SF Pro Reverb delay before tremolo kicks in

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by mbratch, Feb 28, 2009.

  1. Feb 28, 2009 #1
    mbratch

    mbratch Member

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    I have a 1969 Pro Reverb. I click on the tremolo ("vibrato") with my foot switch and it takes a 30 to 60 seconds before the vibrato will start. Anyone know what causes that?
     
    mbratch, Feb 28, 2009
    mbratch, Feb 28, 2009
    #1
  2. Mar 1, 2009 #2
    Dave C

    Dave C Member

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    I'd have a look at the inside of the end of the trem roach to see if the lamp begins flashing when you hit the switch. If it flashes immediately I'd suspect the light dependant resister in the roach isn't reacting as it should. If the lamp doesn't flash immediately...have a look at the oscillator circuit for bad caps or drifted resisters.
     
    Dave C, Mar 1, 2009
    Dave C, Mar 1, 2009
    #2
  3. Mar 1, 2009 #3
    mbratch

    mbratch Member

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    OK, thanks. I'll start checking caps. I had just installed a new surf bug and that didn't make it go away.
     
    mbratch, Mar 1, 2009
    mbratch, Mar 1, 2009
    #3
  4. Mar 7, 2009 #4
    steadygarcia

    steadygarcia Member

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    How did you find that the Surf bug improved your tremolo ... if at all? I'm thinking of getting one for my Super.
     
    steadygarcia, Mar 7, 2009
    steadygarcia, Mar 7, 2009
    #4
  5. Mar 7, 2009 #5
    mark norwine

    mark norwine Member

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    If I could only take one guess, it would be this:

    Replace the cathode bypass cap on the oscillator circuit. if it's old and dried out, then the gain of the oscillator is too low and the feedback won't "start".

    mn
     
    mark norwine, Mar 7, 2009
    mark norwine, Mar 7, 2009
    #5
  6. Mar 7, 2009 #6
    mbratch

    mbratch Member

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    I know the SB gets a lot of good reviews. For my Pro Reverb, I did not notice much of an improvement.
     
    mbratch, Mar 7, 2009
    mbratch, Mar 7, 2009
    #6

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