Korg Poly800/EX800 Users

From: iamakisgr <iamakisgr@...>
To: korgpolyex@yahoogroups.com
Sent: Friday, August 12, 2011 9:05 AM
Subject: [korgpolyex] Problem with my poly800 reverse keys edition... :/


  
Hello...
I recently got a broken poly800 reverse keys edition...
At first i thought it was only the power supply circuit but after i fixed that and turned on the unit there was no sound (the patches  are correct, i build some by myseld but nothing)...
After some minutes and while i was continuously pressing some notes a sweeping sound from max cutoff to min came out of the phones (and the output jack ofc) and when it reached to minimum cutoff it stopped there (bright sound with no cutoff).The notes i play on the keyboard are correct but most functions dont work at all..
1)filter
2)Bender and modulation w lfo
3)EG...
I can change the values on the menu but nothing happens...
I know for sure that the oscillator works and the vcf isnt fried (i tested with external voltage and it works)..
I dont know what to look for or what is fried..
The previous owner told me that it broke because he putted in a 12v ac adapter and not a 9v dc , so there must be some fried ic's...
Does anybody has an idea what could be wrong?
Thanks in advance..!

From: iamakisgr <iamakisgr@...>
To: korgpolyex@yahoogroups.com
Sent: Friday, August 12, 2011 9:05 AM
Subject: [korgpolyex] Problem with my poly800 reverse keys edition... :/


  
Hello...
I recently got a broken poly800 reverse keys edition...
At first i thought it was only the power supply circuit but after i fixed that and turned on the unit there was no sound (the patches  are correct, i build some by myseld but nothing)...
After some minutes and while i was continuously pressing some notes a sweeping sound from max cutoff to min came out of the phones (and the output jack ofc) and when it reached to minimum cutoff it stopped there (bright sound with no cutoff).The notes i play on the keyboard are correct but most functions dont work at all..
1)filter
2)Bender and modulation w lfo
3)EG...
I can change the values on the menu but nothing happens...
I know for sure that the oscillator works and the vcf isnt fried (i tested with external voltage and it works)..
I dont know what to look for or what is fried..
The previous owner told me that it broke because he putted in a 12v ac adapter and not a 9v dc , so there must be some fried ic's...
Does anybody has an idea what could be wrong?
Thanks in advance..!

From: bruno lhuissier <bruno.lhuissier@gmail.com>
To: korgpolyex@yahoogroups.com
Sent: Saturday, August 13, 2011 12:48 PM
Subject: Re: [korgpolyex] Problem with my poly800 reverse keys edition... :/


  
The low to high swooshing sound is the analog to digital sample and hold circuits discharging. Which indicates that the A2D multiplexing is not occurring.


So like I said, check the power rails first. Then let us know what you find.



I check the power rails:

The +5V is good (I recalibrate at +5V)

I ve got -4,42 V for the negative power

>
> -4.42 is too far out of spec. You will need to get that to -4.9 to -5.1.
> 
> 
> 
> 
> ________________________________
> From: bruno lhuissier <bruno.lhuissier@...>
> To: korgpolyex@yahoogroups.com
> Sent: Saturday, August 13, 2011 12:48 PM
> Subject: Re: [korgpolyex] Problem with my poly800 reverse keys edition... :/
> 
> 
> Â  
> The low to high swooshing sound is the analog to digital sample and hold circuits discharging. Which indicates that the A2D multiplexing is not occurring.
> 
> 
> So like I said, check the power rails first. Then let us know what you find.
> 
> 
> 
> I check the power rails:
> 
> The +5V is good (I recalibrate at +5V)
> 
> I ve got -4,42 V for the negative power
>

>
> Hello...
> I recently got a broken poly800 reverse keys edition...
> At first i thought it was only the power supply circuit but after i fixed that and turned on the unit there was no sound (the patches  are correct, i build some by myseld but nothing)...
> After some minutes and while i was continuously pressing some notes a sweeping sound from max cutoff to min came out of the phones (and the output jack ofc) and when it reached to minimum cutoff it stopped there (bright sound with no cutoff).The notes i play on the keyboard are correct but most functions dont work at all..
> 1)filter
> 2)Bender and modulation w lfo
> 3)EG...
> I can change the values on the menu but nothing happens...
> I know for sure that the oscillator works and the vcf isnt fried (i tested with external voltage and it works)..
> I dont know what to look for or what is fried..
> The previous owner told me that it broke because he putted in a 12v ac adapter and not a 9v dc , so there must be some fried ic's...
> Does anybody has an idea what could be wrong?
> Thanks in advance..!
>

