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Discussion about the Korg PolySix synthesizer

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Heat and Modulation problems?

Heat and Modulation problems?

2013-09-18 by <agk_achilles2004@yahoo.com>

Hi guys

I just got on my hands a Polysix but it seems to produce a lot of heat on the back side where the KORG logo is located.
Also the LFO (MG) seems to produce a low level noise that shows on my Mixer.
If i turn the MG level up my mixer goes all the way to red and i hear a low hum. i can change the hum speed using MG frequency.
Any ideas? is that normal on a Polysix? Easily fixable? I really like the synth and would like to buy it.
Greetings!

p.s. sorry about my English

RE: Heat and Modulation problems?

2013-09-19 by <agk_achilles2004@yahoo.com>

OK, so now i notice that the LFO problem occurs when i route the LFO to the VCA.

It seems like the LFO freq is the one that passes as audio. My mixer goes all the way to red if i increase the LFO level and you can hear a big hissing sound that comes and goes. Is that normal? One of the patches that came with the unit produces that as it is... patch B5.

Any help would be appreciated.



--- In PolySix@yahoogroups.com, <polysix@yahoogroups.com> wrote:

Hi guys
I just got on my hands a Polysix but it seems to produce a lot of heat on the back side where the KORG logo is located.
Also the LFO (MG) seems to produce a low level noise that shows on my Mixer.
If i turn the MG level up my mixer goes all the way to red and i hear a low hum. i can change the hum speed using MG frequency.
Any ideas? is that normal on a Polysix? Easily fixable? I really like the synth and would like to buy it.
Greetings!

p.s. sorry about my English

[PolySix] RE: Heat and Modulation problems?

2013-09-19 by Malte Rogacki

First things first:

The heat "problem" usually is not a real problem. The back of the Polysix
doubles as a heat sink for the power supply.

Now, the LFO problem.
The Polysix is insofar a bit different than most synths as the "VCA"
modulation is not really generated in the "real" VCA section of the voice
board. It's generated on the effects board instead. This means that the LFO
signal is passing from KLM367 to the effects board together with the
effects mode and effects intensity signals via CN03 (the orange 7 pin cable
on the left side of KLM367). This connector is dangerously close to the
battery and I've witnessed corrosion in this area frequently. So I wouldn't
rule out the possibility that something there is going wrong.
You may want to check if the symptoms depend also on the effects type.

Last but not least: The problem could also come from the effects board. I
have seen several effects boards which had also battery damage on the edge
next to KLM367.

Re: [PolySix] RE: Heat and Modulation problems?

2013-09-19 by Johannes Hausensteiner

It is hard to tell if the noise you experience is average for a Polysix.
There is quite some audible noise. And it is natural that when the MG
is set to VCA the noise pulsates with the MG.
The MG frequency can be max. about 50Hz, which is already an audible
frequency; this may lead to some strange (sound) effects. I assume that
when the mixer "goes red" that it is still at normal level? If you crank
up the Gain on the mixer without playing any note it should be no
problem to bring up some of the level LEDs. But you could not bear the
high volume when playing the keyboard then.

For the heat issue: again it is difficult to tell whether this is a
malfunction. The back of the Polysix, at the Korg logo, becomes quite
warm. Certainly not so hot that you cannot touch. Since you did not tell
us about burnt fingers or the like I'd assume that it is in the normal
range.

I hope this helps!

Johannes



On 19.09.13 17:54, agk_achilles2004@yahoo.com wrote:
>
>
> OK, so now i notice that the LFO problem occurs when i route the LFO to
> the VCA.
>
> It seems like the LFO freq is the one that passes as audio. My mixer
> goes all the way to red if i increase the LFO level and you can hear a
> big hissing sound that comes and goes. Is that normal? One of the
> patches that came with the unit produces that as it is... patch B5.
>
> Any help would be appreciated.
>
>
>
> --- In PolySix@yahoogroups.com, <polysix@yahoogroups.com> wrote:
>
> Hi guys
> I just got on my hands a Polysix but it seems to produce a lot of heat
> on the back side where the KORG logo is located.
> Also the LFO (MG) seems to produce a low level noise that shows on my
> Mixer.
> If i turn the MG level up my mixer goes all the way to red and i hear a
> low hum. i can change the hum speed using MG frequency.
> Any ideas? is that normal on a Polysix? Easily fixable? I really like
> the synth and would like to buy it.
> Greetings!
>
> p.s. sorry about my English
>
>
>

RE: Heat and Modulation problems?

2013-09-20 by <chipaudette@yahoo.com>

Regarding temperature of your Polysix, if you have the capability to measure temperature, you can compare the measured temperature of your Polysix to mine.


To see where I measured and how hot it got, you can look at this post:


http://synthhacker.blogspot.com/2013/07/polysix-temperature-without-mods.html


The bottom line is that, on the power supply PCB inside the synth, along the metal bar at the top (ie, what should be the hottest part of the whole synth), my Polysix eventually reached between 58-63C. It took about 30 minutes to finally reach that temperature before stabilizing.


Good luck!


Chip






--- In polysix@yahoogroups.com, <johau@...> wrote:

It is hard to tell if the noise you experience is average for a Polysix.
There is quite some audible noise. And it is natural that when the MG
is set to VCA the noise pulsates with the MG.
The MG frequency can be max. about 50Hz, which is already an audible
frequency; this may lead to some strange (sound) effects. I assume that
when the mixer "goes red" that it is still at normal level? If you crank
up the Gain on the mixer without playing any note it should be no
problem to bring up some of the level LEDs. But you could not bear the
high volume when playing the keyboard then.

