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    lm3886t

    Hey guys,
    i got a pair of berhinger studio monitors (active) and one went pop and no sound came out of it however the other is working fine.

    i tested all parts and the circuit board the amp is on is the culprit.

    it has one of the lm3886t chips and some other guys but for some reason i thought its this sucker.

    i tried pulling it off and pulled most pads so now i gotta trace it and get cables running to where it needs to. i never managed to test anything. so dunno if this chip is the problem.

    what i wanted to do is pull it off and stick the known one that works on to test but i decided to wait and just order a new one. i didnt wanna risk braking the working monitor as its a reference for where the pins go to.

    can i test this chip somehow?

    what the speaker did after it popped was, once u powerd them up they did a sound of the ocean, like a white noise slowly pitching up. for about a second till capacitor got filled up. and then quiet. both the bass speaker and the tweeter.

    i also noticed that there were little clear plastic sheets beetween this lm3886 and another one next it and the heatsinks. i think these used to hold the paste and they never got peeled off these chips prior to them getting scewed to heatsinks.

    idk im going to take pictures and mark all points of where the traces go to and write this one up. berhinger brand stuff is normally pretty nice just made with mediocre components and are known for failing. i just wanna be able to fix them knowing that the speaker itself and the power supply is still good.

    BIG QUESTION HOW TO TEST THIS CHIP?? PLZ HELP..
    ALSO WHATS THAT NOISE!!!!???

    these monitors are my favorite possession and all i wanted to do on xmas was have a mix on the decks. and i was listening to them quietly and pop.

    i was soooo frustrated!!!

    any help would be appreciated ill update this post as soon as i get further into this.


    HAVE A MERRY XMAS AND A HAPPY NEW YEAR!!

    #2
    Re: lm3886t


    Ill what else could go wrong?

    Comment


      #3
      Re: lm3886t

      oh yeah and sicne the 3886t and 4701t are both not isolated does that mean i got to isolate one with that tape i took off?
      i did plug it in and it worked ? any ideas sorry to babble.

      Much thanks

      Comment


        #4
        Re: lm3886t

        If the IC mountings have insulator thermal transfer pads then you do need to put them back on.
        This bi-amp setup, one power IC for driving the tweeter and another power IC for driving the woofer. If you hear noise from both speakers (tweeter and woofer) then it will be something that is common that generates the noise and feed into to both amplifier ICs.
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment


          #5
          Re: lm3886t

          yeah after a bit of reading i realized myself i need insulation on those chips. i traced the lifted pads of the 3886 to these points on this image below.

          any one know what could be the culprit on this board?

          im going to plug both in and power them up and have a poke around see what i can muster up. im gonna stick the old 3886 and solder it up to the points shown.

          then ill have a poke around. i lost the mica insulator so had to order a bunch from hong kong. bit confused never fixed an amp.

          any help will be appriciated.

          Comment

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