> From: btmckee9@...
>
> I didn't think of contamination. It's interesting that the
> channels that are the worst are the ones on the ends, where
> contamination might be more significant. Contamination makes
> sense because of the fact that they channels are a bit flaky
> in their behavior. To be honest, I didn't see anything on the
> PCB. There was some dust on the keyboard and under the
> keyboard, but I didn't see much on the PCB... I'll definitely
> take a can of air the next time.

I think airborn contaminants like vaporized cooking oils can cause problems, and you can't really see them, except that they may also attract dust. Alcohol will dissolve that. The air just blows the alcohol and dirt off.

> I bought a full set of replacement caps for the oscillators,
> but I didn't know how physically small they were and the ones
> I bought (in order to get polystyrene) were rated at 100 and
> 400 volts so they are kinda large. I'm not sure they will fit
> well or even at all. I'm going to have to go back to the
> drawing board on those and see if I can find a better source.
> Robert suggested Silver Mica, do you agree they will work as
> well, or should I stick with polystyrene?

Mica caps have nice low ESR, and don't leak, but they're usually pretty large too.

> We spent a great deal of time learning how to test various
> oscillator features. Including turning off one or the other
> (or both) oscillators which was very strange. The best way to
> disable them was to load A1 (which contained the test
> sawtooth) and then set them both to pulse with the sliders
> set to the middle. That's not what the manual said, it said
> you had to slide the sliders to the edges to disable the
> channels. I thought it was odd at the time. Do you know if
> that's the expected behavior?

No, that's not normal. So you're saying that you don't hear anything with the pulse width sliders in the middle? Do you only hear something on one side, but the other side of the range is completely dead? That could be a problem in the sliders, the ADC that measures them, or the auto-tune miscalibrating the pulse width.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...