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Thread

7 voice CS80

2007-11-20 by billwolfer

Someone mentioned modding the CS80 to 7 voices if you have a dead or
troublesome voice. I just had this done, courtesy of David Rogoff, our
moderator and list-owner. One of the VCO chips was misbehaving, so
David asked me if he could change the keyboard circuit to 7 voices. It
sounded like a reasonable, albeit temporary solution, but when I got
the machine home again, now the EG for the ring modulator is not
functioning. I know that this EG is monophonic, and that it was
working before the modification, so my theory is that by crippling one
of the voices, somehow we are bypassing the EG circuit for the ring
modulator. Can anyone verify this?

Put me on the list for people wanting VCO chips. I can't say that I'd
buy a whole set, depends on price, but I want to get this beast back
in shape. It's in very good condition, but has issues, so to speak.
Right now, I'm not even sure if I want to keep it, because I don't
have the tech chops to fix it myself, nor do I want to spend every
weekend humping it to a tech, spending more money on it. My back still
hurts from moving it last Saturday. If it's going to be like trying to
keep a vintage car on the road, it's going to be for sale, because I
don't have the patience for restoration or constant repairs. I don't
want to sell it as is, because someone will wind up making a profit of
about two or three grand after fixing a few things and then re-selling it.

So if I sell it, it's going to be primo, PS re-capped, new ribbon
controller, all eight voices, no issues whatsoever other than the wear
and tear on the tolex. Cosmetically, the whole keyboard and front
panel are flawless.

Anyway, I'm rambling. The point is a caveat and a question: does
setting the keyboard to use just 7 voices affect the EG for the ringmod?

Re: 7 voice CS80

2007-11-20 by David Rogoff

--- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@...> wrote:

Show quoted textHide quoted text

>
> Someone mentioned modding the CS80 to 7 voices if you have a dead or
> troublesome voice. I just had this done, courtesy of David Rogoff, our
> moderator and list-owner. One of the VCO chips was misbehaving, so
> David asked me if he could change the keyboard circuit to 7 voices. It
> sounded like a reasonable, albeit temporary solution, but when I got
> the machine home again, now the EG for the ring modulator is not
> functioning. I know that this EG is monophonic, and that it was
> working before the modification, so my theory is that by crippling one
> of the voices, somehow we are bypassing the EG circuit for the ring
> modulator. Can anyone verify this?

Here's the details on what's happening. Based on the KAS chip
datasheet, I changed the MODE pins from a one (-6.5v) to a zero
(8.5v), which puts the chip in 7-note mode. A side-effect of the way
the KAS works is that in this mode it jams the KO8 gate output active.
This caused the 8th voice cards to drone, which I "fixed" by removing
the VCO chips (one of which was bad, anyway). The other side-effect is
that the TR9 gate signal, which is an OR of the other 8 gates, is
always on. This is the gate used to trigger the EG for the ring-mod.

If this was a longer-term fix, it would be easy to disconnect the 8th
gate buffer (IC8 / TR8 on the KAS board), which would remove both
side-effects.

It is handy that the KAS chip can be set for any number of voices, up
to 8, for emergencies like dead voice cards (and because it was also
used on the 4-voice CS50), although the dead cards have to be the
highest number voices. You can disable, for example, just voice 3,
like some poly-synths were able to do.

David

Re: 7 voice CS80

2007-11-20 by Quazimodo

So once you get it 'Primo' Bill, why not just keep it..?
You know you'd regret seeling it - I know I would.

Sorry...;^)
TOM

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@...> wrote:
> I don't
> want to sell it as is, because someone will wind up making a profit of
> about two or three grand after fixing a few things and then
re-selling > it.
>
> So if I sell it, it's going to be primo, .....

Re: 7 voice CS80

2007-11-21 by kent_spong

David mate,

Here's a thought:

So in therory, if you put all 7 triggers to 2 X 4019 and put it low -
6.5 say and join all the out's together and connect it to the trig 9
wire. You should have your ringmod back....on paper. I think :)
I will give this a go tomorrow and see.

