Discussion about the Korg PolySix synthesizer

That board doesn't look too bad at all. Most look much worse after a battery
leak. Unfortunately that means there is no easy way to point to the problem
without some long and tedious debugging. You will need a digital multimeter,
not just something that goes "beep", and you will need the schematics. It
sounds like a problem on the D0-D7 data bus coming off of IC30 and IC31 and
you will need to check those traces again and actually measure the
resistance. Any trace more than 0.5 ohms should probably be fixed. The data
bus connects many chips together and you will need to check between each
chip, which is why you will need the schematics to see which pins on which
chips should be connected. As mentioned by Andy Jury in several old posts, a
good way to do this is to check continuity from connector CN10 to each of
these chips: IC 30, 31, 26, 24, 33, 28, 29, 34, 35 and CN06 on each of the
eight bus lines. Like I said, tedious.

You will have to watch out for the mislabeled chip in the diagram. There are
two IC 34 in the diagram. The one beside IC 30 is actually IC 24.

 

Don Backshall

 

  _____  

From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
traxus12
Sent: Wednesday, August 07, 2013 5:02 AM
To: PolySix@yahoogroups.com
Subject: [PolySix] Re: Help! Repairing a Polysix with burst battery (sound
demo + photos!)

 

  

Sorry, some of my formatting didn't make it through to the final post. I
meant to include these. 

sound demo:
https://soundcloud.com/ocguitar/korg-polysix-death-sounds

Bank D and Program 4 constantly illuminated:
http://imgur.com/TFEPUPB

Thank you! Any advice would be appreciated.
-Steve

--- In PolySix@yahoogroups.com <mailto:PolySix%40yahoogroups.com> ,
"traxus12" <ocguitar@...> wrote:
>
> Hello! I picked up a Korg Polysix recently and I've been trying to bring
> it back to life. Nothing I've done has changed anything yet so I'm at a
> bit of an impasse and I'm hoping someone out there might be able to help
> me narrow down what I should do next. I know how to use a soldering iron
> but I'm a complete beginner at repairing circuit board traces.
> 
> Let me give you the symptoms.
> 
> 1. It sounds like it's gone absolutely mental with constant oscillation
> and other insanity going on from the moment I power it up.
> 2. The Bank D and Program 4 buttons are constantly illuminated after
> powering up.
> 
> After cleaning up most of the corrosion I could find around the battery,
> it really didn't look as bad as I thought it might so I went ahead and
> just installed a Lithium battery holder (using Old Crow's guide) and
> tried powering up again. Nothing changed.
> 
> After that, I went back in and removed the IC31 chip (74LS08) and tested
> all the traces in the area with a multimeter. Every trace I tested gave
> me a happy little beep, even the uglier looking ones that were near the
> old battery, so I went ahead and soldered in a new socket and 74LS08
> chip at IC31. Powered up. Nothing changed.
> 
> Now, I'm not sure what to do. Did I miss a trace? Should I put jumper
> wires on the ugly looking traces even if my multimeter says they're
> conducting just fine? Should I replace the other ICs that were near the
> battery like IC30 even if they look fine?
> 
> I recorded a sound demo. For the first 40 seconds I don't touch a thing,
> then I start to experiment:
> 
> 
> Bank D and Program 4 constantly illuminated:
> 
> 
> First sight:
> <http://imgur.com/Wv173WQ>
> 
> After initial cleanup:
> <http://imgur.com/M8POlkz>
> 
> Installed battery:
> <http://imgur.com/Pj3kDFT>
> 
> Replaced IC31:
> <http://imgur.com/Nab9GYz>
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>





[Non-text portions of this message have been removed]