Fender twin-amp: reverb not working

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by nuvolablues, Jun 23, 2008.

  1. nuvolablues

    nuvolablues Member

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    hi everybody, I got the following problem, see if anyone can help...

    I have a Fender twin-amp, the '94 edition. The reverb does not work anymore, though if I "shake" the amp you can hear the reverb's coil noise coming out the speaker. So it seems the sound goes from the reverb unit to the amp but not from the amp to the reverb unit... any idea about what the problem could be?

    thank you!
     
  2. SatelliteAmps

    SatelliteAmps Member

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    Could be a bad tube, could be a bad reverb pan, could be a bad cable going to or from the reverb tank.
     
  3. Blue Strat

    Blue Strat Member

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    Yep, the return cable and circuit are working. The driver tube, V3, could have a problem as could the send cable or the tank itself.
     
  4. nuvolablues

    nuvolablues Member

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    I also thought it could be the reverb tube, but I swapped it with the send/return loop one and it neither works... did I do a bad trial?
     
  5. Blue Strat

    Blue Strat Member

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    If you know that the tube you tried works AND it's the right type (Fender typically uses 12AT7s for reverb drivers) it was an ok test.

    On to the send cable!
     
  6. nuvolablues

    nuvolablues Member

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    I'll try that soon... thank you!
     
  7. nuvolablues

    nuvolablues Member

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    which one is it? the red one or the white one?
     
  8. evco

    evco Member

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    Had a 94' Twin amp for a number of years, would go through reverb tubes every year or two. It would never just die though, would develop feedback/ringing in the reverb which new tubes would cure.
     
  9. Blue Strat

    Blue Strat Member

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    Whichever one, when removed, doesn't kill the reverb "boinging" that you're getting now. A semi test is to have the amp on low, reverb up slightly, and tapping the center of the send cable plug with your finger. If this induces audible hum, both cables and the tank are ok. If not, either the send cable (since you already know that the return cable is ok) or the tank is bad. Could also be a bad cable to tank connection in "the bag" at the bottom of the amp.
     

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