>
> I recently call the one who gave me the poly and he told me that a reverse polarity adaptor was used and then it broke...
> 
> --- In korgpolyex@yahoogroups.com, "iamakisgr" <iamakisgr@> wrote:
> >
> > Hello...
> > I recently got a broken poly800 reverse keys edition...
> > At first i thought it was only the power supply circuit but after i fixed that and turned on the unit there was no sound (the patches  are correct, i build some by myseld but nothing)...
> > After some minutes and while i was continuously pressing some notes a sweeping sound from max cutoff to min came out of the phones (and the output jack ofc) and when it reached to minimum cutoff it stopped there (bright sound with no cutoff).The notes i play on the keyboard are correct but most functions dont work at all..
> > 1)filter
> > 2)Bender and modulation w lfo
> > 3)EG...
> > I can change the values on the menu but nothing happens...
> > I know for sure that the oscillator works and the vcf isnt fried (i tested with external voltage and it works)..
> > I dont know what to look for or what is fried..
> > The previous owner told me that it broke because he putted in a 12v ac adapter and not a 9v dc , so there must be some fried ic's...
> > Does anybody has an idea what could be wrong?
> > Thanks in advance..!
> >
>

>
> Hello...
> I recently got a broken poly800 reverse keys edition...
> At first i thought it was only the power supply circuit but after i fixed that and turned on the unit there was no sound (the patches  are correct, i build some by myseld but nothing)...
> After some minutes and while i was continuously pressing some notes a sweeping sound from max cutoff to min came out of the phones (and the output jack ofc) and when it reached to minimum cutoff it stopped there (bright sound with no cutoff).The notes i play on the keyboard are correct but most functions dont work at all..
> 1)filter
> 2)Bender and modulation w lfo
> 3)EG...
> I can change the values on the menu but nothing happens...
> I know for sure that the oscillator works and the vcf isnt fried (i tested with external voltage and it works)..
> I dont know what to look for or what is fried..
> The previous owner told me that it broke because he putted in a 12v ac adapter and not a 9v dc , so there must be some fried ic's...
> Does anybody has an idea what could be wrong?
> Thanks in advance..!
>

 From: Gordon JC Pearce <gordon@...>
To: korgpolyex@yahoogroups.com 
Sent: Monday, December 5, 2011 1:29 PM
Subject: Re: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
 

  
On Mon, 05 Dec 2011 14:42:28 -0000
"iamakisgr" <iamakisgr@...> wrote:

> I recently call the one who gave me the poly and he told me that a reverse polarity adaptor was used and then it broke...

Running it off a 12V adaptor won't make any difference at all.  The stock Korg adaptor puts out around 14V off-load dropping to 11V when you stick the Poly-800 on it.

-- 
Gordon JC Pearce MM0YEQ <gordonjcp@...>

>
> On Mon, 5 Dec 2011 17:41:19 -0800 (PST)
> Michael Hawkins <korgpolyex800@...> wrote:
> 
> > Gordon,
> > 
> > I beg to differ on this point, though I hesitate and exercise a hefty load of humility before doing so.
> 
> No no, you've worked on these instruments a lot more than I have, so you should know ;-)
> 
> > But the problem with your thesis is that no power supply should ever be considered without the load, even despite the proliferation of modern regulated power supplies.
> 
> Right, but the Poly 800 isn't drawing 1A all the time and the average draw is somewhat closer to 800mA.
> 
> Get a 12V power supply and run your Poly 800 off it with a 1 ohm resistor in series and stick your 'scope across said resistor - look at the current, it's all over the place!  At least, it is on mine...
> 
> > And so, if a Poly owner does connect a 12V DC supply that is rated to 1Amp or higher and is (even worse) a regulated supply, then the additional 3 watts of power must be dissipated by the Poly 800 power regulator. Unfortunately, the design of the Poly power supply does not dissipate the additional 3 watts very well at all.
> >
> > Those little BD transistors end up cooked - badly burned actually! Destroyed, busted, kaput!
> 
> I have to say, even at a nominal 12V input I haven't noticed the regulator trannies get even particularly warm.  The standard Korg PSU I have puts out just shy of 11V on load, so one would assume that if the factory PSU does that then the Poly 800 is designed to cope with it.
> 
> I can't see that an additional 3W dissipation would zorch the regulator trannies to that extent, but persistently connecting up a high-current PSU *would* - after it had blown the legs off the protection diode.  I run across this at work quite frequently, with one customer in particular who seems to delight in connecting their radio across the car battery backwards, blowing the fuse, replacing the fuse with a higher rated one, and continuing the process until the radio leaks its magic smoke.  It then makes its way to me for a new protection diode, a new RF power amp and a new audio power amp.  The worrying thing is that this is the workshop of one of the "blue light services" ;-)
> 
> -- 
> Gordon JC Pearce MM0YEQ <gordonjcp@...>
>