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "David Rogoff" <david@...> wrote:
>
> --- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@>
wrote:
> >
> > Someone mentioned modding the CS80 to 7 voices if you have a
dead or
> > troublesome voice. I just had this done, courtesy of David
Rogoff, our
> > moderator and list-owner. One of the VCO chips was misbehaving,
so
> > David asked me if he could change the keyboard circuit to 7
voices. It
> > sounded like a reasonable, albeit temporary solution, but when I
got
> > the machine home again, now the EG for the ring modulator is not
> > functioning. I know that this EG is monophonic, and that it was
> > working before the modification, so my theory is that by
crippling one
> > of the voices, somehow we are bypassing the EG circuit for the
ring
> > modulator. Can anyone verify this?
>
> Here's the details on what's happening. Based on the KAS chip
> datasheet, I changed the MODE pins from a one (-6.5v) to a zero
> (8.5v), which puts the chip in 7-note mode. A side-effect of the
way
> the KAS works is that in this mode it jams the KO8 gate output
active.
> This caused the 8th voice cards to drone, which I "fixed" by
removing
> the VCO chips (one of which was bad, anyway). The other side-
effect is
> that the TR9 gate signal, which is an OR of the other 8 gates, is
> always on. This is the gate used to trigger the EG for the ring-
mod.
>
> If this was a longer-term fix, it would be easy to disconnect the
8th
> gate buffer (IC8 / TR8 on the KAS board), which would remove both
> side-effects.
>
> It is handy that the KAS chip can be set for any number of voices,
up
> to 8, for emergencies like dead voice cards (and because it was
also
> used on the 4-voice CS50), although the dead cards have to be the
> highest number voices. You can disable, for example, just voice 3,
> like some poly-synths were able to do.
>
> David
>

Re: 7 voice CS80

2007-11-21 by Quazimodo

I just LOVE you guy's....

Here we have Techs on this here group helping EACH OTHER out.
This is a sight to behold...;^)

Sorry, I've been drinkin' .... now could one of you please have a look
at my over-looked postings...?...;^)

Hic,
TOM

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
>
> David mate,
>
> Here's a thought:
>
>
> So in therory, if you put all 7 triggers to 2 X 4019 and put it low -
> 6.5 say and join all the out's together and connect it to the trig 9
> wire. You should have your ringmod back....on paper. I think :)
> I will give this a go tomorrow and see.
>

Re: 7 voice CS80

2007-11-21 by kent_spong

Sorry Tom
Well looking at this, if your putting 100nf caps on the power rails,
the yes +8.5 to E and -6.5 to E

Hope this helps

I did think somebody else answered this already

--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...>
wrote:

>
> I just LOVE you guy's....
>
> Here we have Techs on this here group helping EACH OTHER out.
> This is a sight to behold...;^)
>
> Sorry, I've been drinkin' .... now could one of you please have a

look

> at my over-looked postings...?...;^)
>
> Hic,
> TOM
>
>
>
> --- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@>

wrote:

> >
> > David mate,
> >
> > Here's a thought:
> >
> >
> > So in therory, if you put all 7 triggers to 2 X 4019 and put it

low -

> > 6.5 say and join all the out's together and connect it to the

trig 9

Show quoted textHide quoted text

> > wire. You should have your ringmod back....on paper. I think :)
> > I will give this a go tomorrow and see.
> >
>

Re: 7 voice CS80

2007-11-21 by Quazimodo

Thanks for that Kent.
Nope, I just looked at every post since my original - no replies to it.
So there's just the other query about where the 0.1mfd cap sits
between IC pins.

Am I right.. 16pin IC: pins 8 and 16. 14pin IC: pins 7 and 14...?

I have some more questions concerning the Power Supply caps but I'll
wait till I've sobered up.

Thanx again,
TOM

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
>
> Sorry Tom
> Well looking at this, if your putting 100nf caps on the power rails,
> the yes +8.5 to E and -6.5 to E
>
> Hope this helps
>
> I did think somebody else answered this already

Re: 7 voice CS80

2007-11-21 by kent_spong

Hi Tom,

Yeah that's right. To confirm it just look at Old Crow's pic of the
TKC board again and check the orientation of the caps in relation to
the IC's.

And if your putting electrolytic caps on the power rails be shore to
reverse the polarity of the cap on the -6.5 rail. Yo know + to the E.
Just in case yo didn't know. :)

Let's be safe out there people

--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...>
wrote:

>
> Thanks for that Kent.
> Nope, I just looked at every post since my original - no replies

to it.

