Discussion about the Korg PolySix synthesizer

I own a vintage (70s) Korg MS-10. This little bastard works great
excapt for casual pitch drifts. Sometimes it doesn't play the exact
pitch when hitting a key, than hitting it once more will make the
accurate pitch sound. This will also happen when using some "gilde",
than when gliding to a note sometimes it won't target to the exact
pitch...

Should I change all electrolytics ? how about ICs ? Which section
shuold I look at ? VCA ? VCO ?

Thanks

Hi,

don´t know the MS-10 but maybe it´s the failure of a dry capacitor which
is connected between ground and +vcc. Afaik has the MS10 a CV out
connector at the front panel which must be (in my opinion) directly
connected to the resistor ladder of the Keyboard circuit. Did you
measure this connector already while pressing one key twice (in order to
find out if the CV actually changes)?

Or you should take a look into the Service manual (including circuit
diagram)

http://www.phasereffect.com/pub/ms10.pdf (880 kb)



Stef

Pure speculations.

Stef

gil_we wrote:

>I own a vintage (70s) Korg MS-10. This little bastard works great
>excapt for casual pitch drifts. Sometimes it doesn't play the exact
>pitch when hitting a key, than hitting it once more will make the
>accurate pitch sound. This will also happen when using some "gilde",
>than when gliding to a note sometimes it won't target to the exact
>pitch...
>
>Should I change all electrolytics ? how about ICs ? Which section
>shuold I look at ? VCA ? VCO ?
>
>Thanks
>
>
>
>
>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

Ah, at the bottem of the Service manual is the Adjustment procedure.
Didn´t saw that.

Stef

Stefan Rinass wrote:

>Hi,
>
>don´t know the MS-10 but maybe it´s the failure of a dry capacitor which
>is connected between ground and +vcc. Afaik has the MS10 a CV out
>connector at the front panel which must be (in my opinion) directly
>connected to the resistor ladder of the Keyboard circuit. Did you
>measure this connector already while pressing one key twice (in order to
>find out if the CV actually changes)?
>
>Or you should take a look into the Service manual (including circuit
>diagram)
>
>http://www.phasereffect.com/pub/ms10.pdf (880 kb)
>
>
>
>Stef
>
>Pure speculations.
>
>Stef
>
>gil_we wrote:
>
>
>
>>I own a vintage (70s) Korg MS-10. This little bastard works great
>>excapt for casual pitch drifts. Sometimes it doesn't play the exact
>>pitch when hitting a key, than hitting it once more will make the
>>accurate pitch sound. This will also happen when using some "gilde",
>>than when gliding to a note sometimes it won't target to the exact
>>pitch...
>>
>>Should I change all electrolytics ? how about ICs ? Which section
>>shuold I look at ? VCA ? VCO ?
>>
>>Thanks
>>
>>
>>
>>
>>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

Based on the MS-10 service manual pdf, I would suspect the sample/hold
section around parts F2/C4/IC3. I would try replacing C4 first, then IC3,
and lastly FET2.

Crow
/**/

Thank !

I'll try that.

--- In PolySix@yahoogroups.com, The Old Crow <oldcrow@o...> wrote:
>
> Based on the MS-10 service manual pdf, I would suspect the
sample/hold
> section around parts F2/C4/IC3. I would try replacing C4 first,
then IC3,
> and lastly FET2.
>
> Crow
> /**/