>
> On Mon, 26 Dec 2011 15:25:20 -0000
> "iamakisgr" <iamakisgr@...> wrote:
> 
> > Well..I have tried all that..
> > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > I just hear the wave with no cutoff (too bright) and no resonanse..
> > I tried alternating them from the menu but nothing happened.. :/
> > Any other suggestions?
> > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> 
> You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> 
> First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> 
> -- 
> Gordon JC Pearce MM0YEQ <gordonjcp@...>
>

>
> On Mon, 26 Dec 2011 15:25:20 -0000
> "iamakisgr" <iamakisgr@...> wrote:
> 
> > Well..I have tried all that..
> > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > I just hear the wave with no cutoff (too bright) and no resonanse..
> > I tried alternating them from the menu but nothing happened.. :/
> > Any other suggestions?
> > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> 
> You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> 
> First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> 
> -- 
> Gordon JC Pearce MM0YEQ <gordonjcp@...>
>

>
> It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> 
> Check the following and let us know which ones work and which ones don't work:
> 
> 1) parameter 17 - DCO 1 volume control
> 2) parameter 27 - DCO 2 volume control
> 3) parameter 33 - noise level
> 4) parameter 41 - VCF cut off
> 5) parameter 42 - resonance
> 6) parameter 83 - DCO modulation
> 
> 7) parameter 84 - VCF modulation
> 8) joystick bend
> 
> If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> 
> If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> 
> Mike
> 
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Monday, December 26, 2011 5:20 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
>  
> 
> Â  
> There are many functions that dont work..
> first of all the filter...
> The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> I couldnt find the problem going back to beggining of the signal..
> Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> Thanks everyone for trying to help me.
> If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> 
> --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> >
> > On Mon, 26 Dec 2011 15:25:20 -0000
> > "iamakisgr" <iamakisgr@> wrote:
> > 
> > > Well..I have tried all that..
> > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > I tried alternating them from the menu but nothing happened.. :/
> > > Any other suggestions?
> > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > 
> > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > 
> > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > 
> > -- 
> > Gordon JC Pearce MM0YEQ <gordonjcp@>
> >
>

>
> It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> 
> Check the following and let us know which ones work and which ones don't work:
> 
> 1) parameter 17 - DCO 1 volume control
> 2) parameter 27 - DCO 2 volume control
> 3) parameter 33 - noise level
> 4) parameter 41 - VCF cut off
> 5) parameter 42 - resonance
> 6) parameter 83 - DCO modulation
> 
> 7) parameter 84 - VCF modulation
> 8) joystick bend
> 
> If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> 
> If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> 
> Mike
> 
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Monday, December 26, 2011 5:20 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
>  
> 
> Â  
> There are many functions that dont work..
> first of all the filter...
> The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> I couldnt find the problem going back to beggining of the signal..
> Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> Thanks everyone for trying to help me.
> If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> 
> --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> >
> > On Mon, 26 Dec 2011 15:25:20 -0000
> > "iamakisgr" <iamakisgr@> wrote:
> > 
> > > Well..I have tried all that..
> > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > I tried alternating them from the menu but nothing happened.. :/
> > > Any other suggestions?
> > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > 
> > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > 
> > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > 
> > -- 
> > Gordon JC Pearce MM0YEQ <gordonjcp@>
> >
>

>
> It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> 
> Check the following and let us know which ones work and which ones don't work:
> 
> 1) parameter 17 - DCO 1 volume control
> 2) parameter 27 - DCO 2 volume control
> 3) parameter 33 - noise level
> 4) parameter 41 - VCF cut off
> 5) parameter 42 - resonance
> 6) parameter 83 - DCO modulation
> 
> 7) parameter 84 - VCF modulation
> 8) joystick bend
> 
> If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> 
> If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> 
> Mike
> 
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Monday, December 26, 2011 5:20 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> 
> 
> Â  
> There are many functions that dont work..
> first of all the filter...
> The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> I couldnt find the problem going back to beggining of the signal..
> Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> Thanks everyone for trying to help me.
> If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> 
> --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> >
> > On Mon, 26 Dec 2011 15:25:20 -0000
> > "iamakisgr" <iamakisgr@> wrote:
> > 
> > > Well..I have tried all that..
> > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > I tried alternating them from the menu but nothing happened.. :/
> > > Any other suggestions?
> > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > 
> > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > 
> > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > 
> > -- 
> > Gordon JC Pearce MM0YEQ <gordonjcp@>
> >
>