For the heat issue: again it is difficult to tell whether this is a
malfunction. The back of the Polysix, at the Korg logo, becomes quite
warm. Certainly not so hot that you cannot touch. Since you did not tell
us about burnt fingers or the like I'd assume that it is in the normal
range.

I hope this helps!

Johannes



On 19.09.13 17:54, agk_achilles2004@... wrote:
>
>
> OK, so now i notice that the LFO problem occurs when i route the LFO to
> the VCA.
>
> It seems like the LFO freq is the one that passes as audio. My mixer
> goes all the way to red if i increase the LFO level and you can hear a
> big hissing sound that comes and goes. Is that normal? One of the
> patches that came with the unit produces that as it is... patch B5.
>
> Any help would be appreciated.
>
>
>
> --- In PolySix@yahoogroups.com, <polysix@yahoogroups.com> wrote:
>
> Hi guys
> I just got on my hands a Polysix but it seems to produce a lot of heat
> on the back side where the KORG logo is located.
> Also the LFO (MG) seems to produce a low level noise that shows on my
> Mixer.
> If i turn the MG level up my mixer goes all the way to red and i hear a
> low hum. i can change the hum speed using MG frequency.
> Any ideas? is that normal on a Polysix? Easily fixable? I really like
> the synth and would like to buy it.
> Greetings!
>
> p.s. sorry about my English
>
>
>

Re: [PolySix] RE: Heat and Modulation problems?

2013-09-21 by agk agk

Already saw your site Chip, it was very helpful.
Yes my temp seems to be normal , i guess... compared to yours, the problem is that LFO to VCA noise. The level of the noise is higher than the level of sound the notes i play produce.

Johannes, it was my bad English my friend... i meant to say that even when i don't play any note, the lvl LEDs on my Mixer are going all the way up to red just by the pulsating VCA noise. That's why i thought it was a problem , i get that it should make some kind of hum but my speakers went nuts!

Also, i opened the unit last night and saw the power supply, back there... The prob was that the guy that sold me told me that it never heated back there and that there is nothing back there since the power supply is on the side ( i guess he meant the Transformer).
Anyway thanks to your sites i was able to relax about that....
On the other hand he told me that they didn't have any battery leakage, that they changed the battery and just moved it away from the board.
As you might expect, i saw corrosion from the previous battery and they even had some cables running some destroyed lines. also i think they've changed an IC (IC31) i think since the lines went below it.

I didn't saw any sign of corrosion on the Effects board and everything works well when i route the LFO to VCF or VCO.

So... any ideas? Should i keep it and maybe purchase a new KLM-367 PCB , will that fix it?

I really loved the sound of it !!!

Thanks for the Help guys , you are great!



From: "chipaudette@yahoo.com" <chipaudette@yahoo.com>
To: PolySix@yahoogroups.com
Sent: Friday, September 20, 2013 1:41 PM
Subject: [PolySix] RE: Heat and Modulation problems?

Regarding temperature of your Polysix, if you have the capability to measure temperature, you can compare the measured temperature of your Polysix to mine.

To see where I measured and how hot it got, you can look at this post:

http://synthhacker.blogspot.com/2013/07/polysix-temperature-without-mods.html

The bottom line is that, on the power supply PCB inside the synth, along the metal bar at the top (ie, what should be the hottest part of the whole synth), my Polysix eventually reached between 58-63C. It took about 30 minutes to finally reach that temperature before stabilizing.

Good luck!

Chip





--- In polysix@yahoogroups.com, <johau@...> wrote:

It is hard to tell if the noise you experience is average for a Polysix.
There is quite some audible noise. And it is natural that when the MG
is set to VCA the noise pulsates with the MG.
The MG frequency can be max. about 50Hz, which is already an audible
frequency; this may lead to some strange (sound) effects. I assume that
when the mixer "goes red" that it is still at normal level? If you crank
up the Gain on the mixer without playing any note it should be no
problem to bring up some of the level LEDs. But you could not bear the
high volume when playing the keyboard then.

For the heat issue: again it is difficult to tell whether this is a
malfunction. The back of the Polysix, at the Korg logo, becomes quite
warm. Certainly not so hot that you cannot touch. Since you did not tell
us about burnt fingers or the like I'd assume that it is in the normal
range.

I hope this helps!

Johannes



On 19.09.13 17:54, agk_achilles2004@... wrote:
>
>
> OK, so now i notice that the LFO problem occurs when i route the LFO to
> the VCA.
>
> It seems like the LFO freq is the one that passes as audio. My mixer
> goes all the way to red if i increase the LFO level and you can hear a
> big hissing sound that comes and goes. Is that normal? One of the
> patches that came with the unit produces that as it is... patch B5.
>
> Any help would be appreciated.
>
>
>
> --- In PolySix@yahoogroups.com, <polysix@yahoogroups.com> wrote:
>
> Hi guys
> I just got on my hands a Polysix but it seems to produce a lot of heat
> on the back side where the KORG logo is located.
> Also the LFO (MG) seems to produce a low level noise that shows on my
> Mixer.
> If i turn the MG level up my mixer goes all the way to red and i hear a
> low hum. i can change the hum speed using MG frequency.
> Any ideas? is that normal on a Polysix? Easily fixable? I really like
> the synth and would like to buy it.
> Greetings!
>
> p.s. sorry about my English
>
>
>