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Subject: RE: [chromapolaris] ADC Range Adjustment

From: "Paul D. DeRocco" <pderocco@...>
Date: 2019-07-15

> From: sndgroom@...
>
> Yes, I can now see the pulses "dancing" while playing note!
> The setting on R46 was, I believe" responsible as as soon as
> I moved the pot, the flow of waves started.
> BTW, still no sound. Anything else I can do?

Unless R46 is broken, it shouldn't have any major effect. All it does is null the op-amp offset, so that the DAC will be as linear as possible, and the tuning will be accurate. If turning R46 makes a significant sudden change, I'd replace it. Otherwise, you should adjust it until you've got as close to 0V between the two test points as you can measure, ideally with a meter with 100uV resolution.

Are you sure you have anything in the memory? It's common to get no sound if you haven't gone through the calibration procedure outlined in the service manual.

--

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