>
> It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> 
> Check the following and let us know which ones work and which ones don't work:
> 
> 1) parameter 17 - DCO 1 volume control
> 2) parameter 27 - DCO 2 volume control
> 3) parameter 33 - noise level
> 4) parameter 41 - VCF cut off
> 5) parameter 42 - resonance
> 6) parameter 83 - DCO modulation
> 
> 7) parameter 84 - VCF modulation
> 8) joystick bend
> 
> If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> 
> If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> 
> Mike
> 
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Monday, December 26, 2011 5:20 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> 
> 
> Â  
> There are many functions that dont work..
> first of all the filter...
> The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> I couldnt find the problem going back to beggining of the signal..
> Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> Thanks everyone for trying to help me.
> If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> 
> --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> >
> > On Mon, 26 Dec 2011 15:25:20 -0000
> > "iamakisgr" <iamakisgr@> wrote:
> > 
> > > Well..I have tried all that..
> > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > I tried alternating them from the menu but nothing happened.. :/
> > > Any other suggestions?
> > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > 
> > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > 
> > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > 
> > -- 
> > Gordon JC Pearce MM0YEQ <gordonjcp@>
> >
>

>
> I think it is quite safe to say that the microprocessor, memory and ROM and decoding logic are all OK because you have the ability to change parameters. If you did not get "11 P" when you power up then that might mean you have a problem with the CPU but since you do see that and you can change parameters, it would appear that all of the CPU side of things is OK.
> 
> Also, the display is driven by the 81C55 IO chip, so the fact that you see the display and that you can change parameters means that the 81C55 is OK too.
> 
> The multiplexer is IC12 which is a HD14051. You can use a standard CMOS 4051 to replace it.
> 
> Do you have an oscilloscope? It will be easier and much faster to determine where the exact fault is if you have one.
> 
> 
> Mike
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Tuesday, December 27, 2011 5:30 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
>  
> 
> Â  
> Hello!
> Thanks for the reply..!
> None of these work at all..
> All other functions work though..!
> Can you please tell me the ic number that makes the d/a convertion for those features?
> Also,can it be the microcontroler pin outputs the problem?
> Akis
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > 
> > Check the following and let us know which ones work and which ones don't work:
> > 
> > 1) parameter 17 - DCO 1 volume control
> > 2) parameter 27 - DCO 2 volume control
> > 3) parameter 33 - noise level
> > 4) parameter 41 - VCF cut off
> > 5) parameter 42 - resonance
> > 6) parameter 83 - DCO modulation
> > 
> > 7) parameter 84 - VCF modulation
> > 8) joystick bend
> > 
> > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > 
> > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Monday, December 26, 2011 5:20 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Ã&#65533;Â  
> > There are many functions that dont work..
> > first of all the filter...
> > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > I couldnt find the problem going back to beggining of the signal..
> > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > Thanks everyone for trying to help me.
> > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > 
> > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > >
> > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > "iamakisgr" <iamakisgr@> wrote:
> > > 
> > > > Well..I have tried all that..
> > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > I tried alternating them from the menu but nothing happened.. :/
> > > > Any other suggestions?
> > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > 
> > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > 
> > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > 
> > > -- 
> > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > >
> >
>

>
> I think it is quite safe to say that the microprocessor, memory and ROM and decoding logic are all OK because you have the ability to change parameters. If you did not get "11 P" when you power up then that might mean you have a problem with the CPU but since you do see that and you can change parameters, it would appear that all of the CPU side of things is OK.
> 
> Also, the display is driven by the 81C55 IO chip, so the fact that you see the display and that you can change parameters means that the 81C55 is OK too.
> 
> The multiplexer is IC12 which is a HD14051. You can use a standard CMOS 4051 to replace it.
> 
> Do you have an oscilloscope? It will be easier and much faster to determine where the exact fault is if you have one.
> 
> 
> Mike
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Tuesday, December 27, 2011 5:30 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> 
> 
> Â  
> Hello!
> Thanks for the reply..!
> None of these work at all..
> All other functions work though..!
> Can you please tell me the ic number that makes the d/a convertion for those features?
> Also,can it be the microcontroler pin outputs the problem?
> Akis
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > 
> > Check the following and let us know which ones work and which ones don't work:
> > 
> > 1) parameter 17 - DCO 1 volume control
> > 2) parameter 27 - DCO 2 volume control
> > 3) parameter 33 - noise level
> > 4) parameter 41 - VCF cut off
> > 5) parameter 42 - resonance
> > 6) parameter 83 - DCO modulation
> > 
> > 7) parameter 84 - VCF modulation
> > 8) joystick bend
> > 
> > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > 
> > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Monday, December 26, 2011 5:20 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Ã\ufffd  
> > There are many functions that dont work..
> > first of all the filter...
> > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > I couldnt find the problem going back to beggining of the signal..
> > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > Thanks everyone for trying to help me.
> > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > 
> > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > >
> > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > "iamakisgr" <iamakisgr@> wrote:
> > > 
> > > > Well..I have tried all that..
> > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > I tried alternating them from the menu but nothing happened.. :/
> > > > Any other suggestions?
> > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > 
> > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > 
> > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > 
> > > -- 
> > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > >
> >
>

