Discussion about the Korg PolySix synthesizer

My PolySix suddenly got out of tune, so I changed PC-1 to a VTL5C3 and
R93 to a 1K2 resistor. However the PolySix still sounds terrible.
Any suggestions for what to look for ? 
I have a multimeter if there is anything you suggest me to check.

Thanks in advance,
Peter

Hi Peter,

So we'll assume the changing those two components made no difference 
and you are still left with the original problem? Can you confirm that 
all of the voices appear as off key as one another? (i.e, put the P6 
into unison mode, turn the cutoff to 10 and press C3 over and over and 
compare each voice, etc. They all sound just as bad as one another?)

if so, check section 8 of the service manual and make sure all of the 
voltages are within spec. Make sure the supplies to IC17/18/19 are 
accurate. Also, make sure that demultiplexer IC31 is doing its job. 5V 
should appear alternately on pins 13, 14, 15, 12, 1 and 5 when C8 
pressed. Have a look around this part of the circuitry on the KLM-366 
board and see if the voltages look correct. 

Report back your findings and we'll have another head scratch if all 
looks well.

Cheers,
Andy

--- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@...> wrote:

>
> My PolySix suddenly got out of tune, so I changed PC-1 to a VTL5C3 and
> R93 to a 1K2 resistor. However the PolySix still sounds terrible.
> Any suggestions for what to look for ? 
> I have a multimeter if there is anything you suggest me to check.
> 
> Thanks in advance,
> Peter
>

Thanks a lot Andy! :-)

All voices sounds equally bad.

Here are my readings (after at least 10 min. warm-up):

TP-J7 = 14.94V OK
TP-R18 = -14.93V OK
TP-J2 = 4.97V OK
TP-J1 = -4.96V OK

IC31 (first pin (lower left) = 0)
1: -8.05V constant (no change if C8 or other key is pressed)
5:  -8.05v constant (no change if C8 or other key is pressed)
12: -8.05v constant (no change if C8 or other key is pressed)
13: -8.05v constant (no change if C8 or other key is pressed)
14: -8.05v constant (no change if C8 or other key is pressed)
15: -8.05v constant (no change if C8 or other key is pressed)
16 (upper left pin): 4.96v constant 

IC17 (upper left pin)
4.96V constant

IC18 (upper left pin)
14.91V Constant

IC19 (upper left pin)
14.91V constant


Looks like the IC31 is bad?

Cheers
Peter

--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:
Can you confirm that 

> all of the voices appear as off key as one another? (i.e, put the P6 
> into unison mode, turn the cutoff to 10 and press C3 over and over and 
> compare each voice, etc. They all sound just as bad as one another?)
> 
> if so, check section 8 of the service manual and make sure all of the 
> voltages are within spec. Make sure the supplies to IC17/18/19 are 
> accurate. Also, make sure that demultiplexer IC31 is doing its job. 5V 
> should appear alternately on pins 13, 14, 15, 12, 1 and 5 when C8 
> pressed. Have a look around this part of the circuitry on the KLM-366 
> board and see if the voltages look correct. 
> 
> Report back your findings and we'll have another head scratch if all 
> looks well.

Hi Peter,

I am afraid we can't make that assumption until the logic that controls 
IC31 has been tested. This device is basically a switch. You apply a 
binary pattern to lines A, B, C and INH and this determines which one 
of the outputs is connected to the input. The input is marked X the 
outputs marked X0, X1, X2, etc. It is the outputs which we just tested 
and which don't seem to move. Tell me, do the voice LEDs (D10) come on 
in order in Unison mode? Everytime you press a key an alternate voice 
LED should light up. I suspect not?

Can you lay your hands on a logic probe at all?

Cheers,
Andy

Thanks Andy,

The LEDS (D10) does light in order in polymode (which I think was what
you meant?) -in unison they all light simultaniously.
In Polymode all voices sounds equally (bad).


I'm not sure about your last question (Can you lay your hands on a
logic probe at all?)?  


Cheers,
Peter


--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:

>
> Hi Peter,
> 
> I am afraid we can't make that assumption until the logic that controls 
> IC31 has been tested. This device is basically a switch. You apply a 
> binary pattern to lines A, B, C and INH and this determines which one 
> of the outputs is connected to the input. The input is marked X the 
> outputs marked X0, X1, X2, etc. It is the outputs which we just tested 
> and which don't seem to move. Tell me, do the voice LEDs (D10) come on 
> in order in Unison mode? Everytime you press a key an alternate voice 
> LED should light up. I suspect not?
> 
> Can you lay your hands on a logic probe at all?
> 
> Cheers,
> Andy
>

A logic probe is an electronic testing tool.

