Amp Buzz, Need tech's opinion PLZ.

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by disappear_85, Dec 1, 2017.


  1. disappear_85

    disappear_85 Member

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    the amp buzz with nothing connected, only a cab, tried different cabs and different speaker cables.

    I'm not a very technical person, and i won't wanna burden you with explaining a step by step process.

    But now that you mention tube socket, i do remember one time a preamp tube popped and dimmed, so i figured i'll replace it.

    Is that useful information? i don't think so because i don't remember which socket it was or if buzz was there before it popped or not.

    Thank you for your input
     
  2. pdf64

    pdf64 Member

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    I thought that you had swapped out all the tubes already?
    As you mentioned using an electrician, something useful one could do is verify that your domestic electrical installation is good, with particular regarding to a low impedance path to ground (which may be difficult to achieve in very arid regions).
    I know you've got an amp that works fine, but some are more prone to such issues than others.
    On the same theme, trying the amp in a completely different building / area may be useful.
    The electrician, or a technically minded friend, may also be willing to undertake the voltage tests I mentioned.

    BTW your photos can't be seen; photobucket is no use for hosting photos you want anyone else to view, unless you pay to upgrade. There are other image hosting sites that are currently free.
     
    Last edited: Dec 5, 2017
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  3. Avatar Tech

    Avatar Tech Member

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    The photos aren't visible on this page, but I was able to open the album and view them externally.
     
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  4. Avatar Tech

    Avatar Tech Member

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    Can you provide more detail here? You say it "popped"... Was there an audible sound associated with this event?
     
  5. disappear_85

    disappear_85 Member

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    Just the preamp tube popped like a spark from the inside, i dont think the sound went through the speaker, just pop and the glow dimmed, so i replaced it. but for the life of me i cant remember if the buzz came after the pop or not because im trying to fix to amps at the same time and i cant remember.

    Here is something interesting i found, might be nothing, Check the capacitor or whatever it is marked L2 on the board, does it seems defective to you? leaking? This is on the power amp section of the amp ( separate PCB ).

    I poked at it with a stick and nothing changed, no better no worse.

    [​IMG]
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    [​IMG]
    [​IMG]
     
  6. Avatar Tech

    Avatar Tech Member

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    L2 appears to be silicon diode in the pics. They don't typically leak anything when they fail, but they will burn if they dissipate too much power.
    I think a failed rectifier diode in the HT supply would cause problems much worse than what you're experiencing.
     
  7. pdf64

    pdf64 Member

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    I think they're ferrite inductors, from the photos I can't see a problem.
     
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  8. disappear_85

    disappear_85 Member

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    Thank you for all your help, I've already given up but i thought i would share some interesting finds.

    Some of components ( capacitors, resistors and jack cable to the PCB ) transfer sound to the speaker when i turn the volume up & tap on them with a stick, and if i hold the V3 tube ( i think ) it makes a like a ground buzz through the speaker.

    Anyway thank you for taking the time to look into this, and thanks to all who contributed, This amp is going to the storage and die there.
     
    Last edited: Dec 9, 2017
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