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CS60 playing wrong notes problem

CS60 playing wrong notes problem

2008-06-16 by skkatter

Hello! I'm one of the new members mentioned a while ago. :)

I just bought a Yamaha CS60, which according to the seller was in
great working condition, but upon arrival it is exhibiting a problem.
Perhaps somebody has come across this before or could guide me on what
to check?

Basically some of the keys are playing incorrect notes. On each
octave, when I press c, c#, d, f#, g, g# they all play fine.

However when I play the other notes they do the following:

I press d#, I hear a c#
I press e, I hear a c#
press f, I hear a d
press a, I hear a g
press a#, I hear a g
press b I hear a g#

All the notes are perfectly "in tune", but exactly half of them are
playing the wrong note. This happens for all octaves, each wrong note
is in the same octave as the other notes (ie when I press f3 I hear a
d3, when I press f4 I hear a d4).

The seller assured me it was working fine when it left him, and he
tuned it before it left. It travelled via a courier company from Paris
to Berlin so perhaps something has moved around a bit inside (the
seller seems genuine so I believe that it left his place in working
order).

This is my first Yamaha CS synth so don't know much about them (for
example, how do you open up the front panel? :)) I do own a multimeter
and would be willing to measure voltages to find the source of the
problem. Has anybody come across a fault like this before, or knows
what I could check?

One other thing which may be worth nothing, according to the seller, a
French technician called Jean-Loup Dierstein has installed a simple
little kit inside the CS60 which tells you via 8 leds which voice you
are playing when you press a key. (this might come in handy!) I can
hold 8 keys down (ones which play different sounding notes anyway) and
hear 8 notes at the same time .

So, what to check next? (thanks in advance)

-Stephen
--
http://www.skkatter.net

Re: CS60 playing wrong notes problem

2008-06-16 by David Rogoff

skkatter wrote:
> Hello! I'm one of the new members mentioned a while ago. :)
>
> I just bought a Yamaha CS60, which according to the seller was in
> great working condition, but upon arrival it is exhibiting a problem.
> Perhaps somebody has come across this before or could guide me on what
> to check?
>
> Basically some of the keys are playing incorrect notes. On each
> octave, when I press c, c#, d, f#, g, g# they all play fine.
>
> However when I play the other notes they do the following:
>
> I press d#, I hear a c#
> I press e, I hear a c#
> press f, I hear a d
> press a, I hear a g
> press a#, I hear a g
> press b I hear a g#
>
Ok, this is strange. First, look at the KAS chip spec
(http://www.therogoffs.com/cs80/manuals/CS60_Service_Manual/06%20-%20KAS%20ICs.jpg).

Note N4N3N2N1 Note heard
C 0001 Good
C# 1111 Good
D 1110 Good
D# 1101 1111 - N2 stuck @ 1
E 1011 1111 - N3 stuck @ 1
F 1010 1110 - N3 stuck @ 1
F# 1001 Good
G 0111 Good
G# 0110 Good
A 0101 0111 - N2 stuck @ 1
A# 0011 0111 - N3 stuck @ 1
B 0010 0110 - N3 stuck @ 1

I don't see anything obvious. Anyone else?
Have an Oscilloscope? A spare KAS chip :^)

David
Show quoted textHide quoted text
> All the notes are perfectly "in tune", but exactly half of them are
> playing the wrong note. This happens for all octaves, each wrong note
> is in the same octave as the other notes (ie when I press f3 I hear a
> d3, when I press f4 I hear a d4).
>
> The seller assured me it was working fine when it left him, and he
> tuned it before it left. It travelled via a courier company from Paris
> to Berlin so perhaps something has moved around a bit inside (the
> seller seems genuine so I believe that it left his place in working
> order).
>
> This is my first Yamaha CS synth so don't know much about them (for
> example, how do you open up the front panel? :)) I do own a multimeter
> and would be willing to measure voltages to find the source of the
> problem. Has anybody come across a fault like this before, or knows
> what I could check?
>
> One other thing which may be worth nothing, according to the seller, a
> French technician called Jean-Loup Dierstein has installed a simple
> little kit inside the CS60 which tells you via 8 leds which voice you
> are playing when you press a key. (this might come in handy!) I can
> hold 8 keys down (ones which play different sounding notes anyway) and
> hear 8 notes at the same time .
>
> So, what to check next? (thanks in advance)
>
> -Stephen
>