>
> I will check ic 12 if anything happens in the input pin of the chip when i change a value...Well as i saw from the service manual there is no 
> native (IC) DAC for these features at all..!
> Everything goes with a block resistor and a 4050 ic for level normalising..Is it true or i have misunderstood what i saw?
> 
> Yes, that pretty much sums up the D2A and sample and hold section for the controls that are dead.
> 
> As the service manual says for section 12 (see schematic):
> 
> 12) 8-bit D/A converter:
> Uses CMOS noninverting buffer IC32 (HD14050 or â\ufffd\ufffd4050â\ufffd\ufffd), and 8R9 (RKM10L253F or â\ufffd\ufffdBR9â\ufffd\ufffd) a 10-pin (Rm25kohm) R-2R ladder resistor in D/A converter with output of 0V~4V.
> 
> So I would look for the output of the D2A first, then check after the buffer then check the 4050 then the sample and hold buffers.
> 
> 
> So your oscilloscope should be able to see if the D2A is the problem or the multiplexer 4050 or the sample and hold buffers are the problem or something else. And you can also trace the levels for all of the various control signals that go out from the sample and hold buffers to control the VCF, DCO MG, volume etc.
> 
> Mike
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Wednesday, December 28, 2011 7:34 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
>  
> 
> Â  
> Well all envelopes work, also chorus works ,the controlls of the filter chip dont work at all i think...
> I have an oscilloscope but it doesnt have component tester...
> Its an hameg hm-203 (no numbers after it, its the first model) dual channel 20mhz..
> I will check ic 12 if anything happens in the input pin of the chip when i change a value...Well as i saw from the service manual there is no native (IC) DAC for these features at all..!
> Everything goes with a block resistor and a 4050 ic for level normalising..Is it true or i have misunderstood what i saw?
> 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > I think it is quite safe to say that the microprocessor, memory and ROM and decoding logic are all OK because you have the ability to change parameters. If you did not get "11 P" when you power up then that might mean you have a problem with the CPU but since you do see that and you can change parameters, it would appear that all of the CPU side of things is OK.
> > 
> > Also, the display is driven by the 81C55 IO chip, so the fact that you see the display and that you can change parameters means that the 81C55 is OK too.
> > 
> > The multiplexer is IC12 which is a HD14051. You can use a standard CMOS 4051 to replace it.
> > 
> > Do you have an oscilloscope? It will be easier and much faster to determine where the exact fault is if you have one.
> > 
> > 
> > Mike
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Tuesday, December 27, 2011 5:30 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Ã\u19993;Â  
> > Hello!
> > Thanks for the reply..!
> > None of these work at all..
> > All other functions work though..!
> > Can you please tell me the ic number that makes the d/a convertion for those features?
> > Also,can it be the microcontroler pin outputs the problem?
> > Akis
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > > 
> > > Check the following and let us know which ones work and which ones don't work:
> > > 
> > > 1) parameter 17 - DCO 1 volume control
> > > 2) parameter 27 - DCO 2 volume control
> > > 3) parameter 33 - noise level
> > > 4) parameter 41 - VCF cut off
> > > 5) parameter 42 - resonance
> > > 6) parameter 83 - DCO modulation
> > > 
> > > 7) parameter 84 - VCF modulation
> > > 8) joystick bend
> > > 
> > > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > > 
> > > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > > 
> > > Mike
> > > 
> > > 
> > > 
> > > ________________________________
> > >  From: iamakisgr <iamakisgr@>
> > > To: korgpolyex@yahoogroups.com 
> > > Sent: Monday, December 26, 2011 5:20 PM
> > > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > > 
> > > 
> > > Ã\ufffd\ufffdÃ\ufffd  
> > > There are many functions that dont work..
> > > first of all the filter...
> > > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > > I couldnt find the problem going back to beggining of the signal..
> > > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > > Thanks everyone for trying to help me.
> > > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > > 
> > > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > > >
> > > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > > "iamakisgr" <iamakisgr@> wrote:
> > > > 
> > > > > Well..I have tried all that..
> > > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > > I tried alternating them from the menu but nothing happened.. :/
> > > > > Any other suggestions?
> > > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > > 
> > > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > > 
> > > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > > 
> > > > -- 
> > > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > > >
> > >
> >
>

