Low volume output from subwoofer

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  • Emilf
    Member
    • Mar 2014
    • 12
    • Iceland

    #1

    Low volume output from subwoofer

    I've got a KLH ASW12-200b subwoofer that turns on and outputs sound but at a really low volume. I have to max my bass, treble and subwoofer levels in my AV receiver as well as putting the gain to max to get any useful sound out of it.

    I have checked the RCA plugs and they seem fine. But I noticed that some capacitors on the control and power boards seem to be leaking? I'm a newbie when it comes to these types of things so I would appreciate some input from you guys on the best course of action to fix it up.

    Below I have attached pictures of the caps that I believe are damaged.
    Attached Files
  • Andrew F. Ali
    Badcaps Legend
    • Jan 2014
    • 2450
    • Trinidad & Tobago

    #2
    Re: Low volume output from subwoofer

    That stuff around the caps is glue or sometimes silicon used to hold the caps in place during manufacture. I would troubleshoot in this order:
    1. Clean the boards free of dust and other debris that may have accumulated.
    2. Look for loose connections and cold solder joints on the board traces.
    3. Look for resistors that may have burn spots, especially the 1W-3W sizes.
    4. Look for bac caps. Do ESR test.
    5. Power up and connect signal.
    6. Check Output IC/Trasistors for overheeating.
    7. Verify gain control is working.
    8. Check the speaker for increased impedence or loose 'pigtail' wires to the Voice coils.
    Hope this helps.
    AFA

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Low volume output from subwoofer

      Can you take the pictures that will show all the board, also the pictures of the panel that shows the inputs and the controls?
      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

      • Emilf
        Member
        • Mar 2014
        • 12
        • Iceland

        #4
        Re: Low volume output from subwoofer

        Will do that as soon as I get home. Thanks for the input guys.

        Comment

        • Emilf
          Member
          • Mar 2014
          • 12
          • Iceland

          #5
          Re: Low volume output from subwoofer

          Also when I turn it on it flutters for a little bit before settling down.

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Low volume output from subwoofer

            One thing I see are those bad brown glue that will eat away the wires and copper traces, they also become conductive. They should be removed.
            You can also see here what bad glue can do to the boards.
            https://www.badcaps.net/forum/showthread.php?t=34692
            Attached Files
            Last edited by budm; 03-13-2014, 08:58 PM.
            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

            • Emilf
              Member
              • Mar 2014
              • 12
              • Iceland

              #7
              Re: Low volume output from subwoofer

              Under the bigger capacitors is that also glue that should be removed? Also whats the best way to remove the glue?

              Comment

              • budm
                Badcaps Legend
                • Feb 2010
                • 40746
                • USA

                #8
                Re: Low volume output from subwoofer

                Glue on the big caps, by the grey ribbon cable, etc. I use Alcohol to soften them first then scrape them off.
                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

                • Emilf
                  Member
                  • Mar 2014
                  • 12
                  • Iceland

                  #9
                  Re: Low volume output from subwoofer

                  Here are some more pictures. I noticed on the back of the PCB that the soldering seems to be sloppy on some points. Some resistors or capacitors seem to be solder together on the + and - wires. It's noticeable in the upper right corner on the first 2 pictures, is this something I need to worry about?

                  I also scrapped away most of the glue and it changed nothing.

                  I also noticed that the woofer cone seems to flutter a little when I move the Gain dial.
                  Attached Files
                  Last edited by Emilf; 03-15-2014, 04:02 PM.

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: Low volume output from subwoofer

                    It does not look like it will be easy to trace out the connection, I usually trace the circuit back from the power amp input circuit back to the input front end.
                    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

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