Yamaha CS80

Hi guys,

I have a question about the CSY-1 transplant I am finishing off. I've been meaning to finally put the lid on this for a year or so now... so I've revisited it. I 'extracted' the synth part from an old CSY-1 organ amd made a cabinet for it so what I have here is basically a three and a half octave SY-1.

It's all working great considering what it has been through...!

Apart that is, from one thing. The filter resonance slider doesn't seem to do much. It does affect the sound but only with an apparent slight volume level difference when I move the control. The frequency slider works fine.

My question is - is this most likely to be the potted low pass VFC unit? On the schematic there doesn't seem a lot around there... just some resistors and one cap, a 4.7mfd which I have change, but it made no difference. Are there any parts of the circuit other than the potted assembly, that I could look at regarding lack of resonance..?

Any help/pointers much appreciated.
Cheers,
TOM

What range of voltage do you get going into the res CV pin on the
NE10400 from that slider?

Crow
/**/

On 11/23/2011 11:10 AM, Quazimodo wrote:
> Hi guys,
>
> I have a question about the CSY-1 transplant I am finishing off. I've been meaning to finally put the lid on this for a year or so now... so I've revisited it. I 'extracted' the synth part from an old CSY-1 organ amd made a cabinet for it so what I have here is basically a three and a half octave SY-1.
>
> It's all working great considering what it has been through...!
>
> Apart that is, from one thing. The filter resonance slider doesn't seem to do much. It does affect the sound but only with an apparent slight volume level difference when I move the control. The frequency slider works fine.
>
> My question is - is this most likely to be the potted low pass VFC unit? On the schematic there doesn't seem a lot around there... just some resistors and one cap, a 4.7mfd which I have change, but it made no difference. Are there any parts of the circuit other than the potted assembly, that I could look at regarding lack of resonance..?
>
> Any help/pointers much appreciated.
> Cheers,
> TOM
>

Hi Scott,

Thanks for your reply. If you mean the LQ (50) input coming from the slider of the resonance potentiometer - I am getting the full zero-to-10volt swing as expected. As this is virtually at the input pin of the NE10400 should I assume it is faulty?

Also the machine sounds good to me, but it has occured to me that each 'preset' puts a different voltage onto that pin. And that all seems to be working. This then means that none of these 'presets' actually sound like thay should..!?

The HPF and LPF are different units so I cannot swap them around. I know you have diss-assembled one of thees - would you say it could be 'repaired'...?

Cheers,
TOM

--- In yamahacs80@yahoogroups.com, The Old Crow <oldcrow@...> wrote:
>
> What range of voltage do you get going into the res CV pin on the
> NE10400 from that slider?
>
> Crow
> /**/
>
> On 11/23/2011 11:10 AM, Quazimodo wrote:
> > Hi guys,
> >
> > I have a question about the CSY-1 transplant I am finishing off. I've been meaning to finally put the lid on this for a year or so now... so I've revisited it. I 'extracted' the synth part from an old CSY-1 organ amd made a cabinet for it so what I have here is basically a three and a half octave SY-1.
> >
> > It's all working great considering what it has been through...!
> >
> > Apart that is, from one thing. The filter resonance slider doesn't seem to do much. It does affect the sound but only with an apparent slight volume level difference when I move the control. The frequency slider works fine.
> >
> > My question is - is this most likely to be the potted low pass VFC unit? On the schematic there doesn't seem a lot around there... just some resistors and one cap, a 4.7mfd which I have change, but it made no difference. Are there any parts of the circuit other than the potted assembly, that I could look at regarding lack of resonance..?
> >
> > Any help/pointers much appreciated.
> > Cheers,
> > TOM
> >
>

Hi Scott, if you're looking in... would there be anything else on the SM1 board that could cause lack of 'resonance'?

I have been looking around the filter EG but on the schematic that doesn't seem to tie in with resonance, just the filter frequency. Or am I mistaken and it could via the internal components in the potted module?

Cheers,
TOM

--- In yamahacs80@yahoogroups.com, The Old Crow <oldcrow@...> wrote:
>
> What range of voltage do you get going into the res CV pin on the
> NE10400 from that slider?
>
> Crow
> /**/
>
> On 11/23/2011 11:10 AM, Quazimodo wrote:
> > Hi guys,
> >
> > I have a question about the CSY-1 transplant I am finishing off. I've been meaning to finally put the lid on this for a year or so now... so I've revisited it. I 'extracted' the synth part from an old CSY-1 organ amd made a cabinet for it so what I have here is basically a three and a half octave SY-1.
> >
> > It's all working great considering what it has been through...!
> >
> > Apart that is, from one thing. The filter resonance slider doesn't seem to do much. It does affect the sound but only with an apparent slight volume level difference when I move the control. The frequency slider works fine.
> >
> > My question is - is this most likely to be the potted low pass VFC unit? On the schematic there doesn't seem a lot around there... just some resistors and one cap, a 4.7mfd which I have change, but it made no difference. Are there any parts of the circuit other than the potted assembly, that I could look at regarding lack of resonance..?
> >
> > Any help/pointers much appreciated.
> > Cheers,
> > TOM
> >
>