>
> I will check ic 12 if anything happens in the input pin of the chip when i change a value...Well as i saw from the service manual there is no 
> native (IC) DAC for these features at all..!
> Everything goes with a block resistor and a 4050 ic for level normalising..Is it true or i have misunderstood what i saw?
> 
> Yes, that pretty much sums up the D2A and sample and hold section for the controls that are dead.
> 
> As the service manual says for section 12 (see schematic):
> 
> 12) 8-bit D/A converter:
> Uses CMOS noninverting buffer IC32 (HD14050 or â\ufffd\ufffd4050â\ufffd\ufffd), and 8R9 (RKM10L253F or â\ufffd\ufffdBR9â\ufffd\ufffd) a 10-pin (Rm25kohm) R-2R ladder resistor in D/A converter with output of 0V~4V.
> 
> So I would look for the output of the D2A first, then check after the buffer then check the 4050 then the sample and hold buffers.
> 
> 
> So your oscilloscope should be able to see if the D2A is the problem or the multiplexer 4050 or the sample and hold buffers are the problem or something else. And you can also trace the levels for all of the various control signals that go out from the sample and hold buffers to control the VCF, DCO MG, volume etc.
> 
> Mike
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Wednesday, December 28, 2011 7:34 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> 
> 
> Â  
> Well all envelopes work, also chorus works ,the controlls of the filter chip dont work at all i think...
> I have an oscilloscope but it doesnt have component tester...
> Its an hameg hm-203 (no numbers after it, its the first model) dual channel 20mhz..
> I will check ic 12 if anything happens in the input pin of the chip when i change a value...Well as i saw from the service manual there is no native (IC) DAC for these features at all..!
> Everything goes with a block resistor and a 4050 ic for level normalising..Is it true or i have misunderstood what i saw?
> 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > I think it is quite safe to say that the microprocessor, memory and ROM and decoding logic are all OK because you have the ability to change parameters. If you did not get "11 P" when you power up then that might mean you have a problem with the CPU but since you do see that and you can change parameters, it would appear that all of the CPU side of things is OK.
> > 
> > Also, the display is driven by the 81C55 IO chip, so the fact that you see the display and that you can change parameters means that the 81C55 is OK too.
> > 
> > The multiplexer is IC12 which is a HD14051. You can use a standard CMOS 4051 to replace it.
> > 
> > Do you have an oscilloscope? It will be easier and much faster to determine where the exact fault is if you have one.
> > 
> > 
> > Mike
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Tuesday, December 27, 2011 5:30 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Ã\ufffd  
> > Hello!
> > Thanks for the reply..!
> > None of these work at all..
> > All other functions work though..!
> > Can you please tell me the ic number that makes the d/a convertion for those features?
> > Also,can it be the microcontroler pin outputs the problem?
> > Akis
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > > 
> > > Check the following and let us know which ones work and which ones don't work:
> > > 
> > > 1) parameter 17 - DCO 1 volume control
> > > 2) parameter 27 - DCO 2 volume control
> > > 3) parameter 33 - noise level
> > > 4) parameter 41 - VCF cut off
> > > 5) parameter 42 - resonance
> > > 6) parameter 83 - DCO modulation
> > > 
> > > 7) parameter 84 - VCF modulation
> > > 8) joystick bend
> > > 
> > > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > > 
> > > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > > 
> > > Mike
> > > 
> > > 
> > > 
> > > ________________________________
> > >  From: iamakisgr <iamakisgr@>
> > > To: korgpolyex@yahoogroups.com 
> > > Sent: Monday, December 26, 2011 5:20 PM
> > > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > > 
> > > 
> > > Ã\ufffd\ufffdÃ\ufffd  
> > > There are many functions that dont work..
> > > first of all the filter...
> > > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > > I couldnt find the problem going back to beggining of the signal..
> > > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > > Thanks everyone for trying to help me.
> > > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > > 
> > > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > > >
> > > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > > "iamakisgr" <iamakisgr@> wrote:
> > > > 
> > > > > Well..I have tried all that..
> > > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > > I tried alternating them from the menu but nothing happened.. :/
> > > > > Any other suggestions?
> > > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > > 
> > > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > > 
> > > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > > 
> > > > -- 
> > > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > > >
> > >
> >
>

>
> Do you hear anything from the DCO's at all when you hold notes?
> Do the envelope generators work?
> 
> Does the detune work?
> Does the chorus on/off function work?
> 
> Mike
> 
> 
> 
> ________________________________
>  From: iamakisgr <iamakisgr@...>
> To: korgpolyex@yahoogroups.com 
> Sent: Tuesday, December 27, 2011 5:35 PM
> Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
>  
> 
> Â  
> Or maybe i forget some more features that dont work..I am 100% sure that those you have included in your post dont work at all...
> 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > 
> > Check the following and let us know which ones work and which ones don't work:
> > 
> > 1) parameter 17 - DCO 1 volume control
> > 2) parameter 27 - DCO 2 volume control
> > 3) parameter 33 - noise level
> > 4) parameter 41 - VCF cut off
> > 5) parameter 42 - resonance
> > 6) parameter 83 - DCO modulation
> > 
> > 7) parameter 84 - VCF modulation
> > 8) joystick bend
> > 
> > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > 
> > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Monday, December 26, 2011 5:20 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> >   
> > There are many functions that dont work..
> > first of all the filter...
> > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > I couldnt find the problem going back to beggining of the signal..
> > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > Thanks everyone for trying to help me.
> > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > 
> > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > >
> > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > "iamakisgr" <iamakisgr@> wrote:
> > > 
> > > > Well..I have tried all that..
> > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > I tried alternating them from the menu but nothing happened.. :/
> > > > Any other suggestions?
> > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > 
> > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > 
> > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > 
> > > -- 
> > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > >
> >
>

