Troubleshooting reverb tank issue

Discussion in 'Amp Input - Normal or Bright' started by hcski25, Nov 10, 2020.

  1. hcski25

    hcski25 Strat-O-Master

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    I'm hoping someone can help me out with a reverb issue on a 68 Custom Princeton Reverb. There is a really loud humming noise whenever the reverb is on, and above 3 on the dial. When turning it off via footswitch or unplugging the tank cables from the back of the amp, the noise goes away. This leads me to think it is the tank or the cable, but there isn't anything visually wrong with the tank. Does this sound like a reasonable assumption? Or is there something else that it might be?

    To troubleshoot, is it safe to use the reverb tank from a blues jr? Or will the different size tank do damage when connected to the Princeton Reverb?

    Thanks in advance for the help!
     
  2. Bill Moore

    Bill Moore Strat-Talk Member

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    The Princeton reverb is tube driven, and the BJ is SS, the impedance is different.
     
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  3. Tcon

    Tcon Strat-Talker

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  4. hcski25

    hcski25 Strat-O-Master

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    Thanks for the info!

    I have no problem replacing it...just curious if there's anything else it might be, or if all signs point to it being the tank.
     
  5. Tone Guru

    Tone Guru Senior Stratmaster

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    Swap out the cables to the tank.

    Measure the DC resistance values of the tank's transducers.
    Compare those readings to the published values.

    There's not really a whole lot else to troubleshoot that is external to the amp.
     
    Last edited: Nov 10, 2020
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  6. hcski25

    hcski25 Strat-O-Master

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    Ok, thanks. So if it was a bad tube in v2 (or v3?), would the noise still be happening even with the tank unplugged? Unfortunately, I don't have an extra tube on hand to swap it out.
     
  7. Stevem

    Stevem Senior Stratmaster

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    If you slam the amp around with the reverb turned up and do not hear it crash then the outout end of the tank is open, either due to a wire off of the rca jack on that end which is the most common issue, or the output side cable is bad, or the transducer is toast and you need a new tank.

    The same wire and transducer issue takes place on the input side of the tank, but if it's a tube or semiconductor problem it can be harder to pin down.
     
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  8. Stevem

    Stevem Senior Stratmaster

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    If you slam the amp around with the reverb turned up and do not hear it crash then the outout end of the tank is open, either due to a wire off of the rca jack on that end which is the most common issue, or the output side cable is bad, or the transducer is toast and you need a new tank.

    The same wire and transducer issue takes place on the input side of the tank, but if it's a tube or semiconductor problem it can be harder to pin down.
     
  9. hcski25

    hcski25 Strat-O-Master

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    Thanks for all of the guidance so far. I should clarify that the reverb works all the way through the dial, but the background hum/noise gets unbearable around 3. It doesn't get louder as you continue increasing reverb. Sorry for not making that clear in my original post. And again, the noise goes away completely when unplugging the tank or switching reverb off.
     
  10. charlie chitlin

    charlie chitlin Strat-O-Master Silver Member

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    If you need a new tank, don't do Accutronics. They went from industry standard to "stay away" unfortunately.
    MOD are good.