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Thread

Mono/Poly Poly mode issue

2019-04-04 by mauro.tondini@yahoo.com

Hi everyone,

Three month ago i bought a Mono/Poly apparently perfect, but soon i discover a strange issue.

In Mono Arp and Unison works fine, in Poly mode, when i play a legato melody it randomly hold on some notes, even if i release them.

A tipical situation when it happens is:

Poly mode on

Filter cutoff full open

Vca envelope sustain maximum, release minimum

Auto Damp on

Trigger Multi

The strangeness is that the holded oscillator LED switches off correctly

Has anyone had this issue?

Thank you

Re: [korg_mono-poly] Mono/Poly Poly mode issue

2019-04-04 by Florian Anwander

Am 04.04.2019 um 10:54 schrieb mauro.tondini@yahoo.com [korg_mono-poly]:

> A tipical situation when it happens is:
> Poly mode on
> Filter cutoff full open
> Vca envelope sustain maximum, release minimum
> Auto Damp on
> Trigger Multi
> The strangeness is that the holded oscillator LED switches off correctly
> Has anyone had this issue?

The LED and the FET-Switch for the oscillator are fed by the same
signal. So the only suspicion can be the FET itself only. This would
require, that it is always the same voice, which shows this behaviour.

If not, then it could be, that the Auto-Damp-Switch does not work
reliably. You may try to clean the switch as a first attempt.

Florian

--

http://www.florian-anwander.de

Re: Mono/Poly Poly mode issue

2019-04-04 by mauro.tondini@yahoo.com

Thanks for your fast response,

I seen the circuit diagram, and agree with you, the led and the FET shares the same signal, but it's not always the same voice, I also suspected that the problem is in the auto damp circuit.

Now my mono/poly is in a korg service center, but they can't find the issue ( i suspect they don't fixed any of this before)...

Re: [korg_mono-poly] Re: Mono/Poly Poly mode issue

2019-04-04 by Florian Anwander

Hi Mauro

Am 04.04.2019 um 13:07 schrieb mauro.tondini@yahoo.com [korg_mono-poly]:

> I also suspected that the problem is in the auto damp circuit.

I checked the autodamp electronics and I don't find anything which could
act in that "sometimes it fails" kind. My main suspicion is the switch.

> but they can't find the issue ( i suspect they don't fixed any of this
> before)...

:-)
I am quite sure, that the whole service center stands around it. It is
like coming with a 1936 Topolino to a todays FIAT contractor... ;-)

Florian

Re: [korg_mono-poly] Re: Mono/Poly Poly mode issue

2019-04-16 by mauro.tondini@yahoo.com

Hi Florian,

Today I picked up my Mono Poly from the service center, they couldn't find the fault.

The first test i did was to check the Auto Damp switch operation, which seems to work properly.

Testing it deeply i noticed that holding down a key, and playing the rest of the voices, it works properly, no matter which voice is helded down, therefore it seems to exclude a bad functioning of the auto damp switch.

It's a strange defect, when it happens, the voices remains engaged but the corresponding leds switch off correctly..