Yamaha CS80

Thx again, Mike; by the way, is this tendency to drift linked to the 
Sustain/release lenght? I mean, if the Sustain is has long, mid or 
short ranges, does this change in pitch increase in speed (like an 
envelope modulating the pitch) or is that more like a sudden pitch 
drop/raise similar to a regular (lol) CS80 detuning?
M

----Messaggio 
originale----
Da: mborish_2000@...
Data: 25-lug-2011 8.56 PM
A: 
<yamahacs80@yahoogroups.com>
Ogg: [yamahacs80] Re: KAS bug examples

It's really annoying and yes it does happen a lot.  Also, they can 
drift up too which is really fun.  I've got a machine right now that is 
doing it.  There is a long jumper on the top of the SH that goes from 
the 4016 to the non inverting input that sometimes is the problem.  
I've taken them out and put ones in with an insulation jacket and 
sometimes it solves the problem.  I'm curious to see your pics if 
you've got time to post them:)

-Mike

--- In yamahacs80@yahoogroups.
com, "lucidsound" <lucidsound@...> wrote:
>
> The Sustain I bug is the 
exact problem I described on here a while ago, and hardly anyone seemed 
to have come across it before, which surprised me as I've seen it on 
just about every CS50/60/80 that I've worked on. 
> 
> This is where 
the oscillator voltages are disconnected from the KAS and held by the 
capacitors on the SH card during the Release cycle. Gradually (or 
quickly in some cases) the capacitor voltage leaks away and the pitch 
changes. The 'fix' that I came up with was to directly link the 4066 
output, the capacitor and the 3140 input on each voice with wire links 
away from the PCB. It seems that the surface of the PCB goes slightly 
conductive with age, possibly due to airborne contaminants. 
> 
> I 
have a photo of the 'fix' I used if anyone is interested.
> 
> Lucid.
> 
> 
>   ----- Original Message ----- 
>   From: Mike 
>   To: 
yamahacs80@yahoogroups.com 
>   Sent: Monday, July 25, 2011 6:49 AM
>   
Subject: [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]
>   >
> 
> 
> 
>   
> 
> [Non-text portions 
of this message have been removed]
>