Re: CS60 playing wrong notes problem

2008-06-16 by erikfromhere

Strange problem. My guess: either the keycoder is putting out wrong
data or the dac is having problems with it note-ladder-network. Maybe
some faulty resistors in the network ?

I can't imagine someone having soldered wrong the wires coming from
the keyboard to the kas-board. But it can't be wrong checking:
solderpoint 25 on the KAS, D# input, must be a yellow wire for
instance.

Good luck !

Show quoted textHide quoted text
--- In yamahacs80@yahoogroups.com, David Rogoff <david@...> wrote:
>
> skkatter wrote:
> > Hello! I'm one of the new members mentioned a while ago. :)
> >
> > I just bought a Yamaha CS60, which according to the seller was in
> > great working condition, but upon arrival it is exhibiting a
problem.
> > Perhaps somebody has come across this before or could guide me on
what
> > to check?
> >
> > Basically some of the keys are playing incorrect notes. On each
> > octave, when I press c, c#, d, f#, g, g# they all play fine.
> >
> > However when I play the other notes they do the following:
> >
> > I press d#, I hear a c#
> > I press e, I hear a c#
> > press f, I hear a d
> > press a, I hear a g
> > press a#, I hear a g
> > press b I hear a g#
> >
> Ok, this is strange. First, look at the KAS chip spec
> (http://www.therogoffs.com/cs80/manuals/CS60_Service_Manual/06%20-%
20KAS%20ICs.jpg).
>
> Note N4N3N2N1 Note heard
> C 0001 Good
> C# 1111 Good
> D 1110 Good
> D# 1101 1111 - N2 stuck @ 1
> E 1011 1111 - N3 stuck @ 1
> F 1010 1110 - N3 stuck @ 1
> F# 1001 Good
> G 0111 Good
> G# 0110 Good
> A 0101 0111 - N2 stuck @ 1
> A# 0011 0111 - N3 stuck @ 1
> B 0010 0110 - N3 stuck @ 1
>
> I don't see anything obvious. Anyone else?
> Have an Oscilloscope? A spare KAS chip :^)
>
> David
> > All the notes are perfectly "in tune", but exactly half of them
are
> > playing the wrong note. This happens for all octaves, each wrong
note
> > is in the same octave as the other notes (ie when I press f3 I
hear a
> > d3, when I press f4 I hear a d4).
> >
> > The seller assured me it was working fine when it left him, and he
> > tuned it before it left. It travelled via a courier company from
Paris
> > to Berlin so perhaps something has moved around a bit inside (the
> > seller seems genuine so I believe that it left his place in
working
> > order).
> >
> > This is my first Yamaha CS synth so don't know much about them
(for
> > example, how do you open up the front panel? :)) I do own a
multimeter
> > and would be willing to measure voltages to find the source of the
> > problem. Has anybody come across a fault like this before, or
knows
> > what I could check?
> >
> > One other thing which may be worth nothing, according to the
seller, a
> > French technician called Jean-Loup Dierstein has installed a
simple
> > little kit inside the CS60 which tells you via 8 leds which voice
you
> > are playing when you press a key. (this might come in handy!) I
can
> > hold 8 keys down (ones which play different sounding notes
anyway) and
> > hear 8 notes at the same time .
> >
> > So, what to check next? (thanks in advance)
> >
> > -Stephen
> >
>

Re: [yamahacs80] Re: CS60 playing wrong notes problem

2008-06-16 by skkatter

I've had a look at the KAS, all the solder points have the correct
colour wires as per the circuit diagram (and as one would expect!).

