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Polysix Rebuild

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Polysix Rebuild

PostPosted: Wed Jan 13, 2021 7:29 pm
by nickle15
I've purchased a Korg Polysix (or I should say, a Korg Polysix pile of components) that needs lots of love (and a case) for my dad and me to rebuild. Dad is an electrical engineer and I play music so it should be a fun joint effort! Anyway, it arrived last night and I unboxed all of the carefully packaged parts and will be moving the project to dad's place in the next several days. There are a couple of preliminary questions I have that I thought might find the answers for here. And they're not Polysix specific, necessarily. So, for anyone who has repaired or rebuilt a keyboard here they are:

1. I have the metal body panel which is where the controls come through, knobs and buttons and the like. I have the keybed and then I have mostly all the internal components. What I don't have is the rest of the case - so no bottom or sides, or front lip. Would that need to be in place prior to doing much of the other work? I know the keybed bolts onto it but wasn't sure about the rest of the components.

2. One of the keys has a big chunk broken out of it, and a couple others are cracked. I'd really like to get new keys all the way up and down, but I'm not sure how to do a search for keys that are new stock but that would be the right fit for the Polysix. Any tips?

I will certainly try not to be an annoyance with questions here but you guys are always so great at sharing pertinent info and I feel a little spoiled! I'll try to keep this thread updated with our progress. It's certainly exciting!

Re: Polysix Rebuild

PostPosted: Wed Jan 13, 2021 8:33 pm
by BJG145
Any photos? How did it end up in bits? I wouldn't worry about chipped keys. The main problem with these used to be circuitboard damage from battery leaks. I'm intrigued to know what your pile of pieces looks like and how it got into that state. Sounds like a pretty difficult project TBH. Looks like there's a couple of case options on eBay unless you'd rather build your own, though you'd want to make sure it's going to make noises first...

https://www.ebay.co.uk/itm/Korg-Polysix ... SwmY9fNxL4

https://www.ebay.co.uk/itm/Korg-Polysix ... Sw8ilf~0Yb

There's a couple of places selling replacement keys.

https://www.ebay.co.uk/itm/Korg-PolySix ... xyUXVRCNVf

Re: Polysix Rebuild

PostPosted: Wed Jan 13, 2021 8:44 pm
by nickle15
I'll have some photos to share once we get it all completely unpacked and laid out. I only unwrapped the metal chassis and the keyboard. This may be one of those expensive lessons but we'll see. Dad seems fairly confident we can get it done. He got the manual and compared the schematics against what the seller had to determine what might need fixed and replaced.

I've found a few places here in the States to get a case, but just wondered if I could get the board up and running for testing purposes without the physical structure of a case. If so I wouldn't spend the money until I was sure everything was good with the functionality. Thanks for your reply!

Re: Polysix Rebuild

PostPosted: Wed Jan 13, 2021 8:48 pm
by BJG145
nickle15 wrote:I'll have some photos to share once we get it all completely unpacked and laid out. I only unwrapped the metal chassis and the keyboard. This may be one of those expensive lessons but we'll see. Dad seems fairly confident we can get it done. He got the manual and compared the schematics against what the seller had to determine what might need fixed and replaced.

I've found a few places here in the States to get a case, but just wondered if I could get the board up and running for testing purposes without the physical structure of a case. If so I wouldn't spend the money until I was sure everything was good with the functionality. Thanks for your reply!

Well, good luck with it, I'm sure a few here will be interested to watch progress and chip in ideas. I've got a bit of a soft spot for these; bought a damaged one once which made some...interesting sounds...but I couldn't get it working properly. Sounds like your dad has skills here though. I definitely wouldn't be buying a case until I'd got the electronics working to some extent. I'm sure you could just rig something up on a workbench temporarily.