On Wed, Aug 20, 2008 at 11:44 AM, hjulskov <hjulskov@yahoo.com> wrote:
> Thanks Andy,
>
> The LEDS (D10) does light in order in polymode (which I think was what
> you meant?) -in unison they all light simultaniously.
> In Polymode all voices sounds equally (bad).
>
>
> I'm not sure about your last question (Can you lay your hands on a
> logic probe at all?)?
>
>
> Cheers,
> Peter
>
>
> --- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:
>>
>> Hi Peter,
>>
>> I am afraid we can't make that assumption until the logic that controls
>> IC31 has been tested. This device is basically a switch. You apply a
>> binary pattern to lines A, B, C and INH and this determines which one
>> of the outputs is connected to the input. The input is marked X the
>> outputs marked X0, X1, X2, etc. It is the outputs which we just tested
>> and which don't seem to move. Tell me, do the voice LEDs (D10) come on
>> in order in Unison mode? Everytime you press a key an alternate voice
>> LED should light up. I suspect not?
>>
>> Can you lay your hands on a logic probe at all?
>>
>> Cheers,
>> Andy
>>
>
>
>
> ------------------------------------
>
> PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6Yahoo! Groups Links
>
>
>
>



-- 
.sig
-Chromatest J. Pantsmaker
http://www.chromatest.net

Peter,

The logic probe measures whether logic states in TTL or CMOS 
circuitry are a binary 1 or 0. Remember we talked about how the 
binary pattern on lines A, B, C, INH set which outputs on IC31 are 
selected? This tool would tell us how they are set and whether they 
were switching on a the right time.

However, from the description how the six LEDs are lighting up (yes, 
one after the other in POLY mode - I am an idiot!) it sounds like 
IC31 is working correctly and keyboard assigner is sending the right 
binary pattern to the switch. 

I expect the input on pin 3 is the problem. What I will do is take 
some reading from my working Polysix and let you know how the 
circuitry should function. I'll post this after the weekend, if you 
can wait.

Also, I'll take you are playing with the settings in manual mode and 
not from the patch banks? When the SRAM (memory) failed on my P6 the 
patch banks just contained random bit patterns which produced sound 
which could be very much be described as 'out of tune'! Just a 
thought...

Cheers,
Andy




--- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@...> wrote:
>
> Thanks Andy,
> 
> The LEDS (D10) does light in order in polymode (which I think was 
what
> you meant?) -in unison they all light simultaniously.
> In Polymode all voices sounds equally (bad).
> 
> 
> I'm not sure about your last question (Can you lay your hands on a
> logic probe at all?)?  
> 
> 
> Cheers,
> Peter
> 
> 
> --- In PolySix@yahoogroups.com, "Andrew Jury" <andy@> wrote:
> >
> > Hi Peter,
> > 
> > I am afraid we can't make that assumption until the logic that 
controls 
> > IC31 has been tested. This device is basically a switch. You 
apply a 
> > binary pattern to lines A, B, C and INH and this determines which 
one 
> > of the outputs is connected to the input. The input is marked X 
the 
> > outputs marked X0, X1, X2, etc. It is the outputs which we just 
tested 
> > and which don't seem to move. Tell me, do the voice LEDs (D10) 
come on 
> > in order in Unison mode? Everytime you press a key an alternate 
voice 

> > LED should light up. I suspect not?
> > 
> > Can you lay your hands on a logic probe at all?
> > 
> > Cheers,
> > Andy
> >
>

Hi Peter,

Your P6 problem is really starting to bug me! Could you take a 
voltage measurement from IC17 between pins 5, 6, and 7 and ground? It 
will be interesting to see what is going into the mux.

