Sony STR-6046a motorboating

Discussion in 'Solid State' started by STR-6046A, May 19, 2017.

  1. STR-6046A

    STR-6046A Member

    Messages:
    78
    My sony suddenly started making this motor boating sound. I thought it was in the right channel at first. It just appeared, Turned the Sony off one day and the next time on it was there. When I switched the pre-amp off it was gone. So I went and replaced all the caps on the Pre-amp board, but that didn't fix it. So I replaced all the Caps on the Output amp , too... and the Powersupply. To no avail.
    Then I did a desperate attempt of reflowing all the solder joints ,starting with the output amp and then going to the Preamp. There I found a little curled up something stuck between two components. No clue what it is, but when I got it out, the noise was gone.
    Got all Caps replaced now with nice Nichicon NKZ and she sounds pretty sweet, I must say.
    curled up something.jpg
    here is the curled up something uncurled... I'm sure that wasn't supposed to be there.
    curled up something1.jpg
    that 1uF cap still needs to leave...
    curled up something2.jpg
     
  2. 62vauxhall

    62vauxhall Well-Known Member

    Messages:
    920
    A piece of foil trace from the PC board?

    That orange cap may be a low loss Elna or something. Might be best to leave it be.
     
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  3. STR-6046A

    STR-6046A Member

    Messages:
    78
    That low loss Elna is actually made by Nichicon. But it's long gone, I took that photo while I was recapping.

    I thought that too, that it could be a trace, but there is no green side, both are shiny.
     
  4. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

    Messages:
    1,121
    Location:
    Victoria, Australia
    I wonder where that piece of metal came from, good find. I bet it does sound better after your cap replacement, 62vauxhall is correct, that orange Elna is a low leakage cap, you can replace these with Nichicon UKL's.
     
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  5. STR-6046A

    STR-6046A Member

    Messages:
    78
    I think I replaced it with a UKG , actually I'm pretty sure I did. Couldn't get it as a UKZ
     
  6. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

    Messages:
    1,121
    Location:
    Victoria, Australia
    Fair enough, yeah those Nichicon KZ's and FG's do have a fairly low leakage figure also, just not as low as the KL's. It is a bit of an apples vs oranges comparison when trying to compare new electrolytic leakage specs vs the old Pioneer tuning fork low leakage capacitor leakage specs as l have noticed they are tested over a different time factor.
     
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