Discussion about the Korg PolySix synthesizer

My Polysix has developed a fault with its bottom 9 keys (G downwards) -
first they started intermittantly failing to trigger when pressed,
then they started doing odd things like being silent when held down together...... and now they're all just dead.

I dismanted the keyboard assembly and cleaned the conductive studs and contacts on the circuit board - didn't help. I doubt very much they're the problem, as swapping different rubber stud-holders around doesn't change things.
I'm wondering if the multiway cable between the keyboard and voice board could be the culprit? Maybe just one of those yellow wires is dud?
I can't even get it out to swap it, the keyboard end is stuck in its socket.

Any suggestions?

(Oh, and it all plays perfectly if trigger exterenally via MIDI - I have Johannes Hausensteiner's retrofit)

David

Hi,

Speculations ahead. Skip to next part if not interested :)
There are 16 wires going to the keyboard.
I can't from the schematics tell if the keyboard is scanned as 8x8 or 7x9.
8x8 would probably be more "natural" as it allows the P-pins to set "row" and the DB-pins to read column, so to speak.
It requires 8 partial scans, scanning 8 keys at a time. Maximum number of keys 64.
On the other hand, 7x9 might be faster since it only requires 7 scans, scanning 9 keys at a time while still allowing a maximum of 63 keys.
Since we only have 61 keys, and you say 9 keys are dead, I would guess it scans as 7x9.

Next part:
I suspect one wire to the keyboard is open circuit somewhere, or perhaps one of the diodes on the keyboard board?
I don't remember how the diodes are connected on the keyboard and I'm too tired to figure it out :)
Do continuity testing from the solder side of the keyboard connector to where the cable is soldered onto the keyboard board.
But first, wiggle the keyboard connector a bit and then press it down firmly and see if that helps.
It's probably attached with some glue but .. well.. heh..
There are no components between the keyboard and the keyboard scanner controller, though there are other things on those lines as well that might interfere if fried, though I still suspect it's just a mechanical problem with the connector or some solder joint.

BR,
Peter

----- Original Message -----
From: feline1973
To: PolySix@yahoogroups.com
Sent: Saturday, July 28, 2012 11:33 PM
Subject: [PolySix] dead keys :(



My Polysix has developed a fault with its bottom 9 keys (G downwards) -
first they started intermittantly failing to trigger when pressed,
then they started doing odd things like being silent when held down together...... and now they're all just dead.

I dismanted the keyboard assembly and cleaned the conductive studs and contacts on the circuit board - didn't help. I doubt very much they're the problem, as swapping different rubber stud-holders around doesn't change things.
I'm wondering if the multiway cable between the keyboard and voice board could be the culprit? Maybe just one of those yellow wires is dud?
I can't even get it out to swap it, the keyboard end is stuck in its socket.

Any suggestions?

(Oh, and it all plays perfectly if trigger exterenally via MIDI - I have Johannes Hausensteiner's retrofit)

David





[Non-text portions of this message have been removed]

Hi,

The Polysix scans 8x8. So 9 keys failing would be rather odd.
But from G1 downwards it's only 8 keys... So we're back in the game.
The low eight keys are read through D0 (see attachment).
Check for continuity from the Kyboard PCB to MIDI Module/IC5/pin4.

