Korg Poly 61 help locating broken DCO2

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ioth_
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Posts: 7
Joined: Tue Apr 30, 2019 2:12 am

Korg Poly 61 help locating broken DCO2

Post by ioth_ » Mon May 13, 2019 1:39 am

Hey people, so i'm restoring a poly 61 right now, and nearly fixed everything apart from one issue:
On voice six the DCO2 isn't working properly. on some patches it doesn't sound at all, in others it makes weird clicky low-freq noises. All other dco's work fine, so it has to be an error on that specific voice.
I've read the service manual, but I'm not good at reading schematics, so I could use some help :)
I already cleaned the boards, and looked over all components, but couldn't really figure out what part of the voice board is responsible for the dco2.
heres an image: (not my board, don't have a hi resolution cam atm)
http://studiorepair.com/gallery/Korg/Po ... 48705.html
One of my thoughts was, that it maybe doesn't get the clock form the master osc, but again, I don't know where to check. :roll:
Also at the momentI don't have a oscilloscope (i know that makes things way harder), but I hope I can somehow fix it anway.
Any help is appreciated. Cheers!

btw, if it helps, here is the service manual:
https://www.vintagesynthparts.com/wp-co ... Manual.pdf

crafter57
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Re: Korg Poly 61 help locating broken DCO2

Post by crafter57 » Mon May 13, 2019 5:49 am

Hi, you really need an oscilloscope to check if the pulse is arriving at DCO2. You have to check IC14 8253 pin13 output,(SIG6(2)) this signal of 266Hz will feed both IC103 & IC105, but this signal also goes thru CN11 connector pin5 if we follow convention, or maybe it's pin2?..the schematic is a little hard to read. Since you don't have a scope, only thing you can check are those connections on CN11 and tighten them up, the connector may be tight but perhaps the pin is loose, rusted or dirty. good luck!

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