Cheers,
Andy

--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:
>
> Peter,
> 
> The logic probe measures whether logic states in TTL or CMOS 
> circuitry are a binary 1 or 0. Remember we talked about how the 
> binary pattern on lines A, B, C, INH set which outputs on IC31 are 
> selected? This tool would tell us how they are set and whether they 
> were switching on a the right time.
> 
> However, from the description how the six LEDs are lighting up 
(yes, 
> one after the other in POLY mode - I am an idiot!) it sounds like 
> IC31 is working correctly and keyboard assigner is sending the 
right 
> binary pattern to the switch. 
> 
> I expect the input on pin 3 is the problem. What I will do is take 
> some reading from my working Polysix and let you know how the 
> circuitry should function. I'll post this after the weekend, if you 
> can wait.
> 
> Also, I'll take you are playing with the settings in manual mode 
and 
> not from the patch banks? When the SRAM (memory) failed on my P6 
the 
> patch banks just contained random bit patterns which produced sound 
> which could be very much be described as 'out of tune'! Just a 
> thought...
> 
> Cheers,
> Andy
> 
> 
> 
> 
> --- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@> wrote:
> >
> > Thanks Andy,
> > 
> > The LEDS (D10) does light in order in polymode (which I think was 
> what
> > you meant?) -in unison they all light simultaniously.
> > In Polymode all voices sounds equally (bad).
> > 
> > 
> > I'm not sure about your last question (Can you lay your hands on a
> > logic probe at all?)?  
> > 
> > 
> > Cheers,
> > Peter
> > 
> > 
> > --- In PolySix@yahoogroups.com, "Andrew Jury" <andy@> wrote:
> > >
> > > Hi Peter,
> > > 
> > > I am afraid we can't make that assumption until the logic that 
> controls 
> > > IC31 has been tested. This device is basically a switch. You 
> apply a 
> > > binary pattern to lines A, B, C and INH and this determines 
which 

> one 
> > > of the outputs is connected to the input. The input is marked X 
> the 
> > > outputs marked X0, X1, X2, etc. It is the outputs which we just 
> tested 
> > > and which don't seem to move. Tell me, do the voice LEDs (D10) 
> come on 
> > > in order in Unison mode? Everytime you press a key an alternate 
> voice 
> > > LED should light up. I suspect not?
> > > 
> > > Can you lay your hands on a logic probe at all?
> > > 
> > > Cheers,
> > > Andy
> > >
> >
>

Here are my measurements:

5: -9.90v
6: -9.92v
7: -8.55v

Also I discovred an interresting thing -voice 3 + 5 are slightly
distorted -sounds like mg (running at a high frequency) is applied,
but frequency does not change when changing MG, PWM or effect
frequency. Also when probing pin 6 on IC17 all voices are distorted in
a similar way.

/Peter



--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:

>
> Hi Peter,
> 
> Your P6 problem is really starting to bug me! Could you take a 
> voltage measurement from IC17 between pins 5, 6, and 7 and ground? It 
> will be interesting to see what is going into the mux.
>

Peter,

The act of you placing your DVM probes in-circuit is changing the 
eletrical characteristics of it. Hence, the changes in the sound. Did 
you I hear you right? Did you just say that the MG, PWM and effect 
frequency controls aren't working either?! If so I would be looking 
for disconnected tracks on the KLM-367 as a priority!

I'll get you some comparisons after the weekend.

Have a good one,
Andy

If you'd rather take this topic offline rather than bothering all 
these good people with this lengthy topic then please be my guest. We 
can post the answer when we have it!

--- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@...> wrote:
>
> Here are my measurements:
> 
> 5: -9.90v
> 6: -9.92v
> 7: -8.55v
> 
> Also I discovred an interresting thing -voice 3 + 5 are slightly
> distorted -sounds like mg (running at a high frequency) is applied,
> but frequency does not change when changing MG, PWM or effect
> frequency. Also when probing pin 6 on IC17 all voices are distorted 
in
> a similar way.
> 
> /Peter
> 
> 
> 
> --- In PolySix@yahoogroups.com, "Andrew Jury" <andy@> wrote:
> >
> > Hi Peter,
> > 
> > Your P6 problem is really starting to bug me! Could you take a 
> > voltage measurement from IC17 between pins 5, 6, and 7 and 
ground? It 

> > will be interesting to see what is going into the mux.
> >
>

Hi Andy

Sorry to confuse you -all controlls works as they should. I just
wanted to clearify that the distortion on two of the voices wasn't
caused by either MG, PWM or effect.

I'll try to swich the SSM's around to see if that changes which voices
are distorted.

