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]
>