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Polysix mod questions
MUFF WIGGLER Forum Index -> Tubbutec  
Author Polysix mod questions
KurtisLugo
Greetings,

first of all, these upgrades seem awesome! I just joined in here and am now getting into all of this. I'm going to acquire+mod a Polysix sometime during 2016 - a dream of mine for years.

As I'm looking to upgrade to ModyPoly and/or Polysex, am I right to assume I should be on the lookout for a Polysix without any other mods already installed (if it already had the KiwiSix installed for example, would it make installing these more complicated/impossible)?

Also, I want to find a Polysix which, of course, isn't already ruined by any battery leakage or such - but also has a long lifespan ahead of it, with all the major issues sorted out. On the KiwiTechnics' site, alongside the KiwiSix description, they state "we no longer trust the original power regulating circuitry in the Polysix" and offer a power upgrade alongside the KiwiSix.

Is something like this really needed or would I be fine with just finding a nice unit with just the battery replaced and then installing the Tubbutec mod(s)?

In a nutshell - I prefer what the Tubbutec products have to offer over the competitors and want to install them specifically (instead of the KiwiSix for example) and would like to know if installing them is enough (trying to keep the overall costs within reasonable limits..) or should I still be losing sleep over the power supply of this thing?
tubbutec
Quote:
As I'm looking to upgrade to ModyPoly and/or Polysex, am I right to assume I should be on the lookout for a Polysix without any other mods already installed (if it already had the KiwiSix installed for example, would it make installing these more complicated/impossible)?


The Polysex mod is compatible with the Kiwisix
From the FAQ:
Q: Is the Polysex mod compatible with the Kiwisix retrofit?
A: Yes, but it uses the effect section LFO (0.1-7Hz) instead of the PWM LFO and the MG LFO is a square instead of a triangle waveform. There are detailed installation instructions in the construction manual.

ModyPoly+Kiwisix is possible but would require further modification. You will also loose features, so I do not recommend it.
Any other midi retrofit can be removed and replaced by the ModyPoly

Quote:

On the KiwiTechnics' site, alongside the KiwiSix description, they state "we no longer trust the original power regulating circuitry in the Polysix" and offer a power upgrade alongside the KiwiSix.

Is something like this really needed or would I be fine with just finding a nice unit with just the battery replaced and then installing the Tubbutec mod(s)?


While I do not want to contradict the experience of the Kiwisix guys, I personally never encountered a Polysix with a bad power supply, or a Polysix damaged from over voltage. (And so far I had about 50 different Polysix on my work bench).
So to answer your question: No, I don't think something like this is really needed.
KurtisLugo
That's exactly the info I was looking for, thanks so much for the quick reply.
vintagesynthlab
I'd like to also add that as an experienced technician having worked on many Polysix synthesizers, the Tubbutec Modysix is very easy to install.

Also, I agree about the power supply board. I have never seen one that needed any sort of repair and I have been preparing these for near 20 years.

As for the mainboard (CPU board), many of them have the original PCB and are still in good working order. And many of them are still fixable... I have fixed several CPU mainboards and have never had one fail on me. Of course you will still find some CPU mainboards that are beyond repair.
KurtisLugo
Sounds perfect - I'm no expert myself, but I've got some experience here and there with effect pedal builds and such, so this should suit me very well.

Can't wait to get my hands on one of these. Thanks for the additional info.
KurtisLugo
vintagesynthlab wrote:

As for the mainboard (CPU board), many of them have the original PCB and are still in good working order. And many of them are still fixable... I have fixed several CPU mainboards and have never had one fail on me. Of course you will still find some CPU mainboards that are beyond repair.


Ok, I'm drifting slightly off-topic but I was wondering if you guys had a minute or two to shed some light on this.

I just managed to find and purchase a very nice, clean Polysix (to which I'm going to install the Tubbutec upgrade soon) - found a pretty good deal on it, too.

There had been no battery leakage to speak of but a previous owner (not the one I bought it from, but the one before him) had replaced the original Ni-Cd battery with another Ni-Cd battery - instead of, say, replacing it with a battery holder and a lithium battery (while disabling the recharging unit).

The owner guessed it "might be a good idea to maybe replace a new one, since it's already been ages since it was last replaced by the previous guy" but he didn't really know whether this is needed or not.