Good luck,

Johannes

On 29.07.12 00:27, Peter Mörck wrote:
> Hi,
>
> Speculations ahead. Skip to next part if not interested :)
> There are 16 wires going to the keyboard.
> I can't from the schematics tell if the keyboard is scanned as 8x8 or 7x9.
> 8x8 would probably be more "natural" as it allows the P-pins to set "row" and the DB-pins to read column, so to speak.
> It requires 8 partial scans, scanning 8 keys at a time. Maximum number of keys 64.
> On the other hand, 7x9 might be faster since it only requires 7 scans, scanning 9 keys at a time while still allowing a maximum of 63 keys.
> Since we only have 61 keys, and you say 9 keys are dead, I would guess it scans as 7x9.
>
> Next part:
> I suspect one wire to the keyboard is open circuit somewhere, or perhaps one of the diodes on the keyboard board?
> I don't remember how the diodes are connected on the keyboard and I'm too tired to figure it out :)
> Do continuity testing from the solder side of the keyboard connector to where the cable is soldered onto the keyboard board.
> But first, wiggle the keyboard connector a bit and then press it down firmly and see if that helps.
> It's probably attached with some glue but .. well.. heh..
> There are no components between the keyboard and the keyboard scanner controller, though there are other things on those lines as well that might interfere if fried, though I still suspect it's just a mechanical problem with the connector or some solder joint.
>
> BR,
> Peter
>
>
>
> ----- Original Message -----
> From: feline1973
> To: PolySix@yahoogroups.com
> Sent: Saturday, July 28, 2012 11:33 PM
> Subject: [PolySix] dead keys :(
>
>
>
> My Polysix has developed a fault with its bottom 9 keys (G downwards) -
> first they started intermittantly failing to trigger when pressed,
> then they started doing odd things like being silent when held down together...... and now they're all just dead.
>
> I dismanted the keyboard assembly and cleaned the conductive studs and contacts on the circuit board - didn't help. I doubt very much they're the problem, as swapping different rubber stud-holders around doesn't change things.
> I'm wondering if the multiway cable between the keyboard and voice board could be the culprit? Maybe just one of those yellow wires is dud?
> I can't even get it out to swap it, the keyboard end is stuck in its socket.
>
> Any suggestions?
>
> (Oh, and it all plays perfectly if trigger exterenally via MIDI - I have Johannes Hausensteiner's retrofit)
>
> David
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>


[Non-text portions of this message have been removed]

Hi,

I discovered that the attachment did not go through with the email. So
I uploaded the wiring diagram to the files section of the list.
http://launch.groups.yahoo.com/group/PolySix/files/PS6_KEY.PDF

Johannes

On 30.07.12 20:56, Johannes Hausensteiner wrote:
> Hi,
>
> The Polysix scans 8x8. So 9 keys failing would be rather odd.
> But from G1 downwards it's only 8 keys... So we're back in the game.
> The low eight keys are read through D0 (see attachment).
> Check for continuity from the Kyboard PCB to MIDI Module/IC5/pin4.
>
> Good luck,
>
> Johannes
>
>
> On 29.07.12 00:27, Peter Mörck wrote:
>> Hi,
>>
>> Speculations ahead. Skip to next part if not interested :)
>> There are 16 wires going to the keyboard.
>> I can't from the schematics tell if the keyboard is scanned as 8x8 or 7x9.
>> 8x8 would probably be more "natural" as it allows the P-pins to set "row" and the DB-pins to read column, so to speak.
>> It requires 8 partial scans, scanning 8 keys at a time. Maximum number of keys 64.
>> On the other hand, 7x9 might be faster since it only requires 7 scans, scanning 9 keys at a time while still allowing a maximum of 63 keys.
>> Since we only have 61 keys, and you say 9 keys are dead, I would guess it scans as 7x9.
>>
>> Next part:
>> I suspect one wire to the keyboard is open circuit somewhere, or perhaps one of the diodes on the keyboard board?
>> I don't remember how the diodes are connected on the keyboard and I'm too tired to figure it out :)
>> Do continuity testing from the solder side of the keyboard connector to where the cable is soldered onto the keyboard board.
>> But first, wiggle the keyboard connector a bit and then press it down firmly and see if that helps.
>> It's probably attached with some glue but .. well.. heh..
>> There are no components between the keyboard and the keyboard scanner controller, though there are other things on those lines as well that might interfere if fried, though I still suspect it's just a mechanical problem with the connector or some solder joint.
>>
>> BR,
>> Peter
>>
>>
>>
>> ----- Original Message -----
>> From: feline1973
>> To: PolySix@yahoogroups.com
>> Sent: Saturday, July 28, 2012 11:33 PM
>> Subject: [PolySix] dead keys :(
>>
>>
>>
>> My Polysix has developed a fault with its bottom 9 keys (G downwards) -
>> first they started intermittantly failing to trigger when pressed,
>> then they started doing odd things like being silent when held down together...... and now they're all just dead.
>>
>> I dismanted the keyboard assembly and cleaned the conductive studs and contacts on the circuit board - didn't help. I doubt very much they're the problem, as swapping different rubber stud-holders around doesn't change things.
>> I'm wondering if the multiway cable between the keyboard and voice board could be the culprit? Maybe just one of those yellow wires is dud?
>> I can't even get it out to swap it, the keyboard end is stuck in its socket.
>>
>> Any suggestions?
>>
>> (Oh, and it all plays perfectly if trigger exterenally via MIDI - I have Johannes Hausensteiner's retrofit)
>>
>> David
>>
>>
>>
>>
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>> ------------------------------------
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>

