Discussion about the Korg PolySix synthesizer

> Why it was soldered,

> and do i need to unsolder?

On 22.11.2013 11:42, iorlovs@yahoo.com wrote:
>
>
> At the top right corner of KLM368a board i have found soldered diod
> (/*image*/ a/*ttached*/). Why it was soldered, and do i need to unsolder?
>
>
>
> http://groups.yahoo.com/neo/groups/PolySix/photos/albums/1404048030/lightbox/737952942
>
>
>

> On Dec 28, 2013, at 7:02 AM, Terje Winther <terje.winther@wintherstormer.no> wrote:
>
> Hi all,
>
> I do a lot of analog synth service here in Norway. One customer
> brought in no less than 4 Polysix´es for service, and in the end I was
> given one of them as payment for the repairs.
> The one I ended up with was quite good-looking (front panel complete
> with all original parts, keyboard nice, case quite all right etc.). It
> did have some technical issues (one dead voice, several controls not
> working properly, memory system out of order etc.). There was some
> damage after the usual battery problem, and someone had tried to fix
> it, but it was not a professional job. I started repair on the
> processor board, but as I did so, I also searched the web for info,
> and at the same time (good timing!) there was a discussion on the
> Yahoo Polysix discussion list regarding some modifications. This got
> me thinking, and after some reading and considering, I decided to "go
> crazy" with the Polysix as I once did with my old ARP Axxe -
> installing all kinds of modifications. However: all of them should be
> useful, musical and well done. So this is what I did with my newly
> acquired Korg Polysix:
>
> - Completely took everything apart
> - Removed rust
> - Cleaned and dusted everything
> - Replaced missing rubber foot with new original
> - Replaced old hardware with new hardware (screws and spacers)
> - Repaired two broken voices (bad SSM2056 chip on one voice, and bad
> SSM2044 chip on the other)
> - Removed the old power supply board and installed the new power
> supply board from Kiwitechnics (brilliant kit!)
> - Removed the damaged old processor board and installed the new
> processor board from Kiwitechnics: the Kiwisix (even more brilliant!)
> - Removed the two rear cable holders (not needed anymore because of
> the Kiwisix upgrade)
> - Improved grounding as suggested by Kiwitechnics (new wires, some
> cutting in the aluminium foil)
> - Installed the Polysex modulation kit
> - Made a new LFO (MG) as a substitute for the PWM MG to the Polysex
> mod kit, complete with speed pot and dual-colour LED
> - Installed a toggle switch, so that the modwheel control to VCO can
> be selected between internal MG (as original) or the new extra LFO/MG
> installed for the Polysex kit
> - Recapped the 3 electrolytic caps per voice (x 6) in the analog voice
> chain on the voice card with very high quality "gold audio" el. caps
> - Made the FX in/out modification, so I can have direct out, and use
> the FX board as an pure effects board, or use the send/return for
> additional treatments
> - Made the post-effects modification for the effects board, with on/
> off switch (complex multiway switching)
> - Made the bass modification on the effects board, with on/off switch
> - Made the treble modification on the effects, with on/off switch
> - Installed the "VCO to VCF" modification as suggested by the late
> Jürgen Haible (rip) with individual on/off switches per voice, and
> with a total amount pot for all voices. An extra veroboard with 6 VCA
> was needed for this, with a lot of flying wires. This mod was a lot of
> work.
> - Swapped out the 6 tiny LEDs per voice on the voice card, and wired
> the new switches (same switches as the VCO-VCF mod above) with
> internal LEDs on the front panel (these were quite expensive)
> - Changed all 6 LED driver resistors for more brightness on the voice
> LEDs (originally 4.7k, now 1.2k)
> - Did the final touches, like mounting the new Kiwisix front panel
> sticker and manual marking of the various other mods
> - Mounted everything properly
> - Checked, debugged and calibrated everything
>
> Some comments:
> - The Polysex modification kit use several analog signals, including
