Yamaha CS80

Hi. 
My name is Tommaso, live in Italy and I had in the last 10 years 
three CS80! 
The second was in perfect condition and 
I sold to a dear friend in Italy. 
The third I found recently, I could not live without a CS!
I started with the restoration.
Now the beast was in perfect condition externally, perfectly tuned 
but with a  little problem on the five Mboard on Channel One.
With the Sine wave only (VCF volume closed)
In addition to sine,I Feel another waveform  similar to sawtooh.
And the waveform (Saw e Square) of the channel one are closed!
I Change all the IGO chips in the Board,but without any positive 
effect.
Then I changed the polarize electrolytic capacitors.

Same problem...

Now,they may be the 1 Uf 50V not polarized capacitors?
Or the other caps?

Sorry but I do not have an oscilloscope.
Some suggestions?

My guess would be the saw- and/or pulse-gate is always open. Try 
replacing the FET6 or FET7 (2SK30) or TR6 or TR7 (2SA561). However, 
you say the waveform can be heard even when the vcf-volume is 
closed. Then I would say the sinewave is not a pure sinewave. Does 
the waveshaper output a perfect sine ? You'll need a scope for that 
on pin 2 of ic9. Or does vca3 (IG00151) distort the sine-wave ? Try 
replacing vca3...
Good luck.

--- In yamahacs80@yahoogroups.com, "oberheim64" <tommysalsero@...> 
wrote:

>
> Hi. 
> My name is Tommaso, live in Italy and I had in the last 10 years 
> three CS80! 
> The second was in perfect condition and 
> I sold to a dear friend in Italy. 
> The third I found recently, I could not live without a CS!
> I started with the restoration.
> Now the beast was in perfect condition externally, perfectly tuned 
> but with a  little problem on the five Mboard on Channel One.
> With the Sine wave only (VCF volume closed)
> In addition to sine,I Feel another waveform  similar to sawtooh.
> And the waveform (Saw e Square) of the channel one are closed!
> I Change all the IGO chips in the Board,but without any positive 
> effect.
> Then I changed the polarize electrolytic capacitors.
> 
> Same problem...
> 
> Now,they may be the 1 Uf 50V not polarized capacitors?
> Or the other caps?
> 
> Sorry but I do not have an oscilloscope.
> Some suggestions?
>

--- In yamahacs80@yahoogroups.com, "erikfromhere" <moogsynthex@...> 
wrote:
>
> My guess would be the saw- and/or pulse-gate is always open. Try 
> replacing the FET6 or FET7 (2SK30) or TR6 or TR7 (2SA561). However, 
> you say the waveform can be heard even when the vcf-volume is 
> closed. Then I would say the sinewave is not a pure sinewave. Does 
> the waveshaper output a perfect sine ? You'll need a scope for that 
> on pin 2 of ic9. Or does vca3 (IG00151) distort the sine-wave ? Try 
> replacing vca3...
> Good luck.

Thank you. 
Will try to do so, just back from a few days of vacation.

Hi.

Finally I can continue my restoration. 
It was a IGO151 VCA that distort the waveforms!
Thanks erikfromhere.

Now I was the last problem on waveform Pulse,in the same Mboard five 
on Channel One.
In practice with the preset Funky 3, the envelope seems slow compared 
to other items or out of Phase.

It's a fault PWM section...

In the Panel mode with the Slider PM (the third slider of the section 
PWM) all up, the signal disappear!
And moving  the "speed" slider  the signal goes out of phase with the 
same effect that I noticed in the preset "funky 3"


Any suggestions?




--- In yamahacs80@yahoogroups.com, "erikfromhere" <moogsynthex@...> 
wrote:
>
> My guess would be the saw- and/or pulse-gate is always open. Try 
> replacing the FET6 or FET7 (2SK30) or TR6 or TR7 (2SA561). However, 
> you say the waveform can be heard even when the vcf-volume is 
> closed. Then I would say the sinewave is not a pure sinewave. Does 
> the waveshaper output a perfect sine ? You'll need a scope for that 
> on pin 2 of ic9. Or does vca3 (IG00151) distort the sine-wave ? Try 
> replacing vca3...
> Good luck.
> 
> --- In yamahacs80@yahoogroups.com, "oberheim64" <tommysalsero@> 
> wrote:
> >
> > Hi. 
> > My name is Tommaso, live in Italy and I had in the last 10 years 
> > three CS80! 
> > The second was in perfect condition and 
> > I sold to a dear friend in Italy. 
> > The third I found recently, I could not live without a CS!
> > I started with the restoration.
> > Now the beast was in perfect condition externally, perfectly 
tuned 

> > but with a  little problem on the five Mboard on Channel One.
> > With the Sine wave only (VCF volume closed)
> > In addition to sine,I Feel another waveform  similar to sawtooh.
> > And the waveform (Saw e Square) of the channel one are closed!
> > I Change all the IGO chips in the Board,but without any positive 
> > effect.
> > Then I changed the polarize electrolytic capacitors.
> > 
> > Same problem...
> > 
> > Now,they may be the 1 Uf 50V not polarized capacitors?
> > Or the other caps?
> > 
> > Sorry but I do not have an oscilloscope.
> > Some suggestions?
> >
>

Hi does this work ok--Im considering a purchase

thanks David

Well!
I solved the problem in the M board 5 with the bad PWM/PM: a bad 
IG00153 (VCO).
Now I was the last problem to be solved:
The overall volume of output, in my opinion is low. 
This happens even heard from headphone! 
When I bought my cs80 by the previous owner, I noticed that the PRA 
had
had a track repaired.
I changed all the capacitors and you hear a sound very clean.
But I have little volume of output compared to my previous cs80 (I 
had two)

There may be one of the two (or all) PH1 & 2 Led Photo cell?
Or it may be a problem in the VCA section of chorus/tremolo (OE2 
board) ?
Happy Christmas!



--- In yamahacs80@yahoogroups.com, "oberheim64" <tommysalsero@...> 
wrote:
>
> Hi.
> 
> Finally I can continue my restoration. 
> It was a IGO151 VCA that distort the waveforms!
> Thanks erikfromhere.
> 
> Now I was the last problem on waveform Pulse,in the same Mboard 
five 
> on Channel One.
> In practice with the preset Funky 3, the envelope seems slow 
compared 
> to other items or out of Phase.
> 
> It's a fault PWM section...
> 
> In the Panel mode with the Slider PM (the third slider of the 
section 
> PWM) all up, the signal disappear!
> And moving  the "speed" slider  the signal goes out of phase with 
the 

> same effect that I noticed in the preset "funky 3"
> 
> 
> Any suggestions?
>