> So there's just the other query about where the 0.1mfd cap sits
> between IC pins.
>
> Am I right.. 16pin IC: pins 8 and 16. 14pin IC: pins 7 and 14...?
>
> I have some more questions concerning the Power Supply caps but

I'll

> wait till I've sobered up.
>
> Thanx again,
> TOM
>
>
>
> --- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@>

wrote:

> >
> > Sorry Tom
> > Well looking at this, if your putting 100nf caps on the power

rails,

Show quoted textHide quoted text

> > the yes +8.5 to E and -6.5 to E
> >
> > Hope this helps
> >
> > I did think somebody else answered this already
>

Re: 7 voice CS80

2007-11-21 by billwolfer

Hey Tom,

I sure don't want to regret selling it. I have solds TONS of synths
over the years because I always justify buying new gear by turning
over stuff I'm not using much. And with all of the stuff I've sold
over the years, I have two BIG regrets: my Oberheim Xpander (don't
remember WHY I sold it, what a fascinating synth), and my beloved
Hohner Clavinet D6, which I lost to poverty in the late seventies with
a pawn shop.

I usually don't form emotional attachments or sentimentality towards
my equipment, and right now the CS80 is being a pain in the ass. No, a
literal pain in my back, from lugging it to David's house and back,
and finding things still awry. Not David's fault at all, he did a
great job, it's just that it seems that at a certain age, these synths
need more health care than I do, and I'm 54!

Never had patience for this shit, it's why I would never own a vintage
car, no matter how cool it made me look driving down the street. If I
was mechanically minded, and enjoyed working on the car, it would be a
good way to pass my spare time, but I look at cars and instruments as
a means to getting where I'm going, and if they're going to be
unreliable, I look for alternatives.

Nonetheless, the CS80 is a very special instrument, and I intend to
get mine in shape before making the decision. Even if I don't wind up
using it much, I'll probably just put it back in the closet. Imagine
the street price for a CS80 ten years from now!

I DO have emotional attachments to two instruments: my Minimoog that I
bought in 1972, directly from the factory. I intend to keep it
forever. The vice-president of Moog Music got on the line to tell me
that I was the first person from Wyoming to buy a synth from them! It
still sounds good, functions, the oscillator pots are a bit cranky,
but it works. It was one of the last of that bunch with the
transparent wheels.

The other one is my Rhodes Stage 73 that I modified the shit out of,
and played on Paul McCartney's Say Say Say. Not for sale, ever. I
changed out all the hammers, it's bright as shit and has a special
preamp to make it brighter still. Sounds better than the
Dyna-My-Rhodes they were selling back in the days. Put it through a
nice chorus, and it's gorgeous.

OK, enough. Any of you guys regret selling things?

Bill

PS: I miss my clavinet...

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...> wrote:
>
> So once you get it 'Primo' Bill, why not just keep it..?
> You know you'd regret seeling it - I know I would.
>
> Sorry...;^)
> TOM
>
>
>
> --- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@> wrote:
> > I don't
> > want to sell it as is, because someone will wind up making a profit of
> > about two or three grand after fixing a few things and then
> re-selling > it.
> >
> > So if I sell it, it's going to be primo, .....
>

Re: [yamahacs80] Re: 7 voice CS80

2007-11-21 by rj krohn

wow- awesome post, bill! i am truly thrilled to have a synth champ and one of the top cs80 techs in the world on here!

regrets about selling? i've been lucky, i havent let go of anything i was TOO attached to, but i have left things with friends for way too long. guitars, a rhodes-i've had a juno 6 on loan to a friend out of state, every now and then i wish it was under roof. at least its just a juno.

give the CS80 a breather....if its frustrating you, come back to it in a while. i second the "dont sell" notion.

billwolfer <bill.wolfer@...> wrote: Hey Tom,

I sure don't want to regret selling it. I have solds TONS of synths
over the years because I always justify buying new gear by turning
over stuff I'm not using much. And with all of the stuff I've sold
over the years, I have two BIG regrets: my Oberheim Xpander (don't
remember WHY I sold it, what a fascinating synth), and my beloved
Hohner Clavinet D6, which I lost to poverty in the late seventies with
a pawn shop.

I usually don't form emotional attachments or sentimentality towards
my equipment, and right now the CS80 is being a pain in the ass. No, a
literal pain in my back, from lugging it to David's house and back,
and finding things still awry. Not David's fault at all, he did a
great job, it's just that it seems that at a certain age, these synths
need more health care than I do, and I'm 54!

Never had patience for this shit, it's why I would never own a vintage
car, no matter how cool it made me look driving down the street. If I
was mechanically minded, and enjoyed working on the car, it would be a
good way to pass my spare time, but I look at cars and instruments as
a means to getting where I'm going, and if they're going to be
unreliable, I look for alternatives.