> two analog signals from the old Korg processor: MG and the PWM LFO.
> They are not present on the new Kiwisix processor board, because
> everything is processed internally before CVs are sent to the analog
> voice card. However; there is one analog signal called "LFO" coming
> from the Kiwisix processor card, and on the Polysex web site it state
> that you can use this signal, but that is only partially true. There
> is an analog signal there, but it is only for turning the front panel
> LED for the MG on and off. So there is no smooth modulation, only a
> square wave. Useful in some settings, but not as intended. Solutions:
> a. Use it as it is, which gives you "trills" and not sliding detune
> (spread). Works for me, and I will use this alternative for now
> b. Modify the squarewave LFO signal into quasi triangle signal, either
> with a crude RC network, or with a 4046 chip
> c. Make your own LFOs
>
> - Since I made an extra LFO for the Polysex mod kit, I had the idea
> that I could also route the new LFO to the mod wheel, which I did.
> That way I could use the internal LFO (MG) to VCF and VCA, and the new
> LFO to VCO with another setting for added variation. However, because
> the new Kiwisix processor needed access to the modwheel in order to
> handle MIDI I/O, that didn´t work. I still implemented it, though, but
> have to be careful not to overload the outgoing MIDI signal. The
> result is a bit different to what you think, but it does give me some
> alternatives for performance.
>
> - The bass mod. It does works, but either my ears aren´t good enough,
> or my speaker system (with sub-woofer) isn´t good enough, because I
> really can´t hear that much difference. I needed to measure it to
> confirm that it worked properly.
>
> - For the treble mod I first tried with a resistor similar to the one
> in my synth, which was a 4.7k resistor, and not a 33k resistor as in
> the service manual and on the web mod pages (...and the 1k resistor
> that is supposed to be there is not present on my synth). That really
> didn´t work. It was suggested I used a 33k resistor over the 22k
> resistor, and I had a hard time understanding how that could work, but
> in the end I found an 30.9k resistor that worked very good.
>
> - I bought the wrong versions of the front panel switches with
> internal LEDs in them: They had the right colour (green), but I bought
> the versions where the LED on/off are synchronous with the switch. I
> wanted the voice LED to work all the time. Now they will only work
> when the "VCO - VCF" mod is on. On the other hand, then it will be
> clearly visible when the mod is on, and if I want the lightshow I can
> always turn them on, but keep the amount pot at zero.
>
> What is missing:
> - I wanted the plexiglass pitch and modwheels with LEDs, that somebody
> have offered in the past. It seems that they are unobtainable now.
> - I did consider one of those lovely new all-wooden cabinets, that you
> can have in several types of solid wood. I sent out some inquiries,
> but didn´t get any response, and my original cabinet is not that bad-
> looking after all (a little nick in front under the keys and ever so
> slight damage at the rear, lower corners), so I am keeping the
> original cabinet for now.
> - New bushings? The keyboard was quite clean and trigger fine, so no
> need for service there, but I might need to take it all apart, clean
> the contacts, take off all the keys and clean them, and install new
> bushings. Some day…
>
> All-in-all, it was a lot of work to do it all. The drilling, cable
> stripping and pre-soldering, mounting, soldering and debugging was a
> bit of work, and the planning and thinking during the project also
> took a lot of time. However, it was all highly enjoyable work, and I
> now have
> - a much better understanding of the Polysix in general
> - a much better understanding of all the mods and changes involved
> - a great-sounding and great-working polysynth!
>
> Photos of the results are in the Yahoo group photo section, under
> "Polysix Modifications".
>
>
> All the best,
>
> Terje
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo Groups Links
>
>
>

