bad caps or something else?

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  • DireMcCain
    New Member
    • Jan 2012
    • 5
    #1

    bad caps or something else?

    I have a yamaha receiver, rx v2092, that won't turn on. Kicks in the protection circuit and shuts down immediately...unless..

    There is one board with four larger caps...two at one and and four at the other...if I heat the two caps at the front of the board with a hair dryer, the unit comes on when switched. However, if I only heat the four caps at the back of the board, the unit comes on then, too.

    But...if I jiggle either group of caps...up front or in the rear...the unit shuts
    down...

    It's a hot board...with 8 transistors mounted on a big heatsink...don't know if the caps are bad (I do not own as ESR) or if things just need to be resoldered...what you think??


    Thanks,. jim
    Tags: None
    • midibob
      Badcaps Veteran
      • Nov 2008
      • 285
      #2
      Re: bad caps or something else?

      Hi Jim,

      Tricky one to guess. To definitely prove whether it's a heat issue with the caps you really need some freezer spray so you can isolate them from any other components.

      Wiggling them would tend to suggest a bad joint which could be anywhere on the circuit board. Heat blasted all over could also intermittently cure it too as the board expands.

      Being as it's a reputable make, and I don't know how old it is, I probably wouldn't go for the caps as a bad joint on the board sounds more likely. Have you checked for dry joints? Quite easy to spot by eye most times.

      Good luck
      Midibob

        Comment

        • Agent24
          I see dead caps
          • Oct 2007
          • 4950
          • New Zealand
          #3
          Re: bad caps or something else?

          If jiggling the capacitors causes a shutdown it makes sense it could be cracked joints or some other intermittent connection issue.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: bad caps or something else?

              Inspect the solder joints for small ring around the leads.
              Attached Files
              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

                • DireMcCain
                  New Member
                  • Jan 2012
                  • 5
                  #5
                  Re: bad caps or something else?

                  Thanks for your suggestions. The board containing the caps also contains 9 output transistors mounted on a large heat sink. Apparently jiggling the caps also caused the solder connections on some of those Qs to open. I replaced 4 and resoldered them all...
                  everything works now...the Qs run hot and over time the solder fails? I guess the heat
                  from the hair dryer caused something to expand just enough to make temporary contact...
                  Thanks again

                    Comment

                    • cadiman
                      Badcaps Veteran
                      • Mar 2010
                      • 397
                      #6
                      Re: bad caps or something else?

                      When I worked on delco radios I would put them into the freezer to make them act up and also to test them after.

                      Don`t tell my wife.

                      Sometimes spray is quicker and will give you a better idea where to start looking.

                        Comment

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