-S

Show quoted textHide quoted text
On Mon, Jun 16, 2008 at 10:31 PM, erikfromhere <moogsynthex@...> wrote:
> Strange problem. My guess: either the keycoder is putting out wrong
> data or the dac is having problems with it note-ladder-network. Maybe
> some faulty resistors in the network ?
>
> I can't imagine someone having soldered wrong the wires coming from
> the keyboard to the kas-board. But it can't be wrong checking:
> solderpoint 25 on the KAS, D# input, must be a yellow wire for
> instance.
>
> Good luck !
>
> --- In yamahacs80@yahoogroups.com, David Rogoff <david@...> wrote:
>>
>> skkatter wrote:
>> > Hello! I'm one of the new members mentioned a while ago. :)
>> >
>> > I just bought a Yamaha CS60, which according to the seller was in
>> > great working condition, but upon arrival it is exhibiting a
> problem.
>> > Perhaps somebody has come across this before or could guide me on
> what
>> > to check?
>> >
>> > Basically some of the keys are playing incorrect notes. On each
>> > octave, when I press c, c#, d, f#, g, g# they all play fine.
>> >
>> > However when I play the other notes they do the following:
>> >
>> > I press d#, I hear a c#
>> > I press e, I hear a c#
>> > press f, I hear a d
>> > press a, I hear a g
>> > press a#, I hear a g
>> > press b I hear a g#
>> >
>> Ok, this is strange. First, look at the KAS chip spec
>> (http://www.therogoffs.com/cs80/manuals/CS60_Service_Manual/06%20-%
> 20KAS%20ICs.jpg).
>>
>> Note N4N3N2N1 Note heard
>> C 0001 Good
>> C# 1111 Good
>> D 1110 Good
>> D# 1101 1111 - N2 stuck @ 1
>> E 1011 1111 - N3 stuck @ 1
>> F 1010 1110 - N3 stuck @ 1
>> F# 1001 Good
>> G 0111 Good
>> G# 0110 Good
>> A 0101 0111 - N2 stuck @ 1
>> A# 0011 0111 - N3 stuck @ 1
>> B 0010 0110 - N3 stuck @ 1
>>
>> I don't see anything obvious. Anyone else?
>> Have an Oscilloscope? A spare KAS chip :^)
>>
>> David
>> > All the notes are perfectly "in tune", but exactly half of them
> are
>> > playing the wrong note. This happens for all octaves, each wrong
> note
>> > is in the same octave as the other notes (ie when I press f3 I
> hear a
>> > d3, when I press f4 I hear a d4).
>> >
>> > The seller assured me it was working fine when it left him, and he
>> > tuned it before it left. It travelled via a courier company from
> Paris
>> > to Berlin so perhaps something has moved around a bit inside (the
>> > seller seems genuine so I believe that it left his place in
> working
>> > order).
>> >
>> > This is my first Yamaha CS synth so don't know much about them
> (for
>> > example, how do you open up the front panel? :)) I do own a
> multimeter
>> > and would be willing to measure voltages to find the source of the
>> > problem. Has anybody come across a fault like this before, or
> knows
>> > what I could check?
>> >
>> > One other thing which may be worth nothing, according to the
> seller, a
>> > French technician called Jean-Loup Dierstein has installed a
> simple
>> > little kit inside the CS60 which tells you via 8 leds which voice
> you
>> > are playing when you press a key. (this might come in handy!) I
> can
>> > hold 8 keys down (ones which play different sounding notes
> anyway) and
>> > hear 8 notes at the same time .
>> >
>> > So, what to check next? (thanks in advance)
>> >
>> > -Stephen
>> >
>>
>
>



--
http://www.skkatter.net

Re: [yamahacs80] Re: CS60 playing wrong notes problem

2008-06-16 by JH.

