> From: sndgroom@...
>
> I've been waiting some time before answering and tried in the
> meanwhile to read as much as I could about digital circuits,
> to be sure I wasn't alarmed for nothing. What I can now
> deduce is that the processor could be stuck somewhere. The
> only digital signal I see are less that 1v in amplitude and
> mixed with noise.
>
> This is something that happened last week, the synth was
> almost working, maybe measuring around I bridged something
> causing the fault?

The various things you've been seeing indicate that the CPU was running. If it had crashed, you wouldn't see any sequence of stepped voltages on the ADC or DAC lines.

But if you're no longer seeing those, either, yes, I'd check the DC OK line which resets the CPU until the power supply comes up. If you've got the old supply with the R17 trimmer next to the LED, and the LED is off, then you need to turn the trimmer just to the point where the LED turns on, plus another ten degrees or so. That's the most likely thing that would stop the CPU from running, if it was running before.

But if you're not seeing anything more than 1V, check the power supplies themselves. Measure them right where they plug into the main board. Also, are any LEDs on? If they're not within 5% of what they should be, that could be a problem.

--

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