Discussion about the Korg PolySix synthesizer

On 03/11/2010 15:37, "Paulo" <inocencio66@yahoo.com> wrote:

>
>
>
>
>
> Hi,
>
> I´ve got the exact same problem with an old 367a.
>
> Can someone help, please?
>
>
>
>
>



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

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Hi,
>
> Sorry, I must be missing a post here, this isn¹t making any sense. Can you
> describe the exactly problem with the 367? I may well be able to help you
> with this...
>
> Cheers,
> Andy
>
>
> On 03/11/2010 15:37, "Paulo" <inocencio66@...> wrote:
>
> >
> >
> >
> >
> >
> > Hi,
> >
> > I´ve got the exact same problem with an old 367a.
> >
> > Can someone help, please?
> >
> >
> >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>

On 03/11/2010 19:13, "Paulo" <inocencio66@yahoo.com> wrote:

>
>
>
>
>
> Yeah sorry I realize pctech333 is dealing with an old 367a as well.
>
> Well this Polysix I´m trying to restore had the battery leakage problem, which
> I repaired following Old Crow´s instructions. I rewired the traces, installed
> a new nimh battery and new ICs 30 and 31. The programmer now seems to work,
> but when I try to reset the dac only leds 4 and 8 light up.
>
> This synth had also the other problem from the beginning: none of the pots
> work, just the switches. For instance, I can select any effects mode, but the
> speed/intensity doesn´t make any changes. Likewise, vco octave works but pwm
> doesn´t, and so on.
> The exception is MG not working in any way, with the led constantly lit.
>
> I already changed the 4560 chip, which I think is the dac buffer, for a tl072.
> And ic20 and 21 with LM13700. I don´t have a scope yet, so that´s probably the
> last ic swap for now. Well, maybe IC6...
>
> There must be some component that´s "traditionally" known for this
> malfunction. I don´t think it´s the memory nor the CPU. Maybe it´s the DAC?
>
> Cheers,
>
> Paulo
>
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > Hi,
>> >
>> > Sorry, I must be missing a post here, this isn¹t making any sense. Can you
>> > describe the exactly problem with the 367? I may well be able to help you
>> > with this...
>> >
>> > Cheers,
>> > Andy
>> >
>> >
>> > On 03/11/2010 15:37, "Paulo" <inocencio66@...> wrote:
>> >
>>> > >
>>> > >
>>> > >
>>> > >
>>> > >
>>> > > Hi,
>>> > >
>>> > > I´ve got the exact same problem with an old 367a.
>>> > >
>>> > > Can someone help, please?
>>> > >
>>> > >
>>> > >
>>> > >
>>> > >
>> >
>> >
>> >
>> > [Non-text portions of this message have been removed]
>> >
>
>
>
>
>



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

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Hi Paulo,
>
> Yes, afraid to say this is what I used to do when I first started repairing
> Polysix. Changing just about every IC in the hope that it would fix the
> problem. After the first six or seven you start to realize that these types
> of whacky fault are almost exclusively down to o/c tracks. Get yourself a
> logic probe and check all the points where the data bus (D00-D07) terminates
> and make sure you have pulse trains on these lines. Bet you one or more of
> them do not terminate.
>
> You asked if any components are Œtraditionally¹ associated with this type of
> problem? Yes, o/c tracks. If this board is causing you real issues and is
> severely damaged then I would recommend you seek out the parts and build
> yourself a clone. You won¹t regret it.
>
> Cheers,
> Andy
>
>
> On 03/11/2010 19:13, "Paulo" <inocencio66@...> wrote:
>
> >
> >
> >
> >
> >
> > Yeah sorry I realize pctech333 is dealing with an old 367a as well.
> >
> > Well this Polysix I´m trying to restore had the battery leakage problem, which
> > I repaired following Old Crow´s instructions. I rewired the traces, installed
> > a new nimh battery and new ICs 30 and 31. The programmer now seems to work,
> > but when I try to reset the dac only leds 4 and 8 light up.
> >
> > This synth had also the other problem from the beginning: none of the pots
> > work, just the switches. For instance, I can select any effects mode, but the
> > speed/intensity doesn´t make any changes. Likewise, vco octave works but pwm
> > doesn´t, and so on.
> > The exception is MG not working in any way, with the led constantly lit.
> >
> > I already changed the 4560 chip, which I think is the dac buffer, for a tl072.
> > And ic20 and 21 with LM13700. I don´t have a scope yet, so that´s probably the
> > last ic swap for now. Well, maybe IC6...
> >
> > There must be some component that´s "traditionally" known for this
> > malfunction. I don´t think it´s the memory nor the CPU. Maybe it´s the DAC?
> >
> > Cheers,
> >
> > Paulo
> >
> > --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> > Jury <andy@> wrote:
> >> >
> >> > Hi,
> >> >
> >> > Sorry, I must be missing a post here, this isn¹t making any sense. Can you
> >> > describe the exactly problem with the 367? I may well be able to help you
> >> > with this...
> >> >
> >> > Cheers,
> >> > Andy
> >> >
> >> >
> >> > On 03/11/2010 15:37, "Paulo" <inocencio66@> wrote:
> >> >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > > Hi,
> >>> > >
> >>> > > I´ve got the exact same problem with an old 367a.
> >>> > >
> >>> > > Can someone help, please?
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >>> > >
> >> >
> >> >
> >> >
> >> > [Non-text portions of this message have been removed]
> >> >
> >
> >
> >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>

