The No.1 Website for Pro Audio
 All  This Thread  Reviews  Gear Database  Synths for sale     Latest  Trending
Korg Poly 61 Repair advice/parts
Old 22nd July 2017
  #1
Here for the gear
 

Korg Poly 61 Repair advice/parts

Hello,

Recently picked up a Korg Poly 61 project that apparently "doesn't work". Before I turn it on and possibly make anything worse (just to check how broken it is), I'm going through it looking for corrosion, bad previous repairs, missing parts, etc.

.... And I certainly found stuff :p

Current theory is that the battery went, PO replaced the entire main board and tried to "upgrade" the battery to a more modern one and did it wrong (I don't see any diodes).

First though, I want to get all the parts that are missing. I've googled and found some of them, but not everything yet. I figured I'd post here in case someone knows a good place to find them, or has some around.

The A key with spring (on ebay not too tricky)
Pot for the pitch wheel (I can't find this in stock anywhere)
Knob for the joystick (Around and I don't need to replace this now)
Original Korg knobs (I'm sure they are around, and I don't need to do this now)

It's mainly about the pitch wheel/joystick thingy potentiometer. Anyone have any advice? I'd just replace it with something similar but it is not a standard pot I've seen anywhere (4 post with spring).

Thanks! I hope I posted this in the right place, I really like how the forum auto searches for you to see if there's similar threads.

Nik
Old 24th July 2017
  #2
Here for the gear
 

UPDATE:

Looks like I found everything but the OEM knobs. Just got lucky on foreign ebay. Looks like I'll possibly end up with an extra joystick pot, in case someone is needing one in the future.
Old 8th June 2018
  #3
re: Poly 61

I have had a few Korgs now a DW6000 and the Poly 800. I have lusted after the Korg Polysix for a long time. I recently was checking out Craigslist here in Vancouver saw a Poly 61 for sale. It had some issues but I thought I would risk it.

It had the common problem of battery leak and a few keys didn't work. The joystick was not working properly as well.

After pulling out the main board. --I labelled and photographed all connections.
You have to take off the keyboard first.-- I did lots of qtip cleaning with solvent and then tested the trace. I pulled a few resistors where it was the worst and resoldered them in. Aside from looking horrible the trace was still good copper underneath.

I took the keyboard apart and everything looked ok no wear or anything but a few keys were not making good contact still.

The joystick problem turned out to be that the cable pinches against the metal lid. I rerouted the cable and plugged the cable in tightly and it was functioning again.

I had the exact battery from two I got on ebay that were the right spec NiMH to replace the old NiCad one.

When these synths go bad sometimes all the presets get messed up. They have a tape feature so you can factory reset the presets. You find the file online then pipe the audio file from your PC etc. into the back of the Korg "from tape" make sure tape and write are enabled.

Now I had all the original presets back in memory. New battery was saving my changes too.

Now all capacitors were replaced. I have a desoldering station so it made the job much less painful.

I did all the caps in the mainboard first where the battery was, then the power board, then the tuning board and voice board.

Two large 100uf capacitors on the bottom of the power board had to be put on solid core wire leads to fit under the keyboard.

I tuned it with a digital tuning app on my Android phone. Then I did my best to set the VCO, filter resolution pots etc.

Finally after putting it all back together I repeatedly pressed the sick keys and they started to respond again.

It sounds great now like a new machine.

I will make a video and post it hopefully if I have the time.

It is a true joy bringing one of these back to life.
Old 13th November 2018
  #4
Here for the gear
 

Power board

Hey does anyone know where to get a replacement/ substitute for this box capacitor in the power board?
Attached Thumbnails
Korg Poly 61 Repair advice/parts-cd77e924-d845-46e8-8826-db2e91836fc3.jpg   Korg Poly 61 Repair advice/parts-4c00bde7-6b54-4bec-95cb-6d8fdcacc7c4.jpg  
Old 1st January 2019
  #5
Here for the gear
 

I can't help Caspar John, but I should update my original post.

I found the missing pieces on eBay.
The battery corrosion effected the connector pins between the boards and I had to replace a ton of them (even further away from the battery than I had expected).
Traces needed to be re done.
The anti-Log board needed tuning.
Old 13th June 2019
  #6
Here for the gear
Hi Bujbot, I have been reading your repair-story with great enthusiasm :-)
I too have bought a old korg poly 61 which have previously been fixed after a leaked battery. I guess the molex/jst pin next to the battery (12 pins) got damaged because the PO (previous owner) fixed it by soldering the wires straight onto the pins in the PCB. So before I can do any fixing of the synth I need to establish a new molex/jst connection...
And know finally the question:
Would you know which molex/jst connectors to buy? Preferably both male and female parts...
Thank you very much!
Peter
Old 4 weeks ago
  #7
Here for the gear
 

Quote:
Originally Posted by PeterBH View Post
Hi Bujbot, I have been reading your repair-story with great enthusiasm :-)
I too have bought a old korg poly 61 which have previously been fixed after a leaked battery. I guess the molex/jst pin next to the battery (12 pins) got damaged because the PO (previous owner) fixed it by soldering the wires straight onto the pins in the PCB. So before I can do any fixing of the synth I need to establish a new molex/jst connection...
And know finally the question:
Would you know which molex/jst connectors to buy? Preferably both male and female parts...
Thank you very much!
Peter
Hi Peter,

Sorry, I don't know them offhand. It's the same as any of the other connectors on the board. I just took one of those to the local electronic parts shop and walked around until I found the right ones. If I find the old bag of them I'll let you know.
Old 4 weeks ago
  #8
Here for the gear
Quote:
Originally Posted by bujbot View Post
Hi Peter,

Sorry, I don't know them offhand. It's the same as any of the other connectors on the board. I just took one of those to the local electronic parts shop and walked around until I found the right ones. If I find the old bag of them I'll let you know.
Hi Bujbot, thanks but don't spend your time on that as managed to find some and now have a functioning poly 61
Actually the thing that got it working was cleaning and replacing crimps in connectors and the flexi-connector between the boards. Though I also changed an op-amp ic and a capaciter that was placed in wrong direction!
But thanks for getting back to me!
Have you installed midi in yours or done any upgrades that you can recommend?
Best regards
Peter
Old 4 weeks ago
  #9
Here for the gear
 

Quote:
Originally Posted by PeterBH View Post
Hi Bujbot, thanks but don't spend your time on that as managed to find some and now have a functioning poly 61
Actually the thing that got it working was cleaning and replacing crimps in connectors and the flexi-connector between the boards. Though I also changed an op-amp ic and a capaciter that was placed in wrong direction!
But thanks for getting back to me!
Have you installed midi in yours or done any upgrades that you can recommend?
Best regards
Peter
Just remember to play it :p

I haven' done any mods myself.
Old 4 weeks ago
  #10
Here for the gear
Quote:
Originally Posted by bujbot View Post
Just remember to play it :p
So true! :-)
Old 4 weeks ago
  #11
Lives for gear
 
Rob Ocelot's Avatar
Best Poly-61 mod I ever did was was removing the vertical joystick spring so you can keep a permanent modulation.
Old 6 days ago
  #12
Here for the gear
 
Signman's Avatar
Quote:
Originally Posted by Rob Ocelot View Post
Best Poly-61 mod I ever did was was removing the vertical joystick spring so you can keep a permanent modulation.

Might have me some of that Rob
Old 6 days ago
  #13
Lives for gear
 
usedtohaveajuno's Avatar
Now mines is functionally working again, I must try and figure out why the keyboard doesn’t work - thank god for the factory midi kit

Oh plus I need to tune it and calibrate the filters
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump