hey new to the group, been lurking for a while :)

I've tried to find a MP in the States for better part of a year without any
luck! Anyone know of one for sale, or have one they wish to part with? It will
go to a good synth loving home.

--- In korg_mono-poly@yahoogroups.com, Jeppe <joppemadsen@...> wrote:
>
> Hey I was just wondering. Does anyone know how many Mono/Polys korg produced?
In my experience they are often for sale online, so I guess there is a lot
around? How rare are they?
>
> Venlig Hilsen / Regards
> Jeppe
>


According to VSE, around 10000 units were produced.

Hi all,

I'm a owner of a japanese old revision MP4 that died on me yesterday.

What happened:
- I just finished modding the MP4 with several great mods I found here (the MG1
speed and EG speed). It was working fine than I decided while I was on it to
check on the FX on switch that was not working correctly.
So I had to remove the KLM354 board first (I never did it so far) to reach the
switch. I resolder the switch and then I powered the synth on, while still
having the 354 board not in place (but fully plugged). I check that there was no
shorting whith the 354 board floating. It seems ok.

But when it powers on I did not see the leds go on and a few seconds later I saw
smoke coming from the 354 board. I immediately turned it off. I checked where it
could come, it seemed coming from the SSM2033 but I could not confirm, I could
not find a part that was really hot.
I put the 354 back in place, checking every connector to see if there was some
loose or some shorts.
When I second turn the synth on the MG2 led showed, followed by MG1, though they
seemed dimmed. I could play the synth for a second and then it completely died
and I could not turn it on since that.

Now I don't know the exact damages and would like some help to revive it.

What is sure is that the 376 board is damaged because I don't have the +15v -15V
or 5V.
So far the reading I got are (schematic is here:
http://fa.utfs.org/diy/korg_monopoly/mp_10_klm-376_powersupply_klm-357_vcoheater\
_schemo.gif):
- 26.5v out of the transformer (on KLM376/ cn37 connector)
- +37v and -37v from the 1S1885 diodes to the inputs of the M5230L (pin 7 and 4)

I have no output reading from the M5230L. So does it means this one is fried or
can it be some other componant that makes that I have no output from the M5230L
?
I'm not a real technician, I don't know much but if someone can explain I can
track the problem.

Hope someone can help.
Thanx in advance

Hello iscrites

first of all before you switch on the synth: unplug the five connectors
CN 31 - CN 35 from the powersupply before you start working again. Do
not reconnect them until den power supply works correctly. After the
powersupply has been repaired. Connect them one by one and measure the
voltages after adding each connector.


To the problem:

  > - 26.5v out of the transformer (on KLM376/ cn37 connector)
26.5V AC between the two hot transformer outputs looks reasonable.


  > - +37v and -37v from the 1S1885 diodes to the inputs of the M5230L
(pin 7 and 4)
Did you measure this against ground (pin1 of M3250L) or did you measure
7 against 4? If 7 against 4, then it sounds reasonable. What does read 7
against 1 and 4 against 1?

What is broken then I cannot judge? And often it does not make sense to
repair such an old powersupply.

You may use simply a completely different powersupply, which provides
+15,-15 and +5 Volts. You may use also a switching powersupply block
like a Mean Well or a Traco. I prefer Tracos as they are nearly
undestroyable.

Florian





Am 23.10.2012 14:45, schrieb iscrites:
> What is sure is that the 376 board is damaged because I don't have the +15v
-15V or 5V.
> So far the reading I got are (schematic is here:
http://fa.utfs.org/diy/korg_monopoly/mp_10_klm-376_powersupply_klm-357_vcoheater\
_schemo.gif):
> - 26.5v out of the transformer (on KLM376/ cn37 connector)
> - +37v and -37v from the 1S1885 diodes to the inputs of the M5230L (pin 7 and
4)
>
> I have no output reading from the M5230L. So does it means this one is fried
or can it be some other componant that makes that I have no output from the
M5230L ?
> I'm not a real technician, I don't know much but if someone can explain I can
track the problem.
>
> Hope someone can help.
> Thanx in advance
>

--
http://fa.utfs.org/

Thanx for the reply.

I took the precaution of unpluging the 5 left connectors.
Though when I did it I have the 4 VCO leds that lit. I guess the power comes
from the KLM357 board but how does this one get it ?
There is a red wire connecting + side of KLM376 C14 to input of KLM327, so I
guess it come from that.

To answer your question:
- I got -37v between pin 1 and 4 of the M3250L
Actually I have a fried resistor on R15 so I can't read pin 7 but I read 37v on
+ side of C14, so it should be the same on pin 7 wasn't it for the fried
resistor.
I fried that resistor (I guess) by reading C13 yesterday and I guess I short
circuit the C13, there was a explosion and the R15 was fried. Well maybe it was
fried before the explosion but I didn't notice it.
I did not mention this because I guess it should still get the -15v and +5V even
without it, no ? (I just don't have a 130 resistor on hand)
Another thing is I don't always get the same readings. Sometime it's more 35v
and sometimes more 37v.

I thought of changing the power suplly completely (and using a 230v one) but I
lack some knowledge:

- what current rating does it need to be ?
- how should I feed the 36v to the KLM327 ?
- how do I make the 5 connectors (by cannibalizing the KLM376) ?

Can you point me with an appropriate power supply ? (on ebay, mouser, conrad
etc)

Thanx a lot

Hello

> I thought of changing the power suplly completely (and using a 230v one) but I
lack some knowledge:
>
> - what current rating does it need to be ?
I think you will need 150mA for each section, but I am not sure. The
specification in the servicemanual does not name it.

> - how should I feed the 36v to the KLM327 ?
argh! I forgot about these. It will make it complicated.


> - how do I make the 5 connectors (by cannibalizing the KLM376) ?
Yes

> Can you point me with an appropriate power supply ? (on ebay, mouser, conrad
etc)
If my specifications are right
http://de.farnell.com/tracopower/tmp-15515/wandler-ac-dc-5v-15v-15w-module/dp/16\
72148


Maybe you should look out for a used Polysix PSU. They might be identical.


Florian

--
http://fa.utfs.org/

So I guess without the 36v for the KLM327 it is not possible to use another
power supply.

Also forgot to ask earlier but if you use another power supply, how can you fine
tune the voltage to make it meet the specifications in the service manual ?

Hi,

I got a mp4 that I recently  recalibrated and is working very nicely.
Tuning/scaling is very good.
I checked all the voltage and got good and steady readings on the power supply
and keyboard CV voltages.

But when it comes to measure the VCO offset in the klm398 I don't get the 0.000v
+/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I play
notes on the keyboard. The voltages are responsive to the different VR on the
board but I can't make them 0.000v.

So question are:
- Am I reading the good points ? i connected to J12 and to the respective 4
colour wires mentionned in the manual (and corrected here for new version)
- Is there a key to press while reading ?
- Is it dangerous for the OSC to have these readings ? As i mentionned my mp4 is
really nice tuned and scaled, for every oscillators.

Am 29.10.2012 01:53, schrieb ohmstudiste:
> Hi,
>
> I got a mp4 that I recently  recalibrated and is working very nicely.
Tuning/scaling is very good.
> I checked all the voltage and got good and steady readings on the power supply
and keyboard CV voltages.
>
> But when it comes to measure the VCO offset in the klm398 I don't get the
0.000v +/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I
play notes on the keyboard. The voltages are responsive to the different VR on
the board but I can't make them 0.000v.
>
> So question are:
> - Am I reading the good points ? i connected to J12 and to the respective 4
colour wires mentionned in the manual (and corrected here for new version)
> - Is there a key to press while reading ?
> - Is it dangerous for the OSC to have these readings ? As i mentionned my mp4
is really nice tuned and scaled, for every oscillators.

Others may correct me, but I think you misunderstood the adjustment
description: As far as I understand it right this is not a trimming to
absolute 0.000V +/- 1mV, but the voltages should not vary more than 1mV
in relation to each other.

Florian
--
http://fa.utfs.org/

I went through this when I rebuilt my trainwreck Mono/Poly. The offset is
obviously only a part of the overall procedure but it was a case of adjusting to
get as close to zero as possible but measured at pins 1,3,5&7 on connector 39.
The whole procedure I used is in the forum 'Files' section under 'Misc Files' -
'Poly.pdf'.
Good luck
Steve

--- In korg_mono-poly@yahoogroups.com, "ohmstudiste" <ohmstudist@...> wrote:
>
> Hi,
>
> I got a mp4 that I recently  recalibrated and is working very nicely.
Tuning/scaling is very good.
> I checked all the voltage and got good and steady readings on the power supply
and keyboard CV voltages.
>
> But when it comes to measure the VCO offset in the klm398 I don't get the
0.000v +/- 1mv. Instead I read voltages bretween 1v and 3v and they change if I
play notes on the keyboard. The voltages are responsive to the different VR on
the board but I can't make them 0.000v.
>
> So question are:
> - Am I reading the good points ? i connected to J12 and to the respective 4
colour wires mentionned in the manual (and corrected here for new version)
> - Is there a key to press while reading ?
> - Is it dangerous for the OSC to have these readings ? As i mentionned my mp4
is really nice tuned and scaled, for every oscillators.
>

Oh stupid of me !
Than it makes sense of course. And now I managed to adjust them correctly (there
was a 0.05v drift).

