Hey look, I'm not trying to judge you here, but you've a Doctor, you've got a Moog System 55 as well a CS-80 which hardly puts you in the category of starving musician. Furthermore, I've already answered a ton of your questions that I normally charge people for.
I'll walk you through the whole thing and there won't be any mistakes if you buy my light bulbs or send me paypal a PayPal payment for tech support.
I was exactly right about your TKC board wasn't I?
-Mike
--- In yamahacs80@yahoogroups.com, Fernando Zarone <fernandozarone@...> wrote:
>
> Matching the waveforms to a previously calibrated board is what I wanted to do. I tried it and it does work, being also easy to do. And removing the top panel is a brilliant idea. The difficulty, IMHO, is finding the point where to measure 125 ms at 3V!
> I have an old Tektronix 2225, very basic but solid as a rock, but can't buy a new one (as a hobbyist it's enough...).
> Honestly, I did not catch the 5b). Could you please explain more in detail please?
>
> Thanks!
>
> Fernando
>
>
>
>
> Il giorno 09/mag/2011, alle ore 19.44, David Rogoff ha scritto:
>
> > >
> > >
> > >
> > >
> > > ----------------------------------------------------------
> > >
> > > Fernando Zarone <mailto:fernandozarone@...>
> > > May 9, 2011 2:57 AM
> > >
> > >
> > > Hi all,
> > > after the long trip through overhauling my CS 80, I got to the point
> > > of VCF/ VCA calibrations.
> > > David, I appreciated your idea of connecting wires to the trigger
> > > points so much! Now, I am using a square wave from my aux outs of the
> > > 921 oscillator (Moog modular 55) and it works fine.
> > > I am facing the same problem as you did, David: no problem for the
> > > short Attack time, but setting the 3V at AF the slope of the scope
> > > visualization becomes almost horizontal, so the end point is very
> > > tricky to be detented and matching the time measurement to specs is
> > > not easy.
> > > How did you solve the problem? I think that, once having one M-board
> > > calibrated, it should be an (annoying) game, superimposing the other
> > > boards' waveforms to it. But what for the first board ??? Yamaha
> > > suggested to use "one good M-board for comparison", but I found the
> > > short calibrations (8V at AF) longer than required (about 25 ms):
> > > probably they used to be calibrated by ear, so I guess no one board is
> > > reliable as to factory specs.
> > > I think that the topic is paramount.
> > >
> > >
> > > ----------------------------------------------------------
> >
> > Here's what I did.
> > 1) removed top panel so I could get to back of M-cards without removing
> > them from (raised) card cage
> > 2) unsoldered all TRG wires to M cards and soldered in little wire loops
> > I could easily attach clip leads to
> > 3) connected all TRG inputs to Sub Osc square wave (tapped off op-amp,
> > before resistor attenuator
> > 4) calibrated first (M-11) card with 'scope. Took many passes back and
> > forth between 4ms and 125ms settings. 125ms very hard to see with
> > analog 'scope. I used falling edge of Sub Osc as trigger (negative
> > voltage = note on)
> > 5) calibrated other M cards by displaying them at same time as M-11 on
> > screen and getting waveforms to match.
> > 5b) for channel II boards, used 2nd voltmeter to measure difference in
> > attack voltage between Channel I and Channel II and made sure it was 0
> > volts by tweaking panel slider.
> >
>
>
>
> [Non-text portions of this message have been removed]
>