>
> I have a problem similar to this with a Poly-800 that I rescued recently.
> 
> All that has an affect is
> param 84 VCF
> 81 Freq
> 41 Cutoff
> 42 Resonance
> 33 Noise
> Param 24 makes a popping sound when I switch it.
> Chorus seems to work, I can't really get a proper note to sound,it's the same pitch/tone.
> Nothing else works
> IC's 8 and 12 (4050) are good
> Ic's 33,34 seem to be doing something
> I have a logic probe and an oscilloscope but am a total beginner with the scope. 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > Do you hear anything from the DCO's at all when you hold notes?
> > Do the envelope generators work?
> > 
> > Does the detune work?
> > Does the chorus on/off function work?
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Tuesday, December 27, 2011 5:35 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> >  
> > 
> > Â  
> > Or maybe i forget some more features that dont work..I am 100% sure that those you have included in your post dont work at all...
> > 
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > > 
> > > Check the following and let us know which ones work and which ones don't work:
> > > 
> > > 1) parameter 17 - DCO 1 volume control
> > > 2) parameter 27 - DCO 2 volume control
> > > 3) parameter 33 - noise level
> > > 4) parameter 41 - VCF cut off
> > > 5) parameter 42 - resonance
> > > 6) parameter 83 - DCO modulation
> > > 
> > > 7) parameter 84 - VCF modulation
> > > 8) joystick bend
> > > 
> > > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > > 
> > > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > > 
> > > Mike
> > > 
> > > 
> > > 
> > > ________________________________
> > >  From: iamakisgr <iamakisgr@>
> > > To: korgpolyex@yahoogroups.com 
> > > Sent: Monday, December 26, 2011 5:20 PM
> > > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > > 
> > > 
> > >   
> > > There are many functions that dont work..
> > > first of all the filter...
> > > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > > I couldnt find the problem going back to beggining of the signal..
> > > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > > Thanks everyone for trying to help me.
> > > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > > 
> > > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > > >
> > > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > > "iamakisgr" <iamakisgr@> wrote:
> > > > 
> > > > > Well..I have tried all that..
> > > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > > I tried alternating them from the menu but nothing happened.. :/
> > > > > Any other suggestions?
> > > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > > 
> > > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > > 
> > > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > > 
> > > > -- 
> > > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > > >
> > >
> >
>

>
> I have a problem similar to this with a Poly-800 that I rescued recently.
> 
> All that has an affect is
> param 84 VCF
> 81 Freq
> 41 Cutoff
> 42 Resonance
> 33 Noise
> Param 24 makes a popping sound when I switch it.
> Chorus seems to work, I can't really get a proper note to sound,it's the same pitch/tone.
> Nothing else works
> IC's 8 and 12 (4050) are good
> Ic's 33,34 seem to be doing something
> I have a logic probe and an oscilloscope but am a total beginner with the scope. 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > Do you hear anything from the DCO's at all when you hold notes?
> > Do the envelope generators work?
> > 
> > Does the detune work?
> > Does the chorus on/off function work?
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Tuesday, December 27, 2011 5:35 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Â  
> > Or maybe i forget some more features that dont work..I am 100% sure that those you have included in your post dont work at all...
> > 
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > > 
> > > Check the following and let us know which ones work and which ones don't work:
> > > 
> > > 1) parameter 17 - DCO 1 volume control
> > > 2) parameter 27 - DCO 2 volume control
> > > 3) parameter 33 - noise level
> > > 4) parameter 41 - VCF cut off
> > > 5) parameter 42 - resonance
> > > 6) parameter 83 - DCO modulation
> > > 
> > > 7) parameter 84 - VCF modulation
> > > 8) joystick bend
> > > 
> > > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > > 
> > > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > > 
> > > Mike
> > > 
> > > 
> > > 
> > > ________________________________
> > >  From: iamakisgr <iamakisgr@>
> > > To: korgpolyex@yahoogroups.com 
> > > Sent: Monday, December 26, 2011 5:20 PM
> > > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > > 
> > > 
> > >   
> > > There are many functions that dont work..
> > > first of all the filter...
> > > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > > I couldnt find the problem going back to beggining of the signal..
> > > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > > Thanks everyone for trying to help me.
> > > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > > 
> > > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > > >
> > > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > > "iamakisgr" <iamakisgr@> wrote:
> > > > 
> > > > > Well..I have tried all that..
> > > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > > I tried alternating them from the menu but nothing happened.. :/
> > > > > Any other suggestions?
> > > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > > 
> > > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > > 
> > > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > > 
> > > > -- 
> > > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > > >
> > >
> >
>