Something with the discrete DACs may be wrong. There are resistor ladders
which are handled by switches inside the ICs - maybe one of the resistor's
solder joints is bad? That might cause a systematic error such as you
described, as the DAC is not binary, but organized in Octaves and Semitones.

(Just an idea - can't dig deeper into this right now.)

JH.

----- Original Message -----
Show quoted textHide quoted text
From: "skkatter" <skkatter@...>
To: <yamahacs80@yahoogroups.com>
Sent: Monday, June 16, 2008 11:15 PM
Subject: Re: [yamahacs80] Re: CS60 playing wrong notes problem


I've had a look at the KAS, all the solder points have the correct
colour wires as per the circuit diagram (and as one would expect!).

-S

On Mon, Jun 16, 2008 at 10:31 PM, erikfromhere <moogsynthex@...>
wrote:
> Strange problem. My guess: either the keycoder is putting out wrong
> data or the dac is having problems with it note-ladder-network. Maybe
> some faulty resistors in the network ?
>
> I can't imagine someone having soldered wrong the wires coming from
> the keyboard to the kas-board. But it can't be wrong checking:
> solderpoint 25 on the KAS, D# input, must be a yellow wire for
> instance.
>
> Good luck !
>
> --- In yamahacs80@yahoogroups.com, David Rogoff <david@...> wrote:
>>
>> skkatter wrote:
>> > Hello! I'm one of the new members mentioned a while ago. :)
>> >
>> > I just bought a Yamaha CS60, which according to the seller was in
>> > great working condition, but upon arrival it is exhibiting a
> problem.
>> > Perhaps somebody has come across this before or could guide me on
> what
>> > to check?
>> >
>> > Basically some of the keys are playing incorrect notes. On each
>> > octave, when I press c, c#, d, f#, g, g# they all play fine.
>> >
>> > However when I play the other notes they do the following:
>> >
>> > I press d#, I hear a c#
>> > I press e, I hear a c#
>> > press f, I hear a d
>> > press a, I hear a g
>> > press a#, I hear a g
>> > press b I hear a g#
>> >
>> Ok, this is strange. First, look at the KAS chip spec
>> (http://www.therogoffs.com/cs80/manuals/CS60_Service_Manual/06%20-%
> 20KAS%20ICs.jpg).
>>
>> Note N4N3N2N1 Note heard
>> C 0001 Good
>> C# 1111 Good
>> D 1110 Good
>> D# 1101 1111 - N2 stuck @ 1
>> E 1011 1111 - N3 stuck @ 1
>> F 1010 1110 - N3 stuck @ 1
>> F# 1001 Good
>> G 0111 Good
>> G# 0110 Good
>> A 0101 0111 - N2 stuck @ 1
>> A# 0011 0111 - N3 stuck @ 1
>> B 0010 0110 - N3 stuck @ 1
>>
>> I don't see anything obvious. Anyone else?
>> Have an Oscilloscope? A spare KAS chip :^)
>>
>> David
>> > All the notes are perfectly "in tune", but exactly half of them
> are
>> > playing the wrong note. This happens for all octaves, each wrong
> note
>> > is in the same octave as the other notes (ie when I press f3 I
> hear a
>> > d3, when I press f4 I hear a d4).
>> >
>> > The seller assured me it was working fine when it left him, and he
>> > tuned it before it left. It travelled via a courier company from
> Paris
>> > to Berlin so perhaps something has moved around a bit inside (the
>> > seller seems genuine so I believe that it left his place in
> working
>> > order).
>> >
>> > This is my first Yamaha CS synth so don't know much about them
> (for
>> > example, how do you open up the front panel? :)) I do own a
> multimeter
>> > and would be willing to measure voltages to find the source of the
>> > problem. Has anybody come across a fault like this before, or
> knows
>> > what I could check?
>> >
>> > One other thing which may be worth nothing, according to the
> seller, a
>> > French technician called Jean-Loup Dierstein has installed a
> simple
>> > little kit inside the CS60 which tells you via 8 leds which voice
> you
>> > are playing when you press a key. (this might come in handy!) I
> can
>> > hold 8 keys down (ones which play different sounding notes
> anyway) and
>> > hear 8 notes at the same time .
>> >
>> > So, what to check next? (thanks in advance)
>> >
>> > -Stephen
>> >
>>
>
>



