Discussion about the Korg PolySix synthesizer group photo

Yahoo Groups archive

Discussion about the Korg PolySix synthesizer

Archive for polysix.

Index last updated: 2026-03-30 01:17 UTC

Thread

Polysix frying mixer channels

Polysix frying mixer channels

2018-08-30 by Peter Foley

I have a Polysix that seemed to fry a few channels on an old mixer.  I know that this synth works (for the most part) - it boots up fine and produces sound, but when I plugged it into the mixer, it made a momentary god-awful noise as the tip of the TS came in contact with the ground on the synth and the channel died. The synth was plugged into the mains but powered OFF.

I took it downstairs since it needed to be tuned anyway and felt a tiny zap on my arm when the case was open (synth was plugged into the mains but again was turned OFF). I measured roughly 35VAC between the case and a nearby piece of grounded metal. Also measured the same between the case and myself. Unplugged from the mains, I measured nothing of course.

Again, this is all when the synth is powered OFF but plugged into the mains. 





Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Ben Stuyts

Carefull, sounds like a potential death trap.

My guess is:

1) The synth isn’t grounded properly. Some loose wire or corrosion probably.
and
2) Leakage from one of the mains lines into the ground. Could be in the transformer, but don’t forget to check the mains wiring/plug itself.

Checking everything with an Ohm meter would be my first priority. Ground pin on the mains plug to the chassis to begin with.

Ben


On 30 Aug 2018, at 17:00, Peter Foley petereugenefoley@gmail.com [PolySix] <PolySix@yahoogroups.com> wrote:



I have a Polysix that seemed to fry a few channels on an old mixer.  I know that this synth works (for the most part) - it boots up fine and produces sound, but when I plugged it into the mixer, it made a momentary god-awful noise as the tip of the TS came in contact with the ground on the synth and the channel died. The synth was plugged into the mains but powered OFF.

I took it downstairs since it needed to be tuned anyway and felt a tiny zap on my arm when the case was open (synth was plugged into the mains but again was turned OFF). I measured roughly 35VAC between the case and a nearby piece of grounded metal. Also measured the same between the case and myself. Unplugged from the mains, I measured nothing of course.

Again, this is all when the synth is powered OFF but plugged into the mains. 








Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Malte Rogacki

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?


And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.

Re: [PolySix] Polysix frying mixer channels

2018-08-31 by <backshall1@bellsouth.net>

The original power cord on the Polysix is only 2-wire. Has this been modified to use a 3-wire power cord or is everything original as far as you know? Maybe a photo of the transformer and spark killer area would be helpful.
Don B.
 
Sent: Friday, August 31, 2018 7:20 AM
Subject: Re: [PolySix] Polysix frying mixer channels
 
 

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?

And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.

Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Peter Foley

Putting a grounded power cable in the synth did the trick!

On Aug 31, 2018, at 07:20, Malte Rogacki gacki@gacki.sax.de [PolySix] <PolySix@yahoogroups.com> wrote:

 

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?

And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.

Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Malte Rogacki

The European models of the Polysix all had pre-installed 3-wire power cords.

The service manual also gives only schematics for two different 3-wire setups.


But in general: having voltage against ground on the chassis is a bad
thing, regardless if the problem goes away with a grounded plug. This
should be fixed at the root of the problem.

Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Ben Stuyts

Peter, this solves the grounding problem. But not the leakage which should not happen. (At least, not in that amount.) There is still a problem lurking inside there.

Ben


On 31 Aug 2018, at 14:52, Peter Foley petereugenefoley@gmail.com [PolySix] <PolySix@yahoogroups.com> wrote:



Putting a grounded power cable in the synth did the trick!

On Aug 31, 2018, at 07:20, Malte Rogacki gacki@gacki.sax.de [PolySix] <PolySix@yahoogroups.com> wrote:

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?

And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.




Re: [PolySix] Polysix frying mixer channels

2018-08-31 by Peter Foley

With the grounded cable, I’m not measuring any AC anymore. Would this mean it could be an issue in my mains? My house was built about a hundred years ago...