> Others may correct me, but I think you misunderstood the adjustment
> description: As far as I understand it right this is not a trimming to
> absolute 0.000V +/- 1mV, but the voltages should not vary more than 1mV
> in relation to each other.
>
> Florian
> --
> http://fa.utfs.org/
>

Some news:
After several attempts of reviving the power supply I bought a 15v, -15v and 5v
power supply and installed it today.

Good news is that it works and almost every aspect of the monopoly is working.
The only problem I have now is that if the KLM398 board is connected, the sound
of the osc is a weak distorded high pitched sound and I can not pitch the sound
(either with the keyboard or arp or transpose).

If I disconnect the board, I have 4 perfectly sounding osc which I can change
waveform, but still no pitch control.

I thought the 398 was the culprit but I changed the 2x TL072 and it did not
change anything.

I guess the problem is with voltage control of the OSC. Where should I
investigate ?
i checked the voltage on the connectors of every board and I read the 15v, 15v
and 5v.

HI Jeppe,
Have you find a solution to this issue ?

Thank you

--- In korg_mono-poly@yahoogroups.com, "Jeppe" <jeppe@...> wrote:
>
> Hey Florian. Thanks for the info.
> Jeppe
>
> > Hi Jeppe
> >
> >
> > I am not sure, whether I answered you personally or not. So once again
> > to the list: This should be a faulty IC7 on the VCO board. Originally a
> > HD14066BP, but you can take a CD4066B (or even a CD4016B which is pin
> > compatible) without any problem.
> > If you replace this chip, it might(!) be possible that you have to
> > readjust the V/Octave setting
> >
> > Florian
> >
> >
> >
> >> Hello everyone.
> >>
> >> So, I bought my MP almost a year ago, which resulted in me selling all
> >> the other synths I had laying around - they all faded in comparison. It
> >> sounds so fraking good!
> >>
> >> One problem though. My VCO 2 wont stop "portamentoing" before the MP has
> >> been turned on for more then an hour. This means I often have to play it
> >> with VCO 2 turned alle the way down. And in Poly mode it's quite
> >> annoying (even thoughs it is a cool effect with one oscillator sliding
> >> after the other in a sloppy fashion when doing chords).
> >>
> >> When i turn the portamento button all the way down VCO 2 acts like
> >> portamento is turned all the way up. When i turn the portamento button
> >> up a notch VCO 2 acts like the other VCO's.
> >>
> >> Do you have any experience with this problem?
> >>
> >> Oh, and is it possible to repair the microcontroller buttons on the MP?
> >> My "hold" buttons is very bad at senseing when i press it.
> >>
> >> Thanks a lot.
> >> Jeppe
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >
> >
>
>
> --
> Jeppe Madsen
> Tlf. 22395163
> Dalgas Boulevard 137 4. TV.
> 2000 Frederiksberg
> Jeppe@...
>

Hello,
I just read on http://fa.utfs.org/diy/korg_monopoly/modifications.html about a
modification "VCO 4 as alternative modulation source for the modwheel (filter
cross modulation)"

Do you have any more info about this ?

Thank you very much

Hello

Am 22.11.2012 13:13, schrieb dir_marillion:
> Hello,
> I just read on http://fa.utfs.org/diy/korg_monopoly/modifications.html about a
modification "VCO 4 as alternative modulation source for the modwheel (filter
cross modulation)"
>
> Do you have any more info about this ?

What information do you need?

Florian
--
http://fa.utfs.org/

Oh uuuups: I see that the description is missing. Sorry. I had to
restore a backup of these pages some time ago and it seems I did not
have a backup of the latest version. I hope I will find it on my machine
at home. This may take a day or two.

Florian

Am 22.11.2012 13:42, schrieb Florian Anwander:
> What information do you need?
>
> Florian


--
http://fa.utfs.org/

 

HI Jeppe,
Have you find a solution to this issue ?

