Discussion about the Korg PolySix synthesizer

I finally had the chance to start taking apart my PolySix. It needs
a good cleaning on the inside, and I find a 4 of Diamonds playing
card underneath one of the PC boards.

The KLM-367 board has prior to been worked on. Underneath there are
some wires patched into IC-31. I don't think whomever did the work
cleaned the PC board too well as a lot of the solder points on the
top of the board in the area above the battery all the way up to the
connectors suffer from corrosion. This board is beyond my ability to
repair; I am neither knowledgable enough or disciplined enough to do
it. I would consider myself an artist who can maintain his gear
rather than a technician with an affinity for music and/or
synthesizers.

Many questions have I:

Should the pitch bend wheel have springs? I noticed it wasn't
springing back when I first got it, but I didn't think much of it
figuring the springs were unhooked or stretched or something. If it
should have springs, can anyone recommend a replacement? If it came
from the factory spring-less, has anyone tried adding springs?

I'm far from wealthy, I'm hardly even middle class, so my resources
are rather limited. I want the PolySix to come alive, however once
it's alive I want to be as certain as possible I won't have to invest
more money into it for many years. The question is, will replacing
KLM-367 fix the other significant problems it has: waveform selector
not working, the two patch buttons and two program buttons always
staying lit?

I'm not asking anyone to make decisions for me here, it would simply
be very helpful to have some insight on the KLM-367 matter so I know
where I'm at. To be quite honest, I'm now trying to decide whether I
invest money in it now, or cut my losses and sell it as is (and,
unfortunately, another synth) and get something more reliable like a
Juno. For what I'm doing musically, I need the knobs (or sliders).

So, please, any thoughts would be helpful.

Hi there.

The only things i can add to your post are, 1) the Polysix pitch bend
wheel never did have springs (at least, mine didn't) so I just took an
elastic band and wrapped it around the wheel. This works suprisingly
well. And, 2) my Polysix also suffered from the two-LEDs-on problem,
and I was advised that it is a possible bad programmer IC. So I was
forced to cannibalize my machine, and that's the end of that era. I'm
trying to use what boards remain to build other units, which is an
evolving process. Sorry I couldn't be more helpful.

T. Cardinal

Thanks. That's interesting about the pitch bend wheel. I think I'll
figure out a way to attach springs as rubber bands tend to degrade
quickly. I wonder why it wasn't spring loaded from the factory.

Are there trace maps available anywhere? I was looking at Old Crow's
site again and saved some of the shots of the trace maps he uses in
his guide to fixing the battery damage. I already noted an error in
the prior repair done to mine and a few traces that need repair but
weren't. I think I can get by with the shots from Old Crow's, but a
complete map would be handy.

Questions: here's my inexperience showing through, but, where the
traces switch from top to bottom (or bottom to top, as it were), a
lot of those solder points had corrosion on the top of the board.
Now, what I did was first clean the board with alchohol, then I
slapped some baking soda paste on that section of the board, let it
sit, then scrubbed (lightly) to clean it up and neutralize any
remaining acid. Most of those solder points clean up well, but I'm
wondering if I need to drop some fresh stuff in those holes, or if I
can just reflow them? Would I do either from the top or bottom of
the board?

What functions do ICs 30 and 31 handle? Are either of these
the "programmer IC?"

The legs on both are definately in tact; they seemed to have survived
the acid bath fine (I think IC 31 was replaced because it looks
more "fresh" than the other ICs and a trace was removed from
underneath it), so there's no reason to remove them, yes?

Yeah, so, I was despondent last night, and I'm still pissed, but I'm
not giving up yet while the thing sits in my house.

--- In PolySix@yahoogroups.com, "trekpilot" <trekpilot@y...> wrote:
> Hi there.
>
> The only things i can add to your post are, 1) the Polysix pitch
bend
> wheel never did have springs (at least, mine didn't) so I just took
an
> elastic band and wrapped it around the wheel. This works
suprisingly
> well. And, 2) my Polysix also suffered from the two-LEDs-on
problem,
> and I was advised that it is a possible bad programmer IC. So I was
> forced to cannibalize my machine, and that's the end of that era.
I'm
> trying to use what boards remain to build other units, which is an
> evolving process. Sorry I couldn't be more helpful.
>
> T. Cardinal

On Mon, 24 Nov 2003, toorglick wrote:

> Are there trace maps available anywhere? I was looking at Old Crow's
> site again and saved some of the shots of the trace maps he uses in his
> guide to fixing the battery damage. I already noted an error in the
> prior repair done to mine and a few traces that need repair but weren't.
> I think I can get by with the shots from Old Crow's, but a complete map
> would be handy.

The trace diagram is in the service manual. It does not copy well
unless you use a good greyscaling copier. The parts of it I show I did
just by photographing the page.

> Questions: here's my inexperience showing through, but, where the
> traces switch from top to bottom (or bottom to top, as it were), a lot
> of those solder points had corrosion on the top of the board. Now, what
> I did was first clean the board with alchohol, then I slapped some
> baking soda paste on that section of the board, let it sit, then
> scrubbed (lightly) to clean it up and neutralize any remaining acid.
> Most of those solder points clean up well, but I'm wondering if I need
> to drop some fresh stuff in those holes, or if I can just reflow them?
> Would I do either from the top or bottom of the board?

Check to see if they conduct first. If they do, don't add any more
solder. If they don't, you will want to solder in a small piece of wire
to close the circuit.

> What functions do ICs 30 and 31 handle? Are either of these
> the "programmer IC?"

Those chips are just bus drivers so that signals can be sent a few feet
(to the front panel) without overloading the CPU. The "programmer IC" is
IC22, a microcontroller that is pre-programmed to operate the KLM-367 as a
patch manager.

If someone has a broken IC22 I can program a new one for cheap.

> The legs on both are definately in tact; they seemed to have survived
> the acid bath fine (I think IC 31 was replaced because it looks more
> "fresh" than the other ICs and a trace was removed from underneath it),
> so there's no reason to remove them, yes?

Shouldn't be, as long as there are no missing connections/traces.

Crow
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