On 03/11/2010 22:58, "Paulo" <inocencio66@yahoo.com> wrote:

>
>
>
>
>
> Andy,
>
> Many thanks for the wise words, I´ll check the data bus asap.
>



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

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Let us know how you get on!
>
> Cheers,
> Andy

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

On 04/11/2010 20:20, "Paulo" <inocencio66@yahoo.com> wrote:
>
> Sure! Should have bought a logic probe a long time ago. This thing is so handy
> for debugging. Already found IC33 not sending any pulse trains out of pin 4.
> And no DO3 arriving at pin 9! Must have slipped that one. A continuity test
> confirmed it. Time for more soldering :) I´ll post the results later.
>
> Cheers!
> Paulo
>
> --- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> , Andrew
> Jury <andy@...> wrote:
>> >
>> > Let us know how you get on!
>> >
>> > Cheers,
>> > Andy
>



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

On 04/11/2010 22:05, "Paulo" <inocencio66@yahoo.com> wrote:

>
>
>
>
>
> Hi Andy,
>
> Guess you´re right. Damn, no luck. Still no data out of pin 4! When trying to
> adjust the D/A, in Test Mode, the Program LEDs that light up are 4 and 8, and
> VR6 and 7 don´t do a thing.
> In Normal Mode everything works as it should...
>
> Well, my reasoning is that both VR6 and 7 are connected to pin 4 of the DAC,
> and subsequently I´m not reading anything out of IC27, the buffer, that should
> go into ICs 18 and 19. These two should "translate" incoming data into
> continuous voltage control, but there´s nothing arriving at them.
> No response from tweaking the continuous controls such as Resonance and Effect
> Speed is the main problem of this synth.
>
> So what do you think? Maybe this DAC is the real culprit?
>
> Cheers,
> Paulo
>
>
>
>
>



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

>
>
> On 04/11/2010 22:05, "Paulo" <inocencio66@...> wrote:
>
> >
> >
> >
> >
> >
> > Hi Andy,
> >
> > Guess you´re right. Damn, no luck. Still no data out of pin 4! When trying to
> > adjust the D/A, in Test Mode, the Program LEDs that light up are 4 and 8, and
> > VR6 and 7 don´t do a thing.
> > In Normal Mode everything works as it should...
> >
> > Well, my reasoning is that both VR6 and 7 are connected to pin 4 of the DAC,
> > and subsequently I´m not reading anything out of IC27, the buffer, that should
> > go into ICs 18 and 19. These two should "translate" incoming data into
> > continuous voltage control, but there´s nothing arriving at them.
> > No response from tweaking the continuous controls such as Resonance and Effect
> > Speed is the main problem of this synth.
> >
> > So what do you think? Maybe this DAC is the real culprit?
> >
> > Cheers,
> > Paulo
> >
> >
> >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>

On 05/11/2010 19:42, "Paulo" <inocencio66@yahoo.com> wrote:
>
> So I just took the plunge and bought a clone off Jed.
> Until it arrives I´ll still try to fix the old board.
> Just hoping it won´t end up as described in message #2678 i.e. new board, same
> problem.
>
> Maybe the fault is elsewhere. CN10 carries signals related to almost
> everything that´s failing in this synth. Time to study what happens on the
> KLM-366B...
>
>
>



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

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Hi Paulo,
>
> I think considering the hell you are having with the old board you have made
> the right move! I have built what must be over 10 of these for various
> people and I have never once had problems setting up the d/a convertor. If
> you work slowly and methodically through the build you will more than likely
> have a working board by the time when you finish. However, don¹t forget
> there are two tiny track mods to do which are detailed on Jed¹s site.
>
> Cheers,
> Andy

On 08/11/2010 12:52, "Paulo" <inocencio66@yahoo.com> wrote:

>
>
>
>
>
> Hi Andy,
>
> Thanks. The clone will put an end to this nitemare. Not only the traces will
> obviously be intact, most of the components it will be populated with will be
> brand new!
>
> Cheers!
>
> Paulo
>



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

--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> I think you made the right choice. Now this option is open there is no point
> wasting time hunting down broken tracks. Use the time instead to order the
> new parts!
>
> Cheers,
> Andy