>
> I have a problem similar to this with a Poly-800 that I rescued recently.
> 
> All that has an affect is
> param 84 VCF
> 81 Freq
> 41 Cutoff
> 42 Resonance
> 33 Noise
> Param 24 makes a popping sound when I switch it.
> Chorus seems to work, I can't really get a proper note to sound,it's the same pitch/tone.
> Nothing else works
> IC's 8 and 12 (4050) are good
> Ic's 33,34 seem to be doing something
> I have a logic probe and an oscilloscope but am a total beginner with the scope. 
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > Do you hear anything from the DCO's at all when you hold notes?
> > Do the envelope generators work?
> > 
> > Does the detune work?
> > Does the chorus on/off function work?
> > 
> > Mike
> > 
> > 
> > 
> > ________________________________
> >  From: iamakisgr <iamakisgr@>
> > To: korgpolyex@yahoogroups.com 
> > Sent: Tuesday, December 27, 2011 5:35 PM
> > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > 
> > 
> > Â  
> > Or maybe i forget some more features that dont work..I am 100% sure that those you have included in your post dont work at all...
> > 
> > --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> > >
> > > It sounds to me like you should be looking for problems with the digital to analog converter and then perhaps the multiplexer that drives the analog signal out to the various controls for the DCO MG, VCF MG and the master volume control.
> > > 
> > > Check the following and let us know which ones work and which ones don't work:
> > > 
> > > 1) parameter 17 - DCO 1 volume control
> > > 2) parameter 27 - DCO 2 volume control
> > > 3) parameter 33 - noise level
> > > 4) parameter 41 - VCF cut off
> > > 5) parameter 42 - resonance
> > > 6) parameter 83 - DCO modulation
> > > 
> > > 7) parameter 84 - VCF modulation
> > > 8) joystick bend
> > > 
> > > If NONE of these work then the D2A converter, the sample and hold and the multiplexer sections need to be checked.
> > > 
> > > If some of them work then the D2A converter is probably OK but the sample and hold and multiplexer sections need to be checked.
> > > 
> > > Mike
> > > 
> > > 
> > > 
> > > ________________________________
> > >  From: iamakisgr <iamakisgr@>
> > > To: korgpolyex@yahoogroups.com 
> > > Sent: Monday, December 26, 2011 5:20 PM
> > > Subject: [korgpolyex] Re: Problem with my poly800 reverse keys edition... :/
> > > 
> > > 
> > >   
> > > There are many functions that dont work..
> > > first of all the filter...
> > > The chip works cause i tested it with a pot and 3 volt directly and it responds ok...
> > > I couldnt find the problem going back to beggining of the signal..
> > > Maybe i dont know enough to fix it or i cant consentrate,thats why i am asking what to check first...
> > > Thanks everyone for trying to help me.
> > > If theres anything i can make to help you understand whats the problem and what i have done so far in testing and checking please tell me and i will try to explain the best way i can..
> > > 
> > > --- In korgpolyex@yahoogroups.com, Gordon JC Pearce <gordon@> wrote:
> > > >
> > > > On Mon, 26 Dec 2011 15:25:20 -0000
> > > > "iamakisgr" <iamakisgr@> wrote:
> > > > 
> > > > > Well..I have tried all that..
> > > > > I even connected +/- 5volts from a pc psu at the points that the service manual said i should check and have 5 volts...
> > > > > I have sound to the output but the filter dont work at all nor the eg, nor the lfo...
> > > > > I just hear the wave with no cutoff (too bright) and no resonanse..
> > > > > I tried alternating them from the menu but nothing happened.. :/
> > > > > Any other suggestions?
> > > > > What should i look for before changing everything on the motherboard except the eeprom, the sound chip and the filter chip which i have tested and they work?
> > > > 
> > > > You need to stop all this poke and hope stuff, and start trying to diagnose the problem.
> > > > 
> > > > First off, what works?  What doesn't work?  If for example you have the oscillator outputs working but no filtering then perhaps you should start looking at how the filter CV is generated.
> > > > 
> > > > -- 
> > > > Gordon JC Pearce MM0YEQ <gordonjcp@>
> > > >
> > >
> >
>