What do you reckon, is this something I should get out of the way first or is it safe to still keep the existing battery in there - as I don't really know whether the leakage issue arises because of that particular bad Varta-battery, or simply the fact that they chose to use a Ni-Cd battery instead of a lithium one.

I'm under the general impression these sorts of problems can happen more often with Ni-Cads but I'm not really sure, as I've never dealt with replacing batteries before. It's not really a problem for me to replace it with a new one, just don't want to do it unnecessarily, if it's not something that's actually needed.

Prior to purchasing, he had emailed me these pics of the guts:

Picture file

Picture file
KurtisLugo
KurtisLugo wrote:

What do you reckon, is this something I should...


Well, I ended up switching the battery. Upon closer inspection, the semi-old one didn't look too great, so just to be on the safe side, after removing the battery I cleaned the whole area with baking soda paste to neutralize any remains of the nasty stuff there might be and installed a battery holder and a lithium battery (+removed the charging stuff from the board).

The IC right next to the battery had a couple of legs that were not as shiny as the rest, so if anything should fail in the future that would probably be where I'd look first, but the whole rest of the chip and the traces underneath it all looked nice and clean, so I decided to just leave it alone.

Cleaned a few keyboard contacts and a scratchy pot while I was at it, looks super clean now, everything works perfectly and Tubbutec ModyPoly is currently on it's way (going to get Polysex later as well). Sorry for the off-topic bits. wink
KurtisLugo
Works great and installation was a breeze.

My favorite thing is polychord and powerarp combined - all in all, this is an unbelievable mod and great value for money.

Small tip: it would be cool if the manual stated which polarity sustain pedals this uses, it's easy to think 'oh I'll just get a Korg one to match' and well.. wink
tubbutec
Hi,

it was definitely the right decision to replace the battery, I even wrote a blog post about this a long time ago:
https://tubbutec.de/blog/the-importance-of-battery-change-in-korg-poly six-synths/

Thanks for the tip about the sustain pedal, will include it in the manual
KurtisLugo
Hey,

I figured I won't post this under a new topic because it's likely this doesn't have anything to do with the ModyPoly upgrade, but just in case, I wanted to check:

I recently got a problem with my ModyPoly-fitted Polysix. The first of the six voices started taking longer to auto-calibrate to correct pitch after startup (the other five voices are fine - and after warming up for 20 minutes the whole unit remains in perfect tune).

Could this have anything to do with ModyPoly key assigner chip / or do you have any idea what could be causing something like this for a single voice? After powering the synth on, the broken voice starts up very high (a couple of octaves or so) and then immediately starts steadily lowering towards the right pitch.

By observing the leds, I know exactly which voice it is - I checked with a multimeter that the close-by resistors for that voice give the same values as the other voices. I also tried swapping the filter/adsr -chips in question, from other voices, but this had no effect.
tubbutec
Quote:
Could this have anything to do with ModyPoly key assigner chip / or do you have any idea what could be causing something like this for a single voice? After powering the synth on, the broken voice starts up very high (a couple of octaves or so) and then immediately starts steadily lowering towards the right pitch.


I don't think this has anything to do with the ModyPoly as the voice assign timing is identical to the original CPU. ut just to be sure I recommend updating the ModyPoly to the latest firmware. See https://tubbutec.de/tubbutec-firmware-updater/
KurtisLugo
Quote:
I don't think this has anything to do with the ModyPoly as the voice assign timing is identical to the original CPU. ut just to be sure I recommend updating the ModyPoly to the latest firmware. See https://tubbutec.de/tubbutec-firmware-updater/


Cool, I gave it a shot - it didn't fix the issue but thank you anyway. Good to have the latest firmware.

I'll have to think about finding a repair guy somewhere close by (easier said than done though). The synth works perfectly after being warmed up, but it's still quite annoying knowing that something inside is a bit off.

After a very long time of being powered off (=several days to a week) it can take nearly 2 hours to get in tune after a cold start, while in normal conditions (=powered off through the night or for less than 24 hours) it gets in perfect tune within 10-15 minutes. Strange.

If anyone is reading this with experience of a similar issue with just a single voice, any insight would be much appreciated.
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