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Ugh . . Had a pop and hum

Discussion in 'Glowing Bottle Tube Amp Forum' started by jwp333, Nov 8, 2018.

  1. jwp333

    jwp333 Tele-Holic Ad Free Member

    869
    Jul 17, 2013
    Richmond, VA
    I fiddled around for about 3 minutes tonight on my Kustom Coupe 36 tube amp when I had a loud pop followed by a steady hum. I turned it off. Ten minutes later I got the nerve to turn it on again and had no pop, no hum after 10 minutes of playing.

    If I have a bad power tube, can it be hit or miss like this? I've got another set of 6l6's at the ready.

    Probably the oldest tube that I have in it is the 12ax7 phase inverter tube. Does any of this sound like a bad phase inverter tube?
     
  2. jwp333

    jwp333 Tele-Holic Ad Free Member

    869
    Jul 17, 2013
    Richmond, VA
    And I just played through it for about an hour and had no trouble. Sounds fine.
     
  3. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    That sounds more like an electrolytic capacitors that is close to total failure....or a bad connection somewhere. What happens if you slap the side and/or top of the amp hard.....valid test. A tech would probably pull the chassis and do a chopstick test....poking at the board/s trying to induce the bad connection.
     
    Andy B likes this.
  4. 8barlouie

    8barlouie Friend of Leo's Gold Supporter

    Age:
    59
    May 9, 2015
    Seekonk, MA
    The first thing that entered my mind was possible bad connection in the cable or the output jack on the guitar.
     
  5. bondoman

    bondoman TDPRI Member

    Age:
    27
    5
    Saturday
    vallejo ca
    To be honest as that amp is getting up there in age it might not be a bad idea to have it serviced anyway. I have a 72 that I brought in to have some cooling fans added and basic service awhile back. Found some suspect caps while he was in there. Cant say about the 36 but the 72's ran hotter than a two dollar pistol and that takes its toll after awhile.
     
  6. agogetr

    agogetr Tele-Meister

    Age:
    47
    164
    Sep 24, 2018
    nashville
    i tap on the bottom of my tubes with the amp turned up, i have found microphonic tubes and a couple times tubes with shorts in them.
    also a good thing to do when buying an amp to demonstrate tubes may need to be replaced.
    i think wally steered you straight.
     
  7. jwp333

    jwp333 Tele-Holic Ad Free Member

    869
    Jul 17, 2013
    Richmond, VA
    Played it again some yesterday and no problems still.

    Interesting that barlouie mentioned the output jack on the guitar. I kind of wondered about that, it happened with a guitar that I hadn't played much in the last year. It's been modded a few times with new pickups. I'm not sure if I ever disturbed the output jack though. But it is the one that I played for about an hour with no problems.

    The power amp tubes are behind a cage, and I haven't taken anything apart. So I can't tap on the power tubes or the phase inverter.

    This amp was serviced earlier this year when it stopped working. So I'm hoping the internal components are still okay.

    I'll update if anything new happens. Thanks for the advice.
     
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