Korg Poly800/EX800 Users

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Do you have the correct wall wart power supply?
>
> if you do, then I would next check that the -5V power rail is correct.
>
> And we can go from there after that.
>
> Mike
>
> ________________________________
> From: Remo Siemons <remosiemons@...>
> To: korgpolyex@yahoogroups.com
> Sent: Thursday, June 27, 2013 11:02 AM
> Subject: [korgpolyex] Korg Poly 800 DCO problem
>
>
> Hi eveyone, I'm new to the group.
>
> I hope there's someone here who can help me to fix my Korg Poly 800
> (model: PS800)
> I bought it at a second hand store for only 7,50 Euro, but it's not
> working as it should….
>
> I've successfully loaded new sounds to the Korg. but I still hear only
> noises and clicks.
>
> Pitch bend left and rights are not working
> Tune slider is not working
>
> DCO with the joystick in up position is not working
>
> VCF with the joystick in down position is working
>
> I've tried to make a sound myself, to see what parameters respond.
> DCO 1 & DCO 2 do not respond to any change …..
>
> noise & VCF are working
>
> Could it be that it are just 1 or 2 DCO chips that are broken on the
> mainbord ?
>
> I hope there is a solution for this problem.
>
>
> Thanks all!
>
> Remo
>
>
> ------------------------------------
>
> Feel free to upload into the files section any sysex dumps and tape dumps of patches that you may have but please discuss (with the entire group) the posting of other files *before* posting them. This helps us to keep redundant information from showing up everywhere and also allows us to constantly improve the format and structure of the documentation. We talk about the HAWK-800 quite a bit but we also discuss and help owners of the original Poly-800 models. So don't be shy if you haven't got the HAWK-800.Yahoo! Groups Links
>
>
>
>     http://docs.yahoo.com/info/terms/
>

--- In korgpolyex@yahoogroups.com, "remomatic" <remosiemons@...> wrote:
>
> I've tried 2 different power supplies, a 9V 300mA and a 9V 1000mA. I measured the output of the power supply and it's a steady 9V, so that should be ok I think.
>
> How do I check the -5V power rail ? can you maybe advice me where to measure ?
>
> I found a point at C11/C12 where I measure -2.39V that's a bit strange, because I guess that must be -5V
>
> I checked the following parameters :
>
> 1) parameter 17 - DCO 1 volume control - doesn't work…
> 2) parameter 27 - DCO 2 volume control - doesn't work…
> 3) parameter 33 - noise level - WORKS
> 4) parameter 41 - VCF cut off - WORKS
> 5) parameter 42 - resonance - WORKS
> 6) parameter 83 - DCO modulation - doesn't work…
> 7) parameter 84 - VCF modulation - WORKS
> 8) joystick bend - doesn't work…
>
>
> thanks,
> Remo
>
>
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > Do you have the correct wall wart power supply?
> >
> > if you do, then I would next check that the -5V power rail is correct.
> >
> > And we can go from there after that.
> >
> > Mike
> >
> > ________________________________
> > From: Remo Siemons <remosiemons@>
> > To: korgpolyex@yahoogroups.com
> > Sent: Thursday, June 27, 2013 11:02 AM
> > Subject: [korgpolyex] Korg Poly 800 DCO problem
> >
> >
> > Hi eveyone, I'm new to the group.
> >
> > I hope there's someone here who can help me to fix my Korg Poly 800
> > (model: PS800)
> > I bought it at a second hand store for only 7,50 Euro, but it's not
> > working as it should….
> >
> > I've successfully loaded new sounds to the Korg. but I still hear only
> > noises and clicks.
> >
> > Pitch bend left and rights are not working
> > Tune slider is not working
> >
> > DCO with the joystick in up position is not working
> >
> > VCF with the joystick in down position is working
> >
> > I've tried to make a sound myself, to see what parameters respond.
> > DCO 1 & DCO 2 do not respond to any change …..
> >
> > noise & VCF are working
> >
> > Could it be that it are just 1 or 2 DCO chips that are broken on the
> > mainbord ?
> >
> > I hope there is a solution for this problem.
> >
> >
> > Thanks all!
> >
> > Remo
> >
> >
> > ------------------------------------
> >
> > Feel free to upload into the files section any sysex dumps and tape dumps of patches that you may have but please discuss (with the entire group) the posting of other files *before* posting them. This helps us to keep redundant information from showing up everywhere and also allows us to constantly improve the format and structure of the documentation. We talk about the HAWK-800 quite a bit but we also discuss and help owners of the original Poly-800 models. So don't be shy if you haven't got the HAWK-800.Yahoo! Groups Links
> >
> >
> >
> >     http://docs.yahoo.com/info/terms/
> >
>