--
http://www.skkatter.net

------------------------------------

Yahoo! Groups Links

Re: [yamahacs80] CS60 playing wrong notes problem

2008-06-17 by Kyle Jarger

Hi All,

The note assignment table shows the note output in relation to the N1
through N4 signals. The table shows N1 through N4, but IC1 on the KAS board
actually puts out the inverse of these signals, /N1 through /N4. It looks
like you will get the "wrong note pattern" you are showing in the case where
/N2 and /N3 are somehow shorted together, such that if any one of them is
high, it wins the battle and pulls the other one up as well. It looks like
the ouptuts of IC1 each have a 22K pull-down resistor, so it makes sense
that if two signals were shorted, the high level would win the battle (the
high output being actively driven by the IC, the low level being only
passively pulled down by the resistor). My first guess is that two of the
22K resistors running along the side of IC1 in a "vertical mount"
configuration have shorted together, as one resistor has leaned over as
result of the shipping movement, such that the exposed leads of the resistor
are shorting out to the lead of the next resistor over. If this is the
case, it should be visually apparent when looking at the KAS board. A
simple readjustment of the resistor position to get rid of the short should
fix the problem.

If that disn't work, I'd use an ohmmeter (between pins 26 and 27 of IC1 on
the KAS board) to see if there is a dead short between /N2 and /N3. If there
is, maybe you can find a small piece of metal that fell between the pins of
an IC, or on the PC board, from the movement during shipment. I'd check the
bottom of the PCB baord as well, for bent pins or an errant piece of metal.

If its not a dead short between the pins, then it is likely one of the ICs
is bad. In my experience its usually the CMOS support ICs that have failed,
not the custom yamaha ICs, and so I would replace IC4, a TC4050 chip, first.
Even though this chip only has /N2 and /N3 as INPUTs, not Outputs, I recall
that in some cases a failure in the chips can actually affect signals that
are only inputs to the chips. If this doesn't do it, I fear its one of the
Yamaha custom IC's, IC1 or IC2.

Good Luck!

Kyle Jarger

Show quoted textHide quoted text
> octave, when I press c, c#, d, f#, g, g# they all play fine.
>
> However when I play the other notes they do the following:
>
> I press d#, I hear a c#
> I press e, I hear a c#
> press f, I hear a d
> press a, I hear a g
> press a#, I hear a g
> press b I hear a g#

Re: [yamahacs80] CS60 playing wrong notes problem

2008-06-18 by skkatter

Thanks for all the detailed suggestions! I'll be getting back down to
the studio today to perform some further investigations, I'll keep you
updated!