Re: Polysix Rebuild

PostPosted: Wed Jan 13, 2021 8:50 pm
by nickle15
BJG145 wrote:
nickle15 wrote:I'll have some photos to share once we get it all completely unpacked and laid out. I only unwrapped the metal chassis and the keyboard. This may be one of those expensive lessons but we'll see. Dad seems fairly confident we can get it done. He got the manual and compared the schematics against what the seller had to determine what might need fixed and replaced.

I've found a few places here in the States to get a case, but just wondered if I could get the board up and running for testing purposes without the physical structure of a case. If so I wouldn't spend the money until I was sure everything was good with the functionality. Thanks for your reply!

Well, good luck with it, I'm sure a few here will be interested to watch progress and chip in ideas. I've got a big of a soft spot for these; bought a damaged one once which made some...interesting sounds...but I couldn't get it working properly. Sounds like your dad has skills here though.

Thanks! I'll be sure to post our progress.

Re: Polysix Rebuild

PostPosted: Wed Jan 13, 2021 10:11 pm
by nathanscribe
As above, the keys you will be able to find online and the case can be found custom made. The main problem with the Polysix will be battery leakage, they cause havoc and can lead to very heavy corrosion on traces and damage components. You can get replacement boards though, they're being made new by more than one 3rd party. Aside from that, some of the parts will be difficult and/or expensive to source if they've failed, not least the SSM ICs, but there are ways around that too.

Good luck, and keep us posted!

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 9:43 am
by The Elf
Any idea why it is in bits? To me that strongly smacks of being donor parts, and the parts left behind are typically the ones that were found not to work...

Not trying to rain on your garden party, but just worth being realistic.

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 11:20 am
by Folderol
Hmmm, maybe, but then there are times when one can take great delight in restoring 'unrepairable' kit to pristine condition.

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 2:27 pm
by The Elf
Folderol wrote:Hmmm, maybe, but then there are times when one can take great delight in restoring 'unrepairable' kit to pristine condition.
Agreed, but when donor work has been going on it could be that a number of obscure components on numerous different parts have failed - and no guarantee they can be sourced.

As I say, I don't want to be the Eeyore here, but you do have to be realistic.

If you can get it working, all power to you, mate! :clap:

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 2:46 pm
by nickle15
Well now I feel like I bit off more than I could chew! As I mentioned above this could just be a very expensive lesson for me. We'll find out soon enough.

And just to show my lack of experience (I might get kicked out of the forum for this) it never occurred to me to ask how the keyboard got that way. Just never once crossed my mind. I'm sending an inquiry to the seller now just for my own satisfaction but obviously who knows what kind of answer I'll get if any.

Thanks to all for chiming in.

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 4:56 pm
by Tomás Mulcahy
It all depends on attention to detail I think. Here's a seemingly impossible project on a very broken bit of kit. And it is now working.

https://www.gearslutz.com/board/electro ... ation.html

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 6:19 pm
by BJG145
I think as long as you blog it here with lots of pics and details, it's well worth the money. :D

(And they're smashing keyboards when they work.)

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 6:21 pm
by BigRedX
Tomás Mulcahy wrote:It all depends on attention to detail I think. Here's a seemingly impossible project on a very broken bit of kit. And it is now working.

https://www.gearslutz.com/board/electro ... ation.html

And progressing a lot faster than the bloke with the Jupiter 8.

Re: Polysix Rebuild

PostPosted: Thu Jan 14, 2021 6:43 pm
by Sam Spoons
That guy is brilliant :clap: :clap: :clap:

Re: Polysix Rebuild

PostPosted: Fri Jan 15, 2021 4:21 am
by nickle15
FWIW the seller responded to me. He said he picked the keyboard up at a small local music store basically as a salvage project. The story he got was that it was left out at a gig and got backed over. He said he had several projects going on and that he just finally decided he would probably never get to repairing it. Then mentioned "the damaged board can be found, new, on the internet". So if I take him at his word it sounds like there is some hope here. Anyway, I wanted to fill you all in.