this ic
                and im ordering another type of liquid flux
                ive used the same flux for years without any problems
                it wont do any harm to try another flux
                i will report back with results

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                  #28
                  Re: lg 47LB585V help to identify ic please

                  You may also have suffered a MICOM (standby controller and it contains the firmware that controls it) 33 pin. gives the command to turn on just on it.
                  Attached Files

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                    #29
                    Re: lg 47LB585V help to identify ic please

                    Originally posted by lotas View Post
                    You may also have suffered a MICOM (standby controller and it contains the firmware that controls it) 33 pin. gives the command to turn on just on it.
                    thanks for advice ,
                    but as tv works fine with 1.5v injected from bench psu
                    i assume ic is not making good contact ,
                    or i may have damaged it with too much heat
                    i have ordered another

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                      #30
                      Re: lg 47LB585V help to identify ic please

                      while i am waiting for chips to arrive ive been running tv with a LM317 as shown in pic
                      i know the original chip is rated at 3 amp and the lm317 is 1.5 amp
                      the 2 resistor values allow correct 1.5v o/p
                      i just wanted to confirm tv had no other problems ,and it seems fine.
                      the temporary reg only gets slightly warm
                      dont understand why pic is upside down?
                      Attached Files

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