--- In korgpolyex@yahoogroups.com, "bimmerfan222" <bperkins211@...> wrote:
>
> There's a full set of schematics in the files section here.
>
> It indicates where the -5v supply is.
> Also, your joystick PCB has it printed right on the back of the board where -5v is.. You might check there first.
>
> HTH's
> -Blaine
>
> --- In korgpolyex@yahoogroups.com, "remomatic" <remosiemons@> wrote:
> >
> > I've tried 2 different power supplies, a 9V 300mA and a 9V 1000mA. I measured the output of the power supply and it's a steady 9V, so that should be ok I think.
> >
> > How do I check the -5V power rail ? can you maybe advice me where to measure ?
> >
> > I found a point at C11/C12 where I measure -2.39V that's a bit strange, because I guess that must be -5V
> >
> > I checked the following parameters :
> >
> > 1) parameter 17 - DCO 1 volume control - doesn't work…
> > 2) parameter 27 - DCO 2 volume control - doesn't work…
> > 3) parameter 33 - noise level - WORKS
> > 4) parameter 41 - VCF cut off - WORKS
> > 5) parameter 42 - resonance - WORKS
> > 6) parameter 83 - DCO modulation - doesn't work…
> > 7) parameter 84 - VCF modulation - WORKS
> > 8) joystick bend - doesn't work…
> >
> >
> > thanks,
> > Remo
> >
> >
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > Do you have the correct wall wart power supply?
> > >
> > > if you do, then I would next check that the -5V power rail is correct.
> > >
> > > And we can go from there after that.
> > >
> > > Mike
> > >
> > > ________________________________
> > > From: Remo Siemons <remosiemons@>
> > > To: korgpolyex@yahoogroups.com
> > > Sent: Thursday, June 27, 2013 11:02 AM
> > > Subject: [korgpolyex] Korg Poly 800 DCO problem
> > >
> > >
> > > Hi eveyone, I'm new to the group.
> > >
> > > I hope there's someone here who can help me to fix my Korg Poly 800
> > > (model: PS800)
> > > I bought it at a second hand store for only 7,50 Euro, but it's not
> > > working as it should….
> > >
> > > I've successfully loaded new sounds to the Korg. but I still hear only
> > > noises and clicks.
> > >
> > > Pitch bend left and rights are not working
> > > Tune slider is not working
> > >
> > > DCO with the joystick in up position is not working
> > >
> > > VCF with the joystick in down position is working
> > >
> > > I've tried to make a sound myself, to see what parameters respond.
> > > DCO 1 & DCO 2 do not respond to any change …..
> > >
> > > noise & VCF are working
> > >
> > > Could it be that it are just 1 or 2 DCO chips that are broken on the
> > > mainbord ?
> > >
> > > I hope there is a solution for this problem.
> > >
> > >
> > > Thanks all!
> > >
> > > Remo
> > >
> > >
> > > ------------------------------------
> > >
> > > Feel free to upload into the files section any sysex dumps and tape dumps of patches that you may have but please discuss (with the entire group) the posting of other files *before* posting them. This helps us to keep redundant information from showing up everywhere and also allows us to constantly improve the format and structure of the documentation. We talk about the HAWK-800 quite a bit but we also discuss and help owners of the original Poly-800 models. So don't be shy if you haven't got the HAWK-800.Yahoo! Groups Links
> > >
> > >
> > >
> > >     http://docs.yahoo.com/info/terms/
> > >
> >
>

Hi,
I once fried a cmos (analog) demultiplexer (1 to 8 switch) on Juno-106, which caused one vcf to function erratically. I replaced the vcf hybrid at first :P Then I knew to look for the problem up the control signal path.

The question is how do you identity the problem. Well, Juno has service mode, that provides fixed control voltages. But you can also create a  patch that opens the filter (high cutoff). Then measure the vcf OUTPUT pin voltage from the switch circuit. Do the same for vcf closed or any vcf position if possible.

But if the circuit (sorry I'm currently too busy to see it myself) is a demux, measuring the input is not possible without special service mode or oscilloscope, because it has many control voltages alternating rapidly.
But, the circuit diagram should tell if the switch is the most likely damaged part.

Hope this helps...

Sami Jumppanen
http://samijum.pp.fi
- SGS2 -