Nonetheless, the CS80 is a very special instrument, and I intend to
get mine in shape before making the decision. Even if I don't wind up
using it much, I'll probably just put it back in the closet. Imagine
the street price for a CS80 ten years from now!

I DO have emotional attachments to two instruments: my Minimoog that I
bought in 1972, directly from the factory. I intend to keep it
forever. The vice-president of Moog Music got on the line to tell me
that I was the first person from Wyoming to buy a synth from them! It
still sounds good, functions, the oscillator pots are a bit cranky,
but it works. It was one of the last of that bunch with the
transparent wheels.

The other one is my Rhodes Stage 73 that I modified the shit out of,
and played on Paul McCartney's Say Say Say. Not for sale, ever. I
changed out all the hammers, it's bright as shit and has a special
preamp to make it brighter still. Sounds better than the
Dyna-My-Rhodes they were selling back in the days. Put it through a
nice chorus, and it's gorgeous.

OK, enough. Any of you guys regret selling things?

Bill

PS: I miss my clavinet...

Show quoted textHide quoted text

--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...> wrote:
>
> So once you get it 'Primo' Bill, why not just keep it..?
> You know you'd regret seeling it - I know I would.
>
> Sorry...;^)
> TOM
>
>
>
> --- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@> wrote:
> > I don't
> > want to sell it as is, because someone will wind up making a profit of
> > about two or three grand after fixing a few things and then
> re-selling > it.
> >
> > So if I sell it, it's going to be primo, .....
>

---------------------------------
Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now.

[Non-text portions of this message have been removed]

Re: [yamahacs80] Re: 7 voice CS80

2007-11-21 by David Rogoff

kent_spong wrote:

> So in therory, if you put all 7 triggers to 2 X 4019 and put it low -

6.5 say and join all the out's together and connect it to the trig 9
wire. You should have your ringmod back....on paper. I think :) I will
give this a go tomorrow and see.

Kent,

I'm looking at the KAS schematic, and it seems like it should be much
easier. Just lift the end of the 33k register going from the base of Tr8
to IC8 pin 15 and tied it to +8.5v.

NOTE: the gates/trigger signals are active-low. That is, one/on is
-6.5v while zero/off is +8.5v. TR9 is the mono trigger for the ring-mod
EG. It's the "OR" of TR1 through TR8, just using eight diodes (D1-D8)
as the OR gate. However, the diodes look like they go the wrong
direction. This is because is actually a NAND gate, which if you've done
any digital design and studied De Morgan's theorem
(http://en.wikipedia.org/wiki/De_Morgan%27s_laws), is the negative logic
equivalent of an OR gate.

Anyway, that's more than enough digital stuff for a CS80 discussion :^)

David

>
>
>
> --- In yamahacs80@yahoogroups.com, "David Rogoff" <david@...> wrote:
>> --- In yamahacs80@yahoogroups.com, "billwolfer" <bill.wolfer@> wrote:
>>> Someone mentioned modding the CS80 to 7 voices if you have a dead or

troublesome voice. I just had this done, courtesy of David Rogoff, our
moderator and list-owner. One of the VCO chips was misbehaving, so David
asked me if he could change the keyboard circuit to 7 voices. It sounded
like a reasonable, albeit temporary solution, but when I got the machine
home again, now the EG for the ring modulator is not functioning. I know
that this EG is monophonic, and that it was working before the
modification, so my theory is that by crippling one of the voices,
somehow we are bypassing the EG circuit for the ring modulator. Can
anyone verify this?

>> Here's the details on what's happening. Based on the KAS chip

datasheet, I changed the MODE pins from a one (-6.5v) to a zero (8.5v),
which puts the chip in 7-note mode. A side-effect of the way the KAS
works is that in this mode it jams the KO8 gate output active.

>>
>> This caused the 8th voice cards to drone, which I "fixed" by removing

the VCO chips (one of which was bad, anyway). The other side-effect is
that the TR9 gate signal, which is an OR of the other 8 gates, is always
on. This is the gate used to trigger the EG for the ring-mod.

>>
>> If this was a longer-term fix, it would be easy to disconnect the 8th

gate buffer (IC8 / TR8 on the KAS board), which would remove both
side-effects.

>>
>> It is handy that the KAS chip can be set for any number of voices, up

to 8, for emergencies like dead voice cards (and because it was also
used on the 4-voice CS50), although the dead cards have to be the
highest number voices. You can disable, for example, just voice 3, like
some poly-synths were able to do.

Show quoted textHide quoted text

>>