-Stephen

Show quoted textHide quoted text
On Tue, Jun 17, 2008 at 5:51 AM, Kyle Jarger <jkjelec@...> wrote:
> Hi All,
>
> The note assignment table shows the note output in relation to the N1
> through N4 signals. The table shows N1 through N4, but IC1 on the KAS board
> actually puts out the inverse of these signals, /N1 through /N4. It looks
> like you will get the "wrong note pattern" you are showing in the case where
> /N2 and /N3 are somehow shorted together, such that if any one of them is
> high, it wins the battle and pulls the other one up as well. It looks like
> the ouptuts of IC1 each have a 22K pull-down resistor, so it makes sense
> that if two signals were shorted, the high level would win the battle (the
> high output being actively driven by the IC, the low level being only
> passively pulled down by the resistor). My first guess is that two of the
> 22K resistors running along the side of IC1 in a "vertical mount"
> configuration have shorted together, as one resistor has leaned over as
> result of the shipping movement, such that the exposed leads of the resistor
> are shorting out to the lead of the next resistor over. If this is the
> case, it should be visually apparent when looking at the KAS board. A
> simple readjustment of the resistor position to get rid of the short should
> fix the problem.
>
> If that disn't work, I'd use an ohmmeter (between pins 26 and 27 of IC1 on
> the KAS board) to see if there is a dead short between /N2 and /N3. If there
> is, maybe you can find a small piece of metal that fell between the pins of
> an IC, or on the PC board, from the movement during shipment. I'd check the
> bottom of the PCB baord as well, for bent pins or an errant piece of metal.
>
> If its not a dead short between the pins, then it is likely one of the ICs
> is bad. In my experience its usually the CMOS support ICs that have failed,
> not the custom yamaha ICs, and so I would replace IC4, a TC4050 chip, first.
> Even though this chip only has /N2 and /N3 as INPUTs, not Outputs, I recall
> that in some cases a failure in the chips can actually affect signals that
> are only inputs to the chips. If this doesn't do it, I fear its one of the
> Yamaha custom IC's, IC1 or IC2.
>
> Good Luck!
>
> Kyle Jarger
>
>> octave, when I press c, c#, d, f#, g, g# they all play fine.
>>
>> However when I play the other notes they do the following:
>>
>> I press d#, I hear a c#
>> I press e, I hear a c#
>> press f, I hear a d
>> press a, I hear a g
>> press a#, I hear a g
>> press b I hear a g#
>
>



--
http://www.skkatter.net

Re: [yamahacs80] CS60 playing wrong notes problem

2008-06-19 by skkatter

So last night I took a look at the KAS board of my ailing CS60.

I checked the line of resisters near IC1, none of them seemed to be
touching against each other, but there is some dust in there. I
checked the pins underneath and didn't see any obvious signs of a
short. When I screwed the KAS board back down and closed the case and
turned the CS60 back on the problem with the wrong notes seemed to fix
itself!

Then I noticed that the Sustain I-II switch seems to be not working
properly. It appears to be stuck on sustain II mode (I press one note
with sustain turned up, it sustains, I press another, the sustain of
the first one cuts out, this happens at both position I and II of the
sustain switch), so I opened the panel again to see if there was a
loose wire on the switch. There doesn't seem to be, however
unfortunately when I closed the front panel again my original problem
with the wrong notes being triggered has started again. :/

Also, I noticed, when I have the release on the VCA envelope turned
on, when I play a few notes at the same time, their attack rate isn't
the same: I have the attack set to zero, yet some notes fade in as if
the attack rate was set up for that particular voice. When the release
is set to zero (and the attack rate still set to zero) and I play a
chord, all the notes sound at the same time as they should. Perhaps
this is just a voice calibration problem though?

So first things first, there is a bit of dust and debris in there I'd
like to get rid of, how would one normally go about cleaning the dust
out of these things? Spray some canned air in there? That may be the
cause of the wrong note triggering problem (or a loose wire, seeing as
when I moved the KAS board it seemed to fix it), once I fix that I can
take a look at the sustain button problem and the VCA envelope release
problem.

Thanks for all the information and help so far, unfortunately I'm a
complete novice when it comes to electrical repairs, but am not afraid
to give it a go. I'm thinking of investing in an oscilloscope anyway,
any recommendations?