On Aug 31, 2018, at 11:52, Ben Stuyts yahoo@stuyts.nl [PolySix] <PolySix@yahoogroups.com> wrote:

 

Peter, this solves the grounding problem. But not the leakage which should not happen. (At least, not in that amount.) There is still a problem lurking inside there.


Ben


On 31 Aug 2018, at 14:52, Peter Foley petereugenefoley@gmail.com [PolySix] <PolySix@yahoogroups.com> wrote:



Putting a grounded power cable in the synth did the trick!

On Aug 31, 2018, at 07:20, Malte Rogacki gacki@gacki.sax.de [PolySix] <PolySix@yahoogroups.com> wrote:

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?

And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.




Re: [PolySix] Polysix frying mixer channels

2018-09-01 by simon

No. the source of the leakage is within your polysix, the ground wire
merely drains it away (to where ?)

On 31-08-18 19:13, Peter Foley petereugenefoley@gmail.com [PolySix] wrote:
> With the grounded cable, I’m not measuring any AC anymore. Would this
> mean it could be an issue in my mains? My house was built about a
> hundred years ago...
>
> On Aug 31, 2018, at 11:52, Ben Stuyts yahoo@stuyts.nl
> <mailto:yahoo@stuyts.nl> [PolySix] <PolySix@yahoogroups.com
> <mailto:PolySix@yahoogroups.com>> wrote:
>
>> Peter, this solves the grounding problem. But not the leakage which
>> should not happen. (At least, not in that amount.) There is still a
>> problem lurking inside there.
>>
>>
>> Ben
>>
>>
>>> On 31 Aug 2018, at 14:52, Peter Foley petereugenefoley@gmail.com
>>> <mailto:petereugenefoley@gmail.com> [PolySix]
>>> <PolySix@yahoogroups.com <mailto:PolySix@yahoogroups.com>> wrote:
>>>
>>>
>>>
>>> Putting a grounded power cable in the synth did the trick!
>>>
>>> On Aug 31, 2018, at 07:20, Malte Rogackigacki@gacki.sax.de
>>> <mailto:gacki@gacki.sax.de>[PolySix] <PolySix@yahoogroups.com
>>> <mailto:PolySix@yahoogroups.com>> wrote:
>>>
>>>> One possible suspect could be the spark killer.
>>>> If I remember correctly this was also a problem with some Akai devices?
>>>>
>>>> And yes, please be very careful.
>>>>
>>>> In theory, if the grounding isn't damaged (and the house grounding
>>>> is ok),
>>>> something like this should not be possible at all.
>>>>
>>>
>>>
>>
>

--
Met vriendelijke Groet,

Simon Claessen
drukknop.nl

Re: [PolySix] Polysix frying mixer channels

2018-09-03 by Ben Stuyts

This just means that the leakage is not big enough to trip your RCD. So maybe the leakage is low enough that it is not a lethal hazard. Rmember, these are old synths, and problems like this can only get worse. I would definitely check where the leakage is coming from.

Ben


On 31 Aug 2018, at 19:13, Peter Foley petereugenefoley@gmail.com [PolySix] <PolySix@yahoogroups.com> wrote:



With the grounded cable, I’m not measuring any AC anymore. Would this mean it could be an issue in my mains? My house was built about a hundred years ago...

On Aug 31, 2018, at 11:52, Ben Stuyts yahoo@stuyts.nl [PolySix] <PolySix@yahoogroups.com> wrote:

Peter, this solves the grounding problem. But not the leakage which should not happen. (At least, not in that amount.) There is still a problem lurking inside there.


Ben


On 31 Aug 2018, at 14:52, Peter Foley petereugenefoley@gmail.com [PolySix] <PolySix@yahoogroups.com> wrote:



Putting a grounded power cable in the synth did the trick!

On Aug 31, 2018, at 07:20, Malte Rogacki gacki@gacki.sax.de [PolySix] <PolySix@yahoogroups.com> wrote:

One possible suspect could be the spark killer.
If I remember correctly this was also a problem with some Akai devices?

And yes, please be very careful.

In theory, if the grounding isn't damaged (and the house grounding is ok),
something like this should not be possible at all.