Wow!!!

Congrats Terje!!

Most powerful polysix ever????

:)

> Hi all,
>
> I do a lot of analog synth service here in Norway. One customer
> brought in no less than 4 Polysix´es for service, and in the end I was
> given one of them as payment for the repairs.
> The one I ended up with was quite good-looking (front panel complete
> with all original parts, keyboard nice, case quite all right etc.). It
> did have some technical issues (one dead voice, several controls not
> working properly, memory system out of order etc.). There was some
> damage after the usual battery problem, and someone had tried to fix
> it, but it was not a professional job. I started repair on the
> processor board, but as I did so, I also searched the web for info,
> and at the same time (good timing!) there was a discussion on the
> Yahoo Polysix discussion list regarding some modifications. This got
> me thinking, and after some reading and considering, I decided to "go
> crazy" with the Polysix as I once did with my old ARP Axxe -
> installing all kinds of modifications. However: all of them should be
> useful, musical and well done. So this is what I did with my newly
> acquired Korg Polysix:
>
> - Completely took everything apart
> - Removed rust
> - Cleaned and dusted everything
> - Replaced missing rubber foot with new original
> - Replaced old hardware with new hardware (screws and spacers)
> - Repaired two broken voices (bad SSM2056 chip on one voice, and bad
> SSM2044 chip on the other)
> - Removed the old power supply board and installed the new power
> supply board from Kiwitechnics (brilliant kit!)
> - Removed the damaged old processor board and installed the new
> processor board from Kiwitechnics: the Kiwisix (even more brilliant!)
> - Removed the two rear cable holders (not needed anymore because of
> the Kiwisix upgrade)
> - Improved grounding as suggested by Kiwitechnics (new wires, some
> cutting in the aluminium foil)
> - Installed the Polysex modulation kit
> - Made a new LFO (MG) as a substitute for the PWM MG to the Polysex
> mod kit, complete with speed pot and dual-colour LED
> - Installed a toggle switch, so that the modwheel control to VCO can
> be selected between internal MG (as original) or the new extra LFO/MG
> installed for the Polysex kit
> - Recapped the 3 electrolytic caps per voice (x 6) in the analog voice
> chain on the voice card with very high quality "gold audio" el. caps
> - Made the FX in/out modification, so I can have direct out, and use
> the FX board as an pure effects board, or use the send/return for
> additional treatments
> - Made the post-effects modification for the effects board, with on/
> off switch (complex multiway switching)
> - Made the bass modification on the effects board, with on/off switch
> - Made the treble modification on the effects, with on/off switch
> - Installed the "VCO to VCF" modification as suggested by the late
> Jürgen Haible (rip) with individual on/off switches per voice, and
> with a total amount pot for all voices. An extra veroboard with 6 VCA
> was needed for this, with a lot of flying wires. This mod was a lot of
> work.
> - Swapped out the 6 tiny LEDs per voice on the voice card, and wired
> the new switches (same switches as the VCO-VCF mod above) with
> internal LEDs on the front panel (these were quite expensive)
> - Changed all 6 LED driver resistors for more brightness on the voice
> LEDs (originally 4.7k, now 1.2k)
> - Did the final touches, like mounting the new Kiwisix front panel
> sticker and manual marking of the various other mods
> - Mounted everything properly
> - Checked, debugged and calibrated everything
>
> Some comments:
> - The Polysex modification kit use several analog signals, including
> two analog signals from the old Korg processor: MG and the PWM LFO.
> They are not present on the new Kiwisix processor board, because
> everything is processed internally before CVs are sent to the analog
> voice card. However; there is one analog signal called "LFO" coming
> from the Kiwisix processor card, and on the Polysex web site it state
> that you can use this signal, but that is only partially true. There
> is an analog signal there, but it is only for turning the front panel
> LED for the MG on and off. So there is no smooth modulation, only a
> square wave. Useful in some settings, but not as intended. Solutions:
> a. Use it as it is, which gives you "trills" and not sliding detune
> (spread). Works for me, and I will use this alternative for now
> b. Modify the squarewave LFO signal into quasi triangle signal, either
> with a crude RC network, or with a 4046 chip
> c. Make your own LFOs
>
> - Since I made an extra LFO for the Polysex mod kit, I had the idea
> that I could also route the new LFO to the mod wheel, which I did.
> That way I could use the internal LFO (MG) to VCF and VCA, and the new
> LFO to VCO with another setting for added variation. However, because
> the new Kiwisix processor needed access to the modwheel in order to
> handle MIDI I/O, that didn´t work. I still implemented it, though, but
> have to be careful not to overload the outgoing MIDI signal. The
> result is a bit different to what you think, but it does give me some
> alternatives for performance.
>
> - The bass mod. It does works, but either my ears aren´t good enough,
> or my speaker system (with sub-woofer) isn´t good enough, because I
> really can´t hear that much difference. I needed to measure it to
> confirm that it worked properly.
>
> - For the treble mod I first tried with a resistor similar to the one
> in my synth, which was a 4.7k resistor, and not a 33k resistor as in
> the service manual and on the web mod pages (...and the 1k resistor
> that is supposed to be there is not present on my synth). That really
> didn´t work. It was suggested I used a 33k resistor over the 22k
> resistor, and I had a hard time understanding how that could work, but
> in the end I found an 30.9k resistor that worked very good.
>
> - I bought the wrong versions of the front panel switches with
> internal LEDs in them: They had the right colour (green), but I bought
> the versions where the LED on/off are synchronous with the switch. I
> wanted the voice LED to work all the time. Now they will only work
> when the "VCO - VCF" mod is on. On the other hand, then it will be
> clearly visible when the mod is on, and if I want the lightshow I can
> always turn them on, but keep the amount pot at zero.
>
> What is missing:
> - I wanted the plexiglass pitch and modwheels with LEDs, that somebody
> have offered in the past. It seems that they are unobtainable now.
> - I did consider one of those lovely new all-wooden cabinets, that you
> can have in several types of solid wood. I sent out some inquiries,
> but didn´t get any response, and my original cabinet is not that bad-
> looking after all (a little nick in front under the keys and ever so
> slight damage at the rear, lower corners), so I am keeping the
> original cabinet for now.
> - New bushings? The keyboard was quite clean and trigger fine, so no
> need for service there, but I might need to take it all apart, clean
> the contacts, take off all the keys and clean them, and install new
> bushings. Some day…
>
> All-in-all, it was a lot of work to do it all. The drilling, cable
> stripping and pre-soldering, mounting, soldering and debugging was a
> bit of work, and the planning and thinking during the project also
> took a lot of time. However, it was all highly enjoyable work, and I
> now have
> - a much better understanding of the Polysix in general
> - a much better understanding of all the mods and changes involved
> - a great-sounding and great-working polysynth!
>
> Photos of the results are in the Yahoo group photo section, under
> "Polysix Modifications".
>
>
> All the best,
>
> Terje
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo Groups Links
>
>
>

