Discussion about the Korg PolySix synthesizer

--- In PolySix@yahoogroups.com, Malte Rogacki <gacki@...> wrote:
>
> So I managed to complete my first replacement PCB.
> 
> Things don't look too bad but it has a number (?) of problems that are a
> bit difficult to debug for me.
> 
> Basically it runs somewhat unstable. Occasionally it will more or less
> reset itself or will exhibit some other behaviour which will explain in a
> second.
> 
> Nearly all chips are new, except processor, LM13600's and RAM. All
> functionality is there; calibration was more or less successful. I haven't
> yet a battery installed.
> 
> THe most common symptom at the moment is that some LED's on the KLM371
> start to blink or that a number of LED's light up permanently (and others
> get turned off). This has happened with different KLM371's so I suspect the
> error to reside on the KLM367. Oddly enough often the sound isn't affected
> at all initially and the switches still work fine. I can call up other
> programs and other banks.
> 
> Sometimes shortly (or several seconds after this) the LFO modulation is
> turned off (I have programmed this particular test sound to modulate the
> VCF). There might some other parameters change slightly as well; I have not
> yet narrowed this down completely. Sliding the LFO switch back and forth
> restores the modulation; so the actual LFO depth isn't affected, just the
> target.
> 
> So, it appears to me (grain of salt...) that the parameters controlled by
> IC28/29/34/35 may be affected, but not the ones controlled by IC18/19
> (post-DAC).
> This and the working switches leads me so far to the conclusion that the
> data lines D0 to D7 may not be the culprit here and that the problem could
> be related to lines P24 to P27.
> 
> Could this be another "bad RAM" issue? My first salvaged RAM was definitely
> dead; it wouldn't store anything. The current one seems to work as far as
> storing goes.
>

Is someone keeping track of all the issues with the KLM367A?

I'll be building 3 and want to get as much of the "crappy" stuff out of the way

Thanks....Scott , Nerd, Vermont