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have a general question about "something" in my stereo receiver

Discussion in 'General Electronics Discussion' started by billybob, Aug 30, 2012.

  1. billybob

    billybob

    1
    0
    Aug 30, 2012
    Good day to all of you and thank you in advance for your help in answering my few questions,

    What we have here is an old Harman Kardon Stereo (if you are interested it is from 1994 and is a Festival 300). These three pictures are from the output stage.

    The pre-amp was getting very very hot after running about an 20-30 minutes and smelling a bit "electrical funny" so I figured I would open it and carefully blow the dust out, figuring that is what was smelling. I decided to do the same for the output stage and when I opened it I noticed an odd, dried out, yellowish "liquid" and have not a clue what it is.

    1. Can anyone tell me what this yellowish stuff is?
    2. Could this "stuff" be the reason that the pre-amp is getting so hot?
    3. If not what could be a cause for the pre-amp to be getting so hot?

    Just as a further bit of info: I ran the system for an hour without any speakers attached and it got what I would call normal warm. As soon as I ran it with speakers (mid range loud) it started to get really really hot (so that you really did not want to leave your hand on it.) The system is 4 Ohm rated and the speakers 6 Ohm rated, which, if I understand correctly is not a problem. There was more than adequate air circulation.

    I appreciate any feedback I receive here and wish everyone a nice day!

    Thank you.

    BB
     

    Attached Files:

  2. GreenGiant

    GreenGiant

    830
    5
    Feb 9, 2012
    That looks like either glue or thermal paste to help dissipate the heat

    Around the caps i would say that they are leaking but its not the right color and way too much plus it probably wouldnt work at all if the caps had leaked that much

    Not sure where the heat is from, but inspect all the parts and see if any look bad, check some readings etc
     
  3. davenn

    davenn Moderator

    13,246
    1,745
    Sep 5, 2009
    hi BB
    welcome to the forums :)

    yeah... its just glue. often seen around large electro caps to stop them vibrating and causing dry joints.
    Have you tries a different set of speakers in case the ones you are using have gone faulty?
    Have you checked the voltage rails for both the preamp nd the power amp ?
    is the fault present on both channels ?



    Dave
     
    Last edited: Aug 30, 2012
  4. KJ6EAD

    KJ6EAD

    1,114
    157
    Aug 13, 2011
    Try to find out which component(s) are heating excessively.
     
  5. shrtrnd

    shrtrnd

    3,665
    453
    Jan 15, 2010
    Maybe your speakers aren't built for the wattage of your amp, that's where I'd look first.
     
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