Broken PolySix

[Sean Costello]

Andrew Puls Q-Bot Eye wrote:

> My point in telling you all this is that this thing is $80 and I was
> wondering if it seems worthwhile to pick it up to try to fix it. (Are
> the parts for this synth available, is it a simple problem, what kind
> of problem do you suppose it is, etc... If it is not a simple problem,
> how cheaply could I have someone else fix it?)

The vast majority of Polysix problems out there can be traced to battery
damage on the CPU board - Korg mounted the program backup battery right
next to the CPU, and the battery has a nasty tendancy of exploding,
dripping acid all over the board and eating the traces.  It isn't an
easy problem to fix, and you will have a hell of a time finding a new
CPU board, as so many Polysixes out there have this problem.

However, if you are interested in building your own modular, then the
Polysix has got some nice parts for the taking:

- (6) SSM 2044 filter chips - a nice sounding filter, much warmer than
the CEM 3320.  4-pole lowpass w/VC resonance.
- (6) SSM 2056 ENV chips - a nice voltage-controlled envelope generator
chip. 
- A really nice chorus/ensemble board, good for running external signals
through to get that string ensemble-type sound.

The oscillators are some weird discrete linear design, so no good
scavengability there.  Still, the above parts, assuming they all work,
are definitely worth 80 bucks (heck, I paid $19 each for the 2044 chips
I needed to repair my Polysix).  Buy it, take what you want from it, and
sell the remaining working parts on the Internet for people trying to
repair their Polysixes (I bought a keyboard for mine from someone who
was doing this - believe me, there are people out there who will
appreciate your doing such a thing).


Sean Costello  

P.S.  Schematics for DIY applications of the 2044 and 2056 can be found
in Barry Klein's book.