Yamaha CS80

The pitch drift manifests itself when the octave buffer shifts - for example, if playing a high note causes the DC octave buffer to shift from 2 and end at 4 volts, the held down bass note will drift.  If the octave buffer goes from 4 and end at 2 volts, the bass note goes back to where it started.  Also, if you play all 8 keys at exactly the same time, the machine has a tendency to "sag" where every note seems to drop in pitch.  I still don't have the time to address this fully or post audio, sorry.

-Mike

--- In yamahacs80@yahoogroups.com, "faxiomas@..." <faxiomas@...> wrote:
>
> Hi Mike
> 
> Thx for replying; actually I can have two references, one is 
> Fernando's machine, the other is a 60: to be honest I didn't realise 
> such a flaw until you mentioned it, I did really thought it was due to 
> poor tuning in the first place,  so I'd like to go deeper into it; btw, 
> does the pitch drift randomly go from voice to voice (e.g., play low 
> then high note, does the pitch drift to high?) or does it follow 
> anything near to a logic like on the glissando?
> Also, could the bug 
> originate from the idle/busy state in the KAS' FIFO shift register? As 
> it is a fake poly assigner could the KAS  get wrong messages perhaps?
> Let me know, I can't wait for further infos!
> :-)
> 
> M 
> ----Messaggio 
> originale----
> Da: mborish_2000@...
> Data: 25-lug-2011 7.49 AM
> A: 
> <yamahacs80@yahoogroups.com>
> Ogg: [yamahacs80] Re: KAS bug examples
> 
> I'm planning on putting all of the troubleshooting results on my own 
> website in the near future because I need full HTML to reference 
> pictures, audio, and maybe some math. I need a better scope to catch 
> everything related to the bugs on my CS-80 even though I already know 
> temporary solutions for both of them.  I can't really justify or afford 
> an amazing deep memory scope until at least sometime next month and I 
> still might not do it because, well, it's gonna cost at least a few 
> thousand US $.
> 
> The two bugs that I'm going to take a crack at when I 
> make some posts on my website are the SH pitch drop or raise in Sustain 
> I bug and the Volt/Oct Scaling bug.  The SH pitch drop or raise slowly 
> changes the pitch of your release tails when you have the sustain set 
> high.  The Volt/Oct Scaling bug doesn't quite scale the YM26700 
> properly when pin 12 spits out the octave data...I think; this is what 
> I need better test equipment for.  Like I said in the previous post, 
> when you hold down one key and then play another in a different octave, 
> you can hear the held down key jump a few hertz.
> 
> I'm assuming that you 
> and Fernando have run into the same octave scaling problem?  If so, 
> please describe your problems as well as your theory related to the 
> problem.  A temporary fix is to slow down the Master Clock by replacing 
> the 100pf cap in the oscillator loop with a 180pf cap. I'm not going 
> say why I think it works yet because all I have is a theory without the 
> proper test equipment.  This will slow your clock down to about 70K and 
> also clears up about half of the double triggering.  Yes, it slows down 
> the key trigger time slightly which seems like a bad idea at first, 
> but, honestly, my whole machine feels more stable and most of the 
> double triggering is gone.  
> 
> My machine is now tolerable but not quite 
> right after the clock mod.  The held down bass key went from about a 4 
> hertz drift on octave changes in a higher register to about 3/4 hertz 
> drift.  
>  
> Sorry, but I've been busy and haven't had the time to mess 
> with my CS-80 or get further with these issues. 
> 
> -Mike
> 
> --- In 
> yamahacs80@yahoogroups.com, "Max Fazio" <faxiomas@> wrote:
> >
> > Hi 
> again
> > This is for Mike: have you managed to record any example of the 
> supposed KAS' bug?
> > Let me know!
> > M
> > 
> > [Non-text portions of this 
> message have been removed]
> >
>