This is my dream repair and mod job! Very impressive, Terje.

Instead, here's what I have:

1. Part of the repair was ok: managed to remove the old battery, clean up the board, do a lot of point-to-point testing and most of the power calibration (cool!), I still get stuck on the part using Tape as only LEDs 1-4 will light up, and not 7-8 despite turning the required trimmers.

My MG and Cutoff/Resonance/Envelopes are still not working...

Unfortunately, these:

2. Contacted Old Crow for his board cloning service - No reply...

3. Ordered parts for a clone from Newark Canada, but some are still on back-order, so my parts set is incomplete.

4. Ordered the PCB for KLM-367 from Jed, but Canadian Post 'delivered' it to some poor soul residing in my neighbourhood (I don't know who), and who wasn't taken enough with the spirit of Christmas to bring the package to its rightful owner. Jed has been very cool about it so I may still get another one from him (many thanks, Jed).

5. With all the ICs I ordered new, effected replacement and testing, still no luck with MG,Cutoff/Res/Envelope.

Yash

This is my dream repair and mod job! Very impressive, Terje.

Thanks!

My feedback after repairing lots of Polysix´es, and cleaning up many processor boards with battery leakage problems, many of them with similar problems like yours, all I can say is this:

Get yourself a Kiwisix processor upgrade. It really is worth it. Very easy to install, and all your problems is history.

Terje Winther

terje.winther@wintherstormer.no

http://wintherstormer.no/

On 30 Dec 2013, at 11:49, Terje Winther <terje.winther@wintherstormer.no> wrote:

> this sounds really awesome. Do you have any pictures and/or sounds you
>> could share with us?
>
> Yes, I took some photos that I uploaded into the Yahoo-groups website. You can get there from clicking at some link at the bottom of all list mails.
> It is in a foler called "Polysix modification".
> I didn´t understand that the upload took so long, so I thought something had gone wrong and uploaded the photos a second time, so now they are all in doubles. I tried to erase the dublicates, but that didn´t work, so I left it as it is.
> I thought about writing some describtions/text on the photos, but I guess it is all self-explanatory.

When you upload photo’s, they have to be approved by the moderator (me), so that’s why there was a delay. I’ll take care of the duplicates, no worries. Thanks for the great pictures!

Ben

Forgot to mention that Andrew Jury (SynthProf) still offered his service for making a new board, which is very cool.

Yash

Terje,

I was wondering about the Jürgen Haible mod for VCO-to-VCF. Do you have a link to the description or some instructions or schematics, please?

Yash

Thanks a lot Terje.

Looks like it's not a trivial mod, which is expected for a Polyphonic analog.

• Midi in + Midi out
• Sustain Pedal input
• Additional play modes: 2 Voice, 3 Voice, Polychord, extended unison mode
• New arpeggiator / sequencer mode: Powerarp
• All functions are easily accessible via buttons: suitable for live use
• Midi controls arpeggiator clock, triggers the arp, filter and more
• Midi output of arpeggiator, chords and powerarp sequences or simple keypresses
• S/H style LFO for the filter
• Midi channels and various other options can be configured without external tools
• Very easy to install, no soldering required (except for one solder joint if you want midi controlled filter)
• High quality midi sockets and sustain pedal jack
• And more..

More infos here: http://tubbutec.de/modysix

Video here: https://www.youtube.com/watch?v=O11RHvP7YnI