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Rectifier Inserted Wrong, Blows Fuse?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by soundchaser59, Dec 5, 2017.

  1. soundchaser59

    soundchaser59 Supporting Member

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    I bought a used amp and the seller included the full compliment of tubes. I didn't notice that the rectifier tube JJ 5U4GB has the guide pin broken off. So it's possible I inserted the tube incorrectly, wrong pins in the wrong holes.

    When I powered it on, the jewel light came on, then a second or two later it all went dead. The fuse is blown, and the amp won't power on again without a new fuse.

    Could inserting the rectifier incorrectly cause the fuse to blow? And would it ruin the tube?
     
    Last edited: Dec 5, 2017
  2. tresspassor

    tresspassor Member

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    Absolutely. I've been guilty of doing the same thing by improperly inserting a rectifier tube with a broken key. Make sure to verify the heater filaments are glowing properly that recto tube the next time you fire it up. It should be functional if that fuse did its job properly.
     
  3. soundchaser59

    soundchaser59 Supporting Member

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    Thanks! That was my other question, if the tube could be ruined by that mistake. Long term solution is to order a Weber copper top.

    Under a magnifying glass I am able to see the stress mark on the plastic, so I can tell where the guide pin should be. So I should be able to test the tube correctly tomorrow after I get another fuse. Hope to start rockin' after that.
     
  4. soundchaser59

    soundchaser59 Supporting Member

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    Apparently that was all it needed. New fuse and the rectifier inserted correctly, and it's making sound.

    It's still odd though......this is a Frenzel amp, pair of 6L6, 3x 12AX7, advertised as a 40 watt beast, but this is the softest quietest 40 watts I've ever heard.

    Wait, wait.......sorry.......I just remembered this amp has a built in attenuator and I still have it set for 10 watts.

    never mind..........and Thanks for the tip @tresspassor ! It seems to be back in working order!
     
    Sam Sherry and theon like this.
  5. Oatie

    Oatie Member

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    You got lucky, broken guide pins have cooked a few amps...
     
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  6. soundchaser59

    soundchaser59 Supporting Member

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    I took the chassis out of the cab to fix the fuse holder and found the broken plastic guide piece bouncing around inside. The entire black plastic guide broke off, not just the guide pin on the side of the plastic. I'm guessing it broke off when the tube was removed prior to shipping the amp to me.
     
  7. 66 Kicks

    66 Kicks Member

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    You can get an entire black plastic guide piece at places like amprepairparts, tubesandmore, tubedepot, fleabag, etc.
     
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  8. Blue Strat

    Blue Strat Member

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    I've never seen it happen any other way. Glad it worked out! BTW, you can reglue the guide pin.
     

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