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Polysix Rebuild

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Re: Polysix Rebuild

Postby nickle15 » Fri Apr 23, 2021 3:22 pm

jjlonbass wrote:Which microcontroller is missing? There are 2 - one, a 8049, is the "key assigner" and the other, a 8048, is the "programmer".
Both are mask programmed i.e. the software is hard-wired into the chip - there is no separate PROM. This means that you need the exact correct 8049 or 8048 part containing the correct software. Any old 8049 or 8048 won't work.
I suspect that these will be very difficult to find.

John

It's the 8049 that's missing. I was suspicious of how easy it was to find one - but now I know why. Again - your advice/direction is very helpful!
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Re: Polysix Rebuild

Postby rockydennis » Fri Apr 23, 2021 4:53 pm

nickle15 wrote:It's the 8049 that's missing. I was suspicious of how easy it was to find one - but now I know why. Again - your advice/direction is very helpful!

Taking a quick look online, I do see one site selling the 8049 for the Polysix for 30 Euros.

Here's a site with firmware code for various synths available for free, including the Polysix. I'm guessing the 8748 and 8749 which have eprom and are programmable, and are from the same family can be substituted for the 8048 and 8049 but don't quote me on that.
https://dbwbp.com/index.php/9-misc/37-synth-eprom-dumps

Here's someone replacing the 8049 for the Polysix with Arduino with the code made available.
http://synthhacker.blogspot.com/2013/03/polysix-replacing-8049-key-assigner.html
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Re: Polysix Rebuild

Postby nickle15 » Fri Apr 23, 2021 5:28 pm

rockydennis wrote:
nickle15 wrote:It's the 8049 that's missing. I was suspicious of how easy it was to find one - but now I know why. Again - your advice/direction is very helpful!

Taking a quick look online, I do see one site selling the 8049 for the Polysix for 30 Euros.

Here's a site with firmware code for various synths available for free, including the Polysix. I'm guessing the 8748 and 8749 which have eprom and are programmable, and are from the same family can be substituted for the 8048 and 8049 but don't quote me on that.
https://dbwbp.com/index.php/9-misc/37-synth-eprom-dumps

Here's someone replacing the 8049 for the Polysix with Arduino with the code made available.
http://synthhacker.blogspot.com/2013/03/polysix-replacing-8049-key-assigner.html

Excellent - thanks for adding this guidance!
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Re: Polysix Rebuild

Postby blinddrew » Fri Apr 23, 2021 6:49 pm

The level of expert knowledge that is freely given on this site never ceases to amaze me. :clap: :clap: :clap:
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Re: Polysix Rebuild

Postby nickle15 » Fri Apr 23, 2021 7:19 pm

blinddrew wrote:The level of expert knowledge that is freely given on this site never ceases to amaze me. :clap: :clap: :clap:

Amen! :thumbup:
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Re: Polysix Rebuild

Postby rockydennis » Fri Apr 23, 2021 7:50 pm

Maybe replacing the 8049 with Arduino is the way to go -
"As many of you know, I made some pretty substantial modifications to my Korg Polysix. One of the biggest changes was to replace the keybed to enable aftertouch. To make this happen, I had to replace the Polysix's Key Assigner with an Arduino. It was a lot of work, but once I made the core hardware modifications, I found that I was able to add lots of features to the Polysix, such as: aftertouch and portamento, more interesting detuning for unison mode, a poly-unison mode, a Moog-like single-trigger mode, and a sustain pedal. All of these modifications were effected through software changes on the Arduino."
http://synthhacker.blogspot.com/2014/03/polysix-sharing-my-arduino-code.html
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Re: Polysix Rebuild

Postby BJG145 » Fri Apr 23, 2021 8:29 pm

That's hardcore. Respect.
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Re: Polysix Rebuild

Postby Folderol » Fri Apr 23, 2021 8:59 pm

I'd like to know how the guy got hold of a Fatar poly aftertouch keybed.
Oh, and did he have to remortgage the house.
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Re: Polysix Rebuild

Postby The Elf » Sat Apr 24, 2021 10:36 am

Folderol wrote:I'd like to know how the guy got hold of a Fatar poly aftertouch keybed.
Oh, and did he have to remortgage the house.
I've often been told that they don't do one!
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Re: Polysix Rebuild

Postby Hugh Robjohns » Sat Apr 24, 2021 10:43 am

They certainly don't have one listed in their current line up.

They make plenty of keybeds with monophonic (channel) aftertouch, though -- and that's what the Arduino guy used to provide channel aftertouch in his Polysix, basically replicating the mod wheel functions from the keyboard pressure.
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Re: Polysix Rebuild

Postby Folderol » Sat Apr 24, 2021 1:29 pm

I pretty much thought that was the case, but had half a hope I might have been looking in the wrong place.
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Re: Polysix Rebuild

Postby BJG145 » Sat Jun 12, 2021 9:21 pm

How's the jigsaw? I found one of these; untested, but can pop it in an envelope if you want to try it.

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Re: Polysix Rebuild

Postby nickle15 » Sat Jun 12, 2021 9:44 pm

BJG145 wrote:How's the jigsaw? I found one of these; untested, but can pop it in an envelope if you want to try it.

Image

That's very generous of you! Right now we're still stuck looking for a transformer. Not much else we can do until we solve that.

I would be very happy to try out the chip but would also like to pay you a fair price for it. Also, I'm in the US (not sure where you're at) so shipping might be an adventure! :D

PM is welcome if you want to continue the conversation. Thanks for checking in!
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Re: Polysix Rebuild

Postby ajay_m » Mon Jun 14, 2021 10:15 pm

Assuming this is a standard linear power supply with a normal E-I laminated core transformer then there are plenty of options. You need to know the secondary voltage or voltages and the VA rating eg 50VA or whatever and then you can probably get an off the shelf replacement. Quite a lot of transformer manufacturers can also make custom voltages. Another option is to find an external PSU with the right DC voltage and just wire that in instead. Since you're rebuilding the case anyway it doesn't much matter if you do that instead.
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Re: Polysix Rebuild

Postby BJG145 » Tue Jun 15, 2021 8:34 am

nickle15 wrote:Right now we're still stuck looking for a transformer. Not much else we can do until we solve that.

There's one on eBay currently; they might accept an offer.
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