I dissected a dead preamp tube. Pix.

Discussion in 'Amps and Cabs' started by midnightlaundry, Feb 9, 2012.

  1. midnightlaundry

    midnightlaundry Member

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    It wasn't actually dead, but it went to a to a loud buzz. I think a cathode shorted to the grid. So I gutted it.

    I've done this before, but this time I know a little bit more about tubes. I'd say at this point that the Mica's are real important in keeping everything in line, and secured. Loose Mica tolerances probably make for a microphonic tube.

    The Mica material seems to be real crumbly and flakey. The Filament wire is a high tensile strength, with an insulating coating. The Cathode tubes are so tiny, it's amazing they can get the Filaments in there. The Grid wire is about .0015" thick and wound nearly as tight. Only a machine could do it perfect like that.

    I bet that most failures are probably broken leads to the pins. The leads to the pins are very fine and within tight quarters. How would you like to work with these little pieces for 8-10-12 hours a day doing production?

    http://home.comcast.net/~leadfootdriver/JJ1.JPG

    http://home.comcast.net/~leadfootdriver/JJ2.JPG

    http://home.comcast.net/~leadfootdriver/JJ3.JPG

    http://home.comcast.net/~leadfootdriver/JJ4.JPG

    http://home.comcast.net/~leadfootdriver/JJ5.JPG

    http://home.comcast.net/~leadfootdriver/JJ6.JPG

    http://home.comcast.net/~leadfootdriver/JJ7.JPG

    http://home.comcast.net/~leadfootdriver/JJ8.JPG

    http://home.comcast.net/~leadfootdriver/JJ9.JPG

    http://home.comcast.net/~leadfootdriver/JJ10.JPG

    http://home.comcast.net/~leadfootdriver/JJ11.JPG

    http://home.comcast.net/~leadfootdriver/JJ12.JPG

    http://home.comcast.net/~leadfootdriver/JJ13.JPG

    http://home.comcast.net/~leadfootdriver/JJ14.JPG
     
  2. johnnylighton

    johnnylighton Member

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  3. Structo

    Structo Member

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    That's some nice macro photography.

    When I was a kid I used to find raw mica right in the ground near where I lived.

    Tubes are a lost art for the most part.
    Hopefully there will be tubes for as long as I'm alive.
     
  4. cubistguitar

    cubistguitar Member

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    thanks for sharing this
    it is entertaining to us gear geeks
     
  5. tnt365

    tnt365 Supporting Member

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    First, thanks a lot for the post! I don't want to hijack the thread, but could someone point me to a good website that has a good layman explanation of how tubes work? How do they function? What are there different uses?

    Really basic questions, and I've owned 10+ tube amps :bonk
     
  6. ken374

    ken374 Member

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  7. Pa'ani

    Pa'ani Supporting Member

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    Thanks for sharing the cool information and awesome photo's.
     
  8. RocksOff

    RocksOff Member

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    Aspen Pittman's book kind of explains tubes, but probably not really from a laymans perspective.
    Lots of diagrams, though.
     
  9. thosk

    thosk Silver Supporting Member

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    This may help some:
    http://www.thegearpage.net/board/showthread.php?t=871538

    Or this:
    http://www.tubebooks.org/
     
  10. TDJMB

    TDJMB Gold Supporting Member

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    Thanks for the post. I hadn't given much thought to how small all the parts are.
     
  11. Brazen

    Brazen Member

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    I found this on Youtube. :)

    http://www.youtube.com/watch?v=UM3av6moJd4
     
  12. Bandmonster

    Bandmonster Member

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  13. midnightlaundry

    midnightlaundry Member

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    I can see how tube vendors might get a lot of rejections. If you've ever had a job that involves factory production, you start to not care about quality real quick because you're doing the same mind numbing repetitive movements all day long. So with all the tiny parts in the tube, you could get ham handed as the day wears on.
     

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