Doh - yes, sorry, I can't count ;) 8 dead keys.
Thanks for the schematic (curiously, there didn't seem to be one in Korg's original service manual!)
I will try to check the continuity of the D0 line in the multiway cable ... if it's broken then maybe I can fairly easily solder a replacement in. (Sadly the cabled seems glued to its socket, so I can't just swap it!)

--- In PolySix@yahoogroups.com, Johannes Hausensteiner <johau@...> wrote:
>
> Hi,
>
> I discovered that the attachment did not go through with the email. So
> I uploaded the wiring diagram to the files section of the list.
> http://launch.groups.yahoo.com/group/PolySix/files/PS6_KEY.PDF
>
> Johannes
>
>
> On 30.07.12 20:56, Johannes Hausensteiner wrote:
> > Hi,
> >
> > The Polysix scans 8x8. So 9 keys failing would be rather odd.
> > But from G1 downwards it's only 8 keys... So we're back in the game.
> > The low eight keys are read through D0 (see attachment).
> > Check for continuity from the Kyboard PCB to MIDI Module/IC5/pin4.
> >
> > Good luck,
> >
> > Johannes
> >
> >
> > On 29.07.12 00:27, Peter Mörck wrote:
> >> Hi,
> >>
> >> Speculations ahead. Skip to next part if not interested :)
> >> There are 16 wires going to the keyboard.
> >> I can't from the schematics tell if the keyboard is scanned as 8x8 or 7x9.
> >> 8x8 would probably be more "natural" as it allows the P-pins to set "row" and the DB-pins to read column, so to speak.
> >> It requires 8 partial scans, scanning 8 keys at a time. Maximum number of keys 64.
> >> On the other hand, 7x9 might be faster since it only requires 7 scans, scanning 9 keys at a time while still allowing a maximum of 63 keys.
> >> Since we only have 61 keys, and you say 9 keys are dead, I would guess it scans as 7x9.
> >>
> >> Next part:
> >> I suspect one wire to the keyboard is open circuit somewhere, or perhaps one of the diodes on the keyboard board?
> >> I don't remember how the diodes are connected on the keyboard and I'm too tired to figure it out :)
> >> Do continuity testing from the solder side of the keyboard connector to where the cable is soldered onto the keyboard board.
> >> But first, wiggle the keyboard connector a bit and then press it down firmly and see if that helps.
> >> It's probably attached with some glue but .. well.. heh..
> >> There are no components between the keyboard and the keyboard scanner controller, though there are other things on those lines as well that might interfere if fried, though I still suspect it's just a mechanical problem with the connector or some solder joint.
> >>
> >> BR,
> >> Peter
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: feline1973
> >> To: PolySix@yahoogroups.com
> >> Sent: Saturday, July 28, 2012 11:33 PM
> >> Subject: [PolySix] dead keys :(
> >>
> >>
> >>
> >> My Polysix has developed a fault with its bottom 9 keys (G downwards) -
> >> first they started intermittantly failing to trigger when pressed,
> >> then they started doing odd things like being silent when held down together...... and now they're all just dead.
> >>
> >> I dismanted the keyboard assembly and cleaned the conductive studs and contacts on the circuit board - didn't help. I doubt very much they're the problem, as swapping different rubber stud-holders around doesn't change things.
> >> I'm wondering if the multiway cable between the keyboard and voice board could be the culprit? Maybe just one of those yellow wires is dud?
> >> I can't even get it out to swap it, the keyboard end is stuck in its socket.
> >>
> >> Any suggestions?
> >>
> >> (Oh, and it all plays perfectly if trigger exterenally via MIDI - I have Johannes Hausensteiner's retrofit)
> >>
> >> David
> >>
> >>
> >>
> >>
> >>
> >> [Non-text portions of this message have been removed]
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>