Thank you

--- In korg_mono-poly@yahoogroups.com, "Jeppe" <jeppe@...> wrote:
>
> Hey Florian. Thanks for the info.
> Jeppe
>
> > Hi Jeppe
> >
> >
> > I am not sure, whether I answered you personally or not. So once again
> > to the list: This should be a faulty IC7 on the VCO board. Originally a
> > HD14066BP, but you can take a CD4066B (or even a CD4016B which is pin
> > compatible) without any problem.
> > If you replace this chip, it might(!) be possible that you have to
> > readjust the V/Octave setting
> >
> > Florian
> >
> >
> >
> >> Hello everyone.
> >>
> >> So, I bought my MP almost a year ago, which resulted in me selling all
> >> the other synths I had laying around - they all faded in comparison. It
> >> sounds so fraking good!
> >>
> >> One problem though. My VCO 2 wont stop "portamentoing" before the MP has
> >> been turned on for more then an hour. This means I often have to play it
> >> with VCO 2 turned alle the way down. And in Poly mode it's quite
> >> annoying (even thoughs it is a cool effect with one oscillator sliding
> >> after the other in a sloppy fashion when doing chords).
> >>
> >> When i turn the portamento button all the way down VCO 2 acts like
> >> portamento is turned all the way up. When i turn the portamento button
> >> up a notch VCO 2 acts like the other VCO's.
> >>
> >> Do you have any experience with this problem?
> >>
> >> Oh, and is it possible to repair the microcontroller buttons on the MP?
> >> My "hold" buttons is very bad at senseing when i press it.
> >>
> >> Thanks a lot.
> >> Jeppe
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >
> >
>
>
> --
> Jeppe Madsen
> Tlf. 22395163
> Dalgas Boulevard 137 4. TV.
> 2000 Frederiksberg
> Jeppe@...
>

I would also be interested in doying this mod.

Also is there a way to add a random mode to the Arpegiator ??

> > Hello,
> > I just read on http://fa.utfs.org/diy/korg_monopoly/modifications.html about
a modification "VCO 4 as alternative modulation source for the modwheel (filter
cross modulation)"
> >
> > Do you have any more info about this ?

--- In korg_mono-poly@yahoogroups.com, "iscrites" <i.scrites@...> wrote:
>
> I would also be interested in doying this mod.
>
> Also is there a way to add a random mode to the Arpegiator ??
>
> > > Hello,
> > > I just read on http://fa.utfs.org/diy/korg_monopoly/modifications.html
about a modification "VCO 4 as alternative modulation source for the modwheel
(filter cross modulation)"
> > >
> > > Do you have any more info about this ?
>

It seems a very interesting mod

Step 7 in the calibration procedure is the Resonance VCA check and adjustment...
I am curious what is going on here,  the Polysix doesn't have this circuitry in
it's implementation of the SSM2044,  and neither does the PPG wave.  What is
going on here with Q10 and VR4?

is this to compensate for volume loss with increasing Q?

-steve

Hello, any information-schematics-documentation on this modification  (VCO 4 as
alternative modulation source for the modwheel -filter cross modulation)? Please
Florian, share with us, this is probably the mod I was dreaming of for my
mono/poly.

--- In korg_mono-poly@yahoogroups.com, "dir_marillion" <dir_marillion@...>
wrote:
>
>
>
> --- In korg_mono-poly@yahoogroups.com, "iscrites" <i.scrites@> wrote:
> >
> > I would also be interested in doying this mod.
> >
> > Also is there a way to add a random mode to the Arpegiator ??
> >
> > > > Hello,
> > > > I just read on http://fa.utfs.org/diy/korg_monopoly/modifications.html
about a modification "VCO 4 as alternative modulation source for the modwheel
(filter cross modulation)"
> > > >
> > > > Do you have any more info about this ?
> >
>
> It seems a very interesting mod
>

Am 10.12.2012 08:39, schrieb iluvator:
> Hello, any information-schematics-documentation on this modification
> (VCO 4 as alternative modulation source for the modwheel -filter
> cross modulation)? Please Florian, share with us, this is probably
> the mod I was dreaming of for my mono/poly.

I am sorry, but I have not time for things like that at the moment.

I will do that somewhen next year

Florian

--- In korg_mono-poly@yahoogroups.com, Florian Anwander <fanwander@...> wrote:
>
> Am 10.12.2012 08:39, schrieb iluvator:
> > Hello, any information-schematics-documentation on this modification
> > (VCO 4 as alternative modulation source for the modwheel -filter
> > cross modulation)? Please Florian, share with us, this is probably
> > the mod I was dreaming of for my mono/poly.
>
> I am sorry, but I have not time for things like that at the moment.
>
> I will do that somewhen next year
>
> Florian
>

Florian, are you sure that this kind of modification exists and it is not an
opened project ?

I am asking you because I have searched a lot of Mono/Poly relative documents
and never found something like that.

Hello

On 11.12.12 21:36 , dir_marillion wrote:
> Florian, are you sure that this kind of modification exists and it is not an
opened project ?
It works in my MP. It is basically simple:
insert a two position switch in the line between MG1 and Modwheel and
connect the output of VCO4 (pre level 4) to the other pole of the switch.

Florian