And as an additional information -I ofcause changed the battery to a
lithium within 24 hours after I bought it. And luckily the old battery
had not leaked yet :-)

Have a nice weekend too :-)

Peter

> The act of you placing your DVM probes in-circuit is changing the 
> eletrical characteristics of it. Hence, the changes in the sound. Did 
> you I hear you right? Did you just say that the MG, PWM and effect 
> frequency controls aren't working either?! If so I would be looking 
> for disconnected tracks on the KLM-367 as a priority!
> 
> I'll get you some comparisons after the weekend.

Hi Peter,

Lucky you! My processor board was totally frazzled by flying nickel 
cadmium powder! Just wanted to check I understood you OK with regards 
to the controls. I have had a quick inspection of my Polysix and have 
to tell you that I concur with your dc voltage readings around IC31. 
we have an extra days holiday here in the UK tomorrow and I will have 
a bit more of a poke around inside. I'll let you know...

Cheers,
Andy


--- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@...> wrote:
>
> Hi Andy
> 
> Sorry to confuse you -all controlls works as they should. I just
> wanted to clearify that the distortion on two of the voices wasn't
> caused by either MG, PWM or effect.
> 
> I'll try to swich the SSM's around to see if that changes which 
voices
> are distorted.
> 
> And as an additional information -I ofcause changed the battery to a
> lithium within 24 hours after I bought it. And luckily the old 
battery
> had not leaked yet :-)
> 
> Have a nice weekend too :-)
> 
> Peter
> 
> 
> > The act of you placing your DVM probes in-circuit is changing the 
> > eletrical characteristics of it. Hence, the changes in the sound. 
Did 
> > you I hear you right? Did you just say that the MG, PWM and 
effect 
> > frequency controls aren't working either?! If so I would be 
looking 

> > for disconnected tracks on the KLM-367 as a priority!
> > 
> > I'll get you some comparisons after the weekend.
>

Thanks Andy!

I really appreciate your help with my beloved Polysix.

Last night I tried to switch the VCO's (SSM 2056) but no change in
which voice was distorted.

Just a summary:
* All voices are equally out of tune
* 2 voices have a "distorted" effect. I will record and post a
sample... -however the frequency of the distortion changes during the
initial self-tuning procedure.
* All controlls/keys works perfectly
* My tests are performed in manual mode with cutoff=10 and resonance=0

Cheers,
Peter

--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:

> we have an extra days holiday here in the UK tomorrow and I will have 
> a bit more of a poke around inside. I'll let you know...
> 
> Cheers,
> Andy
> 
> 
> --- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@> wrote:
> >
> > Hi Andy
> > 
> > Sorry to confuse you -all controlls works as they should. I just
> > wanted to clearify that the distortion on two of the voices wasn't
> > caused by either MG, PWM or effect.
> > 
> > I'll try to swich the SSM's around to see if that changes which 
> voices
> > are distorted.
> > 
> > And as an additional information -I ofcause changed the battery to a
> > lithium within 24 hours after I bought it. And luckily the old 
> battery
> > had not leaked yet :-)
> > 
> > Have a nice weekend too :-)
> > 
> > Peter
> > 
> > 
> > > The act of you placing your DVM probes in-circuit is changing the 
> > > eletrical characteristics of it. Hence, the changes in the sound. 
> Did 
> > > you I hear you right? Did you just say that the MG, PWM and 
> effect 
> > > frequency controls aren't working either?! If so I would be 
> looking 
> > > for disconnected tracks on the KLM-367 as a priority!
> > > 
> > > I'll get you some comparisons after the weekend.
> >
>

Im no tech-pro, but i was having an unusual 'out-of-tune-voice' problem with my Chroma Polaris that 'experts' on the polaris users group said was caused by bad capacitors in the sample and hold circuits. i dont know if it has anything to do with your polysix problem, but it sounds slightly similar.  the polaris would not play through a scale without sounding like the intervals were wrong. and its self tuning procedure did nothing to fix it.

----- Original Message ----
From: hjulskov <hjulskov@yahoo.com>
To: PolySix@yahoogroups.com
Sent: Tuesday, August 26, 2008 3:32:24 AM
Subject: [PolySix] Re: Suddenly out of tune -but still problems after changing PC-1 and R93


Thanks Andy!

I really appreciate your help with my beloved Polysix.

Last night I tried to switch the VCO's (SSM 2056) but no change in
which voice was distorted.