-Stephen

Show quoted textHide quoted text
On Wed, Jun 18, 2008 at 9:50 AM, skkatter <skkatter@...> wrote:
> Thanks for all the detailed suggestions! I'll be getting back down to
> the studio today to perform some further investigations, I'll keep you
> updated!
>
> -Stephen
>
> On Tue, Jun 17, 2008 at 5:51 AM, Kyle Jarger <jkjelec@...> wrote:
>> Hi All,
>>
>> The note assignment table shows the note output in relation to the N1
>> through N4 signals. The table shows N1 through N4, but IC1 on the KAS board
>> actually puts out the inverse of these signals, /N1 through /N4. It looks
>> like you will get the "wrong note pattern" you are showing in the case where
>> /N2 and /N3 are somehow shorted together, such that if any one of them is
>> high, it wins the battle and pulls the other one up as well. It looks like
>> the ouptuts of IC1 each have a 22K pull-down resistor, so it makes sense
>> that if two signals were shorted, the high level would win the battle (the
>> high output being actively driven by the IC, the low level being only
>> passively pulled down by the resistor). My first guess is that two of the
>> 22K resistors running along the side of IC1 in a "vertical mount"
>> configuration have shorted together, as one resistor has leaned over as
>> result of the shipping movement, such that the exposed leads of the resistor
>> are shorting out to the lead of the next resistor over. If this is the
>> case, it should be visually apparent when looking at the KAS board. A
>> simple readjustment of the resistor position to get rid of the short should
>> fix the problem.
>>
>> If that disn't work, I'd use an ohmmeter (between pins 26 and 27 of IC1 on
>> the KAS board) to see if there is a dead short between /N2 and /N3. If there
>> is, maybe you can find a small piece of metal that fell between the pins of
>> an IC, or on the PC board, from the movement during shipment. I'd check the
>> bottom of the PCB baord as well, for bent pins or an errant piece of metal.
>>
>> If its not a dead short between the pins, then it is likely one of the ICs
>> is bad. In my experience its usually the CMOS support ICs that have failed,
>> not the custom yamaha ICs, and so I would replace IC4, a TC4050 chip, first.
>> Even though this chip only has /N2 and /N3 as INPUTs, not Outputs, I recall
>> that in some cases a failure in the chips can actually affect signals that
>> are only inputs to the chips. If this doesn't do it, I fear its one of the
>> Yamaha custom IC's, IC1 or IC2.
>>
>> Good Luck!
>>
>> Kyle Jarger
>>
>>> octave, when I press c, c#, d, f#, g, g# they all play fine.
>>>
>>> However when I play the other notes they do the following:
>>>
>>> I press d#, I hear a c#
>>> I press e, I hear a c#
>>> press f, I hear a d
>>> press a, I hear a g
>>> press a#, I hear a g
>>> press b I hear a g#
>>
>>
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Re: [yamahacs80] CS60 playing wrong notes problem

2008-06-19 by rj krohn

for cleaning interiors of synths, i usually use my vacuum cleaner with the end thing off and a paint brush. i brush the circuit boards while holding the vacuum cleaner head over that, and it usually sucks up the junk pretty well. i have several paint brushes around my studio and bench area, as they are handy for dusting/cleaning synths.

and if you are taking the plunge, i think a voltmeter is more useful than an oscilloscope, but both are useful eventually.

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--- On Thu, 6/19/08, skkatter <skkatter@...> wrote:
From: skkatter <skkatter@...>
Subject: Re: [yamahacs80] CS60 playing wrong notes problem
To: yamahacs80@yahoogroups.com
Date: Thursday, June 19, 2008, 4:42 AM











So last night I took a look at the KAS board of my ailing CS60.



I checked the line of resisters near IC1, none of them seemed to be

touching against each other, but there is some dust in there. I

checked the pins underneath and didn't see any obvious signs of a

short. When I screwed the KAS board back down and closed the case and

turned the CS60 back on the problem with the wrong notes seemed to fix

itself!



