AW: AW: Wurlie tricks / mods ?

[Don Tillman]

   From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
   Date: Tue, 6 May 1997 11:19:49 +0100

   Got the Wurlie now - what a wonderful instrument!

I'll bet you're already playing Three Dog Night tunes on it!
"Doot-doot, Jeremiah was a bullfrog..."

   It is pretty well in tune, and the electronics are not dead at all
   there is only a lot of  hum and the signal is distorted.

That's a Wurlie all right!  "Mama told me not to come..."

   Guess what the greatest surprise was when I opened it up: It already *has*
   its preamp located on the pickup !! (No FET though)
   It turned out to be a Model 200A, and they changed this from 200 to 200A.

Huh, that's interesting.  I didn't know about this.

   They changed the Tremolo circuit as well; instead of the diode, there is
   now a Vactrol photocoupler.

Here's a rough outline of the circuit for my 200:
  preamp:
    npn common emitter, input impedance is probably around 400K
    npn common emitter plus npn emitter follower
      (diode in feedback path with npn 3 capacitor phase-shift LFO)
    volume control, preamp output jack
  
  power amp:
    npn common emitter
    pnp common emitter
    npn/pnp emitter follower power transistors 
    speakers, headphone output jack

  +15v regulator:
    pnp series pass, npn to sample the output and drive that


  -- Don  ...How about some Supertramp?