5f2a Princeton tweed.

Discussion in 'Amp Tech Center' started by 65GP, Jul 20, 2020.

  1. 65GP

    65GP TDPRI Member

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    Hi I have some problems with my Princeton tweed 5f2a.
    The kit I build worked for a few year, no problems. I used a output trafo that can put out 4,8, and 16 ohm.
    I use 8 ohm but forgot about that and hooked up a 4 ohm speaker....
    It worked but after a switched back to the 8 ohm speaker almost no output and distorted. Switched out tubes and even replaced the output transformer for a spare that I had. Stil, almost no output...
    Anyone any got a clue?
    Thx. Peet
     
  2. dan40

    dan40 Tele-Afflicted

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    You don't happen to have a second output jack (for an extension cab) on the back of the amp do you? Plugging into the extension jack only will result in a "no sound" condition. If this is not the case, we will likely need a full set of voltages from both sockets to be able to identify a problem. I would also check all of your solder joints for a bad joint or loose wire.
     
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  3. Platefire

    Platefire Friend of Leo's

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    I don't think using a mis-matched speaker would cause your amp to do that. I would more likely believe it is a problem unrelated to that. You need to go back over the circuit and check everything like when you originally built the kit. Platefire
     
  4. keithb7

    keithb7 Friend of Leo's

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    Chopstick time!
     
  5. 65GP

    65GP TDPRI Member

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    Thx! I do have a extra speaker output.
    (Standard output is 8 ohm, connecting a extra 8 ohm speaker is switching the OT to 4 ohm and speakers in parallel).
    This always worked fine but I'm gonna check the joints. Thx.
     
  6. King Fan

    King Fan Poster Extraordinaire

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    Guys, read Dan's post carefully. He’s not saying the extension jack doesn’t work, or is mismatched, he’s saying IF you plug into it *by itself* you get no sound. It’d be easy to do that during speaker trials.

    One other thing that’ll do it is accidentally switching the 6V6 and 5Y3 during a tube swap. Don’t ask...

    To be fair, you said your tone was *almost* gone? Swap rectifier for output tube, there's no *almost* about it.
     
    Last edited: Jul 21, 2020
  7. D'tar

    D'tar Friend of Leo's

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    First thought reading the OP is to check your speaker cable. Pull it apart and check your joints, make sure nothing shorts out to the housing, assuming you are using a mono Jack. Although I prefer to solder directly to the speaker terminals, I am guilty of using spade connectors which may eventually cause issues as some are better quality than others.
     
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  8. King Fan

    King Fan Poster Extraordinaire

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    Good ideas here. Dan and D'tar are, logically, thinking around the area you 'worked on' last, speakers. Don't overlook the speaker jack. Is it ¼" or (gack) RCA? RCA can be a world of hurt sometimes, but ¼" also get dirty or bent. Clean and visually inspect the prongs with and without a plug?

    Hmm. Random thoughts. Input jacks can get dirty or bent, too. Many of us have tried testing with 'known good' tubes that are no longer good. Even more common, loose socket springs or dirty pins or loose socket connections (Keith's chopstick -- all around the socket lugs).

    If these ideas and a complete game of whack-a-mole with a chopstick don't help, a complete voltage table and some pics are often helpful.
     
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  9. tonejunkie99

    tonejunkie99 TDPRI Member

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    pics of the output jack and wiring is welcome. You could impedance on the o/t.
     
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