Just a summary:
* All voices are equally out of tune
* 2 voices have a "distorted" effect.. I will record and post a
sample... -however the frequency of the distortion changes during the
initial self-tuning procedure.
* All controlls/keys works perfectly
* My tests are performed in manual mode with cutoff=10 and resonance=0

Cheers,
Peter

--- In PolySix@yahoogroups .com, "Andrew Jury" <andy@...> wrote:
> we have an extra days holiday here in the UK tomorrow and I will have 
> a bit more of a poke around inside. I'll let you know...
> 
> Cheers,
> Andy
> 
> 
> --- In PolySix@yahoogroups .com, "hjulskov" <hjulskov@> wrote:
> >
> > Hi Andy
> > 
> > Sorry to confuse you -all controlls works as they should. I just
> > wanted to clearify that the distortion on two of the voices wasn't
> > caused by either MG, PWM or effect.
> > 
> > I'll try to swich the SSM's around to see if that changes which 
> voices
> > are distorted.
> > 
> > And as an additional information -I ofcause changed the battery to a
> > lithium within 24 hours after I bought it. And luckily the old 
> battery
> > had not leaked yet :-)
> > 
> > Have a nice weekend too :-)
> > 
> > Peter
> > 
> > 
> > > The act of you placing your DVM probes in-circuit is changing the 
> > > eletrical characteristics of it. Hence, the changes in the sound. 
> Did 
> > > you I hear you right? Did you just say that the MG, PWM and 
> effect 
> > > frequency controls aren't working either?! If so I would be 
> looking 
> > > for disconnected tracks on the KLM-367 as a priority!
> > > 
> > > I'll get you some comparisons after the weekend.
> >
>

 


      

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

I'm no expert either, but it sounds possible that the caps needs
replacement -if no other suggestions comes up -that would be my first
attempt to fix it.

Btw. I have uploaded a sample to the files section; First testing the
six voices (you can hear distortion to voice 3 and 5) finally playing
"just can't get enough" :-)

/Peter


--- In PolySix@yahoogroups.com, steven pistrich <wasteking1@...> wrote:
>
> Im no tech-pro, but i was having an unusual 'out-of-tune-voice'
problem with my Chroma Polaris that 'experts' on the polaris users
group said was caused by bad capacitors in the sample and hold
circuits. i dont know if it has anything to do with your polysix
problem, but it sounds slightly similar.  the polaris would not play
through a scale without sounding like the intervals were wrong. and
its self tuning procedure did nothing to fix it.

Peter,

If only the P6 had a sample and hold circuit! Good point about 
capacitors, especially electrolytic types, which could have well 
dried up after 25+ years service. But do test them first before 
binning them. I had what I though was a suspect capacitor in circuit 
(0.33uF). It still measured 0.339uF after all that time!

However, I listened to the sample and the croaky voices sounded just 
like mine before I replaced the VCF chips. I only has a single voice 
out. Try swaping the IC32 between voices (SSM2044) and see what 
happens. 

Did you get the 'private' message I sent you?

Cheers,
Andy

--- In PolySix@yahoogroups.com, "hjulskov" <hjulskov@...> wrote:
>
> I'm no expert either, but it sounds possible that the caps needs
> replacement -if no other suggestions comes up -that would be my 
first
> attempt to fix it.
> 
> Btw. I have uploaded a sample to the files section; First testing 
the
> six voices (you can hear distortion to voice 3 and 5) finally 
playing

> "just can't get enough" :-)
> 
> /Peter
> 
> 
> --- In PolySix@yahoogroups.com, steven pistrich <wasteking1@> wrote:
> >
> > Im no tech-pro, but i was having an unusual 'out-of-tune-voice'
> problem with my Chroma Polaris that 'experts' on the polaris users
> group said was caused by bad capacitors in the sample and hold
> circuits. i dont know if it has anything to do with your polysix
> problem, but it sounds slightly similar.  the polaris would not play
> through a scale without sounding like the intervals were wrong. and
> its self tuning procedure did nothing to fix it.
>

Hi Andy,

I'll try swapping the SSM2044's -after the weekeend (I'm away this
weekend).

I didn't get the PM -try sending it again.

Have a nice weekend!
Peter
 

--- In PolySix@yahoogroups.com, "Andrew Jury" <andy@...> wrote:
...

> However, I listened to the sample and the croaky voices sounded just 
> like mine before I replaced the VCF chips. I only has a single voice 
> out. Try swaping the IC32 between voices (SSM2044) and see what 
> happens. 
> 
> Did you get the 'private' message I sent you?