Then I noticed that the Sustain I-II switch seems to be not working

properly. It appears to be stuck on sustain II mode (I press one note

with sustain turned up, it sustains, I press another, the sustain of

the first one cuts out, this happens at both position I and II of the

sustain switch), so I opened the panel again to see if there was a

loose wire on the switch. There doesn't seem to be, however

unfortunately when I closed the front panel again my original problem

with the wrong notes being triggered has started again. :/



Also, I noticed, when I have the release on the VCA envelope turned

on, when I play a few notes at the same time, their attack rate isn't

the same: I have the attack set to zero, yet some notes fade in as if

the attack rate was set up for that particular voice. When the release

is set to zero (and the attack rate still set to zero) and I play a

chord, all the notes sound at the same time as they should. Perhaps

this is just a voice calibration problem though?



So first things first, there is a bit of dust and debris in there I'd

like to get rid of, how would one normally go about cleaning the dust

out of these things? Spray some canned air in there? That may be the

cause of the wrong note triggering problem (or a loose wire, seeing as

when I moved the KAS board it seemed to fix it), once I fix that I can

take a look at the sustain button problem and the VCA envelope release

problem.



Thanks for all the information and help so far, unfortunately I'm a

complete novice when it comes to electrical repairs, but am not afraid

to give it a go. I'm thinking of investing in an oscilloscope anyway,

any recommendations?



-Stephen



On Wed, Jun 18, 2008 at 9:50 AM, skkatter <skkatter@gmail. com> wrote:

> Thanks for all the detailed suggestions! I'll be getting back down to

> the studio today to perform some further investigations, I'll keep you

> updated!

>

> -Stephen

>

> On Tue, Jun 17, 2008 at 5:51 AM, Kyle Jarger <jkjelec@comcast. net> wrote:

>> Hi All,

>>

>> The note assignment table shows the note output in relation to the N1

>> through N4 signals. The table shows N1 through N4, but IC1 on the KAS board

>> actually puts out the inverse of these signals, /N1 through /N4. It looks

>> like you will get the "wrong note pattern" you are showing in the case where

>> /N2 and /N3 are somehow shorted together, such that if any one of them is

>> high, it wins the battle and pulls the other one up as well. It looks like

>> the ouptuts of IC1 each have a 22K pull-down resistor, so it makes sense

>> that if two signals were shorted, the high level would win the battle (the

>> high output being actively driven by the IC, the low level being only

>> passively pulled down by the resistor). My first guess is that two of the

>> 22K resistors running along the side of IC1 in a "vertical mount"

>> configuration have shorted together, as one resistor has leaned over as

>> result of the shipping movement, such that the exposed leads of the resistor

>> are shorting out to the lead of the next resistor over. If this is the

>> case, it should be visually apparent when looking at the KAS board. A

>> simple readjustment of the resistor position to get rid of the short should

>> fix the problem.

>>

>> If that disn't work, I'd use an ohmmeter (between pins 26 and 27 of IC1 on

>> the KAS board) to see if there is a dead short between /N2 and /N3. If there

>> is, maybe you can find a small piece of metal that fell between the pins of

>> an IC, or on the PC board, from the movement during shipment. I'd check the

>> bottom of the PCB baord as well, for bent pins or an errant piece of metal.

>>

>> If its not a dead short between the pins, then it is likely one of the ICs

>> is bad. In my experience its usually the CMOS support ICs that have failed,

>> not the custom yamaha ICs, and so I would replace IC4, a TC4050 chip, first.

>> Even though this chip only has /N2 and /N3 as INPUTs, not Outputs, I recall

>> that in some cases a failure in the chips can actually affect signals that

>> are only inputs to the chips. If this doesn't do it, I fear its one of the

>> Yamaha custom IC's, IC1 or IC2.

>>

>> Good Luck!

>>

>> Kyle Jarger

>>

>>> octave, when I press c, c#, d, f#, g, g# they all play fine.

>>>

>>> However when I play the other notes they do the following:

>>>

>>> I press d#, I hear a c#

>>> I press e, I hear a c#

>>> press f, I hear a d

>>> press a, I hear a g

>>> press a#, I hear a g

>>> press b I hear a g#

>>

>>

>

>

>

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> http://www.skkatter .net

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