Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

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Subject: Re: [PolySix] RE: Lots of pots not working

From: Bob Grieb <bobgrieb@yahoo.com>
Date: 2014-01-10

I am confused.   Why are you working on the output mux when the problem
seems to be with the front panel input circuitry?  The DAC calibration
procedure does not involve IC18 at all.  Only the comparator that drives
pin 1 of the CPU, and the two pots, and the analog mux that selects their
voltage and feeds it to the comparator.   I would focus on those components.

Bob


From: "josh.nursing@gmail.com" <josh.nursing@gmail.com>
To: PolySix@yahoogroups.com
Sent: Friday, January 10, 2014 1:09 PM
Subject: Re: [PolySix] RE: Lots of pots not working, MG, VCF, EG.

 
What could be the reason that IC18-P12 (Res) picks up the signals from all other Pots?

There do not seem to be any continuity or shorts problems around IC18, and the traces for P2.0 - 2.3 & INH2 are fine. The CPU should be okay too and I swapped new 4501 at IC18 & 19 at one point, and a second time reverted these and used the new 4501 on the two left-most panels.

Doesn't this narrow